摘要:

Pyruvic acid and methane sulfonic acid, both products of photochemical reactions in air, are quantitated by ion chromatography analysis in borate and carbonate buffer, respectively, following sampling with impingers and Teflon filters. Detection limits are 50 and 80 nanogram/mL for pyruvate and sulfonate ions, respectively, and correspond to ∼2-3 parts per billion (gas phase) and ∼1 μg m−3(particulate phase) in air. Other ionic species present as co-products in polluted air, including nitrate, sulfate, chloride, carbonate, formate and acetate do not interfere with the pyruvate and sulfonate measurements.

ISSN:0003-2719    

DOI:10.1080/00032718408065268

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Polycyclic aromatic hydrocarbons are extracted from atmospheric particulate samples with a thermal desorption technique that circumvents the need for lengthy solvent extraction procedures prior to gas chromatographic analysis. The polycyclic aromatic hydrocarbons are extracted by vacuum-sublimation and collected in a cold trap. The sublimed species are then cryogenically focused at the head of a fused silica capillary column by a thermal purging technique and subsequently analyzed. The technique is applicable to screening tests for selected polycyclic aromatic hydrocarbons when used with a sufficiently specific detector, and has the advantages of simplicity and low cost.

ISSN:0003-2719    

DOI:10.1080/00032718408065269

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

An ebulliometric method for the determination of urea in fertilizers was developed. The method is based on the boiling-temperature elevation caused by addition of the sample to the ebulliometer and the following decrease in this temperature due to decomposition of urea. Thermodynamic and kinetic informations were obtained in order to choose the best experimental conditions for the procedure. Determination of urea in synthetic samples of fertilizers was accomplished with a precision of 1%. An overall

ISSN:0003-2719    

DOI:10.1080/00032718408065270

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The on-line analysis of gas streams containing ultra low-level concentrations of CO2over extended time periods presents a unique analytical problem. In the absence of a CO2preconcentration step, many commercially available instruments used for routine gas analysis lack either the sensitivity or stability for ultra low-level CO2monitoring. This paper will address two relatively inexpensive (<$10,000) techniques that were found suitable for such monitoring: (1) CO2methanization with subsequent flame ionization detection and (2) extended-pathlength infrared spectroscopy.

ISSN:0003-2719    

DOI:10.1080/00032718408065271

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The use of the change of colour of a mixture of Ag2HgI4and Cu2HgI4for the detection of the end point of the titration of benzoic acid in the solvent mixture dimethylsulfoxide and acrylonitrile with potassium n-butoxide in n-butanol has been investigated. The results show the possibility of using thermochromic substances as a new kind of visual indicator in titrimetry. They may be employed in the cases where a suitable change in temperature occurs at the end point of the titration.

ISSN:0003-2719    

DOI:10.1080/00032718408065272

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Automted equipment is used to generate selenium hydride from solutions of rock samples prepared by digestion with a mixture of hydrofluoric, perchloric, and nitric acids. The evolved hydride is swept by argon into an electrically heated quartz tube atomizer. The atomic absorption of Se is measured at 196.0 nm. 1, 10-phenanthroline is used to minimize interferences from copper and nickel. The practical detection limit of selenium in rock samples is 0.05 pp. Results for reference rock samples agree closely with published values.

ISSN:0003-2719    

DOI:10.1080/00032718408065273

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Total arsenic determinations in complex food matrices can be performed with a high degree of accuracy and precision using an initial hydride formation step followed by direct current plasma (DCP) emission spectroscopic detection1. The hyphenated technique, HY-DCP, uses a continuous flow hydride formation step with dual mixing of the hydride forming reagents, followed by on-line, continuous introduction of the aqueous arsenic sample. The final aqueous solution of arsine, excess sodium borohydride, and sample components, is directly introduced into the conventional spray chamber of the DCP instrument. Calibration plots for both arsenate and arsenite have been determined, together with linearities and minimum detection limits (MDLs) The overall methods for total arsenic determination have been applied to spiked water and tunafish samples. Accuracy and precision determinations have been performed for these total arsenic analyses, and compared with continuous hydride formation-flame atomic absorption (FAA) detection, as well as sequential hydride formation-FAA methods. All of these results are then compared, with the individual advantages and disadvantages o f each approach summarized.

ISSN:0003-2719    

DOI:10.1080/00032718408065274

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0003-2719    

DOI:10.1080/00032718408065267

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor