Analysis of malachite green and crystal violet in fish with bilinear model

Development of electrochemiluminescent inhibition method for determination of gentian violet in aquatic water

Gentian violet (GV) was found to quench the electrochemiluminescence (ECL) of the tris(2,2'-bipyridyl)ruthenium(II)/tris-n-propylamine (Ru(bpy)3(2+)-TPA) system at a glass carbon electrode (GCE). Based on the ECL signal changes, a simple and ultrasensitive detection method for GV in aquatic water was established. Under the optimized conditions, the quenched ECL intensity versus the logarithm of the concentration of GV was linear over a concentration range from 1.0×10(-10) to 5.0×10(-7) mol L(-1), and the limit of detection (LOD) was found to be 4.5×10(-12) mol L(-1) (S/N=3). The results obtained by the ECL system were better than other reported methods in literatures in terms of sensitivity or linear response range. The method was successfully applied to determine GV in aquatic water, and the relative standard deviations (RSDs) were found less than 6.3%, and the recoveries were obtained from 98.7 to 111.0%. Moreover, a possible mechanism of the quenching effect was primarily discussed based on UV-visible absorption spectra, cyclic voltammograms and IECL-E curves.

Determination of nicotine in tobacco with second-order spectra data of charge-transfer complex in ethanol-water binary solvents processed by parallel factor analysis

A new spectrophotometric method for the determination of nicotine in mixtures without pre-separation has been proposed. Nicotine could react with 2,4-dinitrophenol through a charge-transfer reaction to form a colored complex. The second-order data from the visible absorption spectra of the complex in a series of ethanol-water binary solvents with various water volume fractions could be expressed as the combination of two bilinear data matrices. With the bilinear model, the second-order spectra data of mixtures containing nicotine and other interferents could be analysed by using second-order calibration algorithms, and the determination of nicotine in the mixtures could be achieved. The algorithm used here was parallel factor analysis. The method has been successfully used to determine nicotine in tobacco samples with satisfactory results.

Simultaneous spectrophotometric determination of trace amount of malachite green and crystal violet in water after cloud point extraction using partial least squares regression

In this work, a new method has been proposed to simultaneously determine the trace amount of malachite green and crystal violet from aqueous solution by spectrophotometry after cloud point extraction (CPE) using partial least squares regression. The optimal extraction and operating conditions, such as pH, reagents concentration and effect of time and temperature, and so on, have been investigated using the non-ionic surfactant Triton X-114. The maximum absorption wavelength for malachite green and crystal violet is 624 and 579 nm, respectively; linearity is obeyed in the range of 9.9-800 and 16-1000 ng mL(-1) with detection limit of 2.9 and 4.8 ng mL(-1), and the root mean square error of prediction (RMSEP) are 0.0197 and 0.0343, respectively. The proposed method has been applied successfully to simultaneously determine the trace amount of malachite green and crystal violet in real matrix samples with the recoveries of 92.45-102.5%.