Simplified method for determination of polycarbamate fungicide in water samples by liquid chromatography with tandem mass spectrometry following derivatization with dimethyl sulfate.

A simple and sensitive analytical method for the determination of polycarbamate in water samples was developed. In this method, polycarbamate was cleaved under alkaline conditions and derivatized with dimethyl sulfate to methyl dimethyldithiocarbamate (DMDC-methyl) and dimethyl ethylenebisdithiocarbamate (EBDC-dimethyl). After the solid-phase extraction of the resulting methyl derivatives, they were measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS), based on reversed-phase separation and MS/MS detection with positive atmospheric pressure chemical ionization. The absolute recoveries (mean+/-SD) all through the procedure from polycarbamate to DMDC-methyl and EBDC-dimethyl were 62.6+/-4.3 and 73.5+/-5.9%, respectively. The limits of detection and quantification of polycarbamate in the water samples were 0.061 and 0.20 microg/L in the form of DMDC-methyl, and 0.032 and 0.11 microg/L in the form of EBDC-dimethyl, respectively. The method was validated at levels of 0.25, 1.0, and 5.0 microg/L in the tap water and river water samples, and accuracy was achieved in the range of 94-109%. The proposed method can be applied to the determination of trace amounts of polycarbamate in environmental water samples.

Determination of tetrabromobisphenol A in human serum by liquid chromatography-electrospray ionization tandem mass spectrometry.

A method for the determination of tetrabromobisphenol A (TBBPA) in human serum utilizing solid-phase extractions (SPEs) and liquid chromatography (LC) with electrospray ionization tandem MS (MS/MS) has been developed. After purification and concentration of TBBPA using consecutive SPEs on reversed-phase and normal-phase cartridges, the serum sample was subjected to LC. TBBPA was separated on a C18 reversed-phase column by gradient elution with a mixture of water, methanol, and acetonitrile as the mobile phase, and then detected with electrospray ionization MS/MS in negative ion mode. 13C12-TBBPA was suitable as an internal standard for the reproducible determination of TBBPA in human serum samples (5 g). The method has been validated in TBBPA concentration range of 5-100 pg per g serum, and the recoveries in the concentration range were higher than 83.3%. The repeatabilities of the proposed method of non-spiked control serum (6.3 pg per g serum) and spiked serum (added 5-100 pg per g serum) were within 10.0% as relative standard deviations. The limit of quantification (LOQ) for TBBPA was 4.1 pg per g serum, which was corresponded to 0.63 fmol on column.