a new flow injection system for sensitive spectrophotometric determination of 4-amino benzoic acid based on diazotization of paba and their biological activity investigation

A simple, rapid, and sensitive automated cfia/mz method was suggested for determination of p-amino benzoic acid (paba) in pure material. this procedure was based on the diazotization of paba via the reaction of sodium nitrite with hydrochloric acid in the ice bath (0-5) for 5 min, the diazotized product reacts with 2,6-dihydroxybenzoic acid (dhba)as a coupling agent in alkaline medium to form an colored yellow azo dye, it is water-soluble, extremely stable was measured at λmax=438 nm under the optimized experimental conditions with 1:1 stoichiometric ratio, and all physical and chemical parameters were studied. a reagent concentrations, sequence of addition, flow rate, reaction coil, and value of loop, flow rate is 7 ml.min-1 using distilled water as a carrier, and the linear range of calibration curve was 10 -150 µg.ml-1, where the detection limit was 5 μg.ml-1, and the rsd% was 0.976, with a sample throughput of 72 sample/hr. excipient interferences were investigated, with good average recovery of 98-103 %. the biological activity of the organic acid (paba) was evaluated. it was found that it has biological activity antibacterial and antifungal and antioxidant. the results were compared with studies in this field and the results were convincing.