Simultaneous determination of umbelliferone and scopoletin in Tibetan medicine Saussurea laniceps and traditional Chinese medicine Radix angelicae pubescentis using excitation-emission matrix fluorescence coupled with second-order calibration method

A Comprehensive Review on the Excitation-Emission Matrix Fluorescence Spectroscopic Characterization of Petroleum-Containing Substances: Principles, Methods, and Applications

Petroleum-containing substance (PCS) is a general term used for petroleum and its derivatives. A comprehensive characterization of PCSs is crucial for resource exploitation, economic development and environmental protection. Fluorescence spectroscopy, especially excitation-emission matrix fluorescence (EEMF) spectroscopy, has been proved to be a powerful tool to characterize PCSs since its remarkable sensitivity, selectivity, simplicity and high efficiency. However, there is a lack of systematic review focusing on this field in the literature. This paper reviews the fundamental principles and measurements of EEMF for characterizing PCSs, and makes a systematic introduction to various information mining methods including basic peak information extraction, spectral parameterization and some commonly used chemometric methods. In addition, recent advances in applying EEMF to characterize PCSs during the whole life-cycle process of petroleum are also revisited. Furthermore, the current limitations of EEMF in the measurement and characterization of PCSs are discussed and corresponding solutions are provided. For promoting the future development of this field, the urgent need to build a relatively complete EEMF fingerprint library to trace PCSs, not only pollutants but also crude oil and petroleum products, is proposed. Finally, the extensions of EEMF to high-dimensional chemometrics and deep learning are prospected, with the expectation of solving more complex systems and problems.

A comparative study of three chemometrics methods combined with excitation–emission matrix fluorescence for quantification of the bioactive compounds aesculin and aesculetin in Cortex Fraxini

Cortex Fraxini is an important traditional Chinese herbal medicine with various medical functions. Aesculin and aesculetin are the main effective components of Cortex Fraxini. The fluorescence signals of the two compounds have a high degree of overlap with each other, making quantitative analysis difficult with conventional analytical methods. In the present study, different chemometrics methods, including lasso regression (LAR), interval partial least squares (iPLS), and multidimensional partial least squares (N-PLS) methods, were employed and combined with excitation–emission matrix (EEM) fluorescence for the purpose of accurate quantification of aesculin and aesculetin in Cortex Fraxini samples. The most satisfactory results were obtained by using the N-PLS method based on the EEM spectra without scatterings, with correlation coefficient of calibration and prediction values higher than 0.9972 and 0.9962, respectively, root mean squared errors for calibration and prediction values lower than 0.0304 and 0.1165, respectively, and recovery values in the range of 83.32%–104.62%. The obtained credible models indicated that the N-PLS method combined with EEM spectra has the advantages of being green, low cost, and accurate and it is a good strategy for the determination of active compounds in complex samples. To further confirm the accuracy of the obtained results, the same samples were analyzed by the recognized ultra-performance liquid chromatography method.

Geographical origin traceability of traditional Chinese medicine Atractylodes macrocephala Koidz. by using multi-way fluorescence fingerprint and chemometric methods

Atractylodes macrocephala Koidz. (AM) is an important plant of traditional Chinese medicine (TCM), and its status can be comparable with ginseng in China. The efficacy and quality of AM are closely related to the place of origin. Hence, we proposed a simple and fast strategy to classify AM from different geographical origins by using multi-way fluorescence fingerprint combined with chemometric methods. AM samples with different dilution levels have different fluorescence characteristics, resulting from different content of fluorescence components and chemical microenvironment. Therefore, AM samples were diluted 5-fold, 10-fold, and 20-fold with 40% ethanol aqueous solution to obtain excitation-emission matrix data, and multi-way (three-way and four-way) data arrays were constructed. And then, the fluorescence fingerprints of AM samples were characterized by three-way and four-way parallel factor analysis (PARAFAC). In addition, four pattern recognition methods were used to classify AM from different provinces. The results show that the four-way data array can provide more abundant information than three-way data arrays, so it is more conducive to sample classification. According to the results obtained from the analysis of four-way data array, the correct classification rate (CCR) of the cross-validation and prediction set obtained by partial least squares-discrimination analysis (PLS-DA) were 90.5% and 100%, respectively. To sum up, the proposed method can be regarded as a powerful, feasible, convenient, reliable, and universal classification tool for the classification of AM samples from different provinces and can be used as a promising method to realize the geographical origin traceability of other TCMs.

Scopoletin: a review of its source, biosynthesis, methods of extraction, and pharmacological activities

Scopoletin, also known as 6-methoxy-7 hydroxycoumarin, is one of the naturally occurring coumarin commonly found in many edible plants and plays an important role in human health. Despite the various potential pharmacological properties, the biosynthesis process, method of extraction, and mechanism of action on this compound have not been documented well. In this current review, the biosynthesis pathway, distribution of scopoletin in the plant kingdom, and extraction techniques are elaborated. The in vitro, in vivo, and in silico pharmacological studies are also discussed on antioxidant, antimicrobial, anticancer, anti-inflammation, and neuroprotective aspects of scopoletin. This study may help to understand the benefit of scopoletin containing plants and would be beneficial for the prevention and treatment of diseases.

Fast identification of the geographical origin of Gastrodia elata using excitation-emission matrix fluorescence and chemometric methods

Geographical origin is an important factor affecting the quality of traditional Chinese medicine. In this paper, the identification of geographical origin of Gastrodia elata was performed by using excitation-emission matrix fluorescence and chemometric methods. Firstly, excitation-emission matrix (EEM) fluorescence spectra of Gastrodia elata samples from different geographical origins were obtained. And then three chemometric methods, including multilinear partial least squares discriminant analysis (N-PLS-DA), unfold partial least squares discriminant analysis (U-PLS-DA), and k-nearest neighbor (kNN) method, were applied to build discriminant models. Finally, 45 Gastrodia elata samples could be differentiated from each other by these classification models according to their geographical origins. The results showed that all models obtained good classification results. Compared with the N-PLS-DA and U-PLS-DA, kNN got more accurate and reliable classification results and could identify Gastrodia elata samples from different geographical origins with 100% accuracy on the training and test set. Therefore, the proposed method was available for easily and quickly distinguishing the geographical origin of Gastrodia elata, which can be considered as a promising alternative method for determining the geographic origin of other traditional Chinese medicines.

Coumarin-carbazole based functionalized pyrazolines: synthesis, characterization, anticancer investigation and molecular docking

A series of novel pyrazoline scaffolds from coumarin-carbazole chalcones were synthesized. We explored various acetyl, amide, and phenyl substituents at the N-1 position of the pyrazoline core. The synthesized compounds were characterized by FTIR, 1H-NMR, 13C-NMR, DEPT, and mass spectroscopic techniques. The in vitro cytotoxicity study of all the synthesized compounds was evaluated against HeLa, NCI-H520 and NRK-52E cell lines. Compounds 4a and 7b became the most active compounds and exhibited their potential to arrest the cell cycle progression and induce apoptosis in both the cell lines. In addition, molecular docking studies revealed a higher binding affinity of both the molecules with CDK2 protein. Based on the obtained results, a comprehensive analysis is warranted to establish the role of compounds 4a and 7b as promising cancer therapeutic agents.

Simultaneous determination of skimmin, apiosylskimmin, 7-hydroxycoumarin and 7-hydroxycoumarin glucuronide in rat plasma by liquid chromatography-Orbitrap mass spectrometry and its application to pharmacokinetics

The effective fraction of coumarin glycosides from Hydrangea paniculata Sieb (HP) has been under development for the treatment of chronic kidney diseases for years. Skimmin and apiosylskimmin are the main coumarin glycosides of HP, and the major metabolites in rats are 7-hydroxycoumarin (7-HC) and 7-hydroxycoumarin glucuronide (7-HCG). In this study, a sensitive and reliable liquid chromatography-Orbitrap mass spectrometry (LC-Orbitrap MS) method was developed for the simultaneous determination of skimmin, apiosylskimmin, 7-HC and 7-HCG in rat plasma. The chromatographic separation was performed on a Zobax SB C18 column (2.1 × 100 mm, 3.5 μm) at a flow rate of 0.3 mL/min with a gradient mobile phase of water and acetonitrile containing 0.2% formic acid. Skimmin, apiosylskimmin, and 7-HCG were detected in targeted-selected-ion-monitoring mode at positive ions m/z of 325.0911, 457.1331 and 339.0703, respectively. 7-HC and internal standard were detected in parallel-reaction-monitoring mode at m/z 163.0387→119.0492 and 260.1641→116.1071 to overcame the carryover of 7-HC. Linearity was obtained for the analytes within the range of 20-2000 ng/mL for skimmin, 5-500 ng/mL for apiosylskimmin and 7-HC, and 100-10000 ng/mL for 7-HCG. Validation parameters were all in line with the criteria of international guidance. The method has been applied to the pharmacokinetic study of HP in rats.

A chemometric comparison of different models in fluorescence analysis of dabigatran etexilate and dabigatran

In this paper, a simple, rapid, low-cost and potential method was established for the simultaneous quantitative analysis of dabigatran etexilate (DABE) and dabigatran (DAB) in spiked biological fluids. It combined excitation-emission matrix fluorescence (EEMF) with different second-order calibration methods, including the self-weighted alternating normalized residue fitting (SWANRF) algorithm based on trilinear decomposition model, the multivariate curve resolution - alternating least-squares (MCR-ALS) based on bilinear decomposition model and the unfolded partial least-square coupled with residual bilinearization (U-PLS/RBL) based on latent variables model. The proposed method showed "second-order advantage", that is, satisfactory quantitative results were successfully obtained even in the presence of unknown interferences and serious spectral overlap. The recoveries of DABE and DAB in spiked biological fluids were 91.7%-101.7% for SWANRF, 95.9%-117.8% for MCR-ALS, 83.0%-109.6% for U-PLS/RBL, respectively. Figures of merit and other statistical parameters were also calculated to assess the performance of the proposed method. Moreover, the modeling procedures and characteristics of three different models in EEMF analysis were discussed and compared.

A Review of the Botany, Traditional Use, Phytochemistry, Analytical Methods, Pharmacological Effects, and Toxicity of Angelicae Pubescentis Radix

Angelicae Pubescentis Radix (AP), as a traditional Chinese medicine (TCM), has been used for thousands of years in China. In this paper, the botany, traditional use, phytochemistry, analytical methods, quality control, pharmacological effects, and toxicity of AP were reviewed. It can provide a reference for the further research and lay a foundation for the rational clinical application of AP. The relevant information on AP was collected from scientific databases (such as Baidu Scholar, CNKI, Google Scholar, PubMed, Science Direct, Web of Science, and SciFinder Scholar), Chinese herbal classics, Chinese Pharmacopoeia, PhD and MSc dissertations, and so on. The components which have been isolated and identified in AP include coumarins, volatile oils, organic acids, terpenes, polysaccharides, flavonoids, sterols, and trace elements. Most of them were analyzed by HPLC and GC. A pharmacological study shows that the AP has extensive pharmacological effects, including anti-inflammatory, antirheumatism, sedative and hypnotic, neuroprotection, antioxidation, antitumor, and allergy, and it is widely used in the treatment of the rheumatoid arthritis, knee osteoarthritis, lumbar disc, ankylosing spondylitis, headaches, stroke hemiplegia, Alzheimer's, and arrhythmia. AP is a valuable natural medicinal plant. So far, significant advances have been made in phytochemistry and pharmacology. Some traditional uses have been demonstrated by modern pharmacology. However, the chemical components and pharmacological effects of AP are complex and varied, and there are different standards for the evaluation of its quality and efficacy. The mechanism of action, the structure-activity relationship among the components, and the potential synergistic and antagonistic effects remain to be studied. At the same time, there are few studies on the specific compounds related to its pharmacodynamics. In order to better develop and utilize AP, we should establish a more reasonable, reliable, and accurate quality control standard and focus on the study of bioactive constituents and the demonstration of their mechanism of action.

Impact of diverse background interferences on the alternating trilinear decomposition modeling of excitation-emission matrix fluorescence data acquired from different sample sources

Alternating trilinear decomposition (ATLD) method enables the qualitative and quantitative analysis of excitation-emission matrix fluorescence (EEMF) data acquired from complex samples. However, the impact of diverse background interferences from different sample sources on the performances of ATLD method has never been lucubrated. In this work, simulated and real EEMF data sets from different sample sources with diverse background interferences were collected and subjected to ATLD analysis. The performances of ATLD modeling individual and global EEMF data sets were comprehensively compared in terms of the resolved spectral profiles and quantitative results. It was found that ATLD method can use the same set of calibration samples to resolve and quantify multiple components of interest in multiple complex systems with diverse background interferences, regardless of individual or global modeling. The results revealed that the qualitative and quantitative results provided by ATLD method were affected neither by diversity of background interferences nor by data merging as long as the acquired EEMF data sets conform to the trilinear component model. This property of ATLD method can enrich the "second-order advantage", i.e. the term "unknown interferences" in the concept of "second-order advantage" refers to not only constant background interferences but also diverse background interferences, which will be certain to further expand the practicality of ATLD method in complex sample analysis, especially in the field of fluorescence spectroscopy.

Scopoletin increases glucose uptake through activation of PI3K and AMPK signaling pathway and improves insulin sensitivity in 3T3-L1 cells

Coumarins have been shown to reduce blood glucose levels and improve insulin sensitivity in other studies. The purpose of this study was to investigate the effects of scopoletin, which is a type of coumarin family, on glucose uptake in 3T3-L1 cells to test the hypothesis that scopoletin exerts an antidiabetic function on adipocytes. Scopoletin significantly increased glucose uptake, which was associated with increased expression of the plasma membrane glucose transporter type 4 (PM-GLUT4) in 3T3-L1 adipocytes. This increase in PM-GLUT4 expression was promoted by phosphorylation of protein kinase B, activation of phosphatidylinositol-3-kinase (PI3K), and enhanced intracellular glucose uptake. Scopoletin also promoted phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and enhanced PM-GLUT4 expression. Scopoletin-induced glucose uptake in 3T3-L1 adipocytes was inhibited by treatment with the PI3K inhibitor wortmannin and the AMPK inhibitor compound C. These results suggest that scopoletin has an antidiabetic effect by stimulating GLUT4 translocation to the PM through activation of the PI3K and AMPK pathways in 3T3-L1 adipocytes, thereby upregulating glucose uptake.

An Evaluation of the DNA-Protective Effects of Extracts from Menyanthes trifoliata L. Plants Derived from In Vitro Culture Associated with Redox Balance and Other Biological Activities

Menyanthes trifoliata L. is a valuable medical plant found in Europe, North America, and Asia, which grows on peat bogs and swamps. It has long been used in folk medicine as a remedy for various ailments. This is the first report to demonstrate the protective antioxidant and anti-inflammatory properties of aqueous methanolic extracts derived from the aerial parts (MtAPV) and roots (MtRV) of in vitro grown plants on human umbilical vein endothelial cells (HUVECs). It describes the influence of the tested extracts on the expression of antioxidant (HO-1, NQO1, NRF2, kEAP1, and GCLC) and inflammation-related genes (IL-1α, IL-1β, IL-6, TNF-α, and IFN-γ) in cells stimulated with H₂O₂ or LPS, respectively. In addition, M. trifoliata extracts were found to moderately affect the growth of certain bacterial and fungal pathogens, with the strongest antibacterial effect found against Pseudomonas aeruginosa and Enterococcus faecalis. M. trifoliata extracts demonstrated protective effects against mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) damage caused by ROS, decreasing the numbers of mtDNA lesions in the ND1 and ND2 genes and nDNA damage in the TP53 and HPRT1 genes and reducing cleavage in PARP1- and γ-H2A.X-positive cells. The root extract of in vitro M. trifoliata (MtRV) appears to have better anti-inflammatory, antioxidant, antimicrobial, and protective properties than the extract from the aerial part (MtAPV). These differences in biological properties may result from the higher content of selected phenolic compounds and betulinic acid in the MtRV than in the MtAPV extract.

Simultaneous determination of carbendazim and chlorothalonil pesticide residues in peanut oil using excitation-emission matrix fluorescence coupled with three-way calibration method

A novel fluorescence application for simultaneous determination of two common fungicide pesticides (carbendazim and chlorothalonil) in peanut oil is presented. Using the strategy of combining excitation-emission matrix (EEM) fluorescence with three-way calibration methods, the proposed approach successfully achieved quantitative analysis of carbendazim and chlorothalonil pesticide residues in peanut oil, even with highly overlapped spectra. It needs little preparation, using "mathematical separation" instead of "analytical separation" to achieve concentration prediction of target analytes in complex systems. Each analyte was performed using fluorescence spectroscopy after instrument spectral correction and scatter removal. Then the data were modeled with two three-way calibration algorithms, including alternating trilinear decomposition (ATLD) and alternating penalty trilinear decomposition (APTLD). The results indicated that APTLD performed slightly better than ATLD for this system. The carbendazim and chlorothalonil can be recognized simultaneously with the correlation coefficients all above 0.96 between resolved spectra and actual spectra. Satisfactory results have been achieved with the average recoveries (mean ± standard deviation) of carbendazim and chlorothalonil being 100.2 ± 6.7% and 99.7 ± 6.7%, respectively. Moreover, as for carbendazim and chlorothalonil, the sensitivity (SENs) are 1.50 × 10² and 3.80 × 10² mL ng^-1, the limits of detection (LODs) are 11 ng mL^-1 and 4.3 ng mL^-1, the limit of quantitation (LOQ) are 33.33 ng mL^-1 and 13.03 ng mL^-1, respectively. The above results demonstrated that the proposed method is sensitive, fast and accurate for direct quantitative analysis of multiple pesticide residues in complex matrix such as that of peanut oil.

Coumarins content in wine: application of HPLC, fluorescence spectrometry, and chemometric approach

In this work, high performance liquid chromatography (HPLC) and fluorescence spectrometry methods for determination of natural coumarins in Tokaj wine were developed and compared. Molecularly imprinted solid phase extraction procedure was applied for sample preparation. The separation of esculin, coumarin, herniarin, 4-methylumbelliferone, scoparone, scopoletin was performed on core-shell C18 type of stationary phase (100 × 4.6 mm, 5 µm) with a gradient elution of mobile phase containing 1% aqueous solution of acetic acid and methanol, UV-VIS (280 nm for coumarin) and fluorescence detection (Ex 320 nm, Em 450 nm for other coumarins). The HPLC method was validated in term of linearity, limit of detection, limit of quantification, precision and accuracy. Fluorescence detection offers high sensitivity with limit of detection in the ng mL^-1 range. Scopoletine and 4-methylumbelliferone were identified and quantified in tested wines. Emission spectral data, synchronous fluorescence spectra of coumarins from fluorescence spectrometry and total concentrations of coumarins quantified by the HPLC method were used in the partial least squares regression. The linear regression between the concentrations predicted by the partial least squares model versus true values obtained by HPLC method confirmed good agreement between the two methods.

Simultaneous and fast determination of bisphenol A and diphenyl carbonate in polycarbonate plastics by using excitation-emission matrix fluorescence couples with second-order calibration method

A new strategy for the determination of bisphenol A (BPA) and diphenyl carbonate (DPC) in polycarbonate plastics has been proposed, combing excitation-emission matrix fluorescence and second-order chemometrics methods. The studied compounds are two of the most frequently used chemical raw materials and intermediates, which is mainly used for bio-chemical products. The method is fast and sensitive as it can avoid tedious pretreatment steps and large amounts of organic solvents consumption. Chemometrics allowed accurate and precise quantification of two target analytes even in the presence of severe spectral overlap, unknown and background interferences, which benefit from "second-order advantages" provided by chemometrics multivariate calibration. Reasonable quantification results were obtained in real plastics samples, with limits of detection for two analytes were 0.04 and 1.18 × 10³ ng mL^-1 and limits of quantitation were 0.11 and 3.58 × 10³ ng mL^-1. In addition, the average recoveries for BPA and DPC were 99.35% and 83.50% with relative standard deviation <2.30%. It was proved that the proposed method can be a useful and sensitive tool to the determination of BPA and DPC in different polycarbonate plastics with a simple sample pretreatment at low cost.

Comparison of several third-order correction algorithms applied to fluorescence excitation-emission-sample data array: Interference-free determination of polycyclic aromatic hydrocarbons in water pollution

Interference-free determination of polycyclic aromatic hydrocarbons (PAHs) in water pollution is proposed based on third-order correction algorithms with quadrilinear component modeling applied to the constructed four way fluorescence excitation-emission-sample data array with higher accuracy and better predictive ability than second-order (three-dimension) correction. Alternating weighted residue constraint quadrilinear decomposition (AWRCQLD), quadrilinear parallel factor analysis (4-PARAFAC), alternate penalty quadrilinear decomposition (APQLD) and alternate penalty trilinear decomposition (APTLD) are applied to acenaphthene (ANA), naphthalene (NAP) and fluorene (FLU) respectively. Fulvic acid affects PAHs determination seriously in real-world situation, so it is simulated as an interfering agent. Excitation-emission fluorescence matrixes (EEMs) of PAHs are measured at different volumes of fulvic acid simulated different interference conditions, to construct a four-way data array. After the four-way spectra data is analyzed by AWRCQLD, 4-PARAFAC, and APQLD, three-way EEMs analyzed by APTLD, results show that, on the one hand, PAHs can be measured more accurately with four-way data combined with third-order calibration than lower-order. On the other hand, AWRCQLD algorithm can reflect the superiority of third-order advantage better with higher recovery rate and smaller root mean square error, than other third-order or second-order correction algorithms.

Rapid, simultaneous and interference-free determination of three rhodamine dyes illegally added into chilli samples using excitation-emission matrix fluorescence coupled with second-order calibration method

In this study, a smart and green analytical method based on the second-order calibration algorithm coupled with excitation-emission matrix (EEM) fluorescence was developed for the determination of rhodamine dyes illegally added into chilli samples. The proposed method not only has the advantage of high sensitivity over the traditional fluorescence method but also fully displays the "second-order advantage". Pure signals of analytes were successfully extracted from severely interferential EEMs profiles via using alternating trilinear decomposition (ATLD) algorithm even in the presence of common fluorescence problems such as scattering, peak overlaps and unknown interferences. It is worth noting that the unknown interferents can denote different kinds of backgrounds, not only refer to a constant background. In addition, the method using interpolation method could avoid the information loss of analytes of interest. The use of "mathematical separation" instead of complicated "chemical or physical separation" strategy can be more effective and environmentally friendly. A series of statistical parameters including figures of merit and RSDs of intra- (≤1.9%) and inter-day (≤6.6%) were calculated to validate the accuracy of the proposed method. Furthermore, the authoritative method of HPLC-FLD was adopted to verify the qualitative and quantitative results of the proposed method. Compared with the two methods, it also showed that the ATLD-EEMs method has the advantages of accuracy, rapidness, simplicity and green, which is expected to be developed as an attractive alternative method for simultaneous and interference-free determination of rhodamine dyes illegally added into complex matrices.

A green chemometrics-assisted fluorimetric detection method for the direct and simultaneous determination of six polycyclic aromatic hydrocarbons in oil-field wastewaters

Oil-field wastewaters contain high level of polycyclic aromatic hydrocarbons (PAHs), which have to be analyzed to assess the environmental effects before discharge. In this work, a green fluorimetric detection method that combines excitation-emission matrix (EEM) fluorescence with parallel factor analysis (PARAFAC) algorithm was firstly developed to achieve the direct and simultaneous determination of six U.S. EPA PAHs in two different kinds of complex oil-field wastewaters. Due to the distinctive "second-order advantage", neither time-consuming sample pretreatments nor toxic organic reagents were involved in the determination. By using the environment-friendly "mathematical separation" of PARAFAC, satisfactory quantitative results and reasonable spectral profiles for six PAHs were successfully extracted from the total EEM signals of oil-field wastewaters without need of chromatographic separation. The limits of detection of six PAHs were in the range of 0.09-0.72ngmL^-1, and the average spiked recoveries were between (89.4±4.8)% and (109.1±5.8)%, with average relative predictive errors <2.93%. In order to further confirm the accuracy of the proposed method, the same batch oil-field wastewater samples were analyzed by the recognized GC-MS method. t-test demonstrated that no significant differences exist between the quantitative results of the two methods. Given the advantages of green, fast, low-cost and high-sensitivity, the proposed method is expected to be broadened as an appealing alternative method for multi-residue analysis of overlapped PAHs in complex wastewater samples.

Four-dimensional data coupled to alternating weighted residue constraint quadrilinear decomposition model applied to environmental analysis: Determination of polycyclic aromatic hydrocarbons

Qualitative and quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) was carried out by three-dimensional fluorescence spectroscopy combining with Alternating Weighted Residue Constraint Quadrilinear Decomposition (AWRCQLD). The experimental subjects were acenaphthene (ANA) and naphthalene (NAP). Firstly, in order to solve the redundant information of the three-dimensional fluorescence spectral data, the wavelet transform was used to compress data in preprocessing. Then, the four-dimensional data was constructed by using the excitation-emission fluorescence spectra of different concentration PAHs. The sample data was obtained from three solvents that are methanol, ethanol and Ultra-pure water. The four-dimensional spectral data was analyzed by AWRCQLD, then the recovery rate of PAHs was obtained from the three solvents and compared respectively. On one hand, the results showed that PAHs can be measured more accurately by the high-order data, and the recovery rate was higher. On the other hand, the results presented that AWRCQLD can better reflect the superiority of four-dimensional algorithm than the second-order calibration and other third-order calibration algorithms. The recovery rate of ANA was 96.5%~103.3% and the root mean square error of prediction was 0.04μgL^-1. The recovery rate of NAP was 96.7%~115.7% and the root mean square error of prediction was 0.06μgL^-1.

Simultaneous determination of α-asarone and β-asarone in Acorus tatarinowii using excitation-emission matrix fluorescence coupled with chemometrics methods

A chemometrics-assisted excitation-emission matrix (EEM) fluorescence method was proposed for simultaneous determination of α-asarone and β-asarone in Acorus tatarinowii. Using the strategy of combining EEM data with chemometrics methods, the simultaneous determination of α-asarone and β-asarone in the complex Traditional Chinese medicine system was achieved successfully, even in the presence of unexpected interferents. The physical or chemical separation step was avoided due to the use of "mathematical separation". Six second-order calibration methods were used including parallel factor analysis (PARAFAC), alternating trilinear decomposition (ATLD), alternating penalty trilinear decomposition (APTLD), self-weighted alternating trilinear decomposition (SWATLD), the unfolded partial least-squares (U-PLS) and multidimensional partial least-squares (N-PLS) with residual bilinearization (RBL). In addition, HPLC method was developed to further validate the presented strategy. Consequently, for the validation samples, the analytical results obtained by six second-order calibration methods were almost accurate. But for the Acorus tatarinowii samples, the results indicated a slightly better predictive ability of N-PLS/RBL procedure over other methods.

Interference-free spectrofluorometric quantification of aristolochic acid I and aristololactam I in five Chinese herbal medicines using chemical derivatization enhancement and second-order calibration methods

A rapid interference-free spectrofluorometric method combined with the excitation-emission matrix fluorescence and the second-order calibration methods based on the alternating penalty trilinear decomposition (APTLD) and the self-weighted alternating trilinear decomposition (SWATLD) algorithms, was proposed for the simultaneous determination of nephrotoxic aristolochic acid I (AA-I) and aristololactam I (AL-I) in five Chinese herbal medicines. The method was based on a chemical derivatization that converts the non-fluorescent AA-I to high-fluorescent AL-I, achieving a high sensitive and simultaneous quantification of the analytes. The variables of the derivatization reaction that conducted by using zinc powder in acetose methanol aqueous solution, were studied and optimized for best quantification results of AA-I and AL-I. The satisfactory results of AA-I and AL-I for the spiked recovery assay were achieved with average recoveries in the range of 100.4-103.8% and RMSEPs <0.78ngmL^-1, which validate the accuracy and reliability of the proposed method. The contents of AA-I and AL-I in five herbal medicines obtained from the proposed method were also in good accordance with those of the validated LC-MS/MS method. In light of high sensitive fluorescence detection, the limits of detection (LODs) of AA-I and AL-I for the proposed method compare favorably with that of the LC-MS/MS method, with the LODs <0.35 and 0.29ngmL^-1, respectively. The proposed strategy based on the APTLD and SWATLD algorithms by virtue of the "second-order advantage", can be considered as an attractive and green alternative for the quantification of AA-I and AL-I in complex herbal medicine matrices without any prior separations and clear-up processes.