Separation of pH, dilution, lonic strength and chemical matrix effects for biological monitoring of urines with the Microtox® test using nicotine, cotinine and reference urines
✍ Scribed by Chou, Chin C. ;Hee, Shane S. Que
- Publisher
- John Wiley and Sons
- Year
- 1993
- Weight
- 736 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0884-3996
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✦ Synopsis
The aim was t o investigate the factors influencing light emission from Photobacterium phosphoreum in the Microtox@ test t o interpret bioassay results for urine. Four reference urines were assessed as reference materials for the bioassay. Nicotine and cotinine were investigated as urinary markers for tobacco exposure. The optimum luminescence conditions were: 1.85%-3.25% NaCI, 0.33-0.58 mol/L ionic strength, and pH 5.8-6.7. Low pH values and high concentration of toxic trace metals were important factors in this study. Unexpected toxicity for a Standard Reference Material was attributed t o zinc contamination. Nicotine and cotinine together exhibited antagonistic effects in 2% saline but this could not be observed in the urines because of substantial urine toxicity. Thus practical urinary biological monitoring w i t h the Microtox@ test necessitates excretion of metabolites and compounds that are much more toxic than the urine components. Also, separation of the effects of physical factors like pH, ionic strength and dilution is essential before chemical toxicity effects can be assigned. This is the first report of Microtox@ EC, , values for nicotine and cotinine. The results have application t o environmental samples since analyses are often uncontrolled relative t o pH, ionic strength and dilution.