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NEW APPROACHES TO THE PRESERVATION OF CONTAMINANTS IN WATER SAMPLES
Citation:
Saxena, J. AND E. Nies. NEW APPROACHES TO THE PRESERVATION OF CONTAMINANTS IN WATER SAMPLES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/4-79/007.
Description:
The potential of antibiotics, chemical biocides and lytic enzymes in preserving nutrients, biological oxygen demand and oil and grease in water and sewage effluents was studied. Preliminary studies concerning the effect of drugs on cell growth and oxygen utilization in samples stored at room temperature led to the selection of chlorhexidine, vantocil and many combinations each containing three antibiotics from among polymyxin B, neomycin, erythromycin, streptomycin and chloramphenicol. The effective concentration range was approximately equal to 50 micrograms/ml each antibiotic for clean waters and as high as 200 micrograms/ml each antibiotic for heavily polluted water (e.g. primary effluents). Chlorhexidine and vantocil IB stabilized nitrate and nitrite in fresh waters and relatively clean secondary effluents only. Presence of antibiotics caused interference in determination of orthophosphate. The antimicrobial agents tested interfered with BOD determination by causing inhibition of oxygen depletion and therefore were of no value for preservation of this parameter. Efforts to selectively remove and/or inactivate the drug before BOD determination were unsuccessful. Oil and grease levels were stabilized by antibiotics for up to two weeks in relatively clean waters only. The results demonstrate that antibiotics offer a viable alternative to conventional methods for preservation of some constituents and parameters in fresh water samples but not in sewage effluents.