ABSTRACT
Pyrolysis mass spectrometry (PyMS) was investigated as a rapid tool to distinguish potential bioterror hoax materials from samples containing pathogenic bacteria. A pyrolysis time-of-flight (TOF) mass spectrometer equipped with an alternative ionization technique, metastable atom bombardment (MAB), was used to produce sample spectra. These spectra were analyzed by principal component and discriminant analysis for pattern recognition. Materials investigated were two strains of Vibrio parahaemolyticus, one of which produced the tdh toxin, two Salmonella enterica serotypes, a biological mosquito control product containing spores of Bacillus thuringiensis, and several white to off-white powders (which could be used as hoax materials), such as flour, corn starch, methyl cellulose, and xanthan gum. PyMS distinguished bacterial samples from hoax materials. Furthermore, pattern analysis differentiated Vibrios from Salmonellae, Salmonella enterica Anatum from S. enterica Heidelberg, and the two V. parahaemolyticus strains from each other. The B. thuringiensis mixture was distinguished from other bacteria and powders, suggesting that PyMS with pattern recognition may differentiate samples containing pathogens, including Bacillus spp., from nonbiological agents and that it can be a rapid method for detection of bacteria. MS data acquisition took only 7 min for each sample.
Subject(s)
Bioterrorism , Spectrometry, Mass, Fast Atom Bombardment/methods , Bacillus thuringiensis/isolation & purification , Bacterial Typing Techniques , Flour/analysis , Fraud/prevention & control , Hot Temperature , Methylcellulose/analysis , Polysaccharides, Bacterial/analysis , Salmonella enterica/isolation & purification , Sodium Bicarbonate/analysis , Spores, Bacterial/isolation & purification , Starch/analysis , Tartrates/analysis , Vibrio parahaemolyticus/isolation & purificationABSTRACT
A liquid chromatographic (LC) method for determining 14 sulfonamide (SA) (sulfanilamide, sulfadiazine (SDZ), sulfathiazole, sulfapyridine, sulfamerazine (SMR), sulfamethazine (SMZ), sulfamethizole, sulfamethoxypyridazine, sulfachloropyridazine (SCP), sulfamonomethoxine, sulfadoxine, sulfamethoxazole, sulfadimethoxine (SDM), and sulfaquinoxaline (SQX)) residues in edible catfish, shrimp and salmon tissues was developed and validated at 5, 10 or 20 ng g(-1). The method was then used to determine residues in tissues of catfish, shrimp and salmon dosed with six selected sulfonamides (sulfadiazine, sulfamerazine, sulfamethazine, sulfachloropyridazine, sulfadimethoxine and sulfaquinoxaline). All assays were within U.S. Food and Drug Administration guidelines for recovery and intra-assay variability. The method was developed to determine possible sulfonamide residues in aquacultured catfish, shrimp and salmon produced for food.
Subject(s)
Catfishes , Chromatography, High Pressure Liquid/methods , Crustacea , Drug Residues/analysis , Fish Products/analysis , Salmon , Spectrometry, Fluorescence/methods , Sulfonamides/analysis , Animals , Reproducibility of ResultsABSTRACT
Pyrolysis mass spectrometry was investigated for rapid characterization of food-borne bacterial pathogens. Nine isolates of Vibrio parahaemolyticus and one isolate each of Vibrio fluvialis, Vibrio hollisae, and Vibrio vulnificus were analyzed. Pyrolysis mass spectra, generated via an alternative ionization method, metastable atom bombardment, were subject to principal component-discriminant analysis. The spectral patterns were used to distinguish Vibrio isolates differing in species, serotype and expression of the thermostable direct hemolysin gene. The patterns of similarity and dissimilarity amongst spectra in the Vibrio test set generally reflected those associated with species, serotype or hemolysin-producing genes, though the combined influence of these and other variables in the multi-dimensional data did not produce a simple clustering with respect to any one of these characteristics. These results suggested that with enough examples to model the most common combinations, the method should be able to characterize Vibrio isolates according to their phenotypic characteristics. Pyrolysis-mass spectrometry with metastable atom bombardment and pattern recognition appeared suitable for rapid infraspecific comparison of Vibrio isolates. This integrated analytical, pattern-recognition system should be examined further for potential utility in clinical and public health diagnostic contexts.
Subject(s)
Bacterial Typing Techniques , Vibrio/classification , Animals , Discriminant Analysis , Humans , Mass Spectrometry/methods , Pattern Recognition, Automated , Phenotype , Principal Component Analysis , Serotyping , Spectrometry, Mass, Fast Atom Bombardment/instrumentation , Spectrometry, Mass, Fast Atom Bombardment/methods , Time Factors , Vibrio/chemistry , Vibrio/growth & development , Vibrio parahaemolyticus/chemistry , Vibrio parahaemolyticus/classification , Vibrio parahaemolyticus/growth & developmentABSTRACT
Ethinyl estradiol (EE2) is an extremely potent synthetic estrogen and a common component in oral contraceptives. The drug has a well-characterized pharmacological profile and is used as a positive control in toxicological investigations of compounds having estrogenic activity. An analytical method developed for the determination of low microg/kg levels of EE2 in a casein-based rodent diet is presented. A methanol extract of casein diet is purified for instrumental analysis by a 3-fold solid-phase extraction process. The sample extract is derivatized with pentafluoropropionic anhydride to the pentafluoropropionyl product and analyzed by capillary gas chromatography with electron-capture detection. Recoveries of EE2 from casein diet fortified at 5, 10, and 50 microg/kg average 88.8% and have a relative standard deviation (%) of 7.2. The method limit of detection in a casein-based diet is 1 microg/kg.
