Use of graphitized carbon black in environmental analysis

Measurement of volatile organic compounds by the US Environmental Protection Agency Compendium Method TO-17. Evaluation of performance criteria

An evaluation of performance criteria for US Environmental Protection Agency Compendium Method TO-17 for monitoring volatile organic compounds (VOCs) in air has been accomplished. The method is a solid adsorbent-based sampling and analytical procedure including performance criteria for four merit parameters. These are: (1) the method detection limit (MDL); (2) the method precision; (3) the agreement between two samples taken at different flow-rates over the same time period [a distributed volume pair (DVP)]; and (4) audit accuracy. A two-adsorbent tube packing of Carbotrap and Carboxen 1000 (Supelco) was tested. Synthetic mixtures containing 41 compounds at concentrations of 10 ppb (v/v) or 2 ppb (v/v) each in humidified zero air, and indoor air from a personal residence, were sampled for 1-h periods during which 1-l and 4-l samples were obtained simultaneously. For synthetic samples, the MDL was determined to be < or = 0.5 ppb (v/v) for 29 of the 41 compounds examined for samples at 47% relative humidity (RH), and for 27 of 41 compounds at 85% RH. The method precision at both 2 and 10 ppb (v/v) was < or = 20% for 90+ % of the samples using five sampling runs and the DVP samples were within 25% for 80% of the samples. For the indoor samples, 26 target compounds were tentatively identified and 12 unknowns were detected; all but 10% of these compounds met the DVP criteria.

Gas chromatographic-mass spectrometric evaluation of exhaled tobacco smoke

The impact of cigarette smoking on the distribution of organic substances in ambient air has been determined for the intermediate volatility range. A simple sampling procedure was employed, involving gas-solid adsorption onto an organic polymer followed by direct thermal elution onto a glass capillary column. Aliphatic and substituted aromatic hydrocarbons are predominant in urban atmospheres. Depending on location and weather conditions the total concentration of such volatiles can differ by as much as a factor of 20. This high background variation makes it difficult to analyze for trace substances with low odor threshold values, such as encountered in cigarette smoke. Standard cigarettes were smoked in a relatively small room, having no air filtration system. Air samples of approximately 3.51 were taken. The amount of volatiles added to air by cigarette smoking is unsignificant. Substances were analyzed and identified by gas chromatography and gas chromatography-mass spectrometry with glass capillary columns. Many compounds reported in cigarette smoke condensate have been confirmed.

Evaluation of organic pollutants in the open air and atmospheres in industrial sites using graphitized carbon black traps and gas chromatographic-mass spectrometric analysis with specific detectors

A method for evaluating the organic content of the atmosphere, involving the use of personal samplers, is described. A comparison of the performances of Tenax GC and Carbopack B is given in terms of sample recovery. Apparatus including selective columns, specific detectors and combined gas chromatography-mass spectrometry is also described. Practical examples of the analysis of organic air pollutants trapped in the open air and the atmosphere in a chemical plant are discussed. A comparison of the results of complete gas chromatography and of the total hydrocarbon content is also made.