Modeling the response of passive samplers to varying ambient fluid concentrations of organic contaminants

Abstract

Passive samplers are an important and versatile adjunct to active sampling methods for air and water. The underlying theory is increasingly mature but is often based on the assumption of constant concentrations with time in the ambient fluid. This theoretical work details the passive sampler response to possible environmental situations in which ambient concentrations vary linearly with time, decrease exponentially with time, constitute a pulsed event, or oscillate regularly with time. The modeled shape of sampler response curve with time is characteristic and can be used to determine how fluid concentrations have changed with time. The sampler elimination rate constant is shown to be crucial in governing sampler response. Thus, by using performance reference compounds and under certain conditions, information from the sampler response can in theory be used to derive specific details of the temporal variation of the contaminant in the ambient fluid. For example, data captured by a passive sampler can be used to characterize a contamination pulse. This extends the versatility of passive samplers.