Xylan hydrolysis in Populus trichocarpa × P. deltoides and model substrates during hydrothermal pretreatment.

Previous studies defined easy and difficult to hydrolyze fractions of hemicellulose that may result from bonds among cellulose, hemicellulose, and lignin. To understand how such bonds affect hydrolysis, Populus trichocarpa × Populus deltoides, holocellulose isolated from P. trichocarpa × P.

Stable carbon and nitrogen isotope ratios of sodium and potassium cyanide as a forensic signature.

Sodium and potassium cyanide are highly toxic, produced in large amounts by the chemical industry, and linked to numerous high-profile crimes. The U.S.

Thin-layer chromatography/desorption electrospray ionization mass spectrometry: investigation of goldenseal alkaloids.

Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase thin-layer chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cmx10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed Rf value across the plates versus the stationary desorption electrospray emitter.

Quantitation of cotinine in nonsmoker saliva using chip-based nanoelectrospray tandem mass spectrometry.

A new analytical procedure was developed for the quantitation of nonsmoker salivary cotinine. Small volumes of saliva were diluted with water, fortified with cotinine-d3 (internal standard), then passed through small extraction columns. The analyte and internal standard were eluted with 0.

Self-aspirating atmospheric pressure chemical ionization source for direct sampling of analytes on surfaces and in liquid solutions.

A self-aspirating heated nebulizer probe is described and demonstrated for use in the direct analysis of analytes on surfaces and in liquid samples by atmospheric pressure chemical ionization (APCI) mass spectrometry. Functionality and performance of the probe as a self-aspirating APCI source is demonstrated using reserpine and progesterone as test compounds. The utility of the probe to sample analytes directly from surfaces was demonstrated first by scanning development lanes of a reversed-phase thin-layer chromatography plate in which a three-component dye mixture, viz.

Quantitative thin-layer chromatography/mass spectrometry analysis of caffeine using a surface sampling probe electrospray ionization tandem mass spectrometry system.

Quantitative determination of caffeine on reversed-phase C8 thin-layer chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The thin-layer chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 mum/s.

Development and application of protocols for the determination of response of real-time particle monitors to common indoor aerosols.

Protocols have been developed and applied for the generation of aerosols that are likely to be comparable to those encountered in field settings for the calibration of easily transportable/portable real-time particle monitors. Aerosols generated were simulated environmental tobacco smoke, cedar wood smoke, cooking oil fumes, and propane stove particles. The time-integrated responses of three nephelometers and a monitor for particle-bound polynuclear aromatic hydrocarbons (PAH) were compared with gravimetric respirable suspended particulate matter (RSP) in a controlled-atmosphere chamber.

Determination of atrazine and four organophosphorus pesticides in ground water using solid phase microextraction (SPME) followed by gas chromatography with selected-ion monitoring.

A rapid, sensitive, and convenient method is presented for the determination of atrazine and four organophosphorus pesticides (OPP) in small (10 ml) samples of ground water. Samples are initially fortified with ethion (internal standard), then extracted without organic solvent using a 65-microm thickness polydimethylsiloxane/divinylbenzene (PDMS-DVB) solid-phase microextraction (SPME) fiber. The analytes collected are thermally desorbed in a heated gas chromatographic inlet, separated using a fused-silica capillary column, and detected using a mass selective detector in its selected-ion monitoring (SIM) mode.

Determination of organochlorine pesticides in ground water using solid-phase microextraction followed by dual-column gas chromatography with electron-capture detection.

A rapid, sensitive, convenient, and highly quality-assured method is presented for the determination of 19 organochlorine pesticides (OCPs) in small samples (10 ml) of ground water. Samples are initially fortified with 2,4,5,6-tetrachloro-m-xylene (surrogate) and decachlorobiphenyl (retention time marker), then extracted with a 30-micron thickness polydimethylsiloxane solid-phase microextraction fiber. The analytes collected are thermally desorbed in a heated gas chromatographic inlet, separated using independent fused-silica capillary columns ("primary" and "confirmatory"), and detected using electron-capture detection.