Environmental analysis.
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Environmental Pollutants↗
Biomedical subjects
G A Eiceman
Publications and source records attributed to G A Eiceman.
Detection of bacteria by ion mobility spectrometry.
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Bacteria↗
Screening of solid commercial pharmaceuticals using ion mobility spectrometry.
Ion mobility spectrometry (IMS) was used to analyze vapors generated directly above pharmaceutical solids warmed in air to 100-200 degrees C. Vapors were characterized by IMS/mass spectrometry to evaluate the air-based atmospheric pressure chemical ionization of components in analgesic medicines. A hand-held IMS was used to determine the suitability of membrane-based instrumentation for routine analyses of large polar molecules. Mobility spectra for seven compounds could be individually represented by single or a few intense product ion peaks. Ion source fragmentations were nonexistent with these pharmaceuticals but complex behavior in the IMS involving ion-molecule clustering was pronounced in certain spectra. Mobility spectra were distinct and recognizable for each compound and binary mixtures of individual ingredients and actual over-the-counter medicines produced mobility spectra suggestive of composite spectra. This work represents a first delineation of complex ion mobility spectra for mixtures using spectra from individual components. These findings support further development of IMS for use in quality control during manufacture of such preparations and in routine screening of powders containing analgesic pharmaceuticals.
Acetaminophen↗
Ion mobility spectrometry of halothane, enflurane, and isoflurane anesthetics in air and respired gases.
Three common gaseous anesthetics, halothane, enflurane, and isoflurane, were characterized by using ion mobility spectrometry (IMS)/mass spectrometry, and the dependence of product ion distributions on temperature and concentration was evaluated. At 40 degrees C and 500 ppb, negative ion mobility spectra in air largely consisted of monomer or dimer adducts with Br- or Cl- formed through dissociative electron capture of molecular neutrals. With increased temperature or decreased vapor concentrations, declustering and dissociation of product ions became pronounced. Ion-molecule reactions in the drift region of the IMS were evident as distortions in peak shape in the mass-resolved mobility spectra and in variable reduced mobilities for the same ions. A portable hand-held IMS was used for convenient, real-time detection of enflurane in respired gases following a controlled inhalation episode.
Air↗
Gas chromatography.
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Chromatography, Gas↗
Hydrocarbons and aromatic hydrocarbons in groundwater surrounding an earthen waste disposal pit for produced water in the Duncan oil field of New Mexico.
Samples of groundwater and soil were collected from test pits placed 25 m intervals on five axes extending from an earthen waste disposal pit for produced water near the San Juan River of northwest New Mexico. Samples were obtained at depths of 1.2 to 1.5 m and were analyzed using GC and GC/MS techniques for purgable hydrocarbons, including benzenes, and for solvent extractable organic compounds. Water samples from test pits down-gradient from the disposal pit contained purgable and extractable hydrocarbons that were similar to contents of the waste disposal pit. In contrast, water samples obtained from test pits up-gradient from the waste pit were free of detectable organic components. Major purgable components in the waste pit and in surrounding groundwater included saturated/unsaturated hydrocarbons and aromatic/alkylated aromatic hydrocarbons. Samples collected 25 m from the waste pit contained concentrations of all compounds greater than in samples taken at 50 m in distance on the same exis. Total concentration of purgable aromatic hydrocarbons in groundwater from test plots ranged from a high of 200 ppb at 25 m, to a low of 12 ppb at 50 m on an axis through the plume center.
Fuel Oils↗
Quantitative investigation of rapid injector port derivatization of amphetamine using trifluoroacetic anhydride with packed and capillary column GC and GC/MS methods.
Direct injector port derivatization of amphetamine through coinjection of sample with trifluoroacetic anhydride was quantitatively investigated and found to be a rapid and more sensitive alternative to longer solution-based derivatization procedures. Under optimum conditions determined in this work, limits of detection were 1 ng using gas chromatography with flame ionization detection and 1 pg using single ion monitoring of ion 140.0 amu (M-91+) in gas chromatography/mass spectrometry methods. The previously reported derivatization period of over 12 hr was greatly reduced using instantaneous derivatization with a 100- to 1000-fold increase in limits of detection. Effects of inlet temperature, mass of trifluoroacetic anhydride, and column pre-treatment on chromatographic performance are reported. Application to analysis of serum from amphetamine-dosed rats was used for comparison to accepted solution-based derivatization.
Acetic Anhydrides↗
Determination of prostaglandin precursors in frog tissue using selected-ion monitoring in gas chromatographic-mass spectrometric analysis.
Eicosatrienoic acid, eicosatetraenoic acid (arachidonic acid), and eicosapentaenoic acid are unsaturated fatty acids that are possible precursors for prostaglandin synthesis in amphibians. These compounds have been quantitatively identified in tissues of the American bullfrog by using methods of selected-ion monitoring for fatty acid methyl esters. Results from comparison of yield for four methylation techniques showed that boron trifluoride in methanol gave the best yield and reproducibility. Resolution values of 1.2 and 2.7 for these methyl esters were achieved by using a cyanosilicone liquid phase, and the limits of detection based on ion 79.1 a.m.u. were 0.5 ng absolute. These acids were extracted and methylated with overall recoveries of 47, 37 and 28%, respectively. Methyl esters were detected in extracts of all tissues in concentration ranges 12 to 912 ng/microliters of extract, or 30 to 2810 micrograms/g of tissue for 0.1- to 1.3-g samples.
Animals↗
Chromatography of xanthines on ion-exchange resins.
Short columns of a 4% crosslinked cation-exchange resin gave good chromatography of xanthines, including caffeine, theophylline and hypoxanthine, and related polar aromatic compounds. Elution volumes and sequences can be modified by changing pH, solvent composition and resin counter-ion. A macroporous cation-exchange resin showed exaggerated counter-ion effects. A method is described for determining caffeine and theophylline in blood serum, using the 4% crosslinked resin with aqueous sodium phosphate eluent of pH 7.5; the temperature was 65 degrees. Detection limits are 10 ng and less.
Caffeine↗
Environmental trace analysis of organics in water by glass capillary column chromatography and ancillary techniques. Products of ozonolysis.
A method employing a polymeric sorbent has been used for analysis of volatile organic components in water. Trace level organics are sparged from water with nitrogen gas and are concentrated on Tenax GC prior to analysis with either flame ionization gas chromatography or gas chromatography-mass spectrometry. Glass capillary columns were used to obtain maximum resolution of chromatographic peaks. Specifically, the method has been applied to a qualitative and quantitative study of the products which result from ozonization of secondary treated domestic wastewater. The principal volatile products of ozonolysis are n-hexanal, n-heptanal, n-octanal and n-nonanal. Representative samples contained 0.7 ppb** of n-heptanal and less than 1 ppb of any of the volatile compounds.
Chromatography, Gas↗