Characterization of The Permeation Properties of Membrane Filters and Sorption Properties of Sorbents Used for Polar Organic Chemical Integrative Samplers.

Polar organic chemical integrative samplers (POCIS) are promising devices for measuring the time-weighted average concentrations of hydrophilic compounds in aquatic environments. However, the mechanisms underlying compound uptake by POCIS remain unclear. We investigated the permeation kinetics of polyethersulfone and polytetrafluoroethylene membrane filters, and the sorption kinetics of Oasis HLB (Waters), Envi-Carb (Supelco), and Oasis WAX (Waters) sorbents.

Investigation of variability in the matrix effect on stable isotope-labeled internal standards in liquid chromatography-tandem mass spectrometry analysis of 25 pesticides in vegetables.

The matrix effects (ME) in simultaneous analysis of pesticide residue using liquid chromatography-tandem mass spectrometry (LC-MS/MS) were evaluated by comparing the slopes of matrix-matched and reagent-only calibrations of four types of vegetable samples. Both the sampling and measurement variances of the ME were also determined using one-way analysis of variance. Substantial ion suppression (ME<-20%) was observed in komatsuna, spinach, and tomato when a modified Japanese official method was implemented.

Development and Calibration of the Polar Organic Chemical Integrative Sampler (POCIS) for Neonicotinoid Pesticides.

Neonicotinoid pesticides are highly hydrophilic systemic insecticides that have been extensively used worldwide. To evaluate their environmental risks, the concentrations of these pesticides in the aquatic environment must be monitored. Although the polar organic chemical integrative sampler (POCIS) has proved to be a suitable passive sampler for many highly hydrophilic compounds, Oasis HLB (Waters) POCIS has shown limitations for the monitoring of neonicotinoid pesticides, such as short linear uptake ranges.

Simultaneous analysis of seven neonicotinoid pesticides in agricultural products involving solid-phase extraction and surrogate compensation using liquid chromatography-tandem mass spectrometry.

This study proposes a practical and precise method for the simultaneous analysis of seven neonicotinoid pesticides in agricultural products using liquid chromatography-tandem mass spectrometry from two different approaches. First, the applicability of a cleanup cartridge, comprised of a polymer sorbent consisting of a styrene-divinylbenzene copolymer with N-containing polar groups and methacrylate, in food samples was demonstrated for the first time. Second, applying an internal standard (IS) calibration method at a lower cost was considered by changing the timing of the IS addition and selecting the minimum number of ISs by referring on the matrix effect.