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INVESTIGATOIN OF CYANOBACTERIA TOXINS IN WATER
Citation:
Budde, W L. AND M. Maizels. INVESTIGATOIN OF CYANOBACTERIA TOXINS IN WATER. Presented at Annual Conference of the American Society for Mass Spectrometry, Montreal, CA, June 8-13, 2003.
Impact/Purpose:
The purpose of this research project is to develop a strong qualitative and quantitative "gold standard" laboratory reference analytical method for the simultaneous selective and sensitive identification and measurement of those cyanobacteria toxins that are of the highest priority to EPA and state and local drinking water authorities. These toxins are on the drinking water candidate contaminant list (CCL), but the specific toxins that are the most likely to occur, and which are the potentially most hazardous, are not defined on the CCL. Six toxins were recommended for highest consideration by an EPA workshop in May, 2001. These are the alkaloids anatoxin-a and cylindospermopsin, and the four microcystins abbreviated RR, LR, YR , and LA (these characters are the standard single-character designations for four natural aminoacids). There are no published analytical methods that have been demonstrated to have the ability to detect and reliably measure the concentrations of these six compounds in a single drinking or source water sample. The purpose of this research is to not only develop and demonstrate this capability with real environmental samples, but also to do it in a single economical laboratory analytical method that requires about one hour from initial sample preparation to obtaining the results. It is expected that some other toxins will be found in the real environmental samples tested, and perhaps even new toxins may be discovered in this work. The techniques employed in this work, have the capability of tentatively identifying known and unknown toxins even when standards are not available.
Description:
Introduction:
Approximately 80 alkaloid and cyclic peptide toxins produced by various freshwater and marine cyanobacteria (blue-green algae) have been identified and their structures determined. The U. S. Environmental Protection Agency has identified two neurotoxin alkaloids and four cyclic peptide toxins that have the potential for serious contamination of sources of drinking water for humans and animals. The purpose of this research is to develop a convenient, rapid, but definitive analytical method for these toxins in water.
Methods and Instrumentation:
Four of the six toxins of interest, and three of lessor interest, were available for this work. Anatoxin-a, microcystins RR, LR, and YR, and nodularin were added to laboratory reagent water and to samples of natural waters at environmentally significant concentrations. The analytes were separated from the water by liquid-solid extraction using C-18 silica impregnated filter disks, eluted from the disks with methanol, and the eluate was analyzed using microbore (1 mm ID) LC combined with electrospray and time-of-flight mass spectrometry.
Preliminary Data:
The analytes anatoxin-a, microcystins RR, LR, and YR, and the cyclic peptide nodularin in methanol are separated in about 25 minutes. With about 50 ng of each injected, the LC peaks in the TIC have very good S/N. Microcystin RR gives mainly the (M+2H]2+ ion and the other analyes give the corresponding singly charged ions. In source CID gives a characteristic m/z 135 ion for the microcystins and nodularin, but anatoxin-a does not have the necessary structural feature to give this ion. Mean recoveries from laboratory water for the microcystins and nodularin were in the 85-98% range with RSDs in the 5- 17% range. The mean recovery of anatoxin-a was just 68% (RSD 11%). A suitable internal standard has not been identified and external standardization may account for some of the recoveries and analytical presicion.