Gas Diffusion-Flow Injection System with Preconcentration for the Analysis of Fluoride in Semen
International Journal of Analytical and Bioanalytical Methods
Among the deleterious effects of fluorine in the human body is the alteration of the reproductive system. The measurement of fluoride in urine is usually used as a biomarker of exposure but it provides no information about is incorporation in the reproductive system. So, in order to relate fluoride with effects in male's fertility it is convenient to measure fluoride in semen. Fluorine is one of the elements whose determination is difficult because the final measurement of the fluoride ion is
... e fluoride ion is interfered by other species usually present in the samples. For this reason, separation by distillation of the fluoride as hydrofluoric acid prior to its determination is commonplace. Separation of fluoride by distillation is time-consuming, so new methods are aimed to avoid the distillation step. Biological samples normally contain low levels of fluorine, so it is always necessary a pre-concentration step before the determination, but in the case of semen the sample volume is typically low (not more than 3 ml). So, the main goal was the determination of low levels of fluorine in a small sample volume of biological fluids. We developed a method using and automated FIA (Flow Injection Analysis) system using a gas diffusion cell (GDC) that can be operated in two ways a) Continuous for samples with high concentration and b) An open/close configuration for samples with low concentration. The method is based on the conversion of the fluoride ion to the HMDS derivative (a gas) and permeating the gas through a membrane regenerating the fluoride ion in the acceptor current and measuring it with an Ion Selective Electrode (ISE). The method allows the measurement of fluoride in semen with low detection limits, low sample volume, but allowing a good reliability measured as %RSD: 1.6% RSD for semen samples in the open-closed configuration and 0.68% RSD for the continuous mode. The method was used in the determination of fluoride in semen of 28 individuals from San Luis Potosí, México, exposed to low concentrations of fluoride (drinking water) and a subgroup of occupationally exposed workers with high concentrations of fluoride (laboral exposure) but also to drinking water.