Determination of tryptophan in feed samples by cyclic voltammetry and multivariate calibration methods

Abstract

A voltammetric method for the determination of tryptophan (Trp) in feed samples using multivariate calibration techniques is proposed. The multivariate data consisted of the oxidation wave of cyclic voltammograms registered from 400 to 925 mV using a graphite-methacrylate composite electrode, at which Trp was oxidized around a potential of 900 mV. The interference from other oxidizable amino acids as well as the feed sample matrix was circumvented by using multivariate calibration methods. Principal component regression (PCR) and partial least squares regression (PLS) and non-linear PLS (NL-PLS) were checked for quantifying Trp in these samples. The results obtained using NL-PLS were in agreement with those obtained with the standard method for the determination of amino acids, with an overall prediction error of 7.9%.

Recent Developments, Characteristics, and Potential Applications of Electrochemical Biosensors

“…61 Saurina et al developed an amperometric biosensor for the determination of lysine, which was added as dietary supplement to food or drugs. 31 Three different configurations of the lysine biosensor were proposed, based on rigid-conducting biocomposites (graphite-methacrylate composite electrode for the electrochemical detection of hydrogen peroxide at +1000 mV, peroxidase-modified graphite-methacrylate biocomposite electrode for the reductive electrochemical detection of oxidized peroxidase, and peroxidase-modified graphite-methacrylate biocomposite electrode for the hydroquinone-mediated detection). [61][62][63] The hydroquinone-mediated biosensor was found to work better under reductive electrochemical detection than the graphite-methacrylate electrode biosensor, by diminishing potential interferences.…”

“…It was observed that the stability of the peroxidase-modified biosensor was longer than that of the graphite-methacrylate electrode configuration. 31 After investigating possible interferences for the three configurations, the majority of amino acids were amperometrically detected at +1000 mV with the analysis of lysine for the graphite-methacrylate composite electrode. The noticeable interferences among amino acids were tryptophan, tyrosine, and cysteine acids.…”

“…The amperometric biosensors are used to determine lysine have a detection limit of 0.82 µM and a response time of 42 s in nutrition and pharmaceutical fields. 31 The amperometric biosensors have a response time of 30 s with a detection limit of 9 µmol/l for the determination of phenol compounds such as catechol, in comparison to 6 h response time with 25 µg/l detection limit available for mitomycin C. 20,32 Optical biosensors detect peroxide with a detection limit of 0.025 -1.0 mM and a response time of 20 min. 33…”

“…58,59 Much work has also been done in recent years on the applications of conducting polymer layers in amperometric biosensors and amperometric immunosenors. 9,31,[61][62][63] In the next section, the applications of the amperometric principles are discussed to illustrate some recent results of the intense research for more selective, sensitive, and reliable biological sensors. Such research covers a broad area of emerging technology ideally suited for health care, biochemical processes, food analysis, and environmental monitoring analysis.…”

Comparison of Artificial Neural Networks with Partial Least Squares Regression for Simultaneous Determinations by ICP‐AES

“…[1][2][3][4] Partial least squares regression (PLS) is a chemometrics technique which has been widely used for multivariate calibration in different analytical methods such as nuclear magnetic resonance, 5 spectrophotometry, [6][7][8][9] infrared spectroscopy, 10 fluorimetry, 11 X-ray fluorescence spectrometry, 12 potentiometric titration 13 and cyclic voltammetry. 14 The artificial neural network (ANN) is another technique which is able to approximate relationship between multiple inputs and multiple outputs of a system. It has been applied successfully to the field of multivariate calibration, [15][16][17][18][19][20][21][22] but its applications are narrower than those of PLS.…”