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A selective and sensitive method for determination of total homocysteine (Hcy) in human serum, by gas chromatography coupled to ICP-MS(HR), has been developed. After reduction of the sample with sodium borohydride the liberated Hcy and other aminothiols, such as cysteine (Cys) and methionine (Met), were converted to their N-trifluoroacetyl (TFA)- O-isopropyl derivatives and these were injected into a gas chromatograph equipped with an HP-5 capillary column. Detection was carried out by means of a double-focusing inductively coupled plasma mass spectrometer (DF-ICP-MS) monitoring (32)S at m/Delta m (resolving power)=3000. The transfer line used to transport the analytes from the GC column to the ICP-MS had previously been developed in our laboratory. The different parameters affecting the derivatisation process were optimised, as were the instrumental operating conditions. This optimised GC-ICP-MS(HR) method was successfully applied to the determination of total homocysteine in human serum-values obtained were in agreement with data reported in the literature. Quantitative recoveries and good precision were obtained for spiked human serum, demonstrating the suitability of the method for quantitative determination of total homocysteine in serum.

Size exclusion chromatography (SEC), carried out on a Superdex 200 column, has been coupled on line to a quadrupole ICP-MS instrument, equipped with an octopole reaction cell (ORC), for the multielemental speciation of several essential (P, S, Cr, Mn, Fe, Co, Cu, Zn, Br, Se and I) and toxic elements (such as Al) in premature human breast milk whey and premature infant formulae. Human milk samples were centrifuged at 31000g to obtain the milk whey. A SEC-ICP-(ORC)MS hyphenated technique was optimised and then applied to the multielemental fractionation of such elements in premature (after 28-32 gestational weeks) human milk whey at four different lactating stages, covering the first month after birth (namely: colostrum, 6th day, 14th day and 28th day milks after delivery). Similarly, the technique was also applied to essential and toxic elements fractionation in several formula milks, commercially available for feeding of premature newborns. Results of distribution patterns of the above mentioned elements in the two sample types under study (human and formula milks) are discussed. Important differences in trace element speciation between premature human and formula milks have been demonstrated for many essential elements (e.g. Cu, Fe and Zn). The nutritional significance and practical implications of such differences is highlighted from the point of view of formula milks production for premature babies.