Sodium Benzoate Analysis for On-line Brine Flow Measurements

Abstract

The optimum conditions for the analysis of sodium benzoate in brine matrix using the Shimadzti HPLC Kvstem were determined. This system is composed of a single-pump, an on-line degasser, an auto injector, an oven, a UV detector and an ODs reverse-phase column. This was done in order to develop an accurate, precise, and fast method for the analysis of sodium benzoate, a chemical tracer for on-line brine flow measurements.

Isocratic runs using methanol-phosphate buger eluent of 55:45 v/v ratio and 1.0 mLhinute flow rate at 230 nm wavelength was found to give very good results in terms of baseline stability, peedom from interference and speed of analysis. Benzoate retention time at this conditions is 2.8 minutes. Linearity of the instrument response within the range of at least 0.05 ppm to 200 ppm benzoate, for a j pL sample injection has been established. Accuracy of more than 99 % has been consistent!v obtained for both benzoate standards and actual tracer samples. Precision is vety high with an established COL'of the method of < I %. Matrix interference is found to be vey minimal.

Benzoate is foundprone to degradation due to microbial action. This however, can be controlled by acid treatment, addition of sodium azide solution, or repigeration.