Kinetic determination of tryptophan by using the B-Z oscillating chemical system.
A simple and rapid method was devised for determination of tryptophan, based on the Belousov-Zhabotinskii (B-Z) oscillating chemical system. Changes in oscillating period and amplitude were linearly proportional to the negative logarithm of L-tryptophan concentration over the range of 6.44 x 10(-7)-2.55 x 10(-4) M, with the regression coefficients of near unity and a lower detection limit of 6.5 x 10(-8) M. D-tryptophan was also examined although it is rarely found in most biological fluids, and perhaps not at all in natural proteins. The change of period against to negative logarithm of D-tryptophan concentration over the range of 4.9 x 10(-5)-8.24 x 10(-4) M is linear. Because the optimum conditions for determination of L- and D-tryptophan are not the same, a little amount of D-tryptophan does not affect the determination of L-tryptophan. Various influences were studied and a possible mechanism of perturbation to the B-Z oscillator by tryptophan was also discussed. Spectrophotometry and fluorescence spectrophotofluorimetry were used for comparison and confirmation of the results.
Gao
Jinzhang
J
College of Chemistry and Chemical Engineering, Northwest Normal University, 730070 Lanzhou, People's Republic of China. jzgao@nwnu.edu.cn
Qu
Jie
J
Yang
Wu
W
Wei
Xiaoxia
X
Dai
Hongxia
H
Lv
Dongyu
D
Ren
Jie
J
Chen
Hua
H
D007700:Kinetics; D008722:Methods; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D014364:Tryptophan / Q000032:analysis* / Q000737:chemistry
D014364:Tryptophan