Fractionation drinking water concentrates

Figure 8. Mutagenic activity of a fractionated LH20 drinking water concentrate (neutral fraction) as detected with nitroreductase-deficient bacterial strains. LH20 fractionated drinking water concentrates were tested in the Salmonella mutagenicity test as described in Materials and Methods. Each point represents the average value of three plates.

To determine the chemical composition of drinking water, concentration by headspace, extraction, and XAD-2 adsorption were applied to acquire concentrates. Sensory-directed fractionation of these concentrates has led to the identification of odor-intensive compounds of industrial origin. 

Cells, Treatment, and Chromosome Analysis. About 4 X 105 CHO-K1 cells (Flow Laboratories, Scotland) were seeded into Ham s F10 medium (Flow) supplemented with 10 newborn calf serum (Flow). These cells were incubated at 37 °C and 5 C02 in 25-cm3 tissue culture flasks. Twenty-four hours later, the cells were exposed for 1 h at 37 °C to a maximum of 50 /zL of drinking water concentrate (neutral fraction) in a total volume of 3 mL of Ham s F10, without serum. As a positive control, 4-methoxyaniline, dissolved in DMSO, was used. 

Figure 1. Effect of resin type on the mutagenic activity of drinking water concentrates in the Ames test. The sampling, 7000-fold concentration with either XAD-2 or XAD-4/8, DMSO elution (20 mL, neutral fraction), and subsequent mutagenicity testing were as described in Materials and Methods. Similar concentrates of The Hague tap water were used as controls. Each point represents the average of four plates, and 0.50 mL of concentrate corresponds to 3.5 L of water per plate.

Figure 3. Effect of heating on the activity of a mutagenic drinking water concentrate. A mutagenic XAD-4/8 acetone concentrate (neutral fraction) was heated to 250 °C. The total heating time was 1 h. After this period, the organic residue was dissolved in acetone and retested in the Salmonella...

Figure 4. Molecular weight determination of a drinking water concentrate with Sephadex LH20. Sampling, 10 -fold concentration of drinking water before and after chlorination (L5 mg/L of CI2, Meuse River source) on XAD-4/8, elution with DMSO (neutral fraction), and subsequent gel filtration were as described in Materials and Methods. After measuring the absorbance at 263 mm, the fractions were pooled as indicated. After dilution in water, the fractions were reconcentrated on XAD-4/8, eluted with DMSO, and assayed in the Salmonella mutagenicity test (strain TA98 S9).

Figure 6. Fractionation of a mutagenic drinking water concentrate with Sephadex LH20. On a Sephadex LH20 column, 1.6 mL of a drinking water concentrate (IX 106-fold concentrated, neutral fraction) was separated by using stepwise isopropyl alcohol (ISOP) and dioxane/water (D/W) elution as described in Material and Methods. Fractions were pooled as indicated. After reconcentration the fractions were assayed for mutagenic activity in the Salmonella mutagenicity test and CHO cells (Table I).

Introduction of Chromosomal Aberrations by a LH20 Fraction of Drinking Water Concentrate. Because in previous experiments, analysis of XAD-4/8 concentrates of drinking water in in vitro mammalian cell systems was hampered by the toxicity of the concentrates for the cells, an attempt was made to investigate whether the LH20 fractions obtained could be analyzed for the induction of chromosomal aberrations in CHO cells (Table I). 

Table I shows that a combination of LH20 drinking water fractions II and III (Figure 6) was able to induce chromosomal aberrations in the CHO cells. This experiment was repeated several times with LH20 concentrates throughout the year at the same location three out of five drinking water concentrates showed increased levels of chromosomal aberrations compared to the control, whereas no toxic effects were observed (Table I). The negative results are not shown. The results indicate that the LH20 fractionation procedure may (in part) be suitable for testing drinking water concentrates for genotoxic effects in mammalian cell systems.

Figure 9. Distribution of halogenated hydrocarbons and mutagenic activity in HPLC fractions of a drinking water concentrate (neutral fraction). HPLC fractions obtained by linear-gradient HPLC analysis (H2O-C2H3N) were tested for mutagenic activity in the Salmonella mutagenicity test (TA98) and assayed for halogenated hydrocarbon content as described in Materials...

Prepai ative isolation of nonvolatile and semivolatile organic compounds fractions (hydrophobic weak acids, hydrophobic weak bases, hydrophobic neutrals, humic and fulvic acids) from natural and drinking waters in optimal conditions was systematically investigated by solid-phase extraction method with porous polymer sorbents followed by isolation from general concentrate of antropogenic and/or toxic semivolatile compounds produced in chlorination and ozonation processes. 

Snow, especially its water-soluble fraction, is one of the most sensitive and informative indicators of mass-transfer in the chain air - soil - drinking water. Therefore analytical data on snow-melt samples were selected for inter-laboratory quality control. Inter-laboratory verification of analytical results estimated in all the groups have shown that relative standard errors for the concentrations of all the determined elements do not exceed (5-15)% in the concentration range 0.01 - 10000 microg/1, which is consistent with the metrological characteristics of the methods employed. All analytical data collected by different groups of analysts were tested for reliability and... 

This kind of measurement is sometimes called a mass-mass percent solution because one mass is divided by another. Very dilute concentrations (as in the concentration of a contaminant in drinking water) are sometimes expressed as a special mass percent called parts per million (ppm) or parts per billion (ppb). In these metrics, the mass of the solute is divided by the total mass of the solution, and the resulting fraction is multiplied by 10 (ppm) or by 10 (ppb). 

T HE HIGH COMPLEXITY AND DILUTED FORM in which organic compounds occur in natural and drinking waters require that isolation, concentration, and fractionation procedures be employed to achieve a suitable sample for chemical and toxicological characterization. The use of these methods in analytical schemes has thus far allowed the identification of several hundred trace organic substances in drinking water... 

Concentration, Fractionation, and Characterization of Organic Mutagens in Drinking Water... 

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