TITRIMETRIC DETERMINATION OF PHOSPHATES AND MONOFLUOROPHOSPHATES IN TOOTH PASTES

Titrimetric methods for a fast determination of phosphates and monoflu orophosphates in tooth pastes are described. They are based on the pre cipitation of PO43--ions (directly or after the hydrolysis of PO3F2--i ons) as BiPO4 in nitric acid (pH 0.1-0.5). The end-points are detected visually (back EDTA-titration of the non-bonded Bi3+-ions), or potent iometrically (direct titration of phosphates with bismuth by a special ly prepared Bi/Bi2O3-electrode). The titrations are performed without separating the precipitate. An ultrasonic field is applied to accelera te the destruction of the dentifrices.