Monitoring water samples

A gas chromatographic (GC) method has been described in the literature. GC is based on the oxidation of microcystins which splits the Adda side chain to produce 3-methoxy-2-metlyl-4-pheitylbu-tyric acid (MMPB), which is then determined, either by GC or GC/MS (as its methyl ester) (Sano 1992 Kaya and Sano 1999) or by HPLC/fluoiescence detection (after conversion to a fluorescent derivative) (Sano 1992). GC/MS has been used to monitor microcystins in Japanese lakes (Tanaka 1993) and in sediments (Tsuji 2001). A similar method was developed by Harada (1996), but in this case the MMPB was determined directly without derivatization using GC/MS or LC/MS. The results of this approach ate given in terms of total toxin concentration, which then can be expressed in terms of microcystin-LR. However, individual toxins ate not determined and consequently it is not possible to produce a result in terms of microcystin-LR toxicity equivalents. This procedure cannot therefore be used to monitor water samples in relation to the proposed guideline. 

In cases where it is acceptable to screen or monitor water samples by techniques such as the Microtox test, it would be prudent wherever possible to include other test methods. This would require the services of a reliable centralized chemical and microbiological laboratory suitably equipped with instruments such as atomic absorption spectrometers, gas chromatographs, etc. Tliese facilities would be used to check whether a water source is suitable for long-term use. 

The reactor radiation instruments are listed in Table 5.2.A. It will be noticed that with one - exception these instruments are located in the reactor. The one. exception, the water monitor chambers, can reasonably be included with the reactor instruments since they monitor water samples from the 37 sampling tubes distributed across the bottom of the active lattice. 

Trihalomethanes in Drinking Water (Sampling Analysis, Monitoring and Compliance), U.S. Envkonmental Piotection Agency, EPA/570/9-83-002, Washington, D.C., 1983. 

The metliod developed enables effieient mattix management. Applieation to natural and drinking water samples appeared very promising for future pestieides monitoring. 

Obtaining of data concerning the chemical composition of water is critical significance for monitoring water reservoirs and forecasting the quality of drinking water from different water supply sources. A dry residue is commonly used with the methods AAS, ICP-AES, ICP-MS (analysis of liquid) widely applied for determination of water composition. So it is vital to create a standard sample of the composition of dry residue of ultra-fresh Lake Baikal water, its development launched since 1992 at the Institute of Geochemistry SB RAS. 

Provision for monitoring and sampling, e.g. of oxygen levels, eombustible gases and airborne toxie substanees and the taking of samples from air, water and ground. 

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.

Finally, it should be remembered that effectively controlling specific boiler plant system waterside problems requires diligent monitoring of waterside chemistry. This in turn requires the collection of truly representative steam and water samples and the use of appropriate methods of analysis and sensitivities. 

The solubility of methyl parathion is not sufficient to pose a problem in runoff water as determined by an empirical model of Wauchope and Leonard (1980). Some recent monitoring data, however, indicate that methyl parathion has been detected in surface waters (Senseman et al. 1997). In a study to determine the residue levels of pesticides in shallow groundwater of the United States, water samples from 1,012 wells and 22 springs were analyzed for methyl parathion. No methyl parathion was detected in any of the water samples (Kolpin et al. 1998). In a study of water from near-surface aquifers in the Midwest, no methyl parathion was detected in any of the water samples from 94 wells that were analyzed for pesticide levels (Kolpin et al. 1995). Leaching to groundwater does not appear to be a significant fate process. 

Brass HJ, Feige MA, Halloran T, et al. 1977. The national organic monitoring survey Sampling and analyses for purgeable organic compounds. In Pojasek RB, ed. Drinking Water Quality Enhancement Source Protection. Ann Arbor, Ml Arm Arbor Science, 393-416. 

A monitoring system has been established to determine 90 pesticides including anilides and 10 related degradation products in river water. Pesticide residues in the water sample are collected on a PS-2 cartridge (265-mg) at a flow rate of 10 mL min, eluted with 3 mL of acetone, 3 mL of n-hexane and 3 mL of ethyl acetate successively, and determined by GC/MS. Overall recoveries ranged from 72 to 118%. Recoveries of mepronil, naproanilide, propanil and flutolanil at fortification levels of 0.1 and 2 mg kg Mn water by this method were 80-112%. The LODs were 0.01 -0.1 pg L ... 

The method using GC/MS with selected ion monitoring (SIM) in the electron ionization (El) mode can determine concentrations of alachlor, acetochlor, and metolachlor and other major corn herbicides in raw and finished surface water and groundwater samples. This GC/MS method eliminates interferences and provides similar sensitivity and superior specificity compared with conventional methods such as GC/ECD or GC/NPD, eliminating the need for a confirmatory method by collection of data on numerous ions simultaneously. If there are interferences with the quantitation ion, a confirmation ion is substituted for quantitation purposes. Deuterated analogs of each analyte may be used as internal standards, which compensate for matrix effects and allow for the correction of losses that occur during the analytical procedure. A known amount of the deuterium-labeled compound, which is an ideal internal standard because its chemical and physical properties are essentially identical with those of the unlabeled compound, is carried through the analytical procedure. SPE is required to concentrate the water samples before analysis to determine concentrations reliably at or below 0.05 qg (ppb) and to recover/extract the various analytes from the water samples into a suitable solvent for GC analysis. 

Analytical accuracy. The mixture of all deuterium-labeled internal standards is added to each water sample before extraction. This does not prevent the loss of the unlabeled herbicides from the sample in subsequent processing steps, but a proportional loss of the deuterated internal standard precludes the need to correct for recovery. Although referring to recovery in this type of analysis is inappropriate, the accuracy of this method should be monitored. 

Environmental monitoring of chloroacetanilides requires methods that have the capability to distinguish between complex arrays of related residues. The two example methods detailed here for water monitoring meet this requirement, but the method for metabolites requires sophisticated mass spectral equipment for the detection of directly injected water samples. In the near term, some laboratories may need to modify this method by incorporation of an extraction/concentration step, such as SPE, that would allow for concentration of the sample, so that a less sensitive and, correspondingly, less expensive, mass spectral detector can be used. However, laboratories may want to consider purchasing a sensitive instrument rather than spending time on additional wet chemistry procedures. In the future, sensitive instrumentation may be less expensive and available to all laboratories. Work is under way to expand the existing multi-residue methods to include determination of additional chloroacetanilides and their metabolites in both water and soil samples. 

The goal of a groundwater monitoring plan for pesticides is to produce water samples that are representative of the aquifer under study at the time of sample collection. Materials and methods must be established prior to implementing a monitoring program... 

Polymeric precolumns of styrene-divinylbenzene were used by Aguilar et al. to monitor pesticides in river water. Water samples (50 mL) were trace enriched on-line followed by analysis using LC combined with diode-array detection. LC atmospheric pressure chemical ionization (APCI) MS was used for confirmatory purposes. It was found that after the pesticides had been extracted from the water sample, they could be stored on the precartridges for up to 3 months without any detectable degradation. This work illustrates an advantage of SPE for water samples. Many pesticides which may not be stable when stored in water, even at low temperature, may be extracted and/or enriched on SPE media and stored under freezer conditions with no detectable degradation. This provides an excellent way to store samples for later analysis. 

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