DETERMINATION OF BORIC-ACID IN FOODS - COMPARATIVE-STUDY OF 3 METHODS

Three methods for the determination of boric acid in foods were studied in detail, namely the titrimetric method using mannitol, and two colorimetric procedures using carminic acid or curcumin. Agar-agar strips, pickled mango, noodles and prawns were analysed and the repeatability, sensitivity and recovery of the methods compared. The titrimetric and curcumin methods gave mean values for boric acid which were significantly (P < 0.05) higher than those of the carminic acid method. Results with the titrimetric method did not differ from those with the curcumin method; the latter method gave good recoveries (approximately 100%) for all four foods at all levels of addition. Analyses carried out on NBS Standard Material showed that the curcumin method gave the most accurate results. This method was also found to show the least internal variation both in terms of mean boric acid content and recovery. Furthermore, the method possessed practical advantages over the other two techniques. Based on the results obtained from the comparative studies, the curcumin method was found to be the most reliable and hence would be the method of choice for boric acid determination in foods.