Jian-Yao Wang

Fast analysis of synthetic antioxidants in edible vegetable oil using trilinear component modeling of liquid chromatography–diode array detection data

A new chromatographic methodology is presented for fast quantitative analysis of ten synthetic phenolic antioxidants in five kinds of oil samples: propyl gallate (PG), 2,4,5-trihydroxybutyrophenone (THBP), tert-butylhydroquinone (TBHQ), nordihydroguaiaretic acid (NDGA), ethoxyquin (EQ), 3-tert-butyl-4- hydroxyanisole (BHA), octyl gallate (OG), 2,6-di-tert-butyl-4-hydroxymethyphenol (Ionox-100), dodecyl gallate (DG), 3,5-di-tert-butyl-4-hydroxytoluene (BHT). The second-order calibration, with second-order advantage, based on the alternating penalty trilinear decomposition (APTLD) algorithm has shown to be an excellent tool for modeling the three-way data, where overlapping peaks, uncalibrated inteferences, and baseline drift existed, making the fast determination and resolution of the phenolic antioxidants in oils possible. Such extraction procedure in which the antioxidants of interest would be seperated is unnecessary and the ten antioxidants can be eluted within 6 mins. For the validation of the method, linearity, root-mean-square error of prediction (RMSEP) and limit of detection (LOD) have been performed. The average recovery of antioxidants ranges from 94.9 to 106.1% and the ten analytes can be adequately determined with limits of detection of 0.18-5.72 μgm l(-1).

Fast HPLC-DAD quantification of nine polyphenols in honey by using second-order calibration method based on trilinear decomposition algorithm.

This paper describes the use of second-order calibration for development of HPLC-DAD method to quantify nine polyphenols in five kinds of honey samples. The sample treatment procedure was simplified effectively relative to the traditional ways. Baselines drift was also overcome by means of regarding the drift as additional factor(s) as well as the analytes of interest in the mathematical model. The contents of polyphenols obtained by the alternating trilinear decomposition (ATLD) method have been successfully used to distinguish different types of honey. This method shows good linearity (r>0.99), rapidity (t<7.60 min) and accuracy, which may be extremely promising as an excellent routine strategy for identification and quantification of polyphenols in the complex matrices.

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 phenolic antioxidants in edible vegetable oils by HPLC–FLD assisted with second-order calibration based on ATLD algorithm

A novel strategy that combines the chemometrics method with high performance liquid chromatography with fluorescence detector (HPLC-FLD) was developed for the simultaneous determination of seven phenolic antioxidants in six kinds of oil samples. After a simple dilution step, oil samples can be directly injected into the detecting system and the data were measured in a short time with a chromatographic system operating in the gradient elution mode. Since the chromatographic and spectral peaks among interesting analytes and interferences were heavily overlapped, second-order calibration method based on alternating trilinear decomposition (ATLD) algorithm which fully exploiting the second-order advantage was adopted. Successful resolution was obtained in the presence of different matrix interferences in different oil samples, and the developed approach allows the quantification of the antioxidants at levels found in edible vegetable oils, without the necessity of applying either preconcentration or extraction steps, moreover, a column washing is also not required. Meanwhile, the effectiveness and reproducibility of the proposed method were also validated by some statistical parameters like root mean squared error of prediction (RMSEP), limits of detection (LOD) and relative standard deviation (RSD). Then the proposed method was compared with several commonly selected methods in sample preparation, elution time and LOD.

Simultaneous determination of eight flavonoids in propolis using chemometrics-assisted high performance liquid chromatography-diode array detection.

A fast analytical strategy of second-order calibration method based on the alternating trilinear decomposition algorithm (ATLD)-assisted high performance liquid chromatography coupled with a diode array detector (HPLC-DAD) was established for the simultaneous determination of eight flavonoids (rutin, quercetin, luteolin, kaempferol, isorhamnetin, apigenin, galangin and chrysin) in propolis capsules samples. The chromatographic separation was implemented on a Wondasil™ C18 column (250mm×4.6mm, 5μm) within 13min with a binary mobile phase composed of water with 1% formic acid and methanol at a flow rate of 1.0mLmin(-1) after flavonoids were only extracted with methanol by ultrasound extraction for 15min. The baseline problem was overcome by considering background drift as additional compositions or factors as well as the target analytes, and ATLD was employed to handle the overlapping peaks from analytes of interest or from analytes and co-eluting matrix compounds. The linearity was good with the correlation coefficients no less than 0.9947; the limit of detections (LODs) within the range of 3.39-33.05ngmL(-1) were low enough; the accuracy was confirmed by the recoveries ranged from 91.9% to 110.2% and the root-mean-square-error of predictions (RMSEPs) less than 1.1μg/mL. The results indicated that the chromatographic method with the aid of ATLD is efficient, sensitive and cost-effective and can realize the resolution and accurate quantification of flavonoids even in the presence of interferences, thus providing an alternative method for accurate quantification of analytes especially when the complete separation is not easily accomplished. The method was successfully applied to propolis capsules samples and the satisfactory results were obtained.

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.

Simultaneous determination of pre-emergence herbicides in environmental samples using HPLC-DAD combined with second-order calibration based on self-weighted alternating trilinear decomposition algorithm

This work presents a novel strategy for simultaneous and rapid quantitative analysis of three pre-emergence herbicides in environmental samples using HPLC-DAD combined with second-order calibration based on the self-weighted alternating trilinear decomposition (SWATLD) algorithm. The sample preparation procedure was simplified only by using water as solvent and methanol as extractant and data were measured in less than 4.2 min by applying an isocratic mode. Although the elution and spectral profiles of the analytes, prometryne (PRO), napropamide (NAP) and alachlor (ALA), are heavily overlapped with each other and with matrix constitutes, the method not only extracts the profiles of the analytes, but also simultaneously determines the concentrations of them in actual complex systems, i.e., river sediment and wastewater samples. In the analysis of river sediment and wastewater samples, the obtained average recoveries were 99 ± 6% and 98 ± 5% for PRO, 108 ± 6% and 100 ± 4% for NAP and 98 ± 5% and 97 ± 4% for ALA, respectively. Furthermore, the accuracy and precision of the proposed method was also evaluated through elliptical joint confidence region tests as well as figures of merit. Such a chemometrics-based protocol may be a very promising tool for more analytical applications in environment monitoring, due to its advantages of easy sample pretreatment, green, sufficient spectral resolution and concentration prediction even in the presence of unknown interferences.

A combined theoretical and experimental study for the chiral discrimination of naproxen enantiomers by molecular modeling and second-order standard addition method

In the present study, excitation–emission matrix (EEM) fluorescence data of guest–host complexes between naproxen enantiomers and β-cyclodextrin were used to develop a second-order calibration method that was subsequently used to determine the enantiomeric composition of samples of naproxen. The chiral discrimination of naproxen enantiomers was realized via their difference in interaction with the chiral cavity of β-cyclodextrin due to their difference in stereochemical structure. The strategy combined the use of a self-weighted alternating normalized residue fitting (SWANRF) algorithm, for extraction of the pure analyte signal, with the standard addition strategy, for determination of naproxen enantiomers in the presence of a matrix effect caused by the proteins present in human urine. Feasible results were obtained in a molar fraction range from 60.0 to 85.0% of S-naproxen, providing absolute errors lowers than 7.50%. Finally, molecular modeling was performed to determine the chiral recognition on a molecular level, and the difference in the interaction energies and the patterns of molecular interactions were discussed. The results were in good agreement with experimental data.

Second-order calibration applied to quantification of two active components of Schisandra chinensis in complex matrix

The effectiveness of traditional Chinese medicine (TCM) against various diseases urges more low cost, speed and sensitive analytical methods for investigating the phamacology of TCM and providing a theoretical basis for clinical use. The potential of second-order calibration method was validated for the quantification of two effective ingredients of Schisandra chinensis in human plasma using spectrofluorimetry. The results obtained in the present study demonstrate the advantages of this strategy for multi-target determination in complex matrices. Although the spectra of the analytes are similar and a large number of interferences also exist, second-order calibration method could predict the accurate concentrations together with reasonable resolution of spectral profiles for analytes of interest owing to its ‘second-order advantage’. Moreover, the method presented in this work allows one to simply experimental procedure as well as reduces the use of harmful chemical solvents.

Chemometrics-assisted excitation-emission fluorescence spectroscopy for simultaneous determination of ethoxyquin and tert -butylhydroquinone in biological fluid samples

A novel method applying simple, rapid, effective and inexpensive excitation-emission matrix (EEM) fluorescence spectroscopy coupled with second-order calibration method for simultaneous determination of ethoxyquin (EQ) and tert-butylhydroquinone (TBHQ) contents in biological fluid samples was developed. After a simple data preprocessing that was to insert zeros below the first-order Rayleigh scattering, the second-order calibration method based on the alternating normalization-weighed error (ANWE) algorithm was used to deal with EEM data. Via the introduced “second-order advantage”, the individual concentrations of the analytes of interest could be obtained even in the presence of uncalibrated interferences. The experimental concentration ranges for the analytes were as follows: EQ, from 4.58 to 20.6 μg mL−1 in plasma and from 6.87 to 20.6 μg mL−1 in urine; TBHQ, from 4.49 to 20.2 μg mL−1 in plasma and from 6.73 to 22.4 μg mL−1 in urine. The recoveries from spiked biological fluid samples were in the ranges of 92.8%–106.2% for EQ and 94.6%–107.2% for TBHQ. These results demonstrate that the three-dimensional EEM fluorescence with second-order calibration method is a powerful tool for obtaining both EQ and TBHQ quantitative results in plasma and urine samples, and could be applied to more complex matrices.