Environmental applications, HPLC

Even though PAHs are commonly determined by GC or HPLC, there are no matrix reference materials for PAHs in urine or serum. A number of reference materials certified for PAHs in animal tissue are available, but they are intended for environmental applications, see Section 3.4. 

High-performance liquid chromatography (HPLC) is one of the premier analytical techniques widely used in analytical laboratories. Numerous analytical HPLC analyses have been developed for pharmaceutical, chemical, food, cosmetic, and environmental applications. The popularity of HPLC analysis can be attributed to its powerful combination of separation and quantitation capabilities. HPLC instrumentation has reached a state of maturity. The majority of vendors can provide very sophisticated and highly automated systems to meet users needs. To provide a high level of assurance that the data generated from the HPLC analysis are reliable, the performance of the HPLC system should be monitored at regular intervals. In this chapter some of the key performance attributes for a typical HPLC system (consisting of a quaternary pump, an autoinjector, a UV-Vis detector, and a temperature-controlled column compartment) are discussed [1-8]. 

The resulting materials were used in the separation of three organic molecules commonly studied in environmental applications of HPLC benzene, naphthalene, and biphenyl (Figure 2). Cg-APMS and Cg-MCM-48 both provide excellent separation of these molecules, with... 

Compared to GC columns, HPLC columns are short and thick, ranging from 10 to 25 cm in length and 2 to 4.6 mm in internal diameter. They are filled with an inert material (silica, polymer resin), which is coated with a stationary phase. In normal phase HPLC, the mobile phase is less polar than the stationary phase. In reverse phase HPLC, the opposite is true, and the mobile phase is more polar than the stationary one. Reverse phase HPLC is the technique of choice for environmental applications. Similar to GC columns, analyte-specific HPLC columns are recommended in the published methods. 

The HPLC/MS technique has been only recently initiated into environmental applications. It is considered a non-routine application, and is conducted mostly by the laboratories specializing in pesticide analysis. 

For a good discussion of on-line SPE coupled to HPLC, the work of Hennion and Pichon (1994) and Hennion and co-workers (1990) discuss environmental applications. In their work, the styrene-divinylbenzene copolymers are used as SPE columns with good capacity for many of the environmentally relevant contaminants and allow for direct analysis by HPLC. Hennion and Pichon (1994) discuss and review a number of studies on pesticides and related compounds by on-line SPE. There is also more discussion of on-line SPE methods coupled to GC/MS in Chapter 10. 

The use of automation results in fast, easy, and reliable methods for SPE. There are a number of instruments available for totally automated SPE, as well as automated methods development of SPE, which span the spectrum in cost. In environmental applications, the choices of automation are limited, with only the Autotrace by Tekmar available for large-volume samples (1 L). In the area of on-line SPE-HPLC, nearly all of the workstations for SPE have the option for direct injection into the HPLC. For on-line SPE-GC/MS, there are several instruments and methods available (a modified PROSPEKT, Varian automated SPME, and the Hewlett-Packard solid-phase extraction workstation). For total automation including addition of internal standards, derivatiza-... 

HPLC is a versatile technique applicable to diversified analytes, including labile molecules, ions, organic, and biopolymers. This chapter provides an overview of HPLC applications for the analysis of food, environmental, chemical, polymer, ion-chromatography, and life science samples. In food analysis, HPLC is widely used in product research, quality control, nutritional labeling, and residual testing of contaminants. In environmental testing, HPLC is excellent for the sensitive and specific detection of labile and nonvolatile pollutants... 

It is also important to emphasize that most vendors also offer integrated systems with turnkey application methods that are almost ready to run samples as soon the instrument is installed. Althongh this is not available for all applications, it is becoming a standard offering for some of the more routine environmental applications. Manufacturers are also realizing that most analytical chemists who are experienced at trace element analysis have very little expertise in chromatography. For that reason, they are providing full backup and customer support with HPLC application specialists as well as with the traditional ICP-MS product specialists. 

For selective estimation of phenols pollution of environment such chromatographic methods as gas chromatography with flame-ionization detector (ISO method 8165) and high performance liquid chromatography with UV-detector (EPA method 625) is recommended. For determination of phenol, cresols, chlorophenols in environmental samples application of HPLC with amperometric detector is perspective. Phenols and chlorophenols can be easy oxidized and determined with high sensitivity on carbon-glass electrode. 

The application areas for LC-MS, as will be illustrated later, are diverse, encompassing both qualitative and quantitative determinations of both high-and low-molecular-weight materials, including synthetic polymers, biopolymers, environmental pollutants, pharmaceutical compounds (drugs and their metabolites) and natural products. In essence, it is used for any compounds which are found in complex matrices for which HPLC is the separation method of choice and where the mass spectrometer provides the necessary selectivity and sensitivity to provide quantitative information and/or it provides structural information that cannot be obtained by using other detectors. 

Reversed-phase HPLC followed by post-column derivatization and subsequent fluorescence detection is the most common technique for quantitative determination of oxime carbamate insecticides in biological and environmental samples. However, for fast, sensitive, and specific analysis of biological and environmental samples, detection by MS and MS/MS is preferred over fluorescence detection. Thus, descriptions and recommendations for establishing and optimizing HPLC fluorescence, HPLC/ MS, and HPLC/MS/MS analyses are discussed first. This is followed by specific rationales for methods and descriptions of the recommended residue methods that are applicable to most oxime carbamates in plant, animal tissue, soil, and water matrices. 

The recent use of HPLC for the analysis of sulfophenyl carboxylates (SPCs) has been one of the most interesting applications of this technique for the study of the environmental behaviour of anionic surfactants. SPCs are separated by reversed-phase ion-paired chromatography, in which a hydrophobic stationary phase is used and the mobile phase is eluted with aqueous buffers containing a low concentration of the counter-ion [19]. 

AEOs have been analysed by HPLC and UV or fluorescence detection after suitable derivatisation. The derivatising agents proposed so far are phenyl isocyanate [80,81], 1-anthroylnitrile [82], 3,5-dinitro-benzoyl chloride [83], naphthyl isocyanate [84] and naphthoyl chloride [84], However, the lack of fluorescence activity and the need for synthesis through a multistep reaction for some derivatising agents limits their application in a real-world analysis. In fact, only a few of them were applied in the determination of AEOs in environmental samples. Zanette et al. [84] developed derivatisation and separation... 

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