Simultaneous determination of metronidazole and tinidazole in plasma by using HPLC–DAD coupled with second-order calibration

<正>A method using HPLC-DAD coupled with second-order calibration was developed to simultaneously determine metronidazole and tinidazole in plasma samples in this paper.The second-order calibration method based on APTLD(alternating penalty trilinear decomposition) algorithm was proposed to analyze the three-way HPLC-DAD data from both standard and prediction samples, which makes it possible that calibration can be performed even in the presence of unknown interferences with a simple and green chromatographic condition and short analysis time.The results showed that good recoveries were obtained although the chromatographic and spectral profiles of the analytes of interest as well as background were partially overlapped with each other in plasma samples.     

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 con- centrations 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 g mL 1 in plasma and from 6.87 to 20.6 g mL 1 in urine; TBHQ, from 4.49 to 20.2 g mL-1 in plasma and from 6.73 to 22.4 g 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.     

Highly sensitive fluorescence quantification of irinotecan in biological fluids with the aid of second-order advantage

<正>A rapid,green and highly sensitive excitation-emission matrix(EEM) fluorescence method was proposed for analysis of irinotecan(CPT-11) in biological fluids including human plasma and urine samples of uncalibrated interferences with the aid of second-order advantage.Due to the serious spectral overlapping from biological matrices,the parallel factor analysis(PARAFAC) and the alternating normalization-weighted error(ANWE) have been recommended to perform directly calibration and overcome the problem which makes the traditional fluorospectrophotometer in trouble.Satisfactory results can be achieved.Furthermore, performance of the proposed method was evaluated based on figures of merit and some statistical parameters.The accuracy of both algorithms was validated by the elliptical joint confidence region(EJCR) test.The precision and repeatability were also investigated by the relative standard deviations(RSDs) of intra-day and inter-day.     

Quantitative analysis of elements (C, N, O, Al, Si and Fe) in polyamide with wavelength dispersive X-ray fluorescence spectrometry

A wavelength dispersive X-ray fluorescence (WD-XRF) spectrometry combined with calibration curve method was established for simultaneously analyzing low-Z elements (C,N,O) and Al,Si,Fe in polyamide.To investigate the origin of plastic material causing deposition and blocking in instrument engines and pipelines,polyamide 6 (PA 6,an engineering plastic) was chosen as the study object on account of its common use in industry.The sample preparation with pressed powder disk has been developed for determination of six elements in PA 6.Pure Cu metal was used as the matrix and PA 6 was regarded as standard sample for C,N,O elements.PA 6 particles were firstly smashed to uniform powder in liquid nitrogen,and then mixed with inorganic standard powders (Fe2O3,Al2O3,SiO2,and Na 2 SiO 3).The mixture was ground to obtain homogeneous calibration materials for WD-XRF analysis.The quantitative property of the calibration curve method for each element was reliable.The limits of detection (S/N≤3) of C,N,O,Al,Si and Fe using WD-XRF were 249,120,101,6.2,3.3,and 1.8 μg/g,respectively.To confirm the accuracy of the proposed WD-XRF calibration curve method,inductively coupled plasma optical emission spectroscopy (ICP-OES) detection for Al,Si,Fe and elemental analyzer (EA) analysis for C,N,O were utilized.A good correlation of the WD-XRF results with the measurements of ICP-OES and EA was observed.     

Rapid determination of thiabendazole in orange extract using excitation-emission matrix fluorescence and second-order calibration based on alternating trilinear decomposition/alternating normalization-weighted error algorithms

A novel approach is proposed for direct quantitative analysis of thiabendazole in the orange extract by using excitation-emission matrix fluorescence coupled with second-order calibration methods based on the alternating trilinear decomposition(ATLD) and the alternating normalization-weighted error(ANWE) algorithms,respectively. The average recoveries of thiabendazole in the orange extract by using ATLD and ANWE with an estimated component number of two were 99.7 ± 3.3% and 103.5 ± 4.1%,respectively. Furthermore,the accuracy of the two algorithms was also evaluated through elliptical joint confidence region(EJCR) tests as well as figures of merit,such as sensitivity(SEN),selectivity(SEL) and limit of detection(LOD). The experimental results demonstrate that both algorithms have been satisfactorily applied to the determination of thiabendazole in orange extract,and the perform-ance of ANWE is slightly better than that of ATLD.     

Determination of captopril in pharmaceutical preparation and biological fluids using two- and three-way chemometrics methods

Spectrophotometric method has been developed for the direct quantitative determination of captopril in pharmaceuticalpreparation and biological fluids(human plasma and urine)samples.The method was accomplished based on parallel factoranalysis(PARAFAC)and partial least squares(PLS).The study was carried out in the pH range from 2.0 to 12.8 and with aconcentration from 0.70 to 61.50 μg mL~(-1)of captopril.Multivariate calibration models such as PLS at various pH and PARAFACwere elaborated from ultraviolet spectra deconvolution and captopril determination.The best models for this system were obtainedwith PARAFAC and PLS at pH 2.0.The applications of the method for determination of real samples were evaluated by analysis ofcaptopril in pharmaceutical preparations and biological fluids with satisfactory results.The accuracy of the method,evaluatedthrough the RMSEP,was 0.5801 for captopril with best calibration curve by PARAFAC and 0.6168 for captopril with PLS at pH 2.0model.     

Determination of PCDD/Fs and dioxin-like PCBs in food and feed using gas chromatography-triple quadrupole mass spectrometry

A method was developed on a gas chromatograph coupled to a triple quadrupole mass spectrometer(GC-MS/MS) for trace level determination of polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/Fs) and dioxin-like polychlorinated biphenyls(DL-PCBs) in food and feed. The results demonstrated good sensitivity and repeatability for PCDD/Fs and DL-PCBs at an extremely low level(10 pg mL~(-1) for 2,3,7,8-TCDD/F), as well as wide linear response of over 3 or 4 orders of magnitude in concentration ranges; 0.5–200 ng mL~(-1) for PeCDD/F and 0.2–2000 ng mL~(-1) for DL-PCBs. The method detection limits for PCDD/Fs and DL-PCBs were in the range from 0.018–0.17 pg g~(-1) to 0.13–0.36 pg g~(-1), respectively. The performance of the GC-MS/MS for food and feed sample analysis showed high precision and accuracy compared to the high resolution gas chromatograph/high resolution mass spectrometer. The results indicated the feasibility of GC-MS/MS as a confirmatory method for the measurement of PCDD/Fs and DL-PCBs in food and feed as required by European Union legislation.     

Simultaneous and interference-free determination of eleven non-steroidal anti-inflammatory drugs illegally added into Chinese patent drugs using chemometrics-assisted HPLC-DAD strategy

In this work, a smart strategy that combines three-way high performance liquid chromatography-diode array detection(HPLCDAD) data with second-order calibration method based on alternating trilinear decomposition(ATLD) algorithm was proposed for simultaneous determination of eleven non-steroidal anti-inflammatory drugs(NSAIDs) illegally added into Chinese patent drugs and health products. All target analytes were rapidly eluted out within 14.5 min under a simple gradient elution. With the aid of the prominent "second-order advantage" of the ATLD algorithm, three HPLC problems, i.e. peak overlaps, unknown interferences and baseline drift, could be mathematically calibrated, and pure signals of target analytes could be extracted out from heavy-interference but information-rich HPLC-DAD data. The average spiked recoveries for all target analytes were in the range of 95.9%–106.4% with standard deviations lower than 7.5%. Validation parameters including sensitivity(SEN), selectivity(SEL), limit of detection(LOD), limit of quantitation(LOQ) and precisions of intra-day and inter-day were calculated to validate the accuracy of the proposed method, quantitative results were further confirmed by the classic HPLC method, which proved that chemometrics-assisted HPLC-DAD analytical strategy was highly efficient, accurate and green for drug-abuse monitoring of NSAIDs in Chinese patent drugs and health products.     

Determination of synthetic phenolic antioxidants in essence perfume by high performance liquid chromatography with vortex-assisted,cloud-point extraction using AEO-9

This study aimed to establish a rapid analytical method to determine antioxidants in essence. A simple,efficient and practical, vortex-assisted, cloud-point extraction(VACPE) procedure is proposed for extracting and pre-concentrating four different of synthetic phenolic antioxidants(SPAs), propyl gallate(PG), tert-butylhydroquinone(TBHQ), butylated hydroxyanisole(BHA), butylated hydroxytoluene(BHT) in essence prior to high performance liquid chromatography(HPLC) analysis. The non-ionic surfactant, fatty alcohol polyoxyethylene ether-9(AEO-9), was used as extractant and vortex-mixing was utilized to reduce extraction time and improve extraction efficiency. The effective parameters of the extraction process, such as volume of extraction solvent, pH, vortex-mixing time, equilibration temperature and time, were optimized. Under the optimum conditions, the linear range of PG, TBHQ,BHA and BHT was 8.0–800 ng/mL. All correlation coefficients of the calibration curves were higher than0.996 and relative standard deviations(RSD, n = 5) were 2.36%–5.46%. The proposed method was successfully applied to the extraction and determination of antioxidants in essence samples with satisfactory relative recoveries of 89.4%–103.5%. The results confirmed the SPAs of essence could be effectively monitored by this method and also established good reference criteria for essence.     

HPLC-DAD data coupled with second-order calibration method applied to food analysis: Simultaneous determination of six benzoylurea insecticides in various fruit samples by selecting time region of chromatogram

This work presents a novel application of second-order calibration based on self-weighted alternating trilinear decomposition(SWATLD)algorithm for analyzing the HPLC-DAD data.The proposed method makes it possible to simultaneously determine teflubenzuron,hexaflumuron,flufenoxuron,chlorfluazuron,diflubenzuron and benzoylurea in different fruit samples,i.e.pear,apple and banana,in the selected time region of chromatogram.The concentration,elution time and spectral information of these benzoylurea insecticides are selectively extracted from complex matrices even in the presence of unknown interferences.The root-mean-square error of prediction(RMSEP)and figures of merit,including sensitivity(SEN),selectivity(SEL)and limit of detection(LOD)are employed to access the performance of the method.The LODs obtained for these insecticides are within the range 0.017–0.26 ppm in pears,0.039–0.33 ppm in apples,0.041–0.44 ppm in bananas,respectively.Such a chemometrics-based protocol holds great potential to be extended as a promising alternative for more practical applications in food safety and quality monitoring.     

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.     

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.     

Excitation-emission-kinetic fluorescence coupled with third-order calibration for quantifying carbaryl and investigating the hydrolysis in effluent water

A novel method for determination of carbaryl in effluent was proposed in this study. The kinetic evolution of excitation-emission matrix fluorescence (EEM) for the pesticide were recorded and come into being a four-way data array. The four-way fluorescence data were analyzed using the parallel factor analysis (PARAFAC). The methodology exploits the second-order advantage of three-order calibration based on quadrilinear parallel factor analysis, allowing analyte concentrations to be estimated even in the presence of an uncalibrated fluorescent background. It gave the satisfactory results for determination of the carbaryl in effluent samples. In addition, the kinetic study of degradation of carbaryl was performed according to the kinetic profile provided by the calibration.     

Simultaneous determination of 6-methylcoumarin and 7-methoxycoumarin in cosmetics using three-dimensional excitation-emission matrix fluorescence coupled with second-order calibration methods

This paper reports a simple, rapid, and effective method for quantitative analysis of 6-methylcoumarin (6-MC) and 7-methoxycoumarin (7-MOC) in cosmetics using excitation–emission matrix (EEM) fluorescence coupled with second-order calibration. After simple pretreatments, the adopted calibration algorithms exploiting the second-order advantage, i.e., parallel factor analysis (PARAFAC) and self-weighted alternating tri-linear decomposition (SWATLD), could allow the individual concentrations of the analytes of interest to be predicted even in the presence of uncalibrated interferences. In the analysis of facial spray, with the external calibration method, the average recoveries attained from PARAFAC and SWATLD with the factor number of 3 (N = 3) were 101.4 ± 5.5 and 97.5 ± 4.1% for 6-MC, and 103.3 ± 1.7 and 101.7 ± 1.8% for 7-MOC, respectively. Moreover, in the analysis of oil control nourishing toner, the standard addition method (SAM) was suggested to overcome the partial fluorescence quenching of 6-MC induced by the analyte–background interaction, which also yielded satisfactory prediction results. In addition, the accuracy of the two algorithms was also evaluated through elliptical joint confidence region (EJCR) tests as well as figures of merit (FOM), including sensitivity (SEN), selectivity (SEL) and limit of detection (LOD). It was found that both algorithms could give accurate results, only the performance of SWATLD was slightly better than that of PARAFAC in the cases suffering from matrix effects. The method proposed lights a new avenue to determine quantitatively 6-MC and 7-MOC in cosmetics, and may hold great potential to be extended as a promising alternative for more practical applications in cosmetic quality control, due to its advantages of easy sample pretreatment, non-toxic and non-destructive analysis, and accurate spectral resolution and concentration prediction.     

Spectrofluorimetric determination of chlorophylls and pheopigments using parallel factor analysis

In this study, parallel factor analysis (PARAFAC) was applied to fluorescence excitation emission matrices (EEM) of chlorophylls and pheopigments dissolved in acetone:water (9:1). The excitation wavelength range was from 350 to 500 nm and the emission was recorded from 600 to 730 nm. Nine standards, comprising mixtures of six analytes, were decomposed into a six-component PARAFAC model. Each component resembled the corresponding EEM of the pure analyte, demonstrating the uniqueness properties of PARAFAC. The score matrix obtained from the model was used for calibration and prediction of an independent set of standards and for eleven samples collected in the Baltic proper. The results obtained by the proposed method were compared to classical least squares (CLS) and to predictions by reference methods (HPLC and visible spectroscopy). For the independent set of standards the proposed method and CLS performed equal well in terms of predictive ability. But for the samples the proposed method yielded results that were in good agreement to the reference methods, whereas CLS failed. Also the so-called "second-order advantage" was examined, showing that not all constituents must be included in the calibration set. The concentration range was for chlorophyll a varied between 10 and 75 mug l(-1), and similar for the other analytes.     

Simultaneous determination of tyrosine and dopamine in urine samples using excitation-emission matrix fluorescence coupled with second-order calibration

A "green" and quick analytical method for complex compounds was developed for simultaneous determination of tyrosine (Tyr) and dopamine (DA) in urine samples in this paper. The three-way responsive data recorded by excitation-emission matrix fluorescence (EEM) spectrometer was analyzed using second-order calibration methods based on both parallel factor analysis (PARAFAC) and selfweighted alternating trilinear decomposition (SWATLD) algorithms. The EEM spectra of the analytes were overlapped with the background in urine samples. However the second-order advantage of both PARAFAC and SWATLD methods was exploited, even in the presence of unknown interferences and the satisfactory results can be obtained. Furthermore, the linear ranges of Tyr and DA were determined to be 0.042-6.42 μg/mL and 0.18-4.43 μmg/mL, respectively, and the accuracies of both methods were validated by the analytical figures of merit (FOM).     

Quantitative analysis of hydrolysis of carbaryl in tap water and river by excitation-emission matrix fluorescence coupled with second-order calibration

A novel method was proposed to determine simultaneously carbaryl and its degradation product 1-naphthol in river and tap water in this paper. The parallel factor analysis (PARAFAC) algorithm was adopted to analyze the excitation–emission matrix (EEM) fluorescence data. The second-order advantage of the PARAFAC-based second-order calibration algorithm was exploited, which make it possible that calibration can be performed even in the presence of unknown interferences. Good recoveries were obtained although the excitation and emission spectral profiles of the analytes were overlapped with background in the river water. It was also applied to investigate the hydrolysis kinetics of carbaryl in river water and tap water. The rate equation, the rate constant and the half life were calculated.