Abstract
Analytical methods were developed and validated for the determination of the total concentration of trace elements (Se, Fe, Cu, Zn, Mg, Ca, Mn, Mo, I, Cd and Pb) and the various organic and inorganic selenium species present in human body fluids. Total elemental analysis involved the use of inductively coupled plasma mass spectrometry (ICP-MS). Speciation analysis utilised ion-pair high performance liquid chromatography (HPLC) coupled on-line to a hexapole collision cell ICP-MS. The methods that were developed were then applied to three separate studies. The effect of psychological stress on human fertility was determined by comparing the trace element levels in blood serum from 47 infertile women undergoing in-vitro fertilisation (IVF) treatment. Elemental data was compared with stress-hormone (plasma prolactin and serum cortisol) levels and Spielberger stress questionnaires. Statistical analysis showed no relationship between stress-hormones and blood serum trace element levels and that stress-hormones do not have an adverse effect on human fertility. A further study examined the total trace element levels of blood serum, follicular fluid, endometrial fluid and scalp hair from a study population of 97 women aged between 24 - 44 years undergoing IVF treatment. Selenium levels in blood serum were significantly lower in IVF patients in contrast to 18 (age and gender matched) control cases (P = 0.001, 35 degrees of freedom). This was in agreement with a previous study with infertile women, aged <35 years. Zinc and manganese were determined in endometrial fluid, both showing a high degree of correlation (P = 0.001, 17 degrees of freedom) in the IVF population (no control samples were available for analysis). The levels of each element measured in scalp hair showed no correlation with the levels determined in any other matrix. A major contribution of this research involved speciation analysis of selenium in blood serum, seminal plasma and urine. Commercial selenium supplements were consumed over 28 days and the effect that this had on selenium levels (total and species) within the human body fluids was investigated. Consumption caused an increase in the levels of selenium within all human body fluids and in general, the total level of selenium was found to be higher than the sum of the species present. An in-vitro bioavailability procedure was performed on the supplements and showed that two selenium yeast commercial products contained different selenium species. Some selenium species were identified and the implications of this are discussed.