The wide variety of possible threat agents or contaminants that could be introduced to the
nation's drinking water supplies preclude testing for every possible agent. This forces us to rely
on screening methods capable of detecting a diversity of analytes in a single test. Toxicity assays
are one possibility. What is needed is a low cost easy to use system that can be widely deployed
The Hach ToxTrak£ method makes use of resazurin reduction to measure respiration, a critical
pathway for cell viability. Resazurin is a redox-active dye which, when reduced, changes color
from blue to pink. Substances that are toxic to bacteria can inhibit their metabolism and thus
inhibit the rate of resazurin reduction. This inhibition of resazurin reduction is taken as an
indication 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 interference
and also, allowing the use of a lower level of inoculum to reduce the dye. The use of
gluteraldehyde allows measurement on a low cost instrument such as a spectrophotometer or
colorimeter. Even lower cost visual measurement with a color wheel has also been shown to
work. Any type of bacterial culture may be used. This method has been evaluated and found to
be effective in detecting contamination by a wide variety of threat agents in drinking water
including heavy metals, herbicides, pesticides, rodenticides, radionuclides, industrial chemicals
including cyanide, commercial products, biotoxins and chemical warfare agent surrogates. The
method was found to be effective in detecting almost all compounds tested at levels of interest to
human health. This system represents a cost effective and wide scope sentinel method for use by
drinking water utilities. The low cost, wide range of effectiveness and ease of use entailed in this
system make it ideal for the development of citizen based water monitoring groups that could be
used as an early warning system in the event of a contamination incident. The method could also
find use by first responders and in forensic investigations in tracing contaminant plumes or
verifying system incursions. Includes 7 references, tables, figure.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 490 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 16 |
| Published : | 11/02/2003 |
