A fast and simple turbidimetric method for the determination of sulfate insulfate-reducing bacterial cultures

A standard turbidimetric assay for the determination of sulfate in water wa s modified with the objective of achieving a quick and simple method for mo nitoring the decrease of sulfate in cultures of sulfate-reducing bacteria. The effects of sulfate concentration, mixing time and the ratio of sample t o conditioning reagent were optimized using a central composite face-center ed response surface model design. The results suggested that a mixing rime of 30 s resulted in smaller absorbance variance, the variance in absorbance measurements tended to increase with concentration of sulfate and that the ratio between the amount of conditioning reagent and sample had no signifi cant influence on the absorbance variance. The modified assay thus develope d is simple and quick, and covers a comparatively large sulfate concentrati on range (0-5 mM) compared to the standard turbidimetric assay. (C) 2000 El sevier Science BN. All rights reserved.