ABSTRACT

The basic rule of sampling for solids is that the variability due to sampling becomes greater as the particle size of the material becomes greater, as the sample size becomes smaller, and as the concentration of the analyte becomes more variable from particle to particle. Solid samples often require reduction of particle size before analysis. A soil with a pH below 4 may contain free acids from processes such as the oxidation of sulfides. The preparation of soil or sludge samples for metals analysis is similar to that used for extraction of metals from air aerosol filters. Background levels of mercury in soil can be between 30 and 80 ng/gm, but mercury contamination is quite extensive all over the world. Arsenic and selenium determinations are carried out using the hydride generation method. Portable x-ray fluorescence is becoming popular for on-site solid analysis. The Dumas method is an automated method for the analysis of total nitrogen in solids.