Short Communications: Automated dissolution rate analysis of iron in some vitamin preparations

Since the end of the evaluation the assay has been in routine use and no problem has been exp.erienced, although the reagents were from the same batch. Further clarification of the difficulty is required. Original studies on the uric acid methodology were performed using the Boehringer Urica-quant kit, as recommended by Coulter, but the correlation studies showed poor agreement with standard techniques due primarily to a non-linear reaction course. This phenomenon had been reported previously in an evaluation study on the Abbot ABA-100 analyser by Bullock et al 17]. It was for this reason that a further study on uric acid measurement was performed using an N ADP coupled reaction as detailed by SKI. This is a two-reagent method, uricase being the starter reagent, and is based on the oxidation of acetaldehyde by aldehyde dehydrogenase in the presence of NADP. On the Kern-O-Mat the reaction was found to be linear to 1500 pmo showing a good correlation with the routine method. The creatine kinase assay would appear to give poor between-batch precision, but of the same order as that obtained in the routine laboratory; the difficulty is a reflection of the chemistry and not the functioning of the instruments involved. The reagent costs given in Table 8, show the best and worst cases of reagent utilisation. The manufacturer quotes figures for total reagent consumption whereas the figures found in use are determined from opening a single vial of reagent; the true reagent cost probably falls somewhere between the two. Some of these costs would appear to be high, but when compared with the costs on other instruments in the author's laboratory a net saving can be made on selected chemistries in which expensive reagents are used.