Improved routine speciation of organotin compounds in environmental samples by pulsed flame photometric detection

The high toxicity of the organotin species requires sensitive analytical methods in order to understand the origins of pollution and perform monitoring programs in the water cycle. The optimisation of a new detection method, pulsed flame photometric detection (PFPD), is reported for the simultaneous determination of butyl-, phenyl- and octyltins. The methodology of the experimental designs at two levels was used. It allows the evaluation of the influence of the three gas flow-rates on the peak heights and resolution between the closest peaks obtained using two different wavelengths of detection (390 and 611 nm). The modelling of these two responses, according to second-order polynomials, leads to the precise adjustment of the operating conditions. PFPD has shown two significant improvements over conventional flame photometric detection: increased sensitivity (absolute detection limits: 0.07 to 2 pg as Sn) and greater selectivity, whatever the wavelength used. This new analytical process was validated by the analysis of certified reference material and spiked river water. It was used in routine analysis of environmental samples (wastewater, sludge, sand and oyster).