Quantitat ive Analytica l Methods

We compute the results of a typical quantitative analysis from two measurements. One is the mass or the volume of sample being analyzed. The second measurement is of some quantity that is proportional to the amount of analyte in the sample such as mass, volume, intensity of light, or electrical charge. This second measurement usually completes the analysis, and we usually classify analytical methods according to the nature of this final measurement. In gravimetric methods, we determine the mass of the analyte or some compound chemically related to it. In a volumetric method, we measure the volume of a solution containing sufficient reagent to react completely with the analyte. In electroanalytical methods, we measure electrical properties such as potential, current, resistance, and quantity of electrical charge. In spectroscopic methods, we explore the interaction between electromagnetic radiation and analyte atoms or molecules or the emission of radiation by analytes. Finally, in a group of miscellaneous methods, we measure such quantities as mass-to-charge ratio of ions by mass spectrometry, rate of radioactive decay, heat of reaction, rate of reaction, sample thermal conductivity, optical activity, and refractive index.