Bi-Level Passive Monitor Validation: A Reliable Way of Assuring Sampling Accuracy for a Larger Number of Related Chemical Hazards

Abstract

Abstract Validation of passive monitors is essential to ensure accurate determination of airborne chemical levels. To assist manufacturers and users, the National Institute for Occupational Safety and Health (NIOSH) and the Health and Safety Executive (HSE) have developed comprehensive protocols for the validation of passive monitors. These protocols are extensive and costly to perform on individual chemicals, requiring 350 samples. With multiple analyses and standards, this results in nearly 1600 gas chromatographic tests. The present work considers the value of a bi-level validation approach for a series of chemically related compounds, i.e., members of a homologous series. This bi-level approach includes a full protocol validation on key compounds followed by a partial validation on other members of the series. If accurate sampling can be assured by this procedure, then the cost of validation in time and resources can be reduced by 75 percent and many more chemical hazards can be sampled with confidence. Twenty-eight compounds in three homologous series were evaluated on an SKC passive monitor. Full protocol validation was done on six compounds and a partial validation was done on the remaining twenty-two compounds. Studies in the partial validation included sampling rate and capacity, analytical recovery, and interference effects. The underlying premises for bi-level validation were considered. A literature search and laboratory experiments were conducted to verify these premises. The results would indicate that a bi-level validation procedure assures reliable sampling accuracy for the three hydrocarbon series studied and suggests that this technique could be extended to other series.