RESUMO
In this paper, a fast and efficient analytical strategy was proposed that chemometrics assisted with excitation-emission fluorescence matrices was used to quantify carbaryl (CAR) and thiabendazole (TBZ) in peach, soil and sewage. Even if there are serious overlapped peaks and unknown interferences in fluorescence analysis, the second-order calibration method based on alternating trilinear decomposition (ATLD) algorithm can be used to analyze CAR and TBZ in peach, soil and sewage. The recoveries of CAR and TBZ in peach are 110.4% and 99.7% and their standard deviations are lower than 2.1% and 0.3%, respectively. In addition, the accuracy of the method was assessed with figures of merit as well as intra-day and inter-day precision. The limit of detection, the limit of quantitation of CAR and TBZ in peach are 1.2â¯ngâ¯mL-1 and 0.3â¯ngâ¯mL-1, 3.5â¯ngâ¯mL-1 and 0.8â¯ngâ¯mL-1, respectively. And their root-mean-square error of prediction are 17.0â¯ngâ¯mL-1 and 5.0â¯ngâ¯mL-1 and there are high sensitivity and selectivity in this method. Meanwhile, the results obtained by ATLD algorithm were compared with those obtained by the self-weighted alternate trilinear decomposition algorithm (SWATLD) and the parallel factor analysis (PARAFAC) algorithm, and statistical methods such as the t-test, F-test and the elliptic joint confidence region were used to evaluate for analysis. There were no significant differences among these methods. At last, high performance liquid chromatography-fluorescence detector (HPLC-FLD) was used to evaluate the accuracy and reliability of the proposed method. These results are satisfactory and indicate that the proposed method can be used for accurate and rapid determination of pesticides in complex systems.
Assuntos
Carbaril , Tiabendazol , Algoritmos , Calibragem , Cromatografia Líquida de Alta Pressão , Reprodutibilidade dos Testes , Espectrometria de FluorescênciaRESUMO
This paper describes a novel procedure for the simultaneous determination of four quinolones pipemidic acid, enoxacin, marbofloxacin and enrofloxacin in different edible animal tissues. It is based on third-order data excitation-emission fluorescence matrices modulated by pH gradient, generated in situ through the hydrolysis of glucono delta-lactone. To overcome the strongly overlapped spectra within the analytes, and also with the highly complex tissue matrix, we have used the multivariate calibration procedure unfolded partial least-squares coupled to residual trilinearization (U-PLS/RTL). The method has been validated by application to bovine kidney, chicken and porcine meat samples, fortified at concentration levels between 70 and 600⯵gâ¯kg-1 corresponding to values near the maximum residue level (MRL) regulated by the European Community. Good recoveries were obtained for all analytes, with values between 80% and 113%, depending on the quinolone and the matrix.
Assuntos
Fluorescência , Rim/química , Carne/análise , Quinolonas/análise , Animais , Bovinos , Galinhas , Concentração de Íons de Hidrogênio , Estrutura Molecular , Software , SuínosRESUMO
This study describes a simple and rapid approach of monitoring ibuprofen (IBP). Unfolded principal component analysis-artificial neural network (UPCA-ANN) and excitation-emission spectra resulted from spectrofluorimetry method were combined to develop new model in the determination of IBF in human serum samples. Fluorescence landscapes with excitation wavelengths from 235 to 265 nm and emission wavelengths in the range 300-500 nm were obtained. The figures of merit for the developed model were evaluated. High performance liquid chromatography (HPLC) technique was also used as a standard method. Accuracy of the method was investigated by analysis of the serum samples spiked with various concentration of IBF and an average relative error of prediction of 0.18% was obtained. The results indicated that the proposed method is an interesting alternative to the traditional techniques normally used for determination of IBF such as HPLC.
RESUMO
Primary aromatic amines, PAAs, and their derivatives constitute a health risk and control of their migration from food contact materials is the subject of permanent attention by the authorities. 25.1% of notifications made by Rapid Alert System for Food and Feed in the European Union between 2010 and 2015 concerned PAAs, polyamide cooking utensils being a common source. It is thus useful to have fast and efficient analytical methods for their control. In this work a non-separative, easy, fast and inexpensive spectrofluorimetric method based on the second order calibration of excitation-emission fluorescence matrices (EEMs) was proposed for the determination of aniline (ANL), 2,4-diaminotoluene (2,4-TDA) and 4,4'-methylenedianiline (4,4'-MDA) in polyamide cooking utensils. The procedure made it possible to identify unequivocally each analyte. Trilinearity of the data tensor guarantees the uniqueness of the solution obtained through parallel factor analysis (PARAFAC), so the factors of the decomposition match up with the analytes. The three analytes were unequivocally identified by the correlation between the pure spectra and the PARAFAC excitation and emission spectral loadings. The recovery percentages found were, 82.6%, 112.7% and 84.4% for ANL, 2,4-TDA and 4,4'-MDA respectively. The proposed method was applied to carry out a migration test from polyamide cooking utensils, using a 3% (w/v) acetic acid in aqueous solution as food simulant. Detectable levels of 4,4'-MDA were found in food simulant from some of the investigated cooking utensils. Finally, a kinetic model for the migration of 4,4'-MDA has been fitted to experimental data obtained in the migration test. Thanks to the selectivity of PARAFAC calibration, which greatly simplifies sample treatment avoiding the use of toxic solvents, the developed method follows most green analytical chemistry principles.
RESUMO
This study describes a simple and rapid approach of monitoring celecoxib (CLX). Unfolded principal component analysis-radial basis function neural network (UPCA-RBFNN) and excitation-emission spectra were combined to develop new model in the determination of CLX in human serum samples. Fluorescence landscapes with excitation wavelengths from 250 to 310nm and emission wavelengths in the range 280-450nm were obtained. The figures of merit for the developed model were evaluated. High performance liquid chromatography (HPLC) technique was also used as a standard method. Accuracy of the method was investigated by analysis of the serum samples spiked with various concentration of CLX and a recovery of 103.63% was obtained. The results indicated that the proposed method is an interesting alternative to the traditional techniques normally used for determining CLX such as HPLC.
Assuntos
Celecoxib/sangue , Redes Neurais de Computação , Análise de Componente Principal , Espectrometria de Fluorescência/métodos , Celecoxib/química , Humanos , Cloreto de Metileno/química , Análise de RegressãoRESUMO
This work presents a green and very simple approach which enables the accurate and simultaneous determination of benzo[a]pyrene, dibenz[a,h]anthracene, benz[a]anthracene, and chrysene, concerned and potentially carcinogenic heavy-polycyclic aromatic hydrocarbons (PAHs) in interfering samples. The compounds are extracted from water samples onto a device composed of a small rotating Teflon disk, with a nylon membrane attached to one of its surfaces. After extraction, the nylon membrane containing the concentrated analytes is separated from the Teflon disk, and fluorescence excitation-emission matrices are directly measured on the nylon surface, and processed by applying parallel factor analysis (PARAFAC), without the necessity of a desorption step. Under optimum conditions and for a sample volume of 25 mL, the PAHs extraction was carried out in 20 min. Detection limits based on the IUPAC recommended criterion and relative errors of prediction were in the ranges 20-100 ng L(-1) and 5-7%, respectively. Thanks to the combination of the ability of nylon to strongly retain PAHs, the easy rotating disk extraction approach, and the selectivity of second-order calibration, which greatly simplifies sample treatment avoiding the use of toxic solvents, the developed method follows most green analytical chemistry principles.