简介:2.1 Sample preparation procedures vary by analyte group. Extraction of some groups
requires that the pH of the sample be adjusted to a specified value prior to extraction (see Sec.
7.2). Other groups do not require a p简介:2.1 Sample preparation procedures vary by analyte group. Extraction of some groups
requires that the pH of the sample be adjusted to a specified value prior to extraction (see Sec.
7.2). Other groups do not require a pH adjustment.
2.2 Following any necessary pH adjustment, a measured volume of sample is extracted
by passing it through the solid-phase extraction medium (disks or cartridges), which is held in an
extraction device designed for vacuum filtration of the sample.
2.3 Target analytes are eluted from the solid-phase media using an appropriate solvent
(see Secs. 7.8 and 7.9) which is collected in a receiving vessel. The resulting solvent extract is
dried using sodium sulfate and concentrated, as needed.
2.4 As necessary for the specific analysis, the concentrated extract may be exchanged
into a solvent compatible extract with subsequent cleanup procedures (Chapter Four, Sec. 4.2) or
determinative procedures (Chapter Four, Sec. 4.3) for the measurement of the target analytes.详细>