Correction of the interference by mixing the reagents in the bioluminescent determination of ATP in environmental samples by an interfaced PC photometer and a robust regression procedure

An automated procedure for correcting the interference due to mixing the reagents in the determination of ATP by a bioluminescent technique is described. The measurements were performed by an in-house interfaced PC photometer. An automated procedure based on a robust regression method and outliers detection was applied to exclude the time of the mixing of the reagents from the global time of reaction. In fact the mixing of the reagents is responsible of the poor analytical precision (RSD% > 25) and low sensitivity (limit of detection approximate to 2 x 10(-8) mol/l). By this procedure, the precision (RSD% < 7) and sensitivity (limit of detection approximate to 8 x 10(-10) mol/l) were improved. The method was applied to the determination of ATP in marine sediments and good recovery within 90-108% was obtained. For non-polluted samples the measurement can be carried out by direct comparison with standard solutions. The standard addition procedure is recommended for polluted samples.