Xiao-Li Yin

Multi-targeted interference-free determination of ten β-blockers in human urine and plasma samples by alternating trilinear decomposition algorithm-assisted liquid chromatography-mass spectrometry in full scan mode: comparison with multiple reaction monitoring.

β-blockers are the first-line therapeutic agents for treating cardiovascular diseases and also a class of prohibited substances in athletic competitions. In this work, a smart strategy that combines three-way liquid chromatography-mass spectrometry (LC-MS) data with second-order calibration method based on alternating trilinear decomposition (ATLD) algorithm was developed for simultaneous determination of ten β-blockers in human urine and plasma samples. This flexible strategy proved to be a useful tool to solve the problems of overlapped peaks and uncalibrated interferences encountered in quantitative LC-MS, and made the multi-targeted interference-free qualitative and quantitative analysis of β-blockers in complex matrices possible. The limits of detection were in the range of 2.0×10(-5)-6.2×10(-3) μg mL(-1), and the average recoveries were between 90 and 110% with standard deviations and average relative prediction errors less than 10%, indicating that the strategy could provide satisfactory prediction results for ten β-blockers in human urine and plasma samples only using liquid chromatography hyphenated single-quadrupole mass spectrometer in full scan mode. To further confirm the feasibility and reliability of the proposed method, the same batch samples were analyzed by multiple reaction monitoring (MRM) method. T-test demonstrated that there are no significant differences between the prediction results of the two methods. Considering the advantages of fast, low-cost, high sensitivity, and no need of complicated chromatographic and tandem mass spectrometric conditions optimization, the proposed strategy is expected to be extended as an attractive alternative method to quantify analyte(s) of interest in complex systems such as cells, biological fluids, food, environment, pharmaceuticals and other complex samples.

Chemometrics-assisted high performance liquid chromatography-diode array detection strategy to solve varying interfering patterns from different chromatographic columns and sample matrices for beverage analysis

This work reports a chemometrics-assisted high performance liquid chromatography-diode array detection (HPLC-DAD) strategy to solve varying interfering patterns from different chromatographic columns and sample matrices for the rapid simultaneous determination of six synthetic colorants in five kinds of beverages with little sample pretreatment. The investigation was performed using two types of LC columns under the same elution conditions. Although analytes using different columns have different co-elution patterns that appear more seriously in complex backgrounds, all colorants were properly resolved by alternating trilinear decomposition (ATLD) method and accurate chromatographic elution profiles, spectral profiles as well as relative concentrations were obtained. The results were confirmed by those obtained from traditional HPLC-UV method at a particular wavelength and the results of both methods were consistent with each other. All results demonstrated that the proposed chemometrics-assisted HPLC-DAD method is accurate, economical and universal, and can be promisingly applied to solve varying interfering patterns from different chromatographic columns and sample matrices for the analysis of complex food samples.

Simultaneous determination of metoprolol and α-hydroxymetoprolol in human plasma using excitation–emission matrix fluorescence coupled with second-order calibration methods

BACKGROUND 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. RESULTS 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. CONCLUSION 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.

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.

Rapid and simultaneous determination of five vinca alkaloids in Catharanthus roseus and human serum using trilinear component modeling of liquid chromatography–diode array detection data

A novel chemometrics-assisted high performance liquid chromatography method coupled with diode array detector (HPLC-DAD) was proposed for the simultaneous determination of vincristine (VCR), vinblastine (VLB), vindoline (VDL), catharanthine (CAT) and yohimbine (YHB) in Catharanthus roseus (C. roseus) and human serum samples. With the second-order advantage of the alternating trilinear decomposition (ATLD) method, the resolution and rapid determination of five components of interest in complex matrices were performed, even in the present of heavy overlaps and unknown interferences. Therefore, multi-step purification was omitted and five components could be fast eluted out within 7.5min under simple isocratic elution condition (acetonitrile/0.2% formic acid water, 37:63, v/v). Statistical parameters, such as the linear correlation coefficient (R(2)), root-mean-square error of prediction (RMSEP), limit of detection (LOD) and limit of quantitation (LOQ) had been calculated to investigate the accuracy and reliability of the method. The average recoveries of five vinca alkaloids ranged from 97.1% to 101.9% and 98.8% to 103.0% in C. roseus and human serum samples, respectively. The five vinca alkaloids were adequately determined with limits of detection (LODs) of 29.5-49.3ngmL(-1) in C. roseus and 12.4-27.2ngmL(-1) in human serum samples, respectively. The obtained results demonstrated that the analytical strategy provided a feasible alternative for synchronously monitoring the quality of raw herb and the concentration of blood drugs.

Interference-free analysis of aflatoxin B1 and G1 in various foodstuffs using trilinear component modeling of excitation–emission matrix fluorescence data enhanced through photochemical derivatization

A novel ‘dilute-and-shoot’ analytical strategy coupling a self-weighted alternating normalized residue fitting (SWANRF) algorithm with two-dimensional fluorescence detection enhanced through photochemical derivatization (PD) was proposed in the present work for rapid, simultaneous and accurate quantitative analysis of aflatoxin B1 and G1 in various foodstuffs (including cereals, honey, and edible oil). By coupling the predominant second-order advantage of the SWANRF algorithm with the ultra-sensitivity of fluorescence detection enhanced through off-line photochemical derivatization, the specific quantitative information of both analytes could be successfully extracted from heavily interferential matrices without complicated multi-step purification and chromatographic separation procedures. Consequently, the whole analytical time and expense were significantly decreased, accurate recoveries (with relative standard deviations, RSDs) (93.5 ± 6.6–102.8 ± 4.0% for AFB1, and 96.4 ± 3.6–107.2 ± 6.0% for AFG1) and extremely low limits of detection (LODs) (0.12–0.21 ng mL−1 for AFB1, and 0.27–0.75 ng mL−1 for AFG1) were obtained for analytical foodstuff matrices. In addition, all quantitative results of this proposed strategy were carefully compared with the standard IAC-LC-ESI+-MS method for further confirmation, which proved that SWANRF-EEMs are promising as an alternative analytical strategy for the routine analysis of multiplex aflatoxins, and a theoretical basis for developing portable detecting devices.

Solving signal instability to maintain the second-order advantage in the resolution and determination of multi-analytes in complex systems by modeling liquid chromatography-mass spectrometry data using alternating trilinear decomposition method assisted with piecewise direct standardization.

The application of calibration transfer methods has been successful in combination with near-infrared spectroscopy or other tools for prediction of chemical composition. One of the developed methods that can provide accurate performances is the piecewise direct standardization (PDS) method, which in this paper is firstly applied to transfer from one day to another the second-order calibration model based on alternating trilinear decomposition (ATLD) method built for the interference-free resolution and determination of multi-analytes in complex systems by liquid chromatography-mass spectrometry (LC-MS) in full scan mode. This is an example of LC-MS analysis in which interferences have been found, making necessary the use of second-order calibration because of its capacity for modeling this phenomenon, which implies analytes of interest can be resolved and quantified even in the presence of overlapped peaks and unknown interferences. Once the second-order calibration model based on ATLD method was built, the calibration transfer was conducted to compensate for the signal instability of LC-MS instrument over time. This allows one to reduce the volume of the heavy works for complete recalibration which is necessary for later accurate determinations. The root-mean-square error of prediction (RMSEP) and average recovery were used to evaluate the performances of the proposed strategy. Results showed that the number of calibration samples used on the real LC-MS data was reduced by using the PDS method from 11 to 3 while producing comparable RMSEP values and recovery values that were statistically the same (F-test, 95% confidence level) to those obtained with 11 calibration samples. This methodology is in accordance with the highly recommended green analytical chemistry principles, since it can reduce the experimental efforts and cost with regard to the use of a new calibration model built in modified conditions.

Chemometrics-assisted determination of amiloride and triamterene in biological fluids with overlapped peaks and unknown interferences

BACKGROUND Amiloride (AMI) and triamterene (TRI) are both potassium-saving diuretics, which are ordinarily used as doping to enhance the performance of athletes in sports. For the similar structures and complex matrices existence, chromatography and extraction are commonly employed to realize the determination of AMI and TRI in biological fluids, which are very time-consuming and laborious. RESULTS A novel method is presented to simultaneous interference-free determination of AMI and TRI in complex biological fluids samples using excitation-emission matrix fluorescence coupled with second-order calibration method based on alternating normalization-weight error algorithm. CONCLUSION The proposed method can obtain accurate qualitative and quantitative information of the analytes, even in the presence of the interference from complex biological fluids, which requires few prior purification and separation procedures.

Quantitative investigation of the dynamic interaction of human serum albumin with procaine using a multi-way calibration method coupled with three-dimensional fluorescence spectroscopy

In fluorospectrophotometric studies on protein–drug interactions, the fluorescence intensity of proteins is often vulnerable to interference from ligands or newly produced complexes which exhibit significant fluorescence at the chosen excitation or emission wavelengths. Alternatively, this paper suggests an effective and sensitive method for quantitative determination of free human serum albumin (HSA) in a dynamic interaction system with procaine (PRO) and further investigation of their interaction mechanism using a multi-way calibration method coupled with three-dimensional fluorescence spectroscopy. A second-order calibration method realized the quantitative determination of free HSA in a dynamic system with overlapping spectra even in the presence of an uncalibrated interferent. The quantitative results were used to further calculate the binding parameters, including the binding constant, binding site number, thermodynamic parameters and nature of binding forces. Furthermore, the four-way excitation–emission–temperature–sample data were analyzed to investigate the effect of temperature on the interaction system studied.

Simultaneous Determination of Warfarin and Aspirin Contents in Biological Fluids Using Excitation-Emission Matrix Fluorescence Coupled with a Second-order Calibration Method

In the present work, a practical method that combines excitation-emission matrix fluorescence with a second-order calibration method based on an alternating trilinear decomposition (ATLD) algorithm was developed in order to simultaneously and directly determine the contents of warfarin (WAR) and aspirin (ASA) in human plasma and urine samples, even in the presence of unknown interferences. With the pre-estimated component number of 4, the obtained average spiked recoveries were 105.4 ± 7.8 and 104.2 ± 8.3% for WAR, 96.5 ± 2.8 and 91.2 ± 2.3% for ASA in human plasma and urine samples, respectively. Furthermore, the figures of merit were calculated and also inter- and intra-day experiments were performed that proved the proposed method is of great significance to the monitoring of clinical administration and also being a simple sample pretreatment at low-cost.