Types of Glass and Plastic Materials

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Questions and Answers

What is the relationship between wavelength and energy?

Inversely proportional (correct)

Directly proportional

Proportional to frequency

Independent of each other

In double-beam spectrophotometry, how is the light beam divided?

By reflecting light off a prism

Using a beam splitter to create multiple paths

Using two different light sources

By splitting it between a reference and a sample cuvet (correct)

According to Beer's Law, absorbance is directly proportional to which of the following?

Concentration of the substance (correct)

Wavelength of the light used

Volume of the sample

The logarithm of transmitted light

What is the equation for absorbance according to Beer-Lambert’s Law?

A = abc Signup and view all the answers

What does a shorter wavelength indicate in terms of energy?

Higher energy and frequency Signup and view all the answers

In the equation A = 2 - log %T, what does %T represent?

Percent transmittance of light Signup and view all the answers

Which type of double-beam spectrophotometry uses two photodetectors?

Double-beam-in-space Signup and view all the answers

What is a main advantage of using scintillation counting?

It allows for subpicomolar detection limits. Signup and view all the answers

What is the significance of knowing the concentration of a standard when calculating an unknown analyte concentration?

It provides a basis for comparison to determine the unknown concentration Signup and view all the answers

Which material should not be used for UV wavelength measurements?

Glass Signup and view all the answers

What role does insulin play in glucose metabolism?

It promotes glycolysis and glycogenesis. Signup and view all the answers

Which hormone is primarily responsible for raising blood glucose levels?

Glucagon Signup and view all the answers

What type of immunoassay utilizes microparticles in its method?

Microparticle capture enzyme immunoassay (MEIA) Signup and view all the answers

How does glucagon affect glucose metabolism?

It promotes gluconeogenesis and glycogenolysis. Signup and view all the answers

What is a characteristic of the liquid scintillation technique?

It detects beta particles using labeled ligands. Signup and view all the answers

What is a common component of the Microparticle enzyme immunoassay?

Double antibody system Signup and view all the answers

What is the molarity of a 1-liter solution containing 10 g sodium hydroxide (NaOH) given that the molar mass of NaOH is approximately 40 g/mol?

0.5 M Signup and view all the answers

What is the normality of a 1-liter solution containing 24.5 g of H2SO4, given that the molar mass of H2SO4 is approximately 98 g/mol?

1.0 N Signup and view all the answers

How many moles of solute are in a 3 M sulfuric acid solution if you have 1 liter of that solution?

3 moles Signup and view all the answers

What is the purpose of a blank in spectrophotometry?

To set the spectrophotometer to 0 absorbance Signup and view all the answers

What is the molality of a solution that contains 50 grams of NaCl in 1 kg of water, given that the molar mass of NaCl is approximately 58.5 g/mol?

0.85 m Signup and view all the answers

If you have a 0.3N solution of H3PO4, what would be its molarity considering that phosphoric acid provides 3 equivalents?

0.9 M Signup and view all the answers

What does a standard calibrator do in an assay method?

It helps determine the concentration of an unknown analyte Signup and view all the answers

Which statement about control solutions is true?

Monitoring their performance ensures accuracy and precision. Signup and view all the answers

What is the relationship between normality and molarity for a monobasic acid?

Normality and molarity are equal Signup and view all the answers

What is the conversion factor for molarity to convert 1 L of a 2 M solution to milliliters?

1000 mL Signup and view all the answers

What is the main principle of fluorometry?

Measurement of light emitted by excited molecules Signup and view all the answers

What key components are involved in a single-beam spectrophotometer?

Gas discharge lamps and photomultiplier tubes Signup and view all the answers

To prepare a 40% ethanol solution, how many milliliters of a 70% ethanol solution are needed for 35 mL of the final solution?

25 mL Signup and view all the answers

What advantage does fluorometry have over standard spectrophotometry?

It is more sensitive and specific. Signup and view all the answers

Which of the following is a disadvantage of fluorometry?

It can be affected by quenching. Signup and view all the answers

Why are controls with bovine origin preferred in laboratory assays?

They have lower biohazard issues compared to human sera. Signup and view all the answers

What is the molecular weight of urea?

60 g/mol Signup and view all the answers

What is the correct method to convert BUN to urea?

Multiply by 2.14 Signup and view all the answers

Which method is considered the reference method for analyzing urea?

Isotope Dilution Mass Spectrometry (IDMS) Signup and view all the answers

What can cause a falsely elevated measurement in the alkaline picrate method?

High plasma chromogens Signup and view all the answers

Which of the following affects creatinine clearance?

Impaired kidney function Signup and view all the answers

What does the diacetyl monoxime method directly react with to form a diazine?

Urea Signup and view all the answers

What is a characteristic of the Jaffe method?

Colorimetric and endpoint Signup and view all the answers

Which of the following methods improves the specificity of chemical analysis?

Kinetic timed-rate measurement Signup and view all the answers

What role does cholesterol esterase play in the enzymatic method for measuring cholesterol?

It hydrolyzes cholesterol esters to liberate free cholesterol. Signup and view all the answers

Which method is considered the reference method for measuring cholesterol content in HDL?

Ultracentrifugation. Signup and view all the answers

What is the purpose of using a peroxidase-catalyzed reaction in the cholesterol measurement method?

To couple with hydrogen peroxide and produce a colored product. Signup and view all the answers

What happens to apoB-containing lipoproteins during the two-step method for cholesterol measurement?

They are precipitated and removed from the sample. Signup and view all the answers

How is the intensity of the oxidized chromogen related to cholesterol levels?

It is directly proportional to the level of cholesterol. Signup and view all the answers

What is the main reason for requiring a fasting sample for lipid profiling?

To eliminate chylomicrons from the plasma. Signup and view all the answers

What color is produced by the oxidized chromogen in the enzymatic method?

Red-purple. Signup and view all the answers

Which of the following is NOT a method mentioned for the measurement of HDL-C?

Gas chromatography. Signup and view all the answers

What percentage of cholesterol is esterified in the human body?

70% Signup and view all the answers

Which enzyme deficiency is associated with galactosemia?

Galactose-1-phosphate uridyltransferase (GALT) Signup and view all the answers

What is a common clinical presentation of children affected by galactosemia?

Mental retardation Signup and view all the answers

In the context of hexokinase function, what does an increase in absorbance at 340nm indicate?

Increase in glucose levels Signup and view all the answers

What happens to the polarity of cholesterol when a fatty acid is attached?

Polarity decreases Signup and view all the answers

What is a potential source of error in glucose measurement related to sample quality?

Hemolyzed samples may falsely decrease results Signup and view all the answers

What is a characteristic of hepatic glycogen storage diseases?

Development of hepatomegaly Signup and view all the answers

Which of the following methods is used for newborn screening for galactosemia?

Clinitest Signup and view all the answers

What is fructosamine primarily used to assess?

Glycemic control over the past 2-3 weeks Signup and view all the answers

Which of the following statements about fructosamine is accurate?

It uses serum samples for testing Signup and view all the answers

In which scenario is fructosamine particularly beneficial?

When HbA1c is unreliable due to hemolytic anemia Signup and view all the answers

What is fructosamine primarily a measure of?

Glycosylated albumin Signup and view all the answers

Which group is most likely to benefit from fructosamine assessments?

Populations with high-risk factors such as hypertension Signup and view all the answers

Why are control solutions preferred to be of bovine origin in laboratory assays?

They avoid biohazard issues associated with human sera Signup and view all the answers

What is a key component of a single-beam spectrophotometer?

A photomultiplier tube Signup and view all the answers

What is a major disadvantage of fluorometry?

Quenching of the emitted light Signup and view all the answers

Which type of calibration substance is used exclusively for a single analyte?

Standard/Calibrator Signup and view all the answers

In a single-beam spectrophotometer, what does the primary monochromator do?

Selects wavelengths for detection Signup and view all the answers

What type of light source is used in fluorometry?

Gas discharge lamps Signup and view all the answers

How do you convert BUN to urea?

Multiply by 2.14 Signup and view all the answers

Which method is known for being non-specific in the chemical analysis of urea?

Alkaline picrate method Signup and view all the answers

What compound does diacetyl react with to produce a diazine in urea analysis?

Urea Signup and view all the answers

Which factor directly affects creatinine clearance?

Renal function Signup and view all the answers

What is the purpose of using adsorbents in chemical analysis methods?

To remove interfering substances Signup and view all the answers

Which method is emphasized for its affordability in measuring urea?

Alkaline picrate method Signup and view all the answers

What can falsely increase measurements in the alkaline picrate method?

Plasma chromogens Signup and view all the answers

What confirms the diagnosis of diabetes mellitus based on the provided glucose levels during the oral glucose tolerance test?

Meeting or exceeding two or more glucose level thresholds Signup and view all the answers

Which method is based on the reduction of cupric ions by glucose?

Benedict’s test Signup and view all the answers

Which of the following statements is true about the confirmatory tests for diabetes mellitus?

Tests should be confirmed by a minimum of two samples collected at least 2 hours after glucose load Signup and view all the answers

What is a potential factor that can lead to falsely increased glucose readings in tests?

Presence of reducing substances other than glucose Signup and view all the answers

What is the standard glucose load for the oral glucose tolerance test?

75 grams Signup and view all the answers

Which color results from the reduction of Ferricyanide during a chemical analysis?

Colorless Signup and view all the answers

What is indicated by symptoms such as polyuria, polyphagia, and polydipsia?

Diabetes mellitus Signup and view all the answers

Which test is used as a screening method for gestational diabetes?

1-hour OGTT with 50g glucose Signup and view all the answers

What does accuracy in laboratory testing refer to?

Closeness of the result to the true or actual value Signup and view all the answers

Which of the following describes the purpose of quality assurance in a laboratory setting?

To monitor and verify testing processes to ensure valid results Signup and view all the answers

What does the term 'delta check' refer to in laboratory testing?

A check comparing a current result with a past result for the same patient Signup and view all the answers

Which phase of quality assurance includes specimen collection and handling?

Pre-analytical phase Signup and view all the answers

What does precision in laboratory testing indicate?

The degree to which repeated measurements under unchanged conditions show the same results Signup and view all the answers

What is the purpose of Westgard rules in quality control?

To detect systemic bias and random errors through control limits Signup and view all the answers

What does the 68-95-99 rule in normal distribution relate to?

The percentage of values that fall within certain standard deviations from the mean Signup and view all the answers

What is an example of a systematic error in laboratory testing?

Deterioration of reagents used across multiple tests Signup and view all the answers

Which of the following analytes is measured using the SI unit of mmol/L?

Cholesterol Signup and view all the answers

What is the recommended internal quality control frequency for laboratory analysis?

At least every 24 hours for a minimum of 20 days Signup and view all the answers

What does the term 'random error' signify in laboratory testing?

Unpredictable fluctuations that affect precision Signup and view all the answers

Which factor is critical in verifying a reference interval for an analyte?

At least 20 study individuals must be involved Signup and view all the answers

Which statistic is involved in calculating the Standard Deviation Index (SDI)?

Standard deviation of the peer group results Signup and view all the answers

In quality control, what would it indicate if ten consecutive control values are on the same side of the mean?

There is a potential systemic bias in the testing Signup and view all the answers

Study Notes

Types of Glass Materials

Borosilicate glass (silica-containing) is resistant to heating and sterilization. It's common and is often called Pyrex.
Aluminosilicate glass (silica-containing) is strong and resists scratching and alkali attack. A common brand is Corex.
Soft glass (Boron-free glass) has low thermal resistance and can be used with strong acids and alkalis. It's inexpensive and often used for disposables.
Flint glass (Soda lime glass) is the most inexpensive type. It releases alkali, which can cause errors.
Low actinic glass is amber-colored or coated; used to hold photosensitive substances.

Types of Plastic Materials

Teflon (polytetrafluoroethylene) has excellent temperature tolerance and chemical resistance.
Polypropylene resists most chemicals and is used for pipet tips and test tubes.
Polycarbonate is clear, stronger than polypropylene, and has good temperature tolerance.
Polyethylene resists most chemicals (except concentrated acids) and is used for disposable transfer pipets.
Polystyrene is rigid, clear, and used for test tubes.
Polyvinyl chloride is soft, flexible, but porous and often used as tubing.

Calibration

Gravimetric calibration uses a balance to measure the weight of distilled water a piece of glassware can hold; it's the most accurate method.
Spectrophotometric calibration measures the absorbance of colored solutions. Potassium dichromate or para-nitrophenol are examples of colored solutions.

Semi-Automatic Micropipettes

Air-displacement pipettes use an air cushion between the liquid and the piston. It's recommended for aqueous samples.
Positive displacement pipettes have a piston directly touching the liquid. It's recommended for viscous or high-density samples like those taken from patients.

Centrifuges

Horizontal/Swinging bucket centrifuges spin tubes horizontally, have lower speeds, up to 3000 RPM and have a flat, tightly packed sediment.
Fixed-angle/angle-head centrifuges spin at higher speeds, with less heat buildup, up to 7,000-9,000 RPM (RCF). Slanted sediment is a disadvantage; not recommend for procedures where decantation is needed.
Ultracentrifuges spin at the highest speeds, up to 100,000 RPM which are used for procedures which demand ultra-high RCF that produce higher sediment packing, and are refrigerated.
Cytocentrifuges are used for low-speed cell counting (200-2,000 rpm), especially for CSF analysis.

Glass Pipettes

Volumetric pipettes are the most accurate; they have only one calibration mark.
Ostwald-Folin pipettes are used for serial dilution and measuring reagents.
Serologic pipettes are graduated down to the tip which may be used for serial dilutions and general measuring in the lab.
Mohr pipettes are graduated and used in measuring/delivering fractions of its capacity.
To Contain: Holds but does not deliver the volume marked.
Blow-out: delivers the marked volume plus amounts that may cling to the inside walls of the glass pipettes

Reagent Water Types

Type I water is the purest, subjected to multiple purification techniques for maximum purity. Best for standards.
Type II water is suitable for most laboratory procedures, including reagent preparation.
Type III water is only suitable for some qualitative tests.

Biological Safety Cabinets

Class II cabinets provide the most common level of protection for a variety of materials in the lab.
Class III cabinets protect from exposure to potentially hazardous materials and are completely enclosed; no openings.

Chemical Storage Requirements

Flammable liquids, mineral acids, caustics, perchloric acid, air-reactive substances, and heat-reactive substances that need refrigeration should be stored separately.

Radiation Hazard

Non-ionizing radiation is used in various lab instruments and in disinfection like germicidal lamps, lasers, and microwave energy. It is less harmful than ionizing radiation.

Fire Hazard

The different classes of fire hazards are outlined with examples (wood, paper, cloth, rubber; flammable liquids and gases; electrical panel, motor, wiring; Combustible metals). Each class requires different types of fire extinguishers. Proper methods for fire safety procedures, such as Rescue, Alarm, Confine, and Extinguish/Evacuate are outlined.

Specific Hazard

Information is provided about different categories of hazards like acute toxicity, corrosivity, flammability, instability, and oxidizing properties.
Different types of hazard symbols are shown.

Laboratory Mathematics

Formulas are provided for calculating molarity, normality, and dilutions.
Worked examples involving these calculations are given.

Units of Measure

List of SI and non-SI units of measure is given, and factors/prefix values used with them.

Quality Management

Quality Management (QM) involves quality assurance (QA) and quality control (QC).
Quality assurance/assessment ensures quality results at pre-analytical, analytical, and post-analytical stages. QC is a component of QA.
QC is done via Shewart Levey-Jennings charts to assess accuracy and precision.
Westgard Rules are outlined.

Blood Collection

Venipuncture sites, tourniquets, antiseptics, and methods are outlined, including evacuated tubes and butterfly needles.
Capillary puncture methods are provided for infants and adults.
Order of draw procedures are also outlined

Blood Collection and Specimen Considerations

General precautions and techniques for venipuncture
Venipuncture methods using needles, syringes, and butterfly/winged infusion sets.
Evacuated tube systems for blood collection; color-coded evacuated tubes with or without additives are outlined.
Categories of additives for various tests (including lavender for hematology, pink for crossmatching, light blue for coagulation, gray for ESR or nonprotein nitrogen analysis, green for heparin, orange for separator tubes, red/black/gold for serum separator tubes (SST), light green for plasma separator tubes (PST), and gray for fluoride/oxalate).
Order of draw procedures using evacuated tubes are outlined.

Analytical Techniques and Instrumentation

Types of spectrophotometry
Components of a spectrophotometer (light source, entrance slit, monochromator, exit slit, cuvette, Photomultiplier tube, and readout)
Beer-Lambert's Law is outlined and illustrated by a formula
Solutions in spectrophotometry (blank, standard, control)
Quality assurance items like wavelength accuracy, absorbance check and linearity
Double-beam spectrophotometry (in-space, in-time)
Fluorescence and Chemiluminescence

Solute/Solvent Measurement/Analysis

Scintillation counting methods
Various immunoassay techniques (MEIA, FPIA) are outlined and explained.
Turbidimetry and Nephelometry methods
Mass spectrometry techniques (GC/MS, HPLC-MS, Tandem MS, IDMS, MALDI TOF-MS)
NMR spectroscopy

Point-of-Care Testing (POCT)

Advantages, disadvantages, and examples of POCT devices
Electrochemical techniques for determining electrolytes and blood gases (potentiometry, amperometry, polarography, and coulometry; and their clinical applications).

Chemistry of Other Substances and Poisons

Methods of determination (screening, spectrophotometry and gas chromatography).
Examples of illicit drugs (cocaine, amphetamines, marijuana, phencyclidine, LSD), and other substances and poisons (methanol, isopropanol, ethylene glycol, carbon monoxide, cyanide, and heavy metals).

Acid-Base Homeostasis and Blood Gases

Buffer systems (hemoglobin, plasma proteins, phosphate, and bicarbonate).
Henderson-Hasselbalch equation; relationship between pH, bicarbonate & pCO2.
ABG parameters, causes and interpretation and their clinical value are reviewed.
Acid-base disorders are reviewed and categorized with descriptions of the mechanisms of the respective disorders.

Liver Function

Functions of the liver (storage, synthetic/metabolic, detoxification, secretory and excretory functions, with respect to conjugated and unconjugated bilirubin.
Forms of bilirubin in plasma
Derangement of bilirubin metabolism and clinical applications are provided
Methods of bilirubin determination using direct/indirect/total and the use of accelerator to convert bilirubin to diazo compound for the determination of total bilirubin.

Clinical Enzymology

Classes of enzymes (oxidoreductases/dehydrogenases, transferases, hydrolases, lyases, isomerases, and ligases).
Enzyme kinetics (Michaelis-Menten and Lineweaver-Burke equations)

Specific Enzyme Analysis

Methods/procedures (endpoint and continuous monitoring), conditions that affect enzyme reactions (pH, temperature, cofactors, and inhibitors, including competitive, non-competitive, and uncompetitive inhibition).
Measurement of isoenzymes.
Clinical significance of different enzyme elevations or reductions are reviewed.

Clinical Endocrinology

Review of various hormone classes (proteins/peptides, steroids, amines)
Various hormone functions and clinical significance of abnormal secretion patterns are provided (hyper/hypo-secretion).
Various specific hormone analysis information, their respective testing guidelines and reference values are also reviewed and analyzed.

Other Body Fluids/Urine Analysis

Urine and CSF proteins, myoglobin, and cardiac troponins are extensively reviewed and analyzed with respective methods, reference ranges, and clinical significance.
Natriuretic peptides, cystatin C, β trace protein, fibronectin, and other important protein analysis, and respective testing.
Amyloids and Homocysteine are also analyzed and their respective tests.

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Description

This quiz covers various types of glass and plastic materials commonly used in laboratory settings. Learn about their properties, uses, and advantages in scientific applications. Test your knowledge on the characteristics of materials like borosilicate glass and Teflon.