Second-order Calibration Method Research Articles

三维荧光光谱结合二阶校正法用于石油类污染物的识别和检测

三维荧光光谱结合二阶校正法用于石油类污染物的识别和检测

Investigation of the interactions between indole-3-acetic acid and catalase: A spectroscopic study in combination with second-order calibration and molecular docking methods

The interactions between indole-3-acetic acid (IAA) and the important antioxidant enzyme catalase (CAT) have been studied by Ultraviolet-visible (UV-vis) and fluorescence spectroscopic methods. The decrease of the absorption intensity of CAT at 270 nm and 407 nm in UV-vis spectra with the addition of IAA indicated the interactions between CAT and IAA. The three-way excitation–emission matrix spectra combined with parallel factor analysis (PARAFAC) was used to provide the individual concentration information of IAA, CAT, and IAA–CAT in the reaction system. The PARAFAC analysis showed that a 1:1 IAA–CAT complex formed at the equilibrium point. Constant wavelength synchronous fluorescence spectrometry (SFS) showed that the binding of IAA resulted in the micro-environment changes around tryptophan (Trp) and tyrosine (Tyr) residues. Molecular docking studies provide a good structural basis to explain the experimental results. This work is valuable for providing a deeper insight into the interaction mechanism of IAA with CAT.

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.

Simultaneous Determination of Metoprolol And α-Hydroxymetoprolol in Human Plasma Using Excitation–Emission Matrix Fluorescence Coupled With Second-Order Calibration Methods

Metoprolol (MET) is a β1-adrenoceptor antagonist, which is widely used in the treatment of cardiovascular diseases, and α-hydroxymetoprolol (α-OHM) is its hydroxylated metabolite. Owing to their similar structures, optimization of the condition for the chromatography approach, which is in common use for determination, is both time consuming and laborious. A new and effective strategy that combines the excitation-emission matrix fluorescence with second-order calibration methods was developed for simultaneous determination of MET and α-OHM in human plasma. Although the fluorescence spectra of MET and α-OHM overlapped and a large number of unknown and uncalibrated fluorescent components coexisted, the developed method enables accurate concentrations together with reasonable resolution of excitation and emission profiles for the analytes of interest. An additional advantage of the proposed method is that there is no need for separation and sample pretreatment, in addition to lower cost than traditional methods.

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<7.60min) and accuracy, which may be extremely promising as an excellent routine strategy for identification and quantification of polyphenols in the complex matrices.

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.

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 0.36–0.95ngmL−1 and 1.32–2.69ngmL−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 analysis of bifenthrin and tetramethrin using corona discharge ion mobility spectrometry and Tucker 3 model

In this work, a second-order calibration method, Tucker 3, is proposed to be applied on the ion mobility spectrometry (IMS) data for the first time. Tetramethrin and bifenthrin were analyzed simultaneously using corona discharge IMS. Under the optimized experimental conditions, bifenthrin and tetramethrin showed one and three peaks, respectively. The bifenthrin peak was completely overlapped with the last one of tetramethrin peak. A three way data structure (sample × acquisition time × drift time) was constructed and it was then decomposed by Tucker 3 model to loading matrices and a three-way core array. Tucker 3 was applied, because of a lack of trilinearity in the three way data array and interactions between loading vectors. Tucker 3 models with different numbers of loading vectors were constructed and the model with 5 (sample), 5 (acquisition time), and 3 (drift time) loading vectors was selected as the suitable model. The statistical parameters including root mean squared error of calibration (RMSE) and root mean squared error of prediction (RMSEP) were calculated for the model, which were found to be 4.46, 4.95μg mL−1 for tetramethrin and 3.23, 6.4μg mL−1 for bifenthrin, respectively. The results of Tucker 3 were also compared with the PLS, N-PLS and U-PLS models, indicating superiority of the Tucker 3 model over the others.

Rapid Determination of Oxaprozin Contents in Urine and Combined Pharmacotherapy Samples Using Three-dimensional Fluorescence Coupled with Second-order Calibration Methods

Rapid Determination of Oxaprozin Contents in Urine and Combined Pharmacotherapy Samples Using Three-dimensional Fluorescence Coupled with Second-order Calibration Methods

Determination of Salicylic and Gentisic Acids Using HPLC-DAD Combined with Second-Order Calibration Method

The highly overlapped chromatograms and spectra of salicylic acid (SA), gentisic acid (GA) and uncalibrated interferent, pyrocatechuic acid (PA) were resolved using HPLC-DAD combined with a novel second-order calibration method. Their elution time was set from 0.6628 min to 0.9495 min and the detection wavelength was chosen from 268 nm to 332 nm. Both SA and GA were determined simultaneously in aqueous solution with their recoveries were (101.0 ± 7.1) % and (105.8 ± 5.6) %, respectively. The satisfying results demonstrate this method can be easily performed and applied to solving second-order calibration problems quickly and accurately.

Simultaneous Determination of Sulfadiazine and Sulfamethoxazole in Synthetic Samples and Pharmaceutical Tablets Using HPLC-DAD Combined with Second-Order Calibration Method

The overlapped chromatograms and spectra of sulfadiazine (SD) and sulfamethoxazole (SM) in both synthetic samples and pharmaceutical tablets even in the presence of uncalibrated and interfering sulfanilamide (SN) were resolved by HPLC-DAD combined with a novel second-order calibration method. Their elution time was set from1.077 min to 1.624 min and the detection wavelength was chosen from 230 nm to 316 nm. The recoveries of SD and SM were (99.3 ± 1.3)% and (99.2 ± 3.1)%, respectively. The satisfying results show this method can be easily performed and applied to solving second-order calibration problems quickly and accurately.

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.

A novel method to handle Rayleigh scattering in three-way excitation-emission fluorescence data

Rayleigh scattering, which is often contained in excitation-emission fluorescence data, does not conform to a trilinear structure and its existence can complicate decomposition using second-order calibration methods. In this paper, a novel method, two-direction resection PARAFAC (TDR-PARAFAC) is proposed to deal with three-way fluorescence data including Rayleigh scattering. This is a convenient method where only two parameters, i.e. the scattering regions and the number of components, are required. A simulated data set was employed to demonstrate the reasonability of the new method. It was successfully used to analyze two experimental data sets in which interferents and significant Rayleigh scattering were present. The performance of the new method was compared by inserting missing values within PARAFAC (IMV-PARAFAC). The final results suggest that TDR-PARAFAC can not only obtain more stable and satisfactory resolution than IMV-PARAFAC, but also that it speeds up the analysis. In addition, the new method can be applied to other interferences such as Rayleigh scattering, which appear in the same position in each sample matrix.

Measuring estriol and estrone simultaneously in liquid cosmetic samples using second-order calibration coupled with excitation–emission matrix fluorescence based on region selection

This paper describes a sensitive excitation–emission matrix fluorescence (EEM) method for simultaneously measuring contents of two estrogens, estriol (E3) and estrone (E1), in liquid cosmetic samples with the aid of a second-order calibration method based on a parallel factor analysis (PARAFAC) algorithm. Before processing the obtained three-way data, a better region of the excitation and emission spectra was purposely selected. Then PARAFAC was recommended to acquire the clean spectra and predict the individual concentrations of the analytes of interest even in the presence of uncalibrated interferences. The standard curves of the two analytes are linear within a linear concentration range of 0–0.736 μg mL−1 of E3 and 0–18.000 μg mL−1 of E1 with correlation coefficients typically greater than 0.99. In the analysis of watermelon frost anti-acne toner sold on the internet web site, the limit of detection (LOD) of E3 is 4.7 ng mL−1 with an accuracy of 102.3–113.7%, and for E1, the LOD is 96.1 ng mL−1 with an accuracy of 92.3–111.0%. In the analysis of pagoda flower relaxing lotion from the commercial market in Changsha, the LOD of E3 is 8.9 ng mL−1 with an accuracy of 95.0–107.1%, and for E1, the LOD is 76.9 ng mL−1 with an accuracy of 98.6–119.3%. Generally, a new avenue has been opened up to determine estrogens quantitatively in cosmetic samples. This methodology will achieve greater development and gradually become a more routine approach in cosmetic quality control due to its advantages of high sensitivity, simple pretreatment procedure and non-destructive nature.

Simultaneous Determination of Main Effective Constituents in Traditional Chinese Medicine Kudzuvine Root Using HPLC-DAD Coupled with Second-order Calibration Based on Alternating Trilinear Decomposition

A method for simultaneously quantifying the main effective constituents such as puerarin, daidzin and daidzein in traditional Chinese medicine kudzuvine root was developed in this paper, by using high performance liquid chromatography coupled with diode array detection (HPLC-DAD) and second- order calibration method based on alternating trilinear decomposition (ATLD) algorithm. Profiting from the application of second-order calibration method, it needs very simple chromatographic conditions. The mo- bile phase consisted of methanol (53%, φ) and water (47%, φ), which was pumped at a flow rate of 1.0 mL/min with 20.0 μL injection volume. The column temperature was set at 30 . ℃ The range of scanning wavelengths were 190~380 nm. The predicted contents of puerarin, daidzin and daidzein in kudzuvine root samples were (0.465±0.023), (0.553±0.015) and (0.098±0.005) mg/g, respectively and their spiked re- coveries were (101.3±3.2)%, (100.4±6.4)% and (100.1±4.9)%, respectively.

Using second-order calibration method based on trilinear decomposition algorithms coupled with high performance liquid chromatography with diode array detector for determination of quinolones in honey samples

A novel strategy that combines the second-order calibration method based on the trilinear decomposition algorithms with high performance liquid chromatography with diode array detector (HPLC-DAD) was developed to mathematically separate the overlapped peaks and to quantify quinolones in honey samples. The HPLC-DAD data were obtained within a short time in isocratic mode. The developed method could be applied to determine 12 quinolones at the same time even in the presence of uncalibrated interfering components in complex background. To access the performance of the proposed strategy for the determination of quinolones in honey samples, the figures of merit were employed. The limits of quantitation for all analytes were within the range 1.2–56.7μgkg−1. The work presented in this paper illustrated the suitability and interesting potential of combining second-order calibration method with second-order analytical instrument for multi-residue analysis in honey samples.

Determination of adriamycin in cell culture media by using excitation-emission matrix fluorescent spectra coupled with second-order calibration

This paper reports a simple and rapid method for quantitative analysis of adriamycin in cell culture media without any pretreatment procedure. It combined second-order calibration methods based on the alternating trilinear decomposition (ATLD) and the alternating normalization-weighter error (ANWE) algorithms, respectively, with excitation-emission matrix fluorescent spectra. When the component number in the case was set to 2, the average recoveries of adriamycin in cell culture media were (100.5±1.8)% and (100.3±1.9)%, respectively. The satisfactory results showed that the second-order calibration method can be applied to directly quantify adriamycin in cell culture media. Moreover, in the analysis of cell culture media including four interferences which are the fluorescent materials in cell, the average recoveries attained from ATLD and ANWE with the factor number of 4 were (99.1±2.9)% and (99.2±3.1)%, respectively. It was found that second-order calibration method combined with excitation-emission matrix fluorescent spectra is appropriate for quantitative analysis of drug contents in cell culture media even in the presence of natural fluorescent interferences of cell.

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 0.10molL−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, 0.071ngmL−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.

Simultaneous Determination of Dextromethorphan and Quinidine Contents in Biological Fluid Samples Using Excitation-Emission Matrix Fluorescence Coupled with Second-Order Calibration Methods

This paper presents a novel method for simultaneous determination of dextromethorphan and quinidine contents in biological fluid samples using excitation–emission matrix fluorescence (EEM) coupled with second-order calibration methods. The adopted calibration methods, i.e., parallel factor analysis (PARAFAC), self-weighted alternating tri-linear decomposition (SWATLD), and alternating penalty trilinear decomposition (APTLD), could adequately exploit the second-order advantage. The accuracy of the three methods was evaluated through figures of merit and elliptical joint confidence region (EJCR) tests. It has been found that all the methods could give good results. But, with correct number of factors, the PARAFAC model performed slightly better than the others.

Rapid determination of carbofuran in tuber vegetables, soil and wastewater using three-dimensional fluorescence coupled with second-order calibration

Carbofuran(CF) is a highly effective,systemic and contact carbamate insecticide.A novel method is proposed for the rapid determination of CF in pachyrhizus,potato,carrot,soil and wastewater samples using three-dimension fluorescence coupled with second-order calibration method based on the alternating trilinear decomposition algorithm(ATLD) .When their component numbers were set to 2,the obtained average recoveries of CF were(99.0±5.3) %、(97.2±4.2) %、(102.7±5.9) %、(101.1±3.8) %and(91.3±1.9) %for ATLD,respectively.Furthermore,the accuracy of the algorithm was also evaluated through elliptical joint confidence region(EJCR) tests and root-mean-square error of prediction(RMSEP) as well as figures of merit including sensitivity(SEN) ,selectivity(SEL) and limit of detection(LOD) .It was shown that the proposed method could solve the problem of serious flourescence spectral overlapping of the sought-for analyte(CF) and background interferents and it can be applied to rapid determination of CF even in the presence of unknown,uncalibtation interference(s).