Introduction to Analytical Chemistry PDF

Analytical Chemistry Module I INTRODUCTION TO ANALYTICAL CHEMISTRY Analytical Chemistry Module I SCOPE OF PRESENTATION 1.1 Nature of Analytical Chemistry 1.2 Main Division of...

Analytical Chemistry Module I INTRODUCTION TO ANALYTICAL CHEMISTRY Analytical Chemistry Module I SCOPE OF PRESENTATION 1.1 Nature of Analytical Chemistry 1.2 Main Division of Analytical Chemistry 1.2.1 Qualitative Analysis 1.2.2 Quantitative Analysis 1.3 Quantitative Method of Analysis 1.3.1 Overview of the Nine Steps of Quantitative Analysis 1.4 Tools of Analytical Chemistry 1.4.1 Chemical, apparatus, and operations of analytical chemistry 1.4.2 Using Spreadsheet in Analytical Chemistry 1.4.3 Error in Chemical Analysis 1.1 NATURE OF Analytical Chemistry | Module I ANALYTICAL CHEMISTRY 01 Analytical Chemistry is a branch of chemistry that studies the chemical composition and structure of matter. 02 Separate, identify, and quantify natural and artificial substances by chemical or physical properties. 03 Art and science of determining what matters and how much of it exists. 04 Also known as a measuring science, it is composed of several potent concepts and techniques that are advantageous in the fields of science, medicine, and engineering. Analytical Chemistry Module I APPLICATIONS OF ANALYTICAL CHEMISTRY Determination of the concentration of O2 and CO2 in blood samples Gas emission test for the analysis of hydrocarbons, NOX's and CO Quantitative measurement of nitrogen present in foods Determination of ionized calcium in blood serum Analytical Chemistry Module I Analysis of steel during its production permits adjustments in the concentration of such elements as carbon, nickel and chromium Farmers tailor fertilization and irrigation schedules to meet changing plant needs Performing immunoassay in determining antibodies or antibody related reagents in formulating medicine for COVID-19 virus Measurement of antigen by performing polymerase chain reaction (PCR) test to detect the presence of COVID-19 virus Analytical Chemistry Module I Permits physiologists to study the role of these ions in nerve signal conduction as well as muscle contraction and relaxation Chemical reactions can be calculated from quantitative measurements made at equal time intervals Material scientists rely heavily on quantitative analysis of crystalline germanium and silicon Archaeologists identify the source of volcanic glasses (obsidian) by measuring concentration of minor elements in samples  RELATIONSHIP BETWEEN ANALYTICAL Analytical Chemistry | Module I CHEMISTRY WITH OTHER SCIENTIFIC FIELDS Chemistry Environmental Material Physics Biochemistry Science Science Astrophysics Inorganic Chemistry Ecology Metallurgy Astronomy Organic Chemistry Meteorology Polymers Biophysics Physical Chemistry Oceanography Solid State Biology Engineering Botany Civil Analytical Chemistry Genetics Chemical Microbiology Electrical Zoology Mechanical Geology Social Agriculture Medicine Geophysics Science Agronomy Clinical Chemistry Geochemistry Archeology Food Science Medicinal Chemistry Paleontology Anthropology Crop Science Pharmacy Paleobiology Forensics Horticulture Toxicology Analytical Chemistry Module I 1.2 MAIN DIVISIONS OF ANALYTICAL CHEMISTRY QUANTITATIVE ANALYSIS AND QULAITATIVE ANALYSIS are the two components of chemistry processes. QUALITATIVE ANALYSIS makes the elements and compounds in the sample identifiable and determines what material are contained in a sample. QUANTITATIVE ANALYSIS is any method used for determining the amount of a chemical in a sample.  FOLLOWING TESTS INVOLVES IN QUALITATIVE ANALYSIS SOLUBILITY TEST PRECIPITATION pH TEST FLAME TEST TEST USED TO SEE IF USED TO SEE IF DETERMINE THE USED TO SEE WHAT SOLID SOLID FORMED CONCENTRATION COLOR IS FORMED DISSOLVES IN THE WHEN TWO OF DISSOLVE [H] WHEN THE SOLVENT. DISSOLVED IONS. SUBSTANCE IS SUBSTANCES BURNED. MIXED. Analytical Chemistry Module I  Complete or Ultimate Analysis CATEGORIES OF The amount of all constituents in the sample were determined. QUALITATIVE Elemental/Molecular Analysis Refer to the determination of the amount of elements and molecules. ANALYSIS Partial Analysis Deals with only few constituents are determined. Major/Macro Analysis Implies that constituents is in high concentraiton. Trace Analysis Constituents to be determined are in low concentration. Analytical Chemistry Module I Analytical Chemistry | Module I TYPES OF ANALYSIS IN SAMPLE SIZE TYPES OF CONSTITUENTS AND ANALYTE LEVEL Analytical Chemistry Module I QUANTITATIVE METHODS OF CHEMICAL ANALYSIS QUATITATIVE METHOD DESCRIPTION GRAVIMETRY It uses the mass of the analyte or some compound related to it. Also called “Titrimetry”, it measures the volume of the solution VOLUMETRY containing sufficient reagent to react completely with the analyte. Based between electromagnetic radiation or analyte atoms or SPECTROSCOPY molecules or on the production of such radiation by analyte. It involves the measurement of such electrical properties as ELECTROANALYTICAL potential, current, resistance and quantity of electrical charge. Measurements of such quantities as mass to ratio charge of MISCELLANEOUS GROUP OF METHOD molecules by mass spectrometry, rate of radioactive decay, etc. STEPS OF QUANTITATIVE Analytical Chemistry | Module I ANALYSIS Choosing a Method A crucial first step in any quantitative investigation that calls for both experience and intuition. The desired level of accuracy is one of the initial factors to be taken into account throughout the selection process. Acquiring Samples An analysis must be conducted on the sample that has the same composition as the majority of the material. A sample weighing roughly one gram will be used for the assay. Preparing Samples Under most circumstances, the sample must be process in any of a variety of different ways. 01 Preparing laboratory samples 06 Calculating results A solid laboratory sample is ground to reduce particle size, These are done by the stoichiometry of the analytical combined to guarantee homogeneity, and kept for varying reactions, the parameters of the measurement devices, and amounts of time. the actual experimental data gathered. 02 Defining replicate samples 07 Evaluating result by estimating reliabilty Replication raises the standards of the findings and adds If the experimenter wants the data to have any meaning, they a level of dependability. must quantify the uncertainty surrounding the computed results. Preparing solutions Calibrating/measuring concentration 03 08 These are species that alter the final measurement by The majority of analyses are carried out in solutions of a sample created with an appropriate solvent. boosting or attenuating the quantity being measured, leading to errors in analysis. 04 Eliminating interference 09 Calculating results These are species that alter the final measurement by These are done by the stoichiometry of the analytical boosting or attenuating the quantity being measured, reactions, the parameters of the measurement devices, and leading to errors in analysis. the actual experimental data gathered. 05 Calibrating/measuring concetration 10 Evaluating results by estimating reliabilty If the experimenter wants the data to have any meaning, The final measurement X of the analyte's physical or they must quantify the uncertainty surrounding the chemical characteristic determines the outcome of computed results. every analytical test. Analytical Chemistry Module I Analytical Chemistry Module I 1.4 TOOLS OF ANALYTICAL CHEMISTRY Analytical chemistry is a core set of operations and equipment that is necessary for laboratory work in the discipline and that serves as a foundation for its growth and development. The purity of reagents has an important bearing on the accuracy attained in any analysis. Analytical Chemistry Module I CHEMICAL CLASSIFICATIONS Chemicals in the reagent grade range from 96 to 98 Reagent-grade percent purity, or nearly ACS grade purity. The provider has thoroughly examined primary standard Primary Standard-grade grade reagents, and the assay is printed on the label of the container. Purity has been established by chemical analysis and Secondary Standard-grade serves as reference material for titrimetric methods. Included among these are solvents for spectrophotometry Special Purpose Reagent Chemicals and high performance liquid chromatography. Analytical Chemistry Module I IMPORTANT REQUIREMENTS OF PRIMARY STANDARD High purity Atmospheric stability Absence of hydrate water so that the compound of the solid does not change in variation and humidity Modest cost Reasonable solubility in the titration medium Reasonably large molar mass so that the relative error associated with weighing the standard is minimized Analytical Chemistry Module I SAFETY RULES FOR HANDLING REAGENTS AND SOLUTIONS Select the best grade of chemical available for analytical work. Replace the top of every container immediately after removal of the reagents; do not rely on someone else to do this. Hold the stoppers of reagents between your fingers; never set a stopper on a desktop. Unless specifically directed otherwise, never return any excess reagent to a bottle. Unless directed otherwise, never insert spatulas, spoons, or knives into a bottle that contains a solid chemical. Keep the reagent shelf and the laboratory balance clean and neat. Observe local regulations concerning the disposal of surplus reagents and solutions Analytical Chemistry Module I CLEANING AND MARKING OF LABORATORY WARE 1.Flasks, beakers and some crucibles have small etched areas on which semi-permanent markings can be made with a pencil. 2.Special marking inks are available for porcelain surfaces. The marking is baked permanently into the glaze by heating at a high temperature. 3.An organic solvent, such as benzene or Flask Beaker acetone, may be effective in removing grease.  Analytical Chemistry Module I EVAPORATION OF LIQUIDS Evaporation is the process by which a liquid turns into a gas. This happens when the liquid is heated and its molecules escape into the air as a gas, called water vapor. It is frequently difficult to control because of the tendency of some solutions to overheat locally. To reduce the risk of bumping, which could result in a partial loss of solution, careful and gentle heating will be used. Bumping is reduced by using glass beads. Evaporation of Liquid set-up  Analytical Chemistry Module I DURING EVAPORATION, SOME UNWANTED SPECIES CAN BE ELIMINATED LIKE: 1. Chloride and nitrate can be removed from a solution by adding sulfuric acid and evaporating until copious white fumes of sulfur trioxide are observed. 2. Urea is effective in removing nitrate ion and nitrogen oxides from acidic solutions. 3. Ammonium chloride is best removed by adding concentrated nitric acid and evaporating the solution to a small volume. 4. Ammonium ion is rapidly oxidized when it is heated; the solution is then evaporated to dryness. Analytical Chemistry Module I MEASURING MASS The analytical balance is the tool used to measure mass with a maximum capacity ranging from 1 gram to a few kilograms and precision of at least 1 part in 105 up to 106 at full capacity. Consult with your instructor for detailed instructions on weighing with your particular model of balance. Analytcal Balance Analytical Chemistry | Module I PRECAUTIONS USING A BALANCE 1. Center the load on the pan as well as possible. 2. Protect the balance from corrosion. Objects to be placed on the pan should be limited to non-reactive metals, non-reactive plastics and vitreous materials. 3. Consult the instructor if the balance appears to need adjustment. 4. Keep the balance and its case scrupulously clean. A camel’s – hair brush is useful for removing spilled material or dust. 5. Always allow an object that has been heated to return to room temperature before weighing it. 6. Use tongs or finger pads to prevent the uptake of moisture by dried objects. Analytical Chemistry Module I TYPES OF ANALYTICAL BALANCE Analytical Balance Capacity/Operations Precisions Macrobalances 160-200 grams ±0.1 mg Semi-micro Analytical 10-30 grams ±0.01 mg Micro-analytical 1-3 grams ± 0. 001mg or 1 μg Equal Arm Balance Up to 2000 grams 1 gram sensitivity Single Pan Analytical Balance Usually, 110-160 grams ±0.1 mg Electronic Analytical Balance Usually, 100-600 grams 0.1 mg – 0.001 mg Auxilliary Balance Top Loading 150-200 grams up to 25,000 grams ±1 mg, ±0.05 gram. Triple Beam 2610 grams 0.1 gram  Analytical Chemistry Module I SOURCES OF ERROR IN WEIGHING 1. Bouyancy When the things being weighed have a materially different density from the masses, a weighing error occurs. Equations can provide buoyancy correction for electronic balances. Where is the corrected mass of the object, is the mass of the standard masses, is the density of the object, is the density of the masses, and is the density of the air displaced by them; has a value of 0.0012  Analytical Chemistry Module I SOURCES OF ERROR IN WEIGHING 2. Temperature A large inaccuracy will occur when an object's temperature differs from that of its surroundings. A heated object must have enough time to cool to normal temperature in order to reduce mistakes. Both inaccuracies will involve lower item masses, which could be as little as 10 or 15 mg for a normal porcelain filtering crucible or weighing container. Plot of the Absolute error against the Time after removal from oven at 110°C  Analytical Chemistry Module I SOURCES OF ERROR IN WEIGHING There are two sources of temperature-related error: A. Convection currents within the balance case exert a buoyant effect on the pan and object. B. Warm air trapped in a closed container weighs less than the same volume at a lower temperature. 3. Static Charge When a porcelain or glass object develops static charge, especially in a low humidity environment, a low-level radioactive source in the balance will produce enough ions to discharge the charge. A little damp chamois can also be used to clean the item.  EQUIPMENT AND MANIPULATIONS IN WEIGHING Analytical Chemistry | Module I 1. Weighing Bottles 2. Desicators & Desicants Dry materials are kept in Weighing bottles is a simple tool desiccators while cooling to reduce for drying solids with a ground glass moisture absorption. It reduce the section of a cap-style bottle and do possibility of disrupting the sample. not in contact with the contents, By applying light rotation and there is no chance, the sample will downward pressure on the lid's fall to the surface and be lost. position, an airtight seal is created.  Analytical Chemistry | Module I 3. Filtration and Ignition Solids Simple Crucibles Filtering Crucibles Filter Paper This transforms a precipitate Crucibles used for filtering It is a very important filtering into an appropriate weighing act as both containers and medium. Ashless paper is used form at constant mass. A filters. A vacuum is employed to for samples that ignites. The laboratory glassware used to speed up the filtration, and a important parameters are wet heat, melt, or mix solid chemical variety of rubber adaptors can strength, particle retention, compounds over a burner. be used to create a tight seal. efficiency and capacity. Analytical Chemistry Module I COMPARISON OF FILTERING MEDIA FOR GRAVIMETRIC ANALYSIS Analytical Chemistry Module I HEATING EQUIPMENT The heating equipment can be used are the following: 1. Low temperature drying runs between 1400°C and 260°C, with an acceptable drying temperature of 110°C. Forced circulation was used to dry solids, but another advancement was the flow of pre- dried air through an oven built to function in a partial vacuum. 2. Microwave laboratory ovens are currently quite popular since it shortens drying cycles. It uses electromagnetic waves in the dying of the sample. 3. An ordinary heat lamp can be used to dry a precipitate that has been collected on ashless paper and to char the paper as well. 4. Burners are practical places to get a lot of heat. The greatest temperature that can be reached is determined by the burner's design and the fuel's ability to burn.  Analytical Chemistry Module I MEASURING VOLUME The unit measure of volume is liter (L). A 1-L volume is equivalent to 1000 mL, and. The following are the apparatus for volume measurements: 1. Pipettes Permit the transfer of accurately known volumes from one container to another. A volumetric or transfer pipe delivers a single or fixed volume between 0.05 and 200 mL, color coded by volume for convenience in identification and sorting. Measuring pipes are calibrated in convenient units to permit delivery of any volume up to a maximum capacity of 0.1to 25 mL.  CHARACTERISTICS OF PIPETS Analytical Chemistry Module I  Analytical Chemistry Module I MEASURING VOLUME 2. Burettes 3. Volumetric Flask it can achieve a These are produced in degree of precision that sizes ranging from 5 mL to 5 is significantly higher L, and they are often than a pipet can. A calibrated to hold a burette is made up of a particular volume when valve system for filled to a line etched on the controlling the flow of neck. titrant and a calibrated tube to retain the titrant.  READING VOLUMES OF LIQUID Analytical Chemistry | Module I When a liquid is contained in a small tube, the top surface displays a distinct curve, or meniscus. It is customary to calibrate and operate volumetric equipment by using the meniscus's bottom as a point of reference. Holding a transparent card or piece of paper behind the graduations will help you determine this minimum with more precision. Method Reading Reading The student reads the burette from a 12.58 mL position above a line perpendicular to 2. Burettes the buretteit can andachieve makes a degree of precision that is significantly higher than a pipet can. A burette is made up of a valve a reading. system for controlling the flow of titrant and a calibrated tube to retain the titrant. The student reads the burette from a 12.62 mL position along a line perpendicular to the burette and makes a reading. The student reads the burette from a 12.67 mL position above a line perpendicular to the burette and makes a reading.  Analytical Chemistry Module I CLEANING OF APPARATUS Pipet. Draw detergent solution 2 to 3 cm over the calibration mark using a rubber bulb. Filled the pipet in various portions with tap water. Examine the flange breaks, then repeat this step. Finally, carefully spin the pipet after filling it with distilled water to about 1/3 of its capacity. Rinse this area at least twice more. Burettes. Clean the burette tube completely with detergent and a broad brush. Rinse completely with distilled water is used after using tap water. Look for water leaks. Whenever necessary, repeat the procedure. Volumetric flask. The grease and grime that cause water breaks may typically be removed with a quick soak in a warm detergent solution. It is best to avoid prolonged soaking since a harsh detergent air interface is likely to develop into an area or ring. The equipment needs to be completely rinsed with tap water after cleaning it, and then it needs to be rinsed with three or more parts of distilled water. Analytical Chemistry Module I LABORATORY NOTEBOOK All the data and observations must be directly record to the notebook. Neatness is desirable but must achieve neatness by transcribing data from one notebook to another because it might cause an error. Supply entry or series of entries with heading or labels. Never attempt to erase or obliterate an incorrect entry. Provide date and number for each page of the notebook used. Never remove a page from the notebook. Draw a diagonal line if the page is not being used or wrong entry.  SAFETY IN THE LABORATORY At the outset, learn the Avoid getting these location of the liquids on your skin. In nearest eye fountain, the event of such tire blanket, shower, contact, drench the affected area with a and fire extinguisher. lot ofwater right away. At all times, protect your eyes by wearing NEVER perform an proper eye protection unauthorized due to the risk of serious experiment. and even permanent eye damage.  SAFETY IN THE LABORATORY Always use a bulb or Never work alone in other device to draw the laboratory; be liquids into a pipet: certain that someone NEVER use your mouth is always earshot. to provide suction. Never bring food or Wear adequate beverages into the foot covering laboratory. (no sandals).  SAFETY IN THE LABORATORY Be extremely tentative Use fume hoods in touching objects whenever toxic or that have been noxious gasses are heated. likely to be evolved. Always fire-polish the ends of freshly cut- Notify your glass tubing. NEVER instructor attempt to force immediately in the glass tubing through event of an injury. the hole of a stopper.  Analytical Chemistry Module I ERRORS IN CHEMICAL ANALYSIS ERRORS AND UNCERTAINTIES invariably involved in measurements. The term error has two slightly different meaning: 1. Refers to the difference between the measured value and the true “known” value. 2. Denotes the estimated uncertainty in a measurement or experiment. Usually, faulty calibrations or standardizations are those which frequently cause errors. Also, measurement errors are an inherent part of the world we live; hence it is impossible to do an experiment with a free error. The effect of error in the analytical data is illustrated in Fig. 1.18.  Analytical Chemistry Module I Fig 1.18 Results from six replicate determinations of in aqueous samples of a standard solution We justify the extra effort required to analyze several samples in two ways. 1. The central value of a set should be more reliable than any of the individual results. 2. An analysis of the variation in data allows us to estimate the uncertainty associated with the central result.  ERRORS IN CHEMICAL Analytical Chemistry | Module I ANALYSIS Mean and Median The mean, x, is the most frequently employed central value indicator. The sum of replicate measurements is divided by the total number of measurements in the set to produce the mean, often known as the arithmetic mean or the average: Where xi represents the individual values of x making up the set of N replicate measurements. When repeated data are organized by rising or decreasing value, the median is the midway outcome. Both values greater and smaller than the median are equally common. The median can be calculated immediately for results with an odd number of results. The middle pair's mean is used when the number is even.  EXAMPLE 1.1 Analytical Chemistry | Module I Calculate the mean and median for the data shown in Figure 2.9. 2. Burettes it can achieve a degree of precision that is significantly higher than a pipet can. A burette is made up of a valve Because the set contains an even number of measurements, the system for controlling the flow of titrant and a calibrated tube to retain the titrant. median is the average of the central pair:  ERRORS IN CHEMICAL ANALYSIS These are frequently used to characterize Precision the precision of a collection of repeated data. These three are based on the The reproducibility of measurements, or the deviation from the mean di, which similarity of outcomes, is referred to as precision. measures how far a particular result xi Typically, a measurement's accuracy is just deviates from the mean; repeating the measurement on replicate samples will provide an easy way to determine. 01 Standard Deviation 02 Variance Coefficient of Variation 03 Analytical Chemistry Module I Analytical Chemistry Module I For example, the relative error for the mean of the data in Figure 1.7 is Accuracy and Precision in a dart board  Analytical Chemistry Module I ERRORS AND UNCERTAINTY The discrepancy between your response and the correct one is what is meant by error. Comparison of data from carefully replicated tests makes determining the precision of a measurement simple. Analyst 1 - Obtained relatively high precision and high accuracy. Analyst 2 - Had poor precision but good accuracy. Analyst 3 - are surprisingly common. The precision is excellent, but there is significant error in the numerical average for the data. Analyst 4 - Both the precision and the accuracy are poor for the results of analyst 4.  Analytical Chemistry Module I Fig 1.20 Absolute error in the micro- Kjeldahl determination of nitrogen. Each dot represents the error associated with a single determination. Each vertical line labeled(xi - xt) is the absolute average deviation of the set from the true value. (Data from C.O. Willits and C.L. Ogg, J. Assoc. Offic. Anal. Chem., 1949, 32, 561. With permission).  TYPES OF ERRORS Analytical Chemistry | Module I 1. Random Error 2. Systematic Error Data are more or less A data set's mean can symmetrically dispersed deviate from the expected around a mean value as a value due to error. As an result of error. Review Fig. illustration, the results in Fig. once more. 1.20 and note The systematic error of 1.19 that analysts 1 and 3 have is approximately -0.2 ppm considerably less data Fe. The data of analysts 3 scatter and, hence, and 4 reveal systematic random error than analysts errors of around 0.7% and 2 and 4. Therefore, the 1.2% nitrogen, compared to precision of a the results of analysts 1 and measurement typically 2 in Fig. 1.20, which have reflects the random error in negligible systematic error. that measurement.  TYPES OF ERRORS Analytical Chemistry | Module I 3. Gross Error There are three types of The most common cause of gross error when utilizing systematic errors: an instrument is human error. For instance, 01 Instrumental Errors Are caused by non-ideal instrument behavior, by analytical results will be faulty calibrations, or by use under inappropriate poor if some precipitate is conditions. lost before weighing. After Method Errors 02 Arise from non-ideal chemical or physical behavior a weighing bottle's empty of analytical systems. mass is established, touching it with your Personal Errors 03 Result from the carelessness, inattention, or personal fingers will result in a high limitations of the experimenter mass reading for any solid that is weighed in the contaminated bottle. Analytical Chemistry Module I THANK YOU FOR LISTENING!