Aqueous environmental samples

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). 

Temes TA (2001) Analytical methods for the determination of pharmaceuticals in aqueous environmental samples. Trends Analyt Chem 20 419 34... 

Erbs, M., Hoerger, C.C., Hartmaim, N. and Bucheli, T.D. (2007). Quantification of six phytoestrogens at the nanogram per liter level in aqueous environmental samples using C-13(3)-labeled internal standards. Journal of Agricultural and Food Chemistry 55, 8339-8345. 

Di Corcia, A., Marchetti, M., Samperi, R., and Marcomini, A., Liquid chromatographic determination of linear alkylbenzenesulfonates in aqueous environmental samples, Anal. Chem., 63, 1179, 1991. 

The complex composition of aqueous environmental sample matrices, especially sewage and marine water samples, and the low concentrations in which the surfactants are generally found, have made it necessary to perform an initial stage of concentration and purification of the analytes prior to its analysis. Traditionally, such steps were carried out off-line with procedures based on liquid—liquid extraction (LLE), sublation or steam distillation, followed by chromatographic clean-up steps. 

Prior to the quantitative determination of surfactants from aqueous environmental samples, a preconcentration step is needed to enrich low amounts of target analytes and to remove interfering matrix components. 

Friant, S.L. and Suffet, I.H. Interachve effects of temperature, salt concentration, and pH on head space analysis for isolahng volatile trace organics in aqueous environmental samples. Anal. Chem., 51(13) 2167-2172, 1979. 

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

SFC has been used as a technique to analyse nitroaromatics in aqueous environmental samples [29]. It was necessary to use sample pre-concentration methods (see next section) to obtain suitable detection limits. 

Stepnowski, R, Solid-phase extraction of room temperature imidazolium ionic liquids from aqueous environmental samples. Anal. Bioanal. Chem., 381, 189, 2005. 

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... 

By assuming that a proportional increase in the amount of sample injected results in a proportional increase in the detector response for the solute band of interest, the detector response for chromatogram I in Figure 7 will increase 14 times when the maximum sample volume of 7 /xL is injected. However, for the 4.6-mm i.d. column, the detector response will increase 400 times when the maximum sample volume of 200 (lL is injected. By taking into account the relative detector responses for the 0.5-/xL injection, at the maximum sample injection volumes, the 4.6-mm i.d. column with the 20-/liL detector flow cell will produce approximately five times the detector response of the 1-mm i.d. column with the 5-/zL flow cell. In most cases, studies can be designed to provide excess sample because aqueous environmental samples are seldom limited with respect to volume. 

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. 

Figure 1. Schematic of the strategy for the coupled bioassay-analytical fractionation of residue organics isolated from aqueous environmental samples.

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 ... 

Increased use of liquid chromatography/mass spectrometry (lc/ms) for structural identification and trace analysis has become apparent. Thermo-spray lc/ms has been used to identify by-products in phenyl isocyanate precolumn derivatization reactions Liquid chromatography/thermospray mass spectrometric characterization of chemical adducts of DNA formed during in vitro reaction lias been proposed as an analytical technique to detect and identify those contaminants in aqueous environmental samples which have a propensity to be genotoxic, t.e.. to covalently bond to DNA. 

Coquart, V. and M.C. Hennion (1991). Interference removal in the organic trace-level analysis of aqueous environmental samples by online liquid chromatographic preconcentration techniques with two precolumns. J. Chromatogr., 553 329-343. 

Lukasewycz, M.T. and Durhan, E.J. (1992) Strategies for the identification of non-polar toxicants in aqueous environmental samples using toxicity-based fractionation and gas chromatography-mass spectrometry, Journal of Chromatography 580, 215-28. 

Figura, EM. and McDuffie, B. (1980) Determination of labilities of soluble trace metal species in aqueous environmental samples by A.S.V and Chelex column and batch methods. Anal. Chem., 52, 1433-1439.

Bergstrom, S., T. Barri, J. Norberg, J.A. Jonsson, and L. Mathiasson. 2007. Extracting syringe for extraction of phthalate esters in aqueous environmental samples. Anal. Chim. Acta 594 240-247. 

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