Flow-through photometric sensor for determination of sulfonamides.

A sensor based on integration of spectrophotometric detection and retention of the product of the Bratton-Marshall reaction for the determination of sulfanilamide, sulfamethazine, sulfaquinoxaline and sulfathiazole is reported. The methods developed using this sensor in a flow injection manifold feature linear ranges for these analytes between 10 and 1200 ng ml(-1) with relative standard deviations smaller than 2.6% in all instances and they were applied to the determination of sulfonamides in spiked milk and water samples with excellent results. The two main advantages of these sensor-based methods over other automated and non-automated counterparts are enhanced sensitivity as a result of in situ concentration and avoidance of using a de-bubbler to eliminate the nitrogen produced in the flowing system.