Rapid screening for pesticides using automated online sample preparation with a high-resolution benchtop Orbitrap mass spectrometer.

For pesticide analysis in food products a common approach is to develop a fast multi-residue method that is capable of identifying and quantifying a large number of analytes in various matrices. This study demonstrates rapid screening and accurate mass confirmation of 116 pesticides in oranges and hazelnuts using an automated online sample preparation method with turbulent-flow chromatography technology coupled to a high-resolution benchtop Orbitrap™ mass spectrometer. The limits of quantification (LOQs) for the majority of analytes are well below the maximum residue limit (MRL) set by the European Union and the Japanese government. The recoveries were in the range of 70-120% for over 75% of analytes in both matrices. The present methodology is suitable for routine pesticides analysis in food safety laboratories.

Rapid screening method for detection of bacteria in platelet concentrates.

Public awareness has long focused on the risks of the transmission of viral agents through blood product transfusion. This risk, however, pales in comparison to the less publicized danger associated with the transfusion of blood products contaminated with bacteria, in particular, platelet concentrates. Up to 1,000 cases of clinical sepsis after the transfusion of platelet concentrates are reported annually in the United States. The condition is characterized by acute reaction symptoms and the rapid onset of septicemia and carries a 20 to 40% mortality rate. The urgent need for a method for the routine screening of platelet concentrates to improve patient safety has long been recognized. We describe the development of a rapid and highly sensitive method for screening for bacteria in platelet concentrates for transfusion. No culture period is required; and the entire procedure, from the time of sampling to the time that the final result is obtained, takes less than 90 min. The method involves three basic stages: the selective removal of platelets by filtration following activation with a monoclonal antibody, DNA-specific fluorescent labeling of bacteria, and concentration of the bacteria on a membrane surface for enumeration by solid-phase cytometry. The method offers a universal means of detection of live, nondividing, or dead gram-negative and gram-positive bacteria in complex cellular blood products. The sensitivity is higher than those of the culture-based methods available at present, with a detection limit of 10 to 10(2) CFU/ml, depending upon the bacterial strain.

Baseline studies in the Slave River, NWT, 1990-1994: Part II. Body burden contaminants in whole fish tissue and livers.

The Northwest Territories section of the Slave River is the recipient of chemical compounds from a variety of sources, including upstream industry and agriculture. In 1990, concerned government agencies formulated a practical, focussed, and comprehensive environmental monitoring program to assess contamination in the river and the Slave River Environmental Quality Monitoring Program was established. The program was designed to respond to the distinct requirements of two major monitoring goals. The first priority was to ascertain whether the fish in the Slave River were safe to eat. The second goal was to establish a baseline data set with which to compare future effects from upstream activities and long-range transport of contaminants. From the data gathered in the present study, it appears that whole tissue of fish (muscle) is fit for human consumption. Throughout the monitoring period, consistently low concentrations of organochlorine pesticides, PCBs, dioxin and furan isomers, PAHs, chlorinated phenolics, and heavy metals have been observed and median concentrations have all been below federal fish consumption advisories. Also, the numerous data values below analytical detection limits attest to the relatively uncontaminated nature of the fish. These results were comparable with other studies conducted on arctic animals. The heavy metals observed in fish tissue are probably of natural origins, since inorganic analyses of suspended sediment in the Slave River indicated relatively elevated levels, with no known anthropogenic source. While the present study concluded that contaminant levels in whole fish are low, toxaphene levels in burbot livers should continue to be monitored since concentrations were consistently above fish consumption advisories during the monitoring and are eaten extensively by the native peoples. The second goal of the monitoring program was to develop a baseline data set and the values tabled in the current paper are useful in establishing a foundation for future comparison.

Physicochemical and immunological characterization of the type E botulinum neurotoxin binding protein purified from Clostridium botulinum.

Type E botulinum neurotoxin is produced by Clostridium botulinum along with a neurotoxin binding protein which helps protect the neurotoxin from adverse pH, temperature, and proteolytic conditions. The neurotoxin binding protein has been purified as a 118-kDa protein. Secondary structure content of the neurotoxin binding protein as revealed by far-UV circular dichroism spectroscopy was 19% alpha-helix, 50% beta-sheets, 28% random coils, and 3% beta-turns. This compared to 22% alpha-helix, 44% beta-sheets, 34% random coils, and no beta-turns of the type E botulinum neurotoxin. The complex of the two proteins revealed 25% alpha-helix, 45% beta-sheets, 27% random coils, and 3% beta-turns, suggesting a significant alteration at least in the alpha-helical folding of the two proteins upon their interaction. Tyrosine topography is altered considerably (28%) when the neurotoxin and its binding protein are separated, indicating strong interaction between the two proteins. Gel filtration results suggested that type E neurotoxin binding protein clearly complexes with type E neurotoxin. The interaction is favored at low pH as indicated by an initial binding rate of 8.4 min-1 at pH 5.7 compared to 4.0 min-1 at pH 7.5 as determined using a fiber optic-based biosensor. The neurotoxin and its binding protein apparently are of equivalent antigenicity, as both reacted equally on enzyme-linked immunosorbent assay to polyclonal antibodies raised against the toxoid of their complex.