Chromatography water samples

Preparation of soil—sediment of water samples for herbicide analysis generally has consisted of solvent extraction of the sample, followed by cleanup of the extract through Uquid—Uquid or column chromatography, and finally, concentration through evaporation (285). This complex but necessary series of procedures is time-consuming and is responsible for the high cost of herbicide analyses. The advent of soUd-phase extraction techniques in which the sample is simultaneously cleaned up and concentrated has condensed these steps and thus gready simplified sample preparation (286). 

An ion chromatographic system that included column switching and gradient analysis was used for the deterrnination of cations such as Na", Ca ", Mg ", K", and NH" 4 and anions such as Cf, NO, NO , and in fog water samples (72). Ion-exchange chromatography compares very well with... 

Some water samples contain phosphoms forms other than phosphate, eg, polyphosphate, hexametaphosphate, and organic phosphates. These forms can be hydrolyzed to phosphate in hot sulfuric acid solution and deterrnined by the preceding method. The more refractory organic phosphates require digestion in a sulfuric acid—ammonium persulfate solution. Ion chromatography can also be used to measure at 2 to 10 ppb (21). 

Coimnonly used methods for tlie measurement of pestieides in water samples involve. Solid Phase Exttaetion (SPE) followed by Gas Chromatography or High Performanee Liquid Cliromatography (HPLC) analysis. SPE is a multiple step proeedure and, thus, time eonsuming. 

A solution of testosterone (54 10 g) in 300 ml methanol is cooled to 0° and treated successively with 60 ml of cold 30 % hydrogen peroxide and 20 ml of cold aqueous 10% sodium hydroxide. The reaction mixture is stored for 48 hr at 0° and then poured into ice water. The resultant oil is extracted with methylene dichloride (or ether) and the extract is dried (MgS04). Removal of the solvent affords the crude product, a mixture of 4a,5a- and 4, 5 -isomers, which is purified by chromatography. A sample of pure 17j5-hydroxy-4/3,5 -oxidoandrostan-3-one, mp 157-158°, crystallizes after trituration of the crude product with ether. 

Figure 2.16 Clirotnatograms of a pentane extract of a water sample containing 200 ppb of a naphtha fraction (a) sample extracted by using a continuous flow system, where a pressurized bottle was employed as the sample-delivery system (b) batch-extracted sample. Reprinted from Journal of Chromatography, A 330, J. Roeraade, Automated monitoring of organic Race components in water. I. Continuous flow exti action together with on-line capillary gas cliro-matography , pp. 263 - 274, copyrigth 1985, with permission from Elsevier Science.

Figure 5.3 Analysis of 100 ml of (a) surface water and (b) drinking water sample spiked with 0.1 pig/ml of microcystins, using column-switching HPLC 1, microcystin-RR 2, microcystin-YR 3, microcystin-LR. Reprinted from Journal of Chromatography A, 848, H. S. Lee et al, On-line trace enrichment for the simultaneous determination of microcystins in aqueous samples using high performance liquid chromatography with diode-array detection , pp 179-184, copyright 1999, with permission from Elsevier Science.

Soil extracts are usually very complex. In water samples, humic and fulvic acids make analysis difficult, especially when polar substances are to be determined. Multidimensional chromatography can also make a significant contribution here to this type of analysis. 

Figure 13.10 LC-LC chromatogram of a surface water sample spiked at 2 p.g 1 with ati azine, and its metabolites (registered at 220 nm). Conditions volume of sample injected, 2 ml clean-up time, 2.60 min ti ansfer time, 4.2 min The blank was subtracted. Peak identification is as follows 1, DIA 2, HA 3, DEA 4, atrazine. Reprinted from Journal of Chromatography, A 778, F. Hernandez et al, New method for the rapid detemiination of triazine herbicides and some of thek main metabolites in water by using coupled-column liquid cliromatography and large volume injection , pp. 171-181, copyright 1997, with permission from Elsevier Science.

Moody CA, WC Kwan, JW Martin, DCG Mnir, SA Mabnry (2001) Determination of perfinorinated snrfactants in snrface water samples by two independent analytical techniqnes liqnid chromatography/ tandem mass spectrometry and F NMR. Anal Chem 73 2200-2206. 

Analytical methods for parent chloroacetanilide herbicides in soil typically involve extraction of the soil with solvent, followed by solid-phase extraction (SPE), and analysis by gas chromatography/electron capture detection (GC/ECD) or gas chromatog-raphy/mass spectrometry (GC/MS). Analytical methods for parent chloroacetanilides in water are similarly based on extraction followed by GC with various detection techniques. Many of the water methods, such as the Environmental Protection Agency (EPA) official methods, are multi-residue methods that include other compound classes in addition to chloroacetanilides. While liquid-liquid partitioning was used initially to extract acetanilides from water samples, SPE using... 

Specifically for triazines in water, multi-residue methods incorporating SPE and LC/MS/MS will soon be available that are capable of measuring numerous parent compounds and all their relevant degradates (including the hydroxytriazines) in one analysis. Continued increases in liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) sensitivity will lead to methods requiring no aqueous sample preparation at all, and portions of water samples will be injected directly into the LC column. The use of SPE and GC or LC coupled with MS and MS/MS systems will also be applied routinely to the analysis of more complex sample matrices such as soil and crop and animal tissues. However, the analyte(s) must first be removed from the sample matrix, and additional research is needed to develop more efficient extraction procedures. Increased selectivity during extraction also simplifies the sample purification requirements prior to injection. Certainly, miniaturization of all aspects of the analysis (sample extraction, purification, and instrumentation) will continue, and some of this may involve SEE, subcritical and microwave extraction, sonication, others or even combinations of these techniques for the initial isolation of the analyte(s) from the bulk of the sample matrix. 

Bispyribac in water samples can be directly quantifled by high-performance liquid chromatography (HPLC) using an ultravilot (UV) detector without methylation. 

Sample extracts are cleaned up with a cartridge column before the acetylation of E-2 to E-16 and of E-1 to E-15. The final cleanup, plant material and soil samples are analyzed by gas chromatography (GC)/MSD. The GC/NPD method is applicable to water samples. 

E. M. Thurman and C. Batian, Determination of atrazine and atrazine mercapture in drinking water samples and in urine using immunoaffinity SPE with positive ion spray HPLC/MS , Presented at the 15th Symposium on Liquid Chromatography/Mass Spectrometry, Montreux, Switzerland, November 9-10, 1998. 

Residue analytical methods for neonicotinoids in crops, soil and water samples have been developed. The basic principle of these methods consists of the following steps extraction of the crop and/or soil samples with acetone or the other organic solvent, cleanup by liquid-liquid partition or column chromatography, and quantitative analysis by high-performance liquid chromatography with ultraviolet detection (HPLC/UV). Simple column cleanup procedures are used to improve the accuracy and sensitivity of these methods. 

Water samples are directly partitioned with dichloromethane (DCM). The DCM exAact is then rotary evaporated and driven to dryness with a sAeam of niAogen. The dry residue is dissolved in acetone and analyzed by gas chromatography/nitrogen-phosphorus detection (GC-NPD). 

Fenpyroximate and M-1 residues in the plant (apple, grape, etc.) and soil samples can be analyzed using the multi-residue method Method DFG 819 with some minor deviations. In this method, gel permeation chromatography (GPC) is effectively used as the cleanup procedure. Residues in the water sample can be analyzed by a simpler method. 

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