These methods are intended to promote accuracy, sensitivity, and specificity in industrial hygiene analyses. There will be situations where users of the NIOSH methods will need to modify them (e.g., to accommodate interfering compounds from the workplace, to take advantage of special capabilities of the laboratory, to make possible the analysis of a single sample for several contaminants). When method modifications are made, quality control data showing the reliability of the modified method should be obtained.
- The volume of air sampled on solid sorbents should be reduced in cases of high vapor concentration or high humidity and, in some cases, may be increased if such concentrations are relatively low.
- The automation of sample work-up and measurement procedures usually requires some modification of the nonautomated procedure.
- Chromatographic conditions, including choice of column and detector, can be modified to eliminate interferences during measurement.