SOLID-PHASE EXTRACTION (SPE)

2.1 A measured volume of sample is adjusted to a specified pH (see Table 1) and then extracted using a Solid-phase Extraction (SPE) device. 2.2 Target analytes are eluted from the solid-phase media using methylene chloride or other appropriate solvent. The resulting solvent extract is dried using sodium sulfate and concentrated. 2.3 The concentrated extract may be exchanged into a solvent compatible with subsequent cleanup procedures (Chapter Four, Sec. 4.2) or determinative procedures (Chapter Four, Sec. 4.3) employed for the measurement of the target analytes.