Development of an inline cleaning procedure and a concentration method for analyzing low levels of organophosphate flame retardants and plasticizers in sediment

Abstract

To minimize the background contamination of organophosphate flame retardants and plasticizes (OPFPs) during sediment analysis, an inline cleaning procedure was developed to clean materials (extraction cell, glass fiber filters, diatomic earth, and aluminum oxide) involved in sediment extraction using pressurized liquid extraction (PLE). The materials remain in the extraction cell until sediment extraction takes place, at which time the top 5 grams or so diatomic earth was taken out, sediment was added together with the surrogate standard, and extracted. This inline method minimizes transfer and exposure of diatomic earth and aluminum oxide with possible sources of OPFPs in the laboratory. The recovery efficiency of several concentration methods, including slow evaporation in a fume hood to dryness, fast evaporation to 1-2 mL using a gentle stream of nitrogen gas, and slow evaporation to 1-2 mL in the fume hood, were evaluated. Slow evaporation to 1-2 mL in the fume hood resulted in the least loss of OPFPs among the three evaporation methods examined.OPFPs in 10 surficial sediment samples collected in Long Island Sound (LIS) were analyzed. TCPP (chlorinated) had the highest concentration, consistent with its highest usage and its persistency in the environment. TBEP (non-chlorinated) had the second highest concentrations in LIS sediment. The other chlorinated OPFPs, TCEP and TDCP, were also present in most sediment but with much lower concentrations than TCPP. TBP and TPP (both non-chlorinated) were only detected in one or two sediment samples with very low concentrations, consistent with their high degradability. Generally speaking, western LIS sediment is more contaminated with OPFPs than eastern LIS, possibly due to higher number of wastewater treatment plants in west part of LIS