Sample collection and treatment

Upon arrival, the sample should be logged in the laboratory record book indicating time of arrival, sample temperature, and pH. The sample should in all cases be analyzed for residual chlorine and, if present, oxidized with sodium thiosulfate before it is employed for toxicity evaluation. A portion of the sample should also be removed for alkalinity and hardness analyses. Often it is necessary to coarse filter the sample to remove floe or suspended debris before testing however, this practice may reduce the sample s toxicity. The remainder of the sample should be kept at 4°C for a period not exceeding 72 h after initial sample collection. It is desirable to employ two separate 24 h composite samples for performing a 96 h acute larval fathead minnow test. This would allow renewal after 48 h exposure. In the 7 day tests with Ceriodaphnia and Pimephales, three separate 24 h composite samples should be employed for daily renewal of the various exposure solutions. Toxicity data summary sheets should include daily routine physico-chemical measurements and sample information. It is essential that good laboratory practices be used in all aspects of sample collection, treatment, and analysis to obtain quality and defensible results. 

Quality assurance is about getting the correct result. In environmental analysis and monitoring, this involves several steps, including sample collection, treatment and storage, followed by laboratory analysis. A complete environmental protocol is shown in Figure 2.1. It is likely that the variation in the final measurement is more influenced by the work external to the analytical laboratory than that within the laboratory. Two important terms in quality assurance are accuracy and precision. 

The solubility of chlordecone in water is low (1--3 mg/L) and as with mirex, contamination is more likely to be associated with the particulate matter in the water rather than the water itself. Chlordecone was detected primarily in water samples collected in and around the production facility site in Hopewell, Virginia, and in adjacent waters of the James River estuary. Effluent from the Life Sciences Products Company facility contained 0.1 —1.0 mg/L (ppm) chlordecone, while water in holding ponds at the site contained 2--3 mg/L (ppm) chlordecone (Epstein 1978). Levels of chlordecone in river water in August 1975 ranged from not detectable (<50 ng/L [ppt]) in the York River and Swift Creek areas, to levels of 1--4 pg/L (ppb) in Bailey Creek which received direct effluent discharges from the Hopewell Sewage Treatment Plant. Water concentrations of up to 0.3 p g/L (ppb) were detected in the James River at the mouth of Bailey Creek and in the Appomattox... 

As far as chemical variables are concerned, especially in case of trace determinations, all the steps of sample collection, treatment in the field and storage must be carefully considered in order to maintain sample integrity before analysis. In this respect the selection of appropriate equipment and non-contaminant materials, as well as the application of efficient cleaning procedures, are of paramount importance. For the most critical applications clean chemistry laboratories (equipped with Class 100 laminar flow cabins) must be available in the field or on board. 

Kister LR and Garrett WB (1983) Field Guidelines for Collection, Treatment and Analysis of Water Samples. Arizona District, AZ, USA. 

The use of essential oils for chemosystematic study of North American conifers has been reviewed and many of the problems of sample collection, analysis, and interpretation of data discussed (von Rudloff, 1975). In addition, specific treatments of Abies, Chamaecyparis, Juniperus, Picea, Pinus, Pseudotsuga, Thuja, and Tsuga are summarized. Sampling of these coniferous trees was found to be most reproducible during the dormant period from fall through winter. 

Groundwater samples collected over the last 10 years from monitoring and private water wells in the offpost area of RMA have provided data regarding the extent of diisopropyl methylphosphonate. The data indicate that diisopropyl methylphosphonate in the alluvial aquifer extends from the RMA northwest to the South Platte River. In the 1995 sampling event, diisopropyl methylphosphonate concentrations ranged from less than 0.392 g/L, the detection limit, to just over 600 g/L in this area. The highest reported concentrations were present upstream of the Peoria Street Treatment Plant. The lowest or non-... 

Rainbow trout and channel catfish were exposed to a nominal concentration of 0.02 mg/L of niclosamide for a period of approximately 12 h. Samples of fillet tissue were collected from each fish species before treatment and at 6, 12, 18, 24, 48, 96, and 192 h after exposure. The fish were dissected, homogenized, extracted, and analyzed by HPLC [75],... 

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