Determination of amino acid based on a series piezoelectric quartz crystalsensor

A series piezoelectric quartz crystal (SPQC) sensor has been applied to det ect L-glutamic acid and L-lysine acid. The effect of formaldehyde solution on the frequency shift was studied. Two methods were discussed. For the cal ibration curve method, in a neutralized formaldehyde medium, the linear ran ges for determining L-glutamic acid and L-lysine acid were from 7.1 x 10(-6 ) M to 6.5 x 10(-4) M and from 6.9 x 10(-6) M to 7.4 x 10(-4) M, respective ly, with the detection limit being 7.1 x 10(-6) M and 6.9 x 10(6) M, the re coveries were 99.2% and 100.1%, the R.S.D were 1.63% (n = 6) and 1.83% (n = 6), respectively. Frequencimetric tiration method was also described and t he lowest titratable concentrations were 8.3 x 10(-5) M and 5.5 x 10(-5) M, respectively.