Technique of volumetric analysis

The technique of volumetric analysis is the simplest type of titrimetry, and... 

Part—I has three chapters that exclusively deal with General Aspects of pharmaceutical analysis. Chapter 1 focuses on the pharmaceutical chemicals and their respective purity and management. Critical information with regard to description of the finished product, sampling procedures, bioavailability, identification tests, physical constants and miscellaneous characteristics, such as ash values, loss on drying, clarity and color of solution, specific tests, limit tests of metallic and non-metallic impurities, limits of moisture content, volatile and non-volatile matter and lastly residue on ignition have also been dealt with. Each section provides adequate procedural details supported by ample typical examples from the Official Compendia. Chapter 2 embraces the theory and technique of quantitative analysis with specific emphasis on volumetric analysis, volumetric apparatus, their specifications, standardization and utility. It also includes biomedical analytical chemistry, colorimetric assays, theory and assay of biochemicals, such as urea, bilirubin, cholesterol and enzymatic assays, such as alkaline phosphatase, lactate dehydrogenase, salient features of radioimmunoassay and automated methods of chemical analysis. Chapter 3 provides special emphasis on errors in pharmaceutical analysis and their statistical validation. The first aspect is related to errors in pharmaceutical analysis and embodies classification of errors, accuracy, precision and makes... 

Acid-base titrations are an example of volumetric analysis, a technique in which one solution is used to analyze another. The solution used to carry out the analysis is called the titrant and is delivered from a device called a buret, which measures the volume accurately. The point in the titration at which enough titrant has been added to react exactly with the substance being determined is called the equivalence point, or the stoichiometric point. This point is often marked by the change in color of a chemical called an indicator. The titration procedure is illustrated in Fig. 4.18. 

It must swell extensively in the solvents used for synthesis, allowing all reagents to penetrate readily throughout the particles of the polymer. Interactions of the dry polymeric matrix with appropriate solvents often lead to dramatically expanded structures. The extent of swelling may be quantitated by a variety of techniques, including volumetric analysis [9-13], gravimetric analysis after centrifugation or rapid filtration [14,15], direct microscopic examination... 

Qualitative Analysis involves determining the nature of a pure unknown compound or the compounds present in a mixture. Quantitative Analysis involves measuring the proportions of known components in a mixture, and the chemical techniques include volumetric analysis and gravimetric analysis. Instrumental Analysis include several physical techniques including spectroscopic techniques, mass spectrometry, polarography, nuclear magnetic resonance, etc. 

The most popular device for fluoride analysis is the ion-selective electrode (see Electro analytical techniques). Analysis usiag the electrode is rapid and this is especially useful for dilute solutions and water analysis. Because the electrode responds only to free fluoride ion, care must be taken to convert complexed fluoride ions to free fluoride to obtain the total fluoride value (8). The fluoride electrode also can be used as an end poiat detector ia titration of fluoride usiag lanthanum nitrate [10099-59-9]. Often volumetric analysis by titration with thorium nitrate [13823-29-5] or lanthanum nitrate is the method of choice. The fluoride is preferably steam distilled from perchloric or sulfuric acid to prevent iaterference (9,10). Fusion with a sodium carbonate—sodium hydroxide mixture or sodium maybe required if the samples are covalent or iasoluble. 

However, it is pertinent to mention here that quite a few techniques related to measurement of pharmaceutical substances and reagents involved is more or less common to both gravimetric and volumetric analysis. Besides, in gravimetric analysis, some more additional techniques play a vital role, namely precipitation, filtration, washing of the precipitate and ignition of the precipitate. 

FIGURE 13.5 Calorimetric and volumetric data obtained from adsorption calorimetry measurements Raw pressure and heat flow data obtained for each dose of probe molecule and Thermokinetic parameter (a), Volumetric isotherms (b), Calorimetric isotherms (c), Integral heats (d), Differential heats (e), Site Energy Distribution Spectrum (f). (From Damjanovic, Lj. and Auroux, A., Handbook of Thermal Analysis and Calorimetry, Further Advances, Techniques and Applications, Elsevier, Amsterdam, 387-438, 2007. With permission.)... 

One of the most common laboratory techniques for determining the concentration of a solute is titration. Titrations are used daily to monitor water purity and blood composition, and for quality control in the food industry. The solution being analyzed is called the analyte, and a known volume is transferred into a flask. Then a solution containing a known concentration of reactant is measured into the flask from a narrow calibrated cylinder called a buret until all the analyte has reacted (Fig. L.2). The solution in the buret is called the titrant, and the difference between the initial and final volume readings of the buret tells us the volume of titrant that has drained into the flask. The determination of concentration or amount by measuring volume is called volumetric analysis. 

Some of this theoretical thinking may be utilized in reactor analysis and design. Illustrations of gas-liquid reactors are shown in Fig. 19-26. Unfortunately, some of the parameter values required to undertake a rigorous analysis often are not available. As discussed in Sec. 7, the intrinsic rate constant kc for a liquid-phase reaction without the complications of diffusional resistances may be estimated from properly designed laboratory experiments. Gas- and liquid-phase holdups may be estimated from correlations or measured. The interfacial area per unit reactor volume a may be estimated from correlations or measurements that utilize techniques of transmission or reflection of light, though these are limited to small diameters. The combined volumetric mass-transfer coefficient kLa, can be also directly measured in reactive or nonreactive systems (see, e.g., Char-pentier, Advances in Chemical Engineering, vol. 11, Academic Press, 1981, pp. 2-135). Mass-transfer coefficients, interfacial areas, and liquid holdup typical for various gas-liquid reactors are provided in Tables 19-10 and 19-11. 

Figure 1.7 shows the physisorption isotherm, obtained using the non continuous volumetric technique, of a mesoporous alumina (type IV isotherm) and the results of analysis procedures (BET transform, /-curve, BJH porous distribution). This solid presents a specific surface area of approximately 200 m /g with the narrow pore size distribution at around 10 nm. The shape of the /-curve shows that it does not contain any micropores. 

Volumetric analysis, also known as titrimetric analysis, is a quantitative technique used to determine the amount of a particular substance in a solution of unknown composition. 

High Pressure Ion Chromatography is a relatively recent (1975) and immensely significant development of conventional ion exchange chromatography by Small and co-workers of The Dow Chemical Company. This technique has revolutionized instrumental wet chemical analysis in that micro-amounts of an ion or mixtures of ions may be separated and assessed quantitatively in a matter of minutes compared with hours using traditional techniques. Accurate volumetric dispensing methods means that a quantitative analysis of ions may be achieved whatever their initial concentration. 

This chapter will deal with volumetric analysis, that is analysis carried out by the accurate measurement of volumes. To measure volumes accurately, use must be made of volumetric glassware. There are three pieces of volumetric glassware that are fundamental to successful volumetric analysis. These are the volumetric flask, the pipette and the burette, and each will be described below (see Figure 6.1). It should be stated, however, that no amount of reading about these pieces of apparatus (no matter how eloquently written ) is sufficient to educate a student. Analytical pharmaceutical chemistry is first and foremost a practical subject, and the laboratory is the best place to get to grips with the techniques required for consistent, reproducible analysis. 

While TMA is one of the older and simpler forms of thermal analysis, its importance is in no way diminished by its age. Advances in DSC technology and the appearance of dynamic mechanical analysis (DMA) as a common analytical tool have decreased the use of it for measuring glass transitions, but nothing else allows the measurement of CTE as readily as TMA. In addition, the ability to run standardized material test methods at elevated temperatures easily makes TMA a reasonable alternative to larger mechanical testers. As the electronic, biomedical, and aerospace industries continue to push the operating limits of polymers and their composites, this information will become even more important. During the last 5 years a major renewed interest in dilatometry and volumetric expansion has been seen. Other thermomechanical techniques will also likely be developed or modernized as new problems arise. 

If neither speed of analysis nor continuous analysis is required, the volumetric or manometric techniques may be employed. The volumetric method of gas analysis is based on the selective chemical absorption of components of the gas mixture, first CO2 and then O2. The change in volume, at constant... 

By measuring the volumes of the solutions that have reacted together, and using the balanced equation for the reaction, the unknown solution concentration can be determined. If carried out carefully, volumetric analysis is quite an accurate technique and a skilled worker should determine an unknown concentration within an error of no more than 0.2%. 

Many methods have been developed to access the extent of oxidative deterioration, which are related to the measurement of the concentration of primary or secondary oxidation products or of both. The most commonly used are peroxide value (PV) that measures volumetrically the concentration of hydroperoxides, anisidine value (AV), spectrophotometric measurement in the UV region and gas chromatographic (GC) analysis for volatile compounds. Vibrational spectroscopy, because of its high content in molecular structure information, has also been considered to be useful for the fast measurement of lipid oxidation. In contrast to the time consuming chromatographic methods, modem techniques of IR and Raman spectrometry are rapid and do not require any sample preparation steps prior to analysis. These techniques have been used to monitor oil oxidation under moderate and accelerated conditions and the major band changes have been interpreted. ... 

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