Determination of organophosphate ester plasticisers in blood donor plasma using a new stir‐bar assisted microporous membrane liquid‐liquid extractor

A new stir‐bar assisted microporous membrane liquid‐liquid extractor (MMLLE) was used for clean‐up of organophosphate esters in blood plasma. The plasma sample was stirred on one side of a planar membrane while the receiving organic phase was continuously pumped on the other side. Recoveries for eight different organophosphate esters were between 30 and 89% and relative standard deviations between 1.2 and 15%. The method limits of detection, when extracting 5 g plasma and analysing the extract with gas chromatography and nitrogen phosphorus detector, were between 0.2 and 0.9 ng g–1 plasma at S/N = 3. The extraction efficiency in terms of analyte mass transfer per time unit through the membrane was shown to be much higher for stir‐bar assisted MMLLE compared to the more commonly used flow‐cell type of membrane extractor. Blood donor plasma collected with three different types of whole blood collection bag system was analysed with respect to organophosphate ester plasticisers. In plasma from one type of bag system, triphenyl phosphate (TPhP) and 2‐ethylhexyl diphenyl phosphate (EHDPP) were detected at concentrations of 0.053–0.13 μg g–1 and 0.73–1.2 μg g–1 plasma, respectively. The main source of the organophosphate esters was found to be the whole blood collection bag system, with some parts containing EHDPP at concentrations of approximately 60 μg g–1. In plasma collected with the other two types of bag systems, no detectable levels of organophosphate esters were found.