Forensic Toxicology 1 Full Review
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Questions and Answers

Which of the following is a preliminary/presumptive test used in forensic toxicology?

  • Liquid-liquid extraction
  • Solid phase extraction
  • Immunoassay (correct)
  • Thin Layer Chromatography

    • Which method is considered the 'gold standard' in drug confirmation?

  • Thin Layer Chromatography
  • Gas Chromatography
  • High Performance Liquid Chromatography
  • Mass Spectrometry (correct)

    • What can cause drug degradation?

  • Solid phase extraction
  • Intake into the lab
  • Liquid-liquid extraction
  • Exposure to heat or light (correct)

    • What is the purpose of liquid-liquid extraction in forensic toxicology?

    <p>To separate drug compounds from a sample</p> Signup and view all the answers

    What is the main principle behind immunoassay in forensic toxicology?

    <p>Detection of drug compounds using antibodies</p> Signup and view all the answers

    What type of spectroscopy is commonly used in forensic toxicology for drug analysis?

    <p>Infrared Spectrophotometry</p> Signup and view all the answers

    Discuss the process of processing an unknown sample in forensic toxicology, from intake into the lab through the final confirmatory analysis.

    <p>The process of processing an unknown sample in forensic toxicology involves several steps. First, the sample is received and logged in the laboratory, ensuring proper chain of custody. Then, the sample is prepared for analysis, which may include extraction, purification, and derivatization. Next, preliminary tests are conducted to determine the presence of drugs or other substances. These tests can include color tests, immunoassays, or thin layer chromatography. If the preliminary tests indicate the presence of drugs, confirmatory analysis is performed using more specific and sensitive techniques such as gas chromatography/mass spectrometry (GC/MS) or high performance liquid chromatography/mass spectrometry (HPLC/MS). The final confirmatory analysis provides a definitive identification and quantification of the drugs present in the sample.</p> Signup and view all the answers

    What can cause drug degradation? Why is this important?

    <p>Drug degradation can be caused by various factors such as exposure to light, heat, moisture, or chemical reactions. It is important to understand drug degradation because it can affect the stability, potency, and effectiveness of drugs. In forensic toxicology, drug degradation can also impact the accuracy and reliability of analytical results. Therefore, it is crucial to consider and control potential degradation factors during sample storage, handling, and analysis.</p> Signup and view all the answers

    What are preliminary/presumptive tests in toxicology? Provide different examples and explain how they work in detail.

    <p>Preliminary/presumptive tests in toxicology are initial tests used to detect the presence of drugs or other substances in a sample. These tests provide a preliminary indication of the presence of specific classes of drugs but do not provide definitive identification or quantification. Examples of preliminary tests include color tests, immunoassays, and thin layer chromatography. Color tests involve the use of reagents that react with specific drugs to produce characteristic color changes. Immunoassays utilize antibodies that bind to specific drugs, leading to the formation of a detectable signal. Thin layer chromatography separates the components of a sample based on their different affinities to a stationary phase and a mobile phase, allowing for visual identification of specific drugs.</p> Signup and view all the answers

    Explain the principles and working mechanisms of liquid-liquid extraction in forensic toxicology.

    <p>Liquid-liquid extraction is a sample preparation technique used in forensic toxicology to extract drugs or other compounds from a liquid sample into an organic solvent. It is based on the principle of partitioning, where the analyte of interest partitions between two immiscible liquid phases. The process involves adding the sample to an organic solvent and mixing them to allow for partitioning. After separation, the organic phase containing the analytes is collected for further analysis. The choice of organic solvent and extraction conditions, such as pH and temperature, can influence the efficiency and selectivity of the extraction process.</p> Signup and view all the answers

    Describe the process and working principle of solid phase extraction (SPE) in forensic toxicology.

    <p>Solid phase extraction (SPE) is a sample preparation technique used in forensic toxicology to extract drugs or other compounds from a liquid sample. It involves the use of a solid sorbent, such as a solid-phase cartridge or disk, to selectively retain the analytes of interest while allowing interfering substances to pass through. The process begins by conditioning the solid phase with a solvent to remove impurities. The sample is then applied to the solid phase, and the analytes are retained while the unwanted substances are washed away. Finally, the analytes are eluted from the solid phase using a solvent, and the eluate is collected for analysis. SPE is based on the principles of adsorption and desorption, where analytes are selectively adsorbed onto the solid phase based on their chemical properties.</p> Signup and view all the answers

    Explain the principles and working mechanism of gas chromatography (GC) and mass spectrometry (MS) in forensic toxicology. Why is GC/MS considered the 'gold standard' in drug confirmation?

    <p>Gas chromatography (GC) is a chromatographic technique used to separate and analyze volatile compounds in a sample. It involves the sample being vaporized and injected into a column packed with a stationary phase. The compounds in the sample then undergo partitioning between the stationary phase and a carrier gas, resulting in their separation based on their different affinities. Mass spectrometry (MS) is a technique used to identify and quantify compounds based on their mass-to-charge ratio. It involves the ionization of the separated compounds and the detection of their mass spectra. GC/MS is considered the 'gold standard' in drug confirmation because it combines the separation power of GC with the identification capability of MS. The GC separates the drugs in the sample based on their affinity to the stationary phase, and the MS provides specific identification of the separated compounds based on their mass spectra.</p> Signup and view all the answers

    Which of the following factors can catalyze drug degradation reactions?

    <p>All of the above</p> Signup and view all the answers

    Which type of drug is particularly susceptible to hydrolysis?

    <p>Drugs with an ester bond</p> Signup and view all the answers

    What is the temperature dependence of reaction rates revealed through?

    <p>Arrhenius' equation</p> Signup and view all the answers

    Which factor should be considered when making measurements during the examination of drug samples?

    <p>The accuracy and precision of the measuring device</p> Signup and view all the answers

    What is the recommended storage temperature for biological specimens prior to testing?

    <p>Refrigerated</p> Signup and view all the answers

    What is one of the biggest concerns in a forensic laboratory regarding sample analysis?

    <p>Sample contamination</p> Signup and view all the answers

    Which of the following factors can affect the stability of a drug?

    <p>All of the above</p> Signup and view all the answers

    What can be added to pharmaceutical preparations to prevent degradation of drugs?

    <p>All of the above</p> Signup and view all the answers

    Which type of sample container composition should be considered to prevent interference with drug detection?

    <p>Teflon stoppers/caps</p> Signup and view all the answers

    Which of the following is NOT a factor that should be recorded when acquiring seized drug samples for testing?

    <p>WeighWolume/Amount</p> Signup and view all the answers

    What is the purpose of assessing all associated specimen documents when samples are submitted to a forensic laboratory for testing?

    <p>To verify the authenticity and integrity of the samples</p> Signup and view all the answers

    What is the responsibility of the forensic laboratory in relation to the storage of submitted samples?

    <p>To store the samples in a secure manner</p> Signup and view all the answers

    According to the text, what is the purpose of stability testing in the context of drug substances or drug products?

    <p>To establish a retest period or shelf life for the drug</p> Signup and view all the answers

    According to the text, what are three factors that can influence the stability of a drug?

    <p>Temperature, humidity, and light</p> Signup and view all the answers

    According to the text, what are three forms of drug contamination that can occur in a laboratory environment?

    <p>Contamination with impurities, degradation products, and adulterants</p> Signup and view all the answers

    Which of the following is a disadvantage of color tests for drug identification?

    <p>Color tests are not specific to a single drug</p> Signup and view all the answers

    Which of the following is an advantage of color tests for drug identification?

    <p>Color tests are quick</p> Signup and view all the answers

    What is the name of the color test used to screen for opiate drugs?

    <p>Scott test</p> Signup and view all the answers

    What color change would you expect with Ehrlich's reagent in the presence of LSD?

    <p>Purple</p> Signup and view all the answers

    Why are color tests considered to be preliminary tests and not confirmatory drug identification tests?

    <p>Color tests are not specific to a single drug</p> Signup and view all the answers

    Which of the following is NOT a type of trichome or hair that can be microscopically observed on the cannabis plant?

    <p>Stem hairs</p> Signup and view all the answers

    Which cellular structures of cannabis are specific to the flowering and fruiting tops of the plants?

    <p>Glandular hairs</p> Signup and view all the answers

    Which cellular features of cannabis do not contain cannabis oil?

    <p>Cystolithic hairs</p> Signup and view all the answers

    What is the purpose of the Duquenois-Levine color test in analyzing suspected cannabis samples?

    <p>To identify the presence of THC</p> Signup and view all the answers

    What are the three types of hairs or trichomes that can be microscopically observed on the cannabis plant?

    <p>Cystolithic hairs, glandular hairs, stem hairs</p> Signup and view all the answers

    What are the two chemical substances involved in microcrystal tests?

    <p>Substance tested and test reagent</p> Signup and view all the answers

    Which type of microcrystal test involves a color change or precipitate formation due to some change in the reagent caused by the test substance?

    <p>Indirect tests</p> Signup and view all the answers

    What is the purpose of microcrystal tests in forensic drug identification?

    <p>To identify the presence of compounds that contain basic nitrogen and readily precipitate from aqueous solution</p> Signup and view all the answers

    What is the most common type of reagent used in microcrystal tests?

    <p>Double chlorides</p> Signup and view all the answers

    What is the range of quantities needed for the identification of alkaloids using microcrystal tests?

    <p>1 µg to 100 µg</p> Signup and view all the answers

    What can cause supersaturation in microcrystal tests?

    <p>Evaporation of the solvent</p> Signup and view all the answers

    What is the advantage of using microcrystal tests for preliminary drug identification in forensic cases?

    <p>Directness, simplicity, sensitivity, and rapidity of the technique</p> Signup and view all the answers

    Which of the following is an advantage of microcrystal tests in forensic drug identification?

    <p>They are highly specific and sensitive</p> Signup and view all the answers

    What is the main difference between direct and indirect microcrystal testing?

    <p>Direct testing involves the use of a reagent, while indirect testing does not</p> Signup and view all the answers

    Which of the following is a disadvantage of microcrystal tests?

    <p>They are time-consuming</p> Signup and view all the answers

    Which of the following crystalloptic parameters can be used to identify or distinguish drug microcrystals?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of polarized light microscopy in microcrystal testing?

    <p>To identify specific compounds based on crystallographic features</p> Signup and view all the answers

    What can cause distortions in the crystal habit or form of microcrystals?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is NOT a requirement for microcrystal testing?

    <p>A reagent specific to the drug being tested</p> Signup and view all the answers

    What is one disadvantage of microcrystal tests in forensic drug identification?

    <p>They require a great deal of expertise and experience in microscopy</p> Signup and view all the answers

    Which of the following is true about the extraction of a drug or metabolite from interfering compounds?

    <p>It is achieved by extracting the analyte from an aqueous solution into an organic solvent.</p> Signup and view all the answers

    According to the Bronsted-Lowry Theory of Acids and Bases, which of the following is true?

    <p>A basic substance can only behave as a base in the presence of an acid.</p> Signup and view all the answers

    How are the relative strengths of acids and bases measured?

    <p>By the tendency to give up and accept protons.</p> Signup and view all the answers

    Which of the following is true about the strength of an acid in different solvents?

    <p>The strength of an acid can vary in different solvents.</p> Signup and view all the answers

    Which of the following is an example of a weak acid?

    <p>Acetic acid</p> Signup and view all the answers

    According to the Bronsted-Lowry theory, which of the following statements is true?

    <p>An acid is a proton donor and a base is a proton acceptor.</p> Signup and view all the answers

    What is the Henderson-Hasselbalch equation for acids?

    <p>pH = pKa + log([HA]/[A-])</p> Signup and view all the answers

    What is the Henderson-Hasselbalch equation for bases?

    <p>pOH = pKb + log([BOH]/[B+])</p> Signup and view all the answers

    When extracting an acidic drug with a pKa of 3, what should the pH be to extract the unionized form of the drug, primarily?

    <p>pH &gt; 3</p> Signup and view all the answers

    Which of the following drugs is an example of an acidic drug?

    <p>Aspirin</p> Signup and view all the answers

    Which of the following is true about the strength of an acid?

    <p>The strength of an acid depends on both its ability to give up a proton and the ability of the solvent to accept it.</p> Signup and view all the answers

    Which of the following is true about the ionization process of acids and bases in aqueous solution?

    <p>Weak bases completely ionize in aqueous solution.</p> Signup and view all the answers

    Which of the following is true about the relationship between the acidity of an acid and the basicity of the base?

    <p>The acidity of an acid depends on the basicity of the base that accepts the proton.</p> Signup and view all the answers

    Which of the following is true about protolytic reactions?

    <p>Protolytic reactions involve the transfer of a proton from an acid to a base.</p> Signup and view all the answers

    Which of the following is true about the ionization constant, Ka?

    <p>Ka is a measure of the strength of a weak acid or base.</p> Signup and view all the answers

    Which of the following is an advantage of liquid-liquid extraction in forensic toxicology?

    <p>Requires smaller volumes of solvent</p> Signup and view all the answers

    What is one disadvantage of liquid-liquid extraction in forensic toxicology?

    <p>Requires larger volumes of solvents</p> Signup and view all the answers

    Which of the following is true about amphoteric compounds?

    <p>They can be extracted using acid or base extraction procedures</p> Signup and view all the answers

    What is the optimal pH for extracting morphine in its unionized form?

    <p>pH 8</p> Signup and view all the answers

    What is one advantage of liquid-liquid extraction in forensic toxicology?

    <p>Relatively simple to conduct</p> Signup and view all the answers

    What is one disadvantage of liquid-liquid extraction in forensic toxicology?

    <p>Time consuming and cumbersome</p> Signup and view all the answers

    What is one advantage of solid phase extraction in forensic toxicology?

    <p>Capable of being optimized for different classes of drugs</p> Signup and view all the answers

    What is one disadvantage of solid phase extraction in forensic toxicology?

    <p>Less selective than other extraction methods</p> Signup and view all the answers

    Which of the following factors affects the partition coefficient (K) in liquid-liquid extraction?

    <p>The nature of the drug and the organic solvent</p> Signup and view all the answers

    What determines the degree to which a drug partitions between an aqueous and an organic medium?

    <p>The hydrophilic and lipophilic nature of the compound</p> Signup and view all the answers

    Which type of compound is more likely to partition into the aqueous phase in liquid-liquid extraction?

    <p>Polar compounds</p> Signup and view all the answers

    What is the purpose of making a drug as non-polar as possible during an extraction from a biological matrix?

    <p>To enhance its partitioning into the organic phase</p> Signup and view all the answers

    What is the equation to calculate the partition coefficient (K) in liquid-liquid extraction?

    <p>K = C1 / C2</p> Signup and view all the answers

    What is the main purpose of liquid-liquid extraction in forensic toxicology?

    <p>To remove a drug from a biological matrix</p> Signup and view all the answers

    What does the degree of ionization of a compound depend on?

    <p>The pH of the environment</p> Signup and view all the answers

    What are the advantages of liquid-liquid extraction?

    <p>Low volumes of solvent, vast amount of literature references, relatively simple to conduct, low cost, capable of being optimized for different classes of drugs</p> Signup and view all the answers

    What are the disadvantages of liquid-liquid extraction?

    <p>Immiscible solvents are required, time consuming and cumbersome in some instances, glassware clean up required, larger volumes of solvents needed for traditional methods, less selective than other extraction methods</p> Signup and view all the answers

    What is the optimal pH for extracting morphine?

    <p>Around a pH of 8</p> Signup and view all the answers

    What are amphoteric compounds?

    <p>Compounds that exhibit both acid and base properties</p> Signup and view all the answers

    How are amphoteric compounds best extracted?

    <p>By carefully adjusting the pH to get the drug into an unionized form</p> Signup and view all the answers

    Which of the following is the purpose of sample pretreatment in solid phase extraction?

    <p>To ensure the samples will flow easily through the sorbent bed</p> Signup and view all the answers

    What are the two phases involved in solid phase extraction?

    <p>Liquid phase and stationary sorbent phase</p> Signup and view all the answers

    What is the purpose of pH adjustments in solid phase extraction?

    <p>To isolate the drug(s) of interest</p> Signup and view all the answers

    What is the role of the solid phase cartridges in solid phase extraction?

    <p>To contain the sorbent bed</p> Signup and view all the answers

    What was the initial extraction media used in early solid phase extractions?

    <p>C1S sorbents</p> Signup and view all the answers

    Which of the following solvents is particularly effective for conditioning the sorbent in solid phase extraction?

    <p>Methanol</p> Signup and view all the answers

    What is the purpose of passing a buffer through the extraction cartridge in solid phase extraction?

    <p>To adjust the pH environment</p> Signup and view all the answers

    Which of the following is NOT a step in the solid phase extraction procedure?

    <p>Eluting the analyte of interest</p> Signup and view all the answers

    What is the goal of washing the extraction cartridge with a suitable solvent in solid phase extraction?

    <p>To remove endogenous compounds</p> Signup and view all the answers

    What is the optimal solvent strength for eluting the analyte of interest in solid phase extraction?

    <p>A solvent with moderate polarity</p> Signup and view all the answers

    Which step in the Solid Phase Extraction (SPE) process ensures that acidic drugs become organic solvent soluble?

    <p>Step 7: Elute Acidic Drugs</p> Signup and view all the answers

    What is the purpose of drying the sorbent bed in the Solid Phase Extraction (SPE) process?

    <p>To ensure that all water is removed from the sorbent bed</p> Signup and view all the answers

    What is the purpose of adding 4 ml of 2% ammoniated ethyl acetate (pH = 12) to the sorbent bed in the Solid Phase Extraction (SPE) process?

    <p>To ensure that the basic drugs become unionized</p> Signup and view all the answers

    What is the purpose of adding 4 ml of 1:1 acetone/chloroform to the sorbent bed in the Solid Phase Extraction (SPE) process?

    <p>To attract acidic drugs to the hydrophobic portion of the stationary phase</p> Signup and view all the answers

    Which step in the Solid Phase Extraction (SPE) process ensures that basic drugs become positively charged and will be retained by the cation exchange portion of the stationary phase?

    <p>Step 3: Dry the Sorbent Bed</p> Signup and view all the answers

    What is the purpose of drying the sorbent bed in the Solid Phase Extraction (SPE) process?

    <p>The purpose of drying the sorbent bed in the SPE process is to remove all water from the sorbent bed, as water can interfere with the contact the organic solvent will have with the sorbent during the elution steps.</p> Signup and view all the answers

    What is the purpose of adding 4 ml of 2% ammoniated ethyl acetate (pH = 12) to the sorbent bed in the Solid Phase Extraction (SPE) process?

    <p>The purpose of adding 4 ml of 2% ammoniated ethyl acetate (pH = 12) to the sorbent bed in the SPE process is to raise the pH and ensure that the basic drugs become unionized, allowing them to be removed by the organic solvent.</p> Signup and view all the answers

    What is the optimal pH for extracting morphine?

    <p>The optimal pH for extracting morphine is not mentioned in the text.</p> Signup and view all the answers

    Which of the following is an advantage of solid phase microextractions (SPME) compared to liquid-liquid extractions (LLE)?

    <p>SPME requires less solvent</p> Signup and view all the answers

    Which of the following is a disadvantage of microextraction by packed sorbent (MEPS)?

    <p>MEPS requires more solvents than LLE</p> Signup and view all the answers

    What is the purpose of liquid phase microextractions (LPME) in drug extraction?

    <p>To extract drugs using solvents</p> Signup and view all the answers

    What effect could protein binding have on drug extraction and what steps can be taken to overcome this?

    <p>Protein binding can decrease drug extraction efficiency; protein precipitation can be performed to remove proteins from the sample</p> Signup and view all the answers

    Why is it important to dry a solid phase cartridge prior to eluting drugs of interest with organic solvent?

    <p>To prevent loss of volatile compounds of interest</p> Signup and view all the answers

    Which of the following is NOT a factor that affects the reproducibility of a drug's Rf value in TLC?

    <p>Mobile Phase</p> Signup and view all the answers

    Which of the following is a property of cellulose as a stationary phase in TLC?

    <p>High polarity</p> Signup and view all the answers

    Which of the following is NOT a locating agent used in TLC?

    <p>Ethanol</p> Signup and view all the answers

    What is the definition of Rf value in TLC?

    <p>Relative front value</p> Signup and view all the answers

    Which of the following statements about Thin Layer Chromatography (TLC) is correct?

    <p>TLC is a technique that uses a mobile phase moving across a thin layer of stationary phase</p> Signup and view all the answers

    What is the primary use of Thin Layer Chromatography (TLC)?

    <p>To separate and identify drugs in body fluids and tissues</p> Signup and view all the answers

    What are some reasons for the popularity of Thin Layer Chromatography (TLC)?

    <p>It is a simple, reliable, and cost-effective technique</p> Signup and view all the answers

    What is the purpose of the Rf value in TLC?

    <p>To measure the distance the substance travels from the origin</p> Signup and view all the answers

    What is the advantage of using a reversed-phase system in TLC?

    <p>It allows for the separation of high molecular weight substances</p> Signup and view all the answers

    What are the advantages of TLC compared to gas chromatography and high performance liquid chromatography?

    <p>Ability to run several samples simultaneously</p> Signup and view all the answers

    What are the advantages of Thin Layer Chromatography (TLC)?

    <p>TLC is a quick and cost-effective method for drug analysis. It requires small sample volumes and can separate a wide range of compounds. TLC also allows for visual detection of separated compounds.</p> Signup and view all the answers

    Describe the properties of the following stationary phases used in TLC: Cellulose, Silica gel, Ion exchange resins.

    <ul> <li>Cellulose: Cellulose is a polar stationary phase that interacts mainly via hydrogen bonding. It is suitable for separating polar compounds.</li> <li>Silica gel: Silica gel is also a polar stationary phase, but it interacts via both hydrogen bonding and dipole-dipole interactions. It is commonly used for separating a wide range of compounds.</li> <li>Ion exchange resins: Ion exchange resins are charged stationary phases that interact with analytes based on their charge. They are used for separating charged compounds.</li> </ul> Signup and view all the answers

    Name three locating agents used in TLC and their properties.

    <ul> <li>Iodine: Iodine is a universal locating agent that forms colored complexes with a wide range of compounds.</li> <li>Ultraviolet (UV) light: UV light is used to visualize compounds that absorb UV light, such as aromatic compounds or compounds containing double bonds.</li> <li>Ninhydrin: Ninhydrin reacts with primary and secondary amines, producing a purple color, making it useful for locating amino acids and amines.</li> </ul> Signup and view all the answers

    Which type of antibodies are produced through the immunization process?

    <p>Both polyclonal and monoclonal antibodies</p> Signup and view all the answers

    What are haptens?

    <p>Molecular structures too small to elicit an immune response</p> Signup and view all the answers

    Which of the following is NOT a commonly used carrier protein in antibody production?

    <p>Mouse</p> Signup and view all the answers

    Which type of antibodies have greater affinity for an antigen due to their multisite linkage?

    <p>Polyclonal antibodies</p> Signup and view all the answers

    What is the basis for immunoassay testing?

    <p>The attachment between antigens and antibodies</p> Signup and view all the answers

    Which type of antibodies can attach to several epitopes on an antigen?

    <p>Polyclonal antibodies</p> Signup and view all the answers

    What is the purpose of a label in an immunoassay?

    <p>To create a measurable response</p> Signup and view all the answers

    Which type of immunoassay involves competition between labeled antigens and the sample's antigens for antibodies?

    <p>Competitive immunoassay</p> Signup and view all the answers

    What is the difference between a heterogeneous and homogenous immunoassay?

    <p>Heterogeneous immunoassays require wash steps, while homogenous immunoassays do not</p> Signup and view all the answers

    Which immunoassay technique is used more routinely in forensic toxicology laboratories?

    <p>Competitive immunoassay</p> Signup and view all the answers

    Which type of immunoassay does not require a substrate for detection?

    <p>RIA</p> Signup and view all the answers

    What is the purpose of a stop reagent in ELISA?

    <p>To stop the reaction from continuing</p> Signup and view all the answers

    What is the main advantage of EMIT compared to RIA and ELISA?

    <p>It is a homogenous assay</p> Signup and view all the answers

    What is the purpose of the wash step in ELISA?

    <p>To remove unbound antigens</p> Signup and view all the answers

    Which immunoassay technique was developed first?

    <p>RIA</p> Signup and view all the answers

    Which of the following labels is commonly used in Enzyme-Linked Immunosorbent Assay (ELISA) for antigen detection?

    <p>Enzyme</p> Signup and view all the answers

    What is the purpose of a substrate in Enzyme-Linked Immunosorbent Assay (ELISA)?

    <p>To produce an optically detectable change</p> Signup and view all the answers

    What type of immunoassay is Enzyme-Linked Immunosorbent Assay (ELISA)?

    <p>Heterogeneous</p> Signup and view all the answers

    Which body fluids can be analyzed using immunoassay techniques in forensic toxicology?

    <p>All of the above</p> Signup and view all the answers

    What is the most commonly used immunoassay technique in forensic toxicology laboratories?

    <p>Enzyme-Linked Immunosorbent Assay (ELISA)</p> Signup and view all the answers

    Which of the following is a common strength of immunoassay techniques?

    <p>Sensitive and good precision</p> Signup and view all the answers

    Why is urine usually the matrix of choice for immunoassay?

    <p>It has fewer interfering compounds and decomposition products</p> Signup and view all the answers

    What two parameters may be used to determine drug 'cutoff' levels?

    <p>Limit of detection and linear range</p> Signup and view all the answers

    Which immunoassay technique is more suitable for matrices other than urine?

    <p>RIA</p> Signup and view all the answers

    Which immunoassay technique uses a label which increases sensitivity?

    <p>EMIT</p> Signup and view all the answers

    Which of the following labels is used in Fluorescence Polarization Immunoassay (FPIA)?

    <p>Fluorophore</p> Signup and view all the answers

    Which of the following immunoassay techniques involves a precipitation process?

    <p>KIMS</p> Signup and view all the answers

    What is the label used in Cloned Enzyme Donor Immunoassay (CEDIA)?

    <p>Enzyme</p> Signup and view all the answers

    Which of the following immunoassay techniques is based on the recombination of two inactive protein fragments?

    <p>CEDIA</p> Signup and view all the answers

    What is the relationship between the concentration of drug and the instrumental response in Fluorescence Polarization Immunoassay (FPIA)?

    <p>Inversely proportional</p> Signup and view all the answers

    According to Lambert's Law, what happens to the intensity of radiation transmitted through a homogeneously absorbing system as the path length increases?

    <p>It decreases exponentially</p> Signup and view all the answers

    According to Beer's Law, what happens to the transmitted intensity of radiation through a homogeneously absorbing system as the sample concentration increases?

    <p>It decreases exponentially</p> Signup and view all the answers

    What is the purpose of creating a calibration curve in drug analysis using Beer's Law?

    <p>To determine the concentration of a drug sample</p> Signup and view all the answers

    In the equation for a line, y = mx + b, what does the slope (m) represent in the context of drug analysis using Beer's Law?

    <p>The product of path length and molar absorptivity</p> Signup and view all the answers

    What is the role of chromophores in energy absorption?

    <p>They modify the absorption spectrum</p> Signup and view all the answers

    Which type of lamps are commonly used as a source of visible and near infrared radiation in spectrophotometry?

    <p>Tungsten lamps</p> Signup and view all the answers

    What is the range of usable visible light in spectrophotometry?

    <p>350-2000 nm</p> Signup and view all the answers

    What type of spectrophotometer configuration compensates for fluctuations in the output of the light source?

    <p>Double beam spectrophotometer</p> Signup and view all the answers

    Which region of the infrared spectrum provides useful information about pesticides and drugs?

    <p>Mid infrared</p> Signup and view all the answers

    What type of absorption occurs at frequencies that are multiples of the fundamental band frequency?

    <p>Overtone absorption</p> Signup and view all the answers

    What is the relationship between the spring constant of a bond and its wavenumber or vibrational frequency?

    <p>Stronger bonds have a higher spring constant and higher wavenumber</p> Signup and view all the answers

    Which of the following is an advantage of FTIR compared to dispersive spectrophotometers?

    <p>All frequencies detected simultaneously</p> Signup and view all the answers

    What is the most common phase used when analyzing drugs with FTIR?

    <p>Solid phase</p> Signup and view all the answers

    What is the purpose of Attenuated Total Reflection (ATR) in FTIR analysis?

    <p>To provide a non-destructive avenue for analyzing small samples</p> Signup and view all the answers

    Which of the following is NOT a major component of an IR spectrophotometer?

    <p>Sample holder</p> Signup and view all the answers

    What is the purpose of a monochromator or interferometer in an IR spectrophotometer?

    <p>To produce a traditional IR spectrum</p> Signup and view all the answers

    What type of detector is used in a Fourier Transform Infrared (FTIR) spectrophotometer?

    <p>Quantum detector</p> Signup and view all the answers

    Which of the following is NOT a component of instruments used for measuring UV or visible absorbance?

    <p>Signal processor</p> Signup and view all the answers

    In an aqueous solution, what effect does making the solution more alkaline have on the absorbance spectrum of phenolic compounds?

    <p>Absorption shift to a longer wavelength</p> Signup and view all the answers

    What is the absorption maximum wavelength of barbiturates at pH 9.2?

    <p>240 nm</p> Signup and view all the answers

    What is the basis of the resultant spectrum in Raman spectroscopy?

    <p>Changes in energy or frequency between incident light and scattered light</p> Signup and view all the answers

    What is a disadvantage of using Raman spectroscopy for analyzing fluorescent substances?

    <p>Fluorescence interference</p> Signup and view all the answers

    What is the advantage of using Surface Enhanced Raman Spectroscopy (SERS)?

    <p>Sample can be directly analyzed through packaging, water, and glass</p> Signup and view all the answers

    What is the benefit of using microscopic methods in Raman spectroscopy?

    <p>Provides a three-dimensional look at the sample</p> Signup and view all the answers

    Why is Raman spectroscopy a preferred technique versus traditional color tests for seized drugs?

    <p>High discriminating power</p> Signup and view all the answers

    Which technique can be used for onsite preliminary drug identification of unknown seized drugs?

    <p>ATR-FTIR</p> Signup and view all the answers

    What can ATR-FTIR instruments be combined with for enhanced spatial resolution?

    <p>Microscope</p> Signup and view all the answers

    What are ATR-FTIR instruments being used for in response to increasing fentanyl overdoses?

    <p>Testing street drugs for the presence of fentanyl and other drugs</p> Signup and view all the answers

    What type of light source is generally used in Raman Spectroscopy?

    <p>Monochromatic laser</p> Signup and view all the answers

    What is the change in energy state called when incident photons lose energy to molecular bond vibrations in Raman Spectroscopy?

    <p>Stokes scattering</p> Signup and view all the answers

    Which type of pump is commonly used in chromatography to ensure constant flow rate?

    <p>Dual-piston pump</p> Signup and view all the answers

    What is the purpose of a fixed loop in a manual injection system?

    <p>To hold excess sample</p> Signup and view all the answers

    What are the main differences between gas chromatography (GC) and high-performance liquid chromatography (HPLC)?

    <p>Different types of mobile phases</p> Signup and view all the answers

    What is the primary material used to make HPLC columns?

    <p>Stainless steel</p> Signup and view all the answers

    What is the purpose of the stationary phase in HPLC columns?

    <p>To separate sample components</p> Signup and view all the answers

    What are the main differences between HPLC columns and GC capillary columns?

    <p>Different column diameters</p> Signup and view all the answers

    What are HPLC columns packed with?

    <p>Small porous particles</p> Signup and view all the answers

    What determines the retention time of solutes in HPLC?

    <p>The polarity of the mobile phase</p> Signup and view all the answers

    What is the main purpose of adsorption HPLC?

    <p>To separate non-polar materials</p> Signup and view all the answers

    What are HPLC columns packed with in the case of packed gels?

    <p>Silica</p> Signup and view all the answers

    Which of the following is the most commonly used detector for HPLC?

    <p>Ultraviolet - Variable Wavelength or Diode array</p> Signup and view all the answers

    What is the difference between HPLC and UHPLC?

    <p>UHPLC uses columns that are less than 2 um inner diameter</p> Signup and view all the answers

    What is the purpose of adding an ion pair agent to an HPLC mobile phase?

    <p>To improve the selectivity of the separation</p> Signup and view all the answers

    What is the difference between adsorption phase and partition phase chromatography?

    <p>Adsorption phase chromatography uses a solid stationary phase, while partition phase chromatography uses a liquid stationary phase</p> Signup and view all the answers

    What are theoretical plates in chromatography?

    <p>Theoretical calculations used to predict the separation efficiency of a chromatographic column</p> Signup and view all the answers

    Which of the following is an advantage of fluorescence detectors in chromatography?

    <p>Improved sensitivity over UV detectors</p> Signup and view all the answers

    What is the main disadvantage of electrochemical detectors in chromatography?

    <p>Electrodes require high maintenance</p> Signup and view all the answers

    Which type of compounds can be detected by fluorescence detectors in chromatography?

    <p>Only compounds with a chromophore can be detected</p> Signup and view all the answers

    What is the main advantage of electrochemical detectors in chromatography?

    <p>Sensitive to pg/ml levels</p> Signup and view all the answers

    Which of the following is a disadvantage of fluorescence detectors in chromatography?

    <p>Eluent may absorb at the optimum detection wavelength</p> Signup and view all the answers

    Which of the following is true about the operation of an electron multiplier in a mass spectrometer?

    <p>The electron multiplier creates a cascade effect of electrons being generated.</p> Signup and view all the answers

    What is the unit of measurement for mass-to-charge ratio (m/z) in a mass spectrum?

    <p>Atomic mass units (amu)</p> Signup and view all the answers

    What is the purpose of Total Ion Current (TIC) in mass spectrometry?

    <p>To measure the total number of ions in the mass spectrum.</p> Signup and view all the answers

    What is the purpose of Single Ion Monitoring (SIM) in mass spectrometry?

    <p>To measure the intensity of a specific ion in the mass spectrum.</p> Signup and view all the answers

    What is the molecular ion in a mass spectrum?

    <p>The ion with the highest mass-to-charge ratio.</p> Signup and view all the answers

    What is the base peak in a mass spectrum?

    <p>The ion with the highest relative abundance.</p> Signup and view all the answers

    Where does ionization take place when using Electrospray Ionization (ESI)?

    <p>In the ion trap.</p> Signup and view all the answers

    Why would a laboratory choose to use a LCMSMS versus a GCMS?

    <p>LCMSMS provides higher sensitivity.</p> Signup and view all the answers

    What is the main difference in the operation of a quadrupole mass spectrometer compared with an ion trap?

    <p>Quadrupole mass spectrometers use a series of dynodes.</p> Signup and view all the answers

    What is the purpose of the electron multiplier in a mass spectrometer?

    <p>To release electrons to increase the signal.</p> Signup and view all the answers

    Which term describes a pattern where the variance of measured residuals is homogenous or uniform across the calibration curve?

    <p>Homoscedasticity</p> Signup and view all the answers

    What type of model is appropriate when the residual plot reveals a U-shape?

    <p>Quadratic least square regression model</p> Signup and view all the answers

    When is a weighted regression model needed?

    <p>When the variance of measured residuals is heterogenous</p> Signup and view all the answers

    What does a funnel-shaped residual plot indicate?

    <p>Heteroscedasticity</p> Signup and view all the answers

    What is the purpose of a weighted regression model?

    <p>To establish an appropriate relationship between instrumental response and concentration</p> Signup and view all the answers

    What can be done to determine the concentration of an analyte using a nonlinear model?

    <p>Mathematical transformation process of both variables</p> Signup and view all the answers

    What is the main difference between a linear model and a nonlinear model?

    <p>The type of regression used</p> Signup and view all the answers

    What is the purpose of a quadratic least square regression model?

    <p>To capture nonlinearity in the data</p> Signup and view all the answers

    What is the role of weighting in regression models?

    <p>To account for heteroscedasticity in the data</p> Signup and view all the answers

    What should a laboratory assess in determining the most appropriate model to use?

    <p>The shape of the residual plot</p> Signup and view all the answers

    Which of the following best describes measurement uncertainty?

    <p>A statistical description of how certain the laboratory is about their reported results</p> Signup and view all the answers

    What is the purpose of determining uncertainty when validating a method?

    <p>To identify potential sources of error</p> Signup and view all the answers

    How is uncertainty initially determined when validating a method?

    <p>Through the use of a budget or spreadsheet</p> Signup and view all the answers

    What is the expanded uncertainty?

    <p>The uncertainty calculated during method validation</p> Signup and view all the answers

    When should the expanded uncertainty be recalculated?

    <p>Following the method's validation and routine analyses</p> Signup and view all the answers

    Why is it necessary to recalculate the expanded uncertainty?

    <p>To account for any changes in the method</p> Signup and view all the answers

    What is the purpose of using a coverage factor and confidence level when reporting the expanded uncertainty?

    <p>To provide a measure of the laboratory's confidence in the reported results</p> Signup and view all the answers

    What is the advantage of recalculation using data gathered from routine analyses?

    <p>To improve the accuracy of the measurements</p> Signup and view all the answers

    What is the primary purpose of determining uncertainty in laboratory measurements?

    <p>To determine the accuracy of the measurements</p> Signup and view all the answers

    What is the role of standard deviations in determining uncertainty?

    <p>To calculate the expanded uncertainty</p> Signup and view all the answers

    Which parties may need access to validation information?

    <p>Designated laboratory personnel</p> Signup and view all the answers

    What measures should be taken during validation to ensure a quality process?

    <p>All of the above</p> Signup and view all the answers

    When should the uncertainty of measurement be determined?

    <p>During validation</p> Signup and view all the answers

    What should be done if changes need to be made to the method?

    <p>Both B and C</p> Signup and view all the answers

    What should be done when deviations occur during continuous monitoring of a validated method?

    <p>They should be documented and approved</p> Signup and view all the answers

    What is the general approach to forensic analysis for a seized drug sample?

    <p>The general approach to forensic analysis for a seized drug sample involves sample preparation, identification, quantification, and interpretation of the results.</p> Signup and view all the answers

    What is the general approach to forensic analysis for a biological specimen?

    <p>The general approach to forensic analysis for a biological specimen involves sample collection, preservation, analysis, and interpretation of the results.</p> Signup and view all the answers

    What are the main steps in the forensic analysis of a seized drug sample?

    <p>The main steps in the forensic analysis of a seized drug sample include sample extraction, separation, identification, quantification, and data interpretation.</p> Signup and view all the answers

    What are two techniques that can be used for confirmatory forensic drug analysis?

    <p>Infrared Spectroscopy (IR) and Mass Spectrometry (MS)</p> Signup and view all the answers

    What is the purpose of the TLC technique in drug identification?

    <p>To separate and retain different components of the sample based on their distribution between the mobile and stationary phase</p> Signup and view all the answers

    What is the advantage of using mass spectrometry for structural identification?

    <p>Mass spectrometry is considered the gold standard for structural identification and provides the most accepted technique for confirmation.</p> Signup and view all the answers

    Which of the following techniques is primarily used to distinguish isomers such as dextromethorphan and levomethorphan?

    <p>Microcrystal Tests</p> Signup and view all the answers

    What is the purpose of the mobile phase in Thin Layer Chromatography (TLC)?

    <p>To produce colored spots on the plate</p> Signup and view all the answers

    Which technique is considered the gold standard for structural identification and confirmation of drugs?

    <p>Thin Layer Chromatography (TLC)</p> Signup and view all the answers

    What is the purpose of Infrared Spectroscopy (IR) in forensic drug analysis?

    <p>To separate and retain components of the sample</p> Signup and view all the answers

    What is the purpose of the stationary phase in Thin Layer Chromatography (TLC)?

    <p>To form crystals characteristic of the drug</p> Signup and view all the answers

    Which of the following is a common method used to prepare a sample for LCMSMS analysis?

    <p>Precipitating proteins by diluting the sample in acetonitrile</p> Signup and view all the answers

    In a forensic chemistry lab, how is a sample typically prepared for analysis using gas chromatography and/or mass spectrometry?

    <p>Dissolving the sample in a solvent like methanol</p> Signup and view all the answers

    What is added to a sample prior to extraction or analysis in order to ensure accurate quantitation?

    <p>An internal standard</p> Signup and view all the answers

    What information is reported when cocaine and its major metabolites are found in a sample?

    <p>The associated measurement uncertainty</p> Signup and view all the answers

    What is the purpose of reconstituting the extract with the appropriate diluent in LCMSMS preparation?

    <p>To ensure accurate quantitation of the extract</p> Signup and view all the answers

    What is the purpose of LCMSMS preparation?

    <p>The purpose of LCMSMS preparation is to dilute a small portion of the sample in a solvent, precipitate proteins, and reconstitute the extract for analysis using liquid chromatography coupled with mass spectrometry.</p> Signup and view all the answers

    What is the role of an internal standard in forensic chemistry analysis?

    <p>The role of an internal standard in forensic chemistry analysis is to ensure accurate quantitation of cocaine and its major metabolites by providing a reference measurement.</p> Signup and view all the answers

    What is the purpose of evaporating and reconstituting the subsequent supernatant in LCMSMS preparation?

    <p>The purpose of evaporating and reconstituting the subsequent supernatant in LCMSMS preparation is to prepare the extract for analysis using liquid chromatography.</p> Signup and view all the answers

    Which of the following is NOT a requirement for maintaining the appropriate storage and security conditions in a forensic laboratory?

    <p>Recording storage temperatures at least once a day</p> Signup and view all the answers

    What is a required part of a forensic scientist's courtroom testimony?

    <p>All of the above</p> Signup and view all the answers

    Why is documentation important in forensic cases?

    <p>All of the above</p> Signup and view all the answers

    What is gas chromatography and what is its purpose?

    <p>Gas chromatography is a technique used to separate and analyze volatile compounds in a mixture. Its purpose is to identify and quantify the components of a sample.</p> Signup and view all the answers

    What are the steps involved in thin layer chromatography?

    <p>The steps involved in thin layer chromatography include sample application, development, visualization, and calculation of Rf values.</p> Signup and view all the answers

    What are the advantages and disadvantages of liquid-liquid extraction?

    <p>The advantages of liquid-liquid extraction include high selectivity and the ability to handle complex samples. However, it can be time-consuming and requires the use of large volumes of solvents.</p> Signup and view all the answers

    Which of the following is the primary goal of forensic toxicology?

    <p>To determine the role of toxic agents in causing death</p> Signup and view all the answers

    What is the most commonly used specimen for drug analysis in forensic toxicology?

    <p>Blood</p> Signup and view all the answers

    What do blood drug concentrations represent?

    <p>The drugs currently affecting the body</p> Signup and view all the answers

    Why is blood preferred over urine for analyzing the behavioral effects of drugs?

    <p>Blood provides more accurate results</p> Signup and view all the answers

    What is the ultimate goal of a forensic toxicologist?

    <p>To provide answers during investigations</p> Signup and view all the answers

    Which body fluids are commonly analyzed in forensic toxicology?

    <p>Urine and blood</p> Signup and view all the answers

    What can the presence and amount of drugs in a person's body fluids help determine?

    <p>The behavioral effects of drugs</p> Signup and view all the answers

    What types of cases do forensic toxicology typically involve?

    <p>All of the above</p> Signup and view all the answers

    Which of the following questions may a forensic toxicologist be asked to answer during an investigation?

    <p>All of the above</p> Signup and view all the answers

    What is the significance of drug and/or metabolite levels in a person's body fluids?

    <p>All of the above</p> Signup and view all the answers

    Study Notes

    Forensic Toxicology Overview

    • Preliminary/presumptive tests are initial screenings to detect the presence of drugs in samples.
    • Gas Chromatography-Mass Spectrometry (GC/MS) is recognized as the 'gold standard' for drug confirmation.
    • Drug degradation can be caused by environmental factors such as light, heat, moisture, and pH.
    • Liquid-liquid extraction aids in isolating drugs from biological matrices by separating compounds based on solubility differences in immiscible solvents.
    • Immunoassays utilize antibodies to detect specific drugs or their metabolites, based on specific binding interactions.

    Instrumentation and Techniques

    • Spectroscopy, particularly ultraviolet-visible (UV-Vis) and infrared (IR), is widely used in drug analysis within forensic toxicology.
    • Solid Phase Extraction (SPE) separates compounds based on their interactions with a solid stationary phase and a liquid mobile phase.
    • GC uses vaporized samples to separate compounds, while MS identifies and quantifies them by measuring mass-to-charge ratios.

    Sample Processing

    • The process begins with sample intake, followed by homogenization, extraction, and analysis of drug components.
    • Stability testing determines how environmental factors affect drug integrity over time, which is crucial for accurate forensic results.
    • Sample storage must be controlled, typically at low temperatures to preserve biological specimens ahead of testing.

    Drug Identification and Testing Methods

    • Color tests provide preliminary analyses, such as the Duquenois-Levine test for cannabis, but are not definitive confirmations.
    • Microcrystal tests utilize the formation of distinct crystals for identification, relying on careful dinitro and polarizing light microscopy techniques.

    Chemical Principles

    • The Bronsted-Lowry theory defines acids as proton donors and bases as proton acceptors, influencing drug behavior in solutions.
    • Henderson-Hasselbalch equations relate pH, pKa, and the concentrations of ionized and unionized forms of acids and bases.
    • Acidic drugs require specific pH conditions for optimal extraction, with pH values typically below the pKa favoring the unionized species.

    Techniques and Protocols

    • Liquid-liquid extraction is advantageous for separating organic compounds but disadvantages include time consumption and solvent use.
    • SPE offers effective sample cleanup and concentration, though it may require complex optimization depending on the analyte's properties.
    • Factors such as temperature and pH influence the partition coefficient (K) during extraction processes, crucial for efficient drug isolation.

    Other Considerations

    • Amphoteric compounds can act as either acids or bases, affecting their extraction efficiency based on pH conditions.
    • Proper documentation during sample collection ensures chain of custody, elemental characterization, and proper laboratory analysis.
    • Environmental conditions in the lab can lead to contamination, impacting the reliability of test results.

    Final Thoughts

    • Overall quality in forensic toxicology hinges on accurate testing methods, meticulous sampling protocols, and a solid understanding of chemical principles governing drug behavior in various environments.

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    Description

    Test your knowledge on forensic toxicology drug analysis, drug degradation, preliminary/presumptive tests, and examination processes. Learn how to process unknown samples, identify causes of drug degradation, understand the importance of preliminary tests, and gain detailed insights into examination processes.

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