Determination of molybdenum in sea water by solid-phase spectrophotometry

A simple and sensitive spectrophotometric method for the determination of molybdenum(VI) in sea water samples was developed. It is based on the extraction of the Mo(VI)-phenylfluorone complex on a membrane filter by simple filtration and direct measurement of the absorbance on the filter. The extraction was done in the presence of zephiramine and only 2–10 ml of sample solution was required. No preliminary treatment of the sea water sample was required to isolate molybdenum(VI) from the matrix. The absorbance was measured by the zero and first derivative modes. The tolerance limit for foreign ions was improved by measuring the first derivative absorbance.