Showing papers in "Analytical Chemistry in 1982"

Reduction of water with zinc for hydrogen isotope analysis

Abstract: A 1-10 mg portion of water is reduced with Zn metal in a sealed tube at 450 /sup 0/C to prepare hydrogen for isotopic analysis. After reaction the tube is attached directly to the mass spectrometer without further processing. Replicate analyses of water samples give reproducibility of 0.2-0.4% (1sigma); fluid inclusion samples, 1.9%; and water of hydration of gypsum, released and reduced in the sealed tube, 1.1%. A batch of 10 samples can be prepared in 1 h.

Characterization of lignin by gas capillary chromatography of cupric oxide oxidation products

Abstract: A sensitive, reproducible method is described for the characterization of lignin in untreated plant and geochemical samples containing 10 mg or less organic matter. The whole sample is treated with alkaline cupric oxide at 170 degrees to produce simple lignin- derived phenols that are extracted with ethyl oxide and analyzed by gas capillary chromatography on fused silica columns. A pattern of 11 or less phenols is produced that reflects the relative concentration and plant tissue sources of lignins present in the sample.

Analysis of nitrated polycyclic aromatic hydrocarbons in diesel particulates

Abstract: The analysis of nitrated polycyclic aromatic hydrocarbons (nitro-PAH) in diesel particulate extracts using a combination of high-performance liquid chromatography, gas chromatography/mass spectrometry, high-resolution mass spectrometry, and mass spectrometry/mass spectrometry (MS/MS) techniques is described. Triple stage quadrupole (TSQ)-MS/MS operated in the constant neutral loss mode is described for the rapid qualitative screening of nitro-PAH isomer groups in solvent extracts of diesel particulates. Twenty such isomer groups of nitro-PAH derivatives were found, many of these groups containing a large number of possible compounds. Mass analyzed ion kinetic energy spectrometry (MIKES)-MS/MS was found to be much less selective than the TSQ-MS/MS for the analysis of nitro-PAH in unfractionated diesel extracts. HPLC prefractionation was required to remove interferences in the MIKES analysis. Fused silica capillary GC/MS using on-column injection was found to be necessary for identifying specific nitro-PAH isomers and minimizing decomposition. The highly mutagenic 1-nitropyrene (1-NP) was the only compound found in the nitro(pyrenes and fluoranthenes) isomer group. The MIKES and TSQ techniques gave comparable results for the quantitation of 1-NP.

Ion-Selective Electrodes.

Abstract: This review focuses on the more significant contributions to the understanding and use of ion-selective electrodes (ISE's). There is a strong interest in this field as over 1400 articles and abstracts were found during the writing of this review which covers the period from January 1986 through December 1987. The major analytical and electrochemical journals were read and a hand search of Chemical Abstracts uncovered the remaining articles. Unlike previous fundamental reviews, this paper will not attempt to list all the pertinent papers on ISE's. Rather, the more interesting works and applications are covered to illustrate examples of the general trends and directions of ISE interests.

Determination of natural actinides and plutonium in marine particulate material

Abstract: The natural actinides /sup 227/Ac, /sup 228/Th, /sup 230/Th, /sup 232/Th, /sup 234/Th, /sup 231/Pa, /sup 238/U, and /sup 234/U and the ..cap alpha..-emitting plutonium isotopes are determined in samples of suspended marine particulate material and sediments. Analysis involves total dissolution of the samples to allow equilibration of the natural isotopes with added isotope yield monitors followed by coprecipitation of hydrolyzable metals at pH 7 with natural Fe and Al acting as carriers to remove alkali and alkaline earth metals. Final purification is by ion exchange chromatography (Dowex AG1-X8) and solvent extraction for Pa. Overall chemical yields generally range from 50 to 90%. The method has been successfully interfaced with published methods to include the determination of /sup 55/Fe, /sup 137/Cs, /sup 90/Sr, and /sup 241/Am on the same samples.

Supercritical fluid chromatography with small particle diameter packed columns

Abstract: Supercritical fluid chromatography is carried out with 10, 5, and 3 ..mu..m particle diameter packed columns. Reduced plate heights between 2.0 and 3.0 are achieved in the region of the van Deemter minimum. Using polycyclic aromatic hydrocarbons as probe molecules, the relationship of density of supercritical carbon dioxide to log capacity factor was studied between 32 and 100/sup 0/C. The efficiency of the columns appears to improve as the particle diameter becomes smaller. With a UV detector, minimum detectable quantities are in the range of 1 ng mass injected. Resolution per unit time is 5-10 times better than HPLC with the same columns due to more favorable diffusivity in supercritical fluids. Usable regions of temperature, pressure, density, and flow rate are defined. 9 figures.

Collision-induced dissociation with Fourier transform mass spectrometry

Abstract: Collision-induced dissociations (CID) is demonstrated on a number of primary and secondary ions using a Nicolet prototype Fourier transform mass spectrometer (FT-MS). Like the triple quadrupole technique, CID using FT-MS is a relatively low energy and efficient process. The ability to study a wide range of ion-molecule reaction products is exemplified by results on proton-bound dimers and transition metal containing ionic species. Variation of collision energy by varying the RF irradiation level can provide information about product distributions as a function of energy as well as yield ion structural information. Like the triple quadrupole technique, no slits are employed and virtually all of the fragment ions formed by the CID process may be detected. Unlike all previous mass spectrometric techniques for studying CID, a tandem instrument is not required, and different experiments are performed by making software modifications rather than hardware modifications.

Collection and Analysis of Hazardous Organic Emissions

Abstract: Over the past 8 years, research has been conducted on developing the analytical capability to collect, characterize, and quantify volatile organic compounds present in typical ambient air environments. This paper summarizes the overall progress made on this development. The described analysis system encompasses the collection and concentration of organic pollutants from ambient air using tubes packed with polymeric beads. After sampling, the cartridges are thermally heated under a He flow, the compounds desorbed, cryofocused, and subsequently introduced into a high-resolution glass or fused capillary for characterization and measurement by gas chromatography/mass spectrometry/computer (GS/MS/COMP) techniques. 7 figures, 1 table.

Determination of rare earth elements in geological materials by inductively coupled argon plasma/atomic emission spectrometry

Abstract: Inductively coupled argon plasma/optical emission spectrometry (ICAP/OES) is useful as a simultaneous, multielement analytical technique for the determination of trace elements in geological materials. A method for the determination of trace-level rare earth elements (REE) in geological materials using an ICAP 63-channel emission spectrometer is described. Separation and preconcentration of the REE and yttrium from a sample digest are achieved by a nitric acid gradient cation exchange and hydrochloric acid anion exchange. Precision of 1-4% relative standard deviation and comparable accuracy are demonstrated by the triplicate analysis of three spills of BCR-1 and BHVO-1. Analyses of other geological materials including coals, soils, and rocks show comparable precision and accuracy.