Liquid chlorine analytical methods

A number of analytical methods have been developed for the determination of chlorotoluene mixtures by gas chromatography. These are used for determinations in environments such as air near industry (62) and soil (63). Liquid crystal stationary columns are more effective in separating m- and chlorotoluene than conventional columns (64). Prepacked columns are commercially available. ZeoHtes have been examined extensively as a means to separate chlorotoluene mixtures (see Molecularsieves). For example, a Y-type 2eohte containing sodium and copper has been used to separate y -chlorotoluene from its isomers by selective absorption (65). The presence of ben2ylic impurities in chlorotoluenes is determined by standard methods for hydroly2able chlorine. Proton (66) and carbon-13 chemical shifts, characteristic in absorption bands, and principal mass spectral peaks are available along with sources of reference spectra (67). 

For many years, one of the most common methods for performing analytical separations on complex environmental, pharmaceutical, food, and petroleum samples was based on extraction of bulk samples with hydrocarbon or chlorinated organic solvents using a Soxhiet extractor. Unfortunately, liquid extractions frequently fail to meet several of the ideal criteria listed in the previous paragraph. They usually require several hours or more to achieve satisfactory recoveries of analytes, and sometimes never do. The solvent costs are often high. The solution of the recovered analyte is often so dilute that a concentration step must follow the extraction. Analyte degradation-or loss as well as atmospheric pollution may accom )any this concentration step. 

As a commercial company that provides analytical services for the determination of radionuclides for a wide variety of clients, AMEC required a more accurate and reliable method to be developed. It needed to use relatively low hazard chemicals, have improved accuracy and precision and utilise common radiochemical analytical laboratory equipment such as liquid scintillation counters and gravity fed chromatography columns. In addition, the process must have realistic and commercially viable batch sizes, operator time and turnaround times, so that samples can be analysed in a cost-effective manner. Ideally the whole process for a batch of samples should not exceed more than one working week. As part of the validation process both internal and external quality control (QC) samples were used along with statistical tests, such as zeta (Q scores and student t-tests , to determine the accuracy of the improved method. In addition, elution profiles for iodine and chlorine and decontamination tests for potentially interfering radionuclides were also carried out in order to further validate the process. 

---