Aqueous environmental samples compounds

P. De Voogt, Cliromatographic clean-up methods for the determination of persistent organic compounds in aqueous environmental samples . Trends. Anal. Chem. 13 389-397(1994). 

The Identification and Measurement of Volatile Organic Compounds in Aqueous Environmental Samples... 

In this chapter, the current and future capabilities of HPLC for the determination of trace organic compounds in aqueous environmental samples will be assessed. This assessment will include approaches to sample cleanup or analyte isolation for those species likely to be candidates for analysis by HPLC. Column technology, as it contributes to the use of HPLC for trace organic analyses, will be surveyed. Finally, detection of the compounds eluting from the system will be examined. The ultimate detector will always adequately identify and measure the compounds of interest. 

Graham and Garrison (17) evaluated on-line trace enrichment for the determination of trace organic compounds in aqueous environmental samples. These workers were primarily interested in nonvolatile and thermally labile compounds that were not readily analyzed by GC methodology. A 2-mm i.d. X 70-mm long stainless steel precolumn was packed with 30-75 pm diameter octadecyl-derivatized silica. This precolumn was substituted for the sample loop in a conventional, high-pressure, six-port valve. Water samples, 10-100 mL, were pumped directly on the precolumn. After loading, the valve was switched to... 

Most of the articles in the scientific literature dealing with analytical methods using HPLC technology for the analysis of aqueous environmental samples employ the reversed-phase mode. This finding is not surprising, as the data in Table V attest to. The flexibility of the reversed-phase mode suits environmental analyses. Many metabolites of environmentally important organic compounds are ionic or ionizable and ideally suited to separation by ion-pair techniques. A variety of... 

In the past 5 years the frequency of reports on the use of HPLC technology for the determination of trace organic compounds in aqueous environmental samples has been steadily increasing. Many innovative approaches to sample cleanup and analyte isolation have been reported. Reversed-phase separation, with its many mobile-phase adaptations, has been and continues to be the most popular HPLC separation mode. The development of fast columns and microbore columns should provide optimal configurations for particular applications. The operating characteristics of microbore columns also make... 

An attempt has been made to survey the current status of technology in HPLC as it applies to the analysis of trace organic compounds in aqueous environmental samples. No doubt, some developments relative to this topic have been overlooked, but the overall assessment should provide a glimpse of what has been done and also of what is possible. 

Chemical and biological analyses of trace organic mixtures in aqueous environmental samples typically require that some type of isolation-concentration method be used prior to testing these residues the inclusion of bioassay in a testing scheme often dictates that large sample volumes (20-500 L) be processed. Discrete chemical analysis only requires demonstration that the isolation technique yields the desired compounds with known precision. However, chemical and/or toxicological characterization of the chemical continuum of molecular properties represented by the unknown mixtures of organics in environmental samples adds an extra dimension of the ideal isolation technique ... 

G6mez-Ariza, J.L., J.A. Pozas, I. Giraldez et al. 1999. Use of solid phase extraction for speciation of selenium compounds in aqueous environmental samples. Analyst 124 75-78. 

Gardiner [84,85] described a gas chromatographic method for the determination of EDTA in aqueous environmental samples. The separation of the major peaks is increased by preparing the ethyl derivatives of the sample compounds, 1,6-hexanediamine tetraacetic acid (HDTA) being used as internal standard. The lower limit of detection of the method is approximately 15pg L 1 with 25mL samples. In this method the ethyl derivatives of the sample components were prepared so that the major peaks would be well separated. The ethyl esters of fatty acids up to and including the Qg fatty acids eluted well before the EDTA derivatives and did not interfere. 

Bellar TA, Budde WL, Eichelberger JW. 1979. The identification and measurement of volatile organic compounds in aqueous environmental samples. IN Schuetzle D, ed. Monitoring toxic substances. American Chemical Society Symposium Series No. 94. Washington, DC American Chemical Society, 49-62. ISBM 0-8412-0480-2. 

Bellar, T. A. and Budde, W. L., Determination of nonvolatile organic compounds in aqueous environmental samples using liquid chromatography/mass spectrometry. Anal. Chem., 60, 2076-2083, 1988. 

The principal analytical methods employed in the analysis of pharmaceuticals in aqueous environmental samples include both GC and FC coupled to MS or MS/MS. In general, FC-MS methods have demonstrated lower relative standard deviations than GC-MS methods that have derivatization prior to analysis. FC-ESI-MS/MS is presented as the technique of choice for polar, unstable, and high molecular mass compounds, such as most pharmaceuticals and their metabolites. MS detection has preferably been performed with the ESI interface. An analytical protocol applying FC-ESI-MS/MS with previous filtration of the water sample, with addition of NaiEDTA to avoid complexation of analytes (especially tetracyclines) with metals present in the water, was proposed for the analysis of antibiotics corresponding to the classes of macrolides, sulfonamides, penicillins, and tetracyclines in water samples. 

Table 6 summarizes relevant analytical data on the sensitivity of SPE GC-MS of, chiefly, aqueous environmental samples such as tap water, surface water, and wastewater. The main conclusions that can be drawn from the data are rather promising. Sample volumes of about 10 ml suffice to obtain full-scan MS traces such as are shown in Figure 9. Detection limits were in the 20 to 50 ng/L range or lower for essentially all compounds. As a demonstration of the identification power of the procedure, the traces of the four characteristic ions of peak 11 (benz-aldehyde) in the raw, i.e., nonspiked, water are included. Comparison with the 0.5- ig/L spiked trace shows that benzaldehyde was present at a level of approximately 40 ng/L. This system is well suited for the screening of rather volatile as well as high(er) boiling compounds. 

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