OPTIMIZATION OF A FLAME PHOTOMETRIC DETECTOR FOR SUPERCRITICAL-FLUID CHROMATOGRAPHY OF ORGANOTIN COMPOUNDS

A single flame photometric detector has been optimized for capillary supercritical fluid chromatography (cSFC) of trialkyltin chlorides for the first time. Detection variables (temperature, hydrogen and air flow-rates) were optimized by a combination of factorial experimental design and simplex. Furthermore, the position of the restrictor in the flame and injection volumes were also considered. Optimum sensitivity was achieved using high hydrogen-air ratios (1.8). Using the optimum conditions, baseline was stable during pressure programming. The detection limit of tributyltin chloride (S/N=3) was around 40 pg (as tin). Reproducibility was high (R.S.D. = 3.8%, n = 5) and dynamic range was measured over two orders of magnitude. Furthermore, dibutyl-, diphenyl- and triphenyltin chlorides were also successfully eluted for the first time using linear density programming (carbon dioxide, 50-degrees-C).