Development of a photometric procedure for tin determination in canned foods employing a multicommuted flow analysis approach
This work describes an automated analytical procedure for the photometric determination of tin in canned foods, employing a multicommuted flow analysis process. The flow system manifold comprised a set of three-way solenoid valves to handle solutions and a multisyringe module for fluid propelling. A PIC microcontroller, run using a software written in Visual Basic 6.0 language, was used to control the flow analysis setup and to perform data acquisition. Photometric detection was accomplished employing a homemade photometer, which consisted of an ultra-bright LED, a photodiode and a homemade flow cell with an optical path length of 200 mm. The procedure was based on the reaction of Sn(IV) with pyrocatechol violet (PCV) in the presence of surfactants. After selecting the best operational conditions, profitable features such as, a linear response ranging from 0.10 to 1.25 mg L−1, a limit of detection of 0.04 mg L−1, a variation coefficient of 1.30% (n = 10) and a sampling rate of 49 determinations per hour were achieved. By spiking samples with tin, recoveries between 95 and 110% were achieved.