[Use of x-ray fluorescence analysis for determination of bromine in drug synthesis, with a look at chlorine (sulfur) and fluorine].

In this paper the determination of bromine as represented in the literature is briefly reviewed with the matrix and background effects being considered. The results obtained in determining low contents of bromine in pharmaceutical substances of light matrix (Z less than or equal to 8) by the use of a wavelength dispersive X-ray fluorescence spectrometer VRA-20 have shown the sample thickness to influence the Br-Ka radiation. The calibration of a chloroorganic matrix is performed with a so-called substitute standard substance consisting of cellulose and ammonium chloride, which is advantageous, if standard material free of analyte is difficult to get or only small amounts of sample are available. Additional measurements have been carried out to determine chlorine also by the use of a vacuum-tight liquid cell. Detection limits of 3 ppm Br (10 ppm Cl) in a light matrix and of 60 ppm Br in a chloroorganic matrix can be obtained without analyte enrichment by the powder-compressing process. The present possibilities of measuring the F-Ka radiation in active pharmaceutic substances are discussed.