AWWA WQTC58859

The wide variety of possible threat agents or contaminants that could be introduced to thenation's drinking water supplies preclude testing for every possible agent. This forces us to relyon screening methods capable of detecting a diversity of analytes in a single test. Toxicity assaysare one possibility. What is needed is a low cost easy to use system that can be widely deployedThe Hach ToxTrak£ method makes use of resazurin reduction to measure respiration, a criticalpathway for cell viability. Resazurin is a redox-active dye which, when reduced, changes colorfrom blue to pink. Substances that are toxic to bacteria can inhibit their metabolism and thusinhibit the rate of resazurin reduction. This inhibition of resazurin reduction is taken as anindication of toxicity in the test. The method makes use of an accelerant (gluteraldehyde: U.S.patent 5,413,916) in the method to reduce the reaction time thus preventing oxygen interferenceand also, allowing the use of a lower level of inoculum to reduce the dye. The use ofgluteraldehyde allows measurement on a low cost instrument such as a spectrophotometer orcolorimeter. Even lower cost visual measurement with a color wheel has also been shown towork. Any type of bacterial culture may be used. This method has been evaluated and found tobe effective in detecting contamination by a wide variety of threat agents in drinking waterincluding heavy metals, herbicides, pesticides, rodenticides, radionuclides, industrial chemicalsincluding cyanide, commercial products, biotoxins and chemical warfare agent surrogates. Themethod was found to be effective in detecting almost all compounds tested at levels of interest tohuman health. This system represents a cost effective and wide scope sentinel method for use bydrinking water utilities. The low cost, wide range of effectiveness and ease of use entailed in thissystem make it ideal for the development of citizen based water monitoring groups that could beused as an early warning system in the event of a contamination incident. The method could alsofind use by first responders and in forensic investigations in tracing contaminant plumes orverifying system incursions. Includes 7 references, tables, figure.

Product Details

Edition:

Vol. - No.

Published:

11/02/2003

Number of Pages:

16

File Size:

1 file , 490 KB