The use of gas chromatography with ion-trap MS/MS detection for the determination of planar PCBs in biota and sediment

Combining capillary GC with ion-trap detection in the MS/MS mode allows the determination of trace levels of the highly toxic PCB congeners, CB 77, 126 and 169 in complex biological tissues, suspended matter and sediment. The high selectivity and sensitivity of MS/MS detection in the resonant and non-resonant modes yield detection limits of 60 fg, 300 fg and 200 fg for CB 77, 126, and 169, respectively.     

Bioavailability to rats of bound [14C] pirimiphos-methyl in stored wheat.

Stored wheat treated with radiolabelled pirimiphos-methyl (0-2-diethyl-amino-6-methyl-pyrimidin-4-yl 0,0-dimethyl phosphorothioate) formed bound (nonextractable) 14C residues. Supercritical fluid extraction, gas chromatography and mass spectrometric techniques were used to identify and quantitate the 14C bound residues in wheat grains. The amount of bound 14C residues present after 28 weeks of storage was about 9.9% of the applied radioactivity. Pirimiphos-methyl accounted for 80% of the bound residue. Grain-bound residues were fed to rats for 5 days. After a total period of 8 days a substantially large percentage of the administered bound 14C residues (72.9%) was eliminated in urine while feces contained only 17.9%. Bound pirimiphos-methyl in wheat grain was metabolized in rats by processes involving hydrolysis, N-dealkylation and 0-demethylation. The results indicate that wheat-bound residues of pirimiphos-methyl are highly bioavailable to the rat and may possess a toxicological potential as manifested by a significant reduction in body weight gain.     

Field desorption of ions from electrolytic droplets

The Science of Nature -     

Olfactory and chemical characterization of indoor air. Towards a psychophysical model for air quality

The relationship between the odor strength of total air samples and the odor strengths of the constituents was investigated in three field experiments in an office building and a new preschool. The odor strength was scaled by magnitude estimation according to a master scale principle which results in comparable values for the total and the constituent odors. Between 60 and 120 chemical components were detected by GC/FID in the indoor air samples (N = 66). Most (81%) of the detected components in an air sample were odorous, even though most of them were of the low concentrations. By a method of pattern analysis, chemical as well as odor patterns of indoor air were found to be characteristics of different buildings. From the odor patterns (POG), the “odor print” of the outdoor air associated with the buildings was also recognized in the indoor air. Thus, the “odor print” of an air sample is different from its “chemical print”. A model was found that predicts the overall odor strength of an air sample from the number of FID-detected components most frequently reported to have a strong odor.     

Spatial distribution of polybrominated diphenyl ethers in coastal marine sediments receiving industrial and municipal effluents in Kuwait

Polybrominated diphenyl ether (PBDE) concentrations were measured in surficial sediments from coastal sediments receiving industrial and municipal effluents in Kuwait. The summation PBDE concentrations varied by two orders of magnitude ranging from 80 to 3800 pg g(-1)dw. The congener distribution was dominated by BDE 183, with minor contributions from BDEs 154 and 153. The similarity between the congener profile to that of the technical octa formulation (Bromkal 79-8DE) suggests a source of this product in Kuwait. The observed gradient in concentration distribution, with high summation PBDE concentrations near the shore and an exponential decrease seaward, indicates that wastewater discharge from industrial activities in the study area is the primary source of these compounds in the sediments.