Rapid determination of total bromide in human serum using an energy-dispersive X-ray spectrometer

Since the bromide preparations useful in the treatment of intractable infantile epilepsy show a tendency to accumulate in the body, they may cause chronic toxicosis. To prevent this, determination of the bromide ion concentration in the serum is essential. After establishing a simple and rapid technique using energy-dispersive X-ray spectroscopy for the analysis of the serum total bromide level, we applied this technique in a clinically diagnosed epilepsy patient. The standard curve for total bromide showed linearity (r=0.999) in the range of 10-2000 microg/ml, and the lowest detection limit was 5 microg/ml. The mean recovery rate of bromide added to reference serum to yield a concentration of 50 microg/ml was 93.5% (n=5, coefficient of variation=9.1%). Analysis took only 20 min. On analysis of the serum of a 10-year-old girl whose treatment was initiated with orally administered potassium bromide 1.0 g/kg, a good correlation was found between the total bromide level obtained with energy-dispersive X-ray spectroscopic analysis and the level of bromide ions determined by ion-exchange HPLC. The determination of serum total bromide by rapid energy-dispersive X-ray spectroscopic analysis is a useful method of monitoring to prevent bromide poisoning.