A Analytical Samples and Methods

Many factors are involved in the choice of a specific analytical method, as discussed in Section lC-1. Among the most important factors are the amount of sample and the concentration of the analyte. 

Analytical methods can be classified in many different ways. Often we distinguish a method of identifying chemical species, a qualitative analysis, from one that deteiTnines the amount of a constituent, a quantitative analysis. Quantitative methods, as discussed in Section IB, are traditionally classified as gravimetric. 

Determination of Hg in the ppb to pspm range in a 1-p.L ( I mg) sample of river water would be a micro analysis of a trace constituent. Determinations of trace and ultratrace constituents are particularly demanding because of potential interferences and contaminations. In extreme cases, determinations must be per- 

The analysis of real samples is complicated by the presence of the sample matrix. This matrix can contain species that have chemical properties similar to the analyte. Such species can react with the same reagents as the analyte or they can 

As discussed in Section 1C, samples are analyzed, but species or concentrations are determined. Hence, we can correctly discuss the determination of glucose in blood serum or the analysis of blood serum for glucose. 

---