RAPID DETECTION OF L-GLUTAMIC ACID USING A SERIES-ELECTRODE PIEZOELECTRIC QUARTZ-CRYSTAL SENSOR

Two methods are described for the determination of L-glutamic acid usi ng a series-electrode piezoelectric quartz crystal sensor. The effect of formaldehyde solution on the frequency shift is discussed. For the calibration curve method, in formaldehyde medium, the detection limit is 3.8 . 10(-5) M, the recovery is 100.4%, the relative standard devia tion is 3.32% (n = 5) and the frequency shift is linear up to 8 . 10(- 4) M; in aqueous medium, the above values are 2.0 . 10(-5) M, 99.1%, 3 .01% (n = 6) and 1.1 . 10(-3) M, respectively. The frequencimetric tit ration method is also described and the lowest titratable concentratio n of L-glutamic acid is 7.0 . 10(-5) M. The detecting results for tabl et samples show good agreement with the values determined by the pharm aceutical method.