Aqueous two-phase systems coupled with chemometrics-enhanced HPLC-DAD for simultaneous extraction and determination of flavonoids in honey.

In this study, an accurate, rapid, green, and environment friendly method for the extraction and quantitative analysis of flavonoids in honey was established by using the aqueous two-phase extraction combined with the chemometrics-assisted HPLC-DAD. The first purpose of this study was to extract seven flavonoids in five different types of honey using alcohol/salt aqueous two-phase system (ATPS). The system with 2.82 mL sodium citrate (30%), 1.58 mL water, and 3.10 mL isopropanol, showed the highest flavonoids extraction yields in the top phase (87.66-101.50%). Additionally, the three-way array of honey samples based on HPLC-DAD was decomposed mathematically by the alternating trilinear decomposition (ATLD) algorithm to obtain reasonable chromatograms, spectra, and concentration profiles for each analyte. Compared with the traditional solid-phase extraction method, the ATPS-ATLD-based method showed satisfactory spiked recoveries, lower limit of detection, and higher sensitivity, further verifying its accuracy and stability.

A comprehensive review of the current trends and recent advancements on the authenticity of honey.

The authenticity of honey currently poses challenges to food quality control, thus requiring continuous modernization and improvement of related analytical methodologies. This review provides a comprehensively overview of honey authenticity challenges and related analytical methods. Firstly, direct and indirect methods of honey adulteration were described in detail, commenting the existing challenges in current detection methods and market supervision approaches. As an important part, the integrated metabolomic workflow involving sample processing procedures, instrumental analysis techniques, and chemometric tools in honey authenticity studies were discussed, with a focus on their advantages, disadvantages, and scopes. Among them, various improved microscale extraction methods, combined with hyphenated instrumental analysis techniques and chemometric data processing tools, have broad application potential in honey authenticity research. The future of honey authenticity determination will involve the use of simplified and portable methods, which will enable on-site rapid detection and transfer detection technologies from the laboratory to the industry.

Discrimination of the harvesting season of green tea by alcohol/salt-based aqueous two-phase systems combined with chemometric analysis.

The flavor and aroma quality of green tea are closely related to the harvest season. The aim of this study was to identify the harvesting season of green tea by alcohol/salt-based aqueous two-phase system (ATPS) combined with chemometric analysis. In this paper, the single factor experiments (SFM) and response surface methodology (RSM) optimization were designed to investigate and select the optimal ATPS. A total of 180 green tea samples were studied in this work, including 86 spring tea and 94 autumn tea. After the active components in green tea samples were extracted by the optimal ethanol/(NH4)2SO4 ATPS, the qualitative and quantitative analysis was realized based on HPLC-DAD combined with alternating trilinear decomposition-assisted multivariate curve resolution (ATLD-MCR) algorithm, with satisfactory spiked recoveries (86.00 %-112.45 %). The quantitative results obtained from ATLD-MCR model were subjected to chemometric pattern recognition analysis. The constructed partial least squares-discriminant analysis (PLS-DA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) models showed better results than the principal component analysis (PCA) model, and the R2Xcum values (>0.835) and R2Ycum (>0.937) were close to 1, the Q2cum values were greater than 0.75 (>0.933), and the differences between R2Ycum and Q2cum were not larger than 0.2, indicating excellent cross-validation prediction performance of the models. Furthermore, the classification results based on the hierarchical clustering analysis (HCA) were consistent with the PCA, PLS-DA and OPLS-DA results, establishing a good correlation between tea active components and the harvesting seasons of green tea. Overall, the combination of ATPS and chemometric methods is accurate, sensitive, fast and reliable for the qualitative and quantitative determination of tea active components, providing guidance for the quality control of green tea.

Comparison of three second-order multivariate calibration methods for the rapid identification and quantitative analysis of tea polyphenols in Chinese teas using high-performance liquid chromatography.

Retention time shifts in second-order calibration-assisted chromatographic analysis seriously impact the modeling and quantitative accuracies in complex systems. In this work, three second-order methods, i.e. alternating trilinear decomposition (ATLD) algorithm, multivariate curve resolution-alternating least squares (MCR-ALS), alternating trilinear decomposition-assisted multivariate curve resolution (ATLD-MCR), were compared their performance to process liquid chromatographic data in the presence of retention time shifts and overlapped peaks. Firstly, the validation samples contain five tea polyphenols at three concentrate levels within the calibration ranges, helped to understand, visualize and interpret these features of three second-order multivariate methods. Secondly, experimental data were studied concerning the determination of polyphenols in Chinese tea samples by HPLC-DAD. The results showed that all three second-order multivariate methods realized satisfactory quantification for five targeted analytes in Pu-Er ripe tea samples and Green tea samples even with the interference of slight retention time shifts, average recoveries were 91.23% -113.16% for ATLD, 89.96%-115.96% for ATLD-MCR, 90.64%-117.60% for MCR-ALS, respectively. However, ATLD was disappointing in the case of larger time shifts (approx. 4.00 s and 6.40 s) occurring for the quantitative analysis of Black tea and Clinacanthus nutans tea, the average recoveries were just 67.33-84.05%. Relatively, MCR-ALS and ATLD-MCR were more significantly excellent, satisfactory results still can be obtained, the average recoveries for MCR-ALS and ATLD-MCR were in the range of 86.04-117.60% and 89.96-115.96%, respectively.

A novel fourth-order calibration method based on alternating quinquelinear decomposition algorithm for processing high performance liquid chromatography-diode array detection- kinetic-pH data of naptalam hydrolysis.

Five-way high performance liquid chromatography-diode array detection (HPLC-DAD)-kinetic-pH data were obtained by recording the kinetic evolution of HPLC-DAD signals of samples at different pH values and a new fourth-order calibration method, alternating quinquelinear decomposition (AQQLD) based on pseudo-fully stretched matrix forms of the quinquelinear model, was developed. Simulated data were analyzed to investigate the performance of AQQLD in comparison with five-way parallel factor analysis (PARAFAC). The tested results demonstrated that AQQLD has the advantage of faster convergence rate and being insensitive to the excess component number adopted in the model. Then, they have been successfully applied to investigate quantitatively the kinetics of naptalam (NAP) hydrolysis in two practical systems. Additionally, the serious chromatographic peak shifts were accurately corrected by means of chromatographic peak alignment method based on abstract subspace difference. The good recoveries of NAP were obtained in these samples by selecting the time region of chromatogram. The elution time, spectral, kinetic time and pH profiles resolved by the chemometric techniques were in good agreement with experimental observations. It demonstrates the potential for the utilization of fourth-order data for some complex systems, opening up a new approach to fourth-order data generation and subsequent fourth-order calibration.

Interference-free determination of indole-3-acetic acid in two real systems using second-order calibration method coupled with excitation-emission matrix fluorescence.

In this work, a simple and practicable method that combines excitation-emission matrix (EEMs) fluorescence with a second-order calibration method based on parallel factor analysis-alternative least-squares (PARAFAC-ALS) algorithm was developed for the direct interference-free determination of indole-3-acetic acid (IAA) in two real systems, coconut water (CW) and coconut milk (CM). Although the excitation and emission profiles of IAA heavily overlapped with that of unknown interferents in the complex real systems, the actual contents and satisfactory recoveries were still obtained successfully. The contents of IAA in CW and CM were 10.8 ± 0.3 and 4.9 ± 0.2 µg mL(-1), respectively, which were consistent with those reported by LC-MS/MS assays in the reference material. The average spike recoveries of IAA in the validation set based on CW and CM were 102.1 ± 3.2 and 98.0 ± 1.9%, respectively. In addition, routine experiments were performed for establishing the validity of the assay to internationally accepted criteria.

Quantitative determination of butylated hydroxyanisole and n-propyl gallate in cosmetics using three-dimensional fluorescence coupled with second-order calibration.

This work presents a novel approach for simultaneous determination of butylated hydroxyanisole (BHA) and propyl gallate (PG) in a very interfering environment by combining the sensitivity of molecular fluorescence and the selectivity of the second-order calibration method. The excitation-emission fluorescence matrix data are processed by applying the second-order calibration method based on the self-weighted alternating normalized residue fitting (SWANRF) algorithm. The limits of detection (LOD) were 1.2-1.3 ng/ml for BHA and 2.2-2.9 ng/ml for PG. The recoveries from spiked cosmetics samples are in the ranges 95.7-103.9% for BHA and 95.9-105.7% for PG. The proposed method avoids preconcentration and elution procedures, so it considerably decreases the analytical time and the experimental expenses. Because the instrument involved in the measurement is nonsophisticated, the experiments could be carried out in routine laboratories. Then it is compared with the HPLC method in dosage of cosmetics and organic reagents, runtime, cost per analysis and LOD.

Simultaneous determination of plant growth regulators in environmental samples using chemometrics-assisted excitation-emission matrix fluorescence: experimental study on the prediction quality of second-order calibration method.

In this work, with the purpose of developing an effective and inexpensive method, excitation-emission matrix fluorescence data and second-order calibration method based on the self-weighted alternating trilinear decomposition (SWATLD) algorithm were combined for simultaneous determination of 2-naphthoxyacetic acid (NOA) and 1-naphthaleneacetic acid methyl ester (NAAME) in environmental samples, i.e. soil and sewage samples. In order to investigate the prediction quality of the proposed method, different strategies, such as taking spectroscopic measurements in the presence of different matrix interferents and at different fluorescence spectrophotometers, were introduced to build calibration models and comparisons among them were done subsequently. The root-mean-square error of prediction and t-test were used to compare different SWATLD-based calibration models. The limits of detection obtained for NOA and NAAME were 0.36-0.95 ng mL(-1) and 1.32-2.69 ng mL(-1), respectively, for different models. Such a chemometrics-based protocol may possess great potential to be extended as a promising alternative for more practical applications in environment monitoring and for the design of small intelligent and field-portable analytical instruments that rely on statistical discrimination, not complete instrumental separation, of the target analytes even in the presence of unknown and uncalibrated interferences.

The maintenance of the second-order advantage: second-order calibration of excitation-emission matrix fluorescence for quantitative analysis of herbicide napropamide in various environmental samples.

A rapid non-separative spectrofluorometric method based on the second-order calibration of excitation-emission matrix (EEM) fluorescence was proposed for the determination of napropamide (NAP) in soil, river sediment, and wastewater as well as river water samples. With 0.10 mol L(-1) sodium citrate-hydrochloric acid (HCl) buffer solution of pH 2.2, the system of NAP has a large increase in fluorescence intensity. To handle the intrinsic fluorescence interferences of environmental samples, the alternating penalty trilinear decomposition (APTLD) algorithm as an efficient second-order calibration method was employed. Satisfactory results have been achieved for NAP in complex environmental samples. The limit of detection obtained for NAP in soil, river sediment, wastewater and river water samples were 0.80, 0.24, 0.12, 0.071 ng mL(-1), respectively. Furthermore, in order to fully investigate the performance of second-order calibration method, we test the second-order calibration method using different calibration approaches including the single matrix model, the intra-day various matrices model and the global model based on the APTLD algorithm with nature environmental datasets. The results showed the second-order calibration methods also enable one or more analyte(s) of interest to be determined simultaneously in the samples with various types of matrices. The maintenance of second-order advantage has been demonstrated in simultaneous determinations of the analyte of interests in the environmental samples of various matrices.

Quantitative analysis of triazine herbicides in environmental samples by using high performance liquid chromatography and diode array detection combined with second-order calibration based on an alternating penalty trilinear decomposition algorithm.

A novel application of second-order calibration method based on an alternating penalty trilinear decomposition (APTLD) algorithm is presented to treat the data from high performance liquid chromatography-diode array detection (HPLC-DAD). The method makes it possible to accurately and reliably analyze atrazine (ATR), ametryn (AME) and prometryne (PRO) contents in soil, river sediment and wastewater samples. Satisfactory results are obtained although the elution and spectral profiles of the analytes are heavily overlapped with the background in environmental samples. The obtained average recoveries for ATR, AME and PRO are 99.7±1.5, 98.4±4.7 and 97.0±4.4% in soil samples, 100.1±3.2, 100.7±3.4 and 96.4±3.8% in river sediment samples, and 100.1±3.5, 101.8±4.2 and 101.4±3.6% in wastewater samples, respectively. Furthermore, the accuracy and precision of the proposed method are evaluated with the elliptical joint confidence region (EJCR) test. It lights a new avenue to determine quantitatively herbicides in environmental samples with a simple pretreatment procedure and provides the scientific basis for an improved environment management through a better understanding of the wastewater-soil-river sediment system as a whole.