Dosage polarographique du brome a l'echelle du nanogramme: Application à la determination du brome sanguin et urinairePolarographic determination of bromide at nanomolar levels. Application to the determination of bromide in blood and urine

Polarographic determination of bromide at nanomolar levels. Application to the determination of bromide in blood and urine.Colorimetric methods for bromide determination lack adequate sensitivity for normal levels in biological fluids. A sensitive amplification process is recommended: bromide is oxidized to bromate with hypochlorite; after reaction between bromate and excess of bromide, the bromine formed is extracted into chloroform and then reduced to bromide by ammonia; these different steps can be repeated. Alternating current polarography of bromate allows selective evaluation in biological fluids. The detection limit is 10^-6 M and can be reduced to 10^-9 M with further amplification steps. The effects of iodide and of instrumental parameters are discussed.     

Utilisation d'un “blanc interferences” dans la determination des nitrates par potentiometrie selective

(Use of an interference blank in the determination of nitrate by ion-selective potentiometry.) During selective potentiometry of nitrate in meat product additives, a new interference originating from polyphosphate ions was encountered. The selectivity coefficients measured were 5 × 10^?2 for tripolyphosphate, 10^?2 for chloride, 8 × 10^?4 for pentapolyphosphate and 6 × 10^?4 for pyrophosphate. An “interference blank” techniques is proposed; nitrate is destroyed in the medium to be studied, so that calibration is possible in the presence of interfering substances regardless of their identity or concentration. The method is successfully applied to monitoring of meat product additives.