Carbon tetrachloride sample analysis method

The identification and quantification of potentially cytotoxic carbonyl compounds (e.g. aldehydes such as pentanal, hexanal, traw-2-octenal and 4-hydroxy-/mAW-2-nonenal, and ketones such as propan- and hexan-2-ones) also serves as a useful marker of the oxidative deterioration of PUFAs in isolated biological samples and chemical model systems. One method developed utilizes HPLC coupled with spectrophotometric detection and involves precolumn derivatization of peroxidized PUFA-derived aldehydes and alternative carbonyl compounds with 2,4-DNPH followed by separation of the resulting chromophoric 2,4-dinitrophenylhydrazones on a reversed-phase column and spectrophotometric detection at a wavelength of378 nm. This method has a relatively high level of sensitivity, and has been successfully applied to the analysis of such products in rat hepatocytes and rat liver microsomal suspensions stimulated with carbon tetrachloride or ADP-iron complexes (Poli etui., 1985). 

The purpose of this chapter is to describe the analytical methods that are available for detecting, and/or measuring, and/or monitoring carbon tetrachloride, its metabolites, and other biomarkers of exposure and effect to carbon tetrachloride. The intent is not to provide an exhaustive list of analytical methods. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used for environmental samples are the methods approved by federal agencies and organizations such as ERA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods are included that modify previously used methods to obtain lower detection limits, and/or to improve accuracy and precision. 

The most variable aspect of carbon tetrachloride analysis is the procedure used to separate carbon tetrachloride from the medium and prepare a sample suitable for GC analysis. As a volatile organic compound of relatively low water solubility, carbon tetrachloride is easily lost from biological and environmental samples, so appropriate care must be exercised in handling and storing such samples for chemical analysis. Brief summaries of the methods available for extraction and detection of carbon tetrachloride in biological and environmental samples are provided below. 

The proposed method is rather simple and quick. The analysis involves solution of the sample in the inert solvent (usually carbon tetrachloride) and recording a spectrum. In this case the duration of the analysis is no more than 20 minutes. The duration of the analysis may be shortened if to exclude the stage of solution preparation. It is well-taken because spectra of neat liquid samples practically don not differ from those obtained for their solutions in analytical regions (Fig.4). 

Fraga [1] has developed an infrared-near-infrared method of analysis of carbon tetrachloride solutions of polybutadienes suitable for the evaluation of cis-1,4, 5000-714.2 cm" (2-14 pm), trans-1,4, 9708 cm" (10.3 pm) and vinyl, 9091 cm" (11.0 pm) structures. Only poly butadiene is required for calibration purposes. The method is applicable to carbon tetrachloride soluble polybutadienes containing 0-97% cis-1,4 structure, 0-70% trans-1,4 structure, and 0-90% vinyl structure. Some typical spectra are shown in Figure 12.1 for a high cis-1,4 polybutadiene, and high trans-1,4 polybutadiene, and a high 1,2 (atactic) polybutadiene, and other samples of different cis and trans compositions. 

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