Doubling the Production and Precision of the MBTH Spectrophotometric Assay for Dissolved Carbohydrates in Seawater

Extensive use of the three step 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) method for determining concentrations of both free and combined dissolved carbohydrate occurring in diverse marine environments has shown its suitability for studies of carbohydrate dynamics. Modification of the analytical sequence to extend over 2 working days to eliminate a confusing and error producing overlap of analytical operations allows a single analyst to determine 15 instead of 8 samples in the same 2-day period. This modification also permits an increase in the number of blank plus replicate determinations from 5 to 7 per sample so that a total of 105 reaction tubes can be assayed every 2 days compared to 40–50 for the original procedure. For a series of 7 Narragansett Bay samples, the standard deviation of the method serendipitously decreased by 50% (from ±5.3 to ±2.7 μg C l−1) when the original procedure was compared with the modified procedure. Postponing the final analytical step for a day when the analyses can be completed with an autoprocessor will free the analyst for the processing of more samples, causing an additional doubling in productivity