Jianhe Wei

Occurrence of toxigenic fungi and determination of mycotoxins by HPLC-FLD in functional foods and spices in China markets.

Twenty-four samples including 14 functional foods and 10 spices obtained from Chinese markets were examined for their mould profile. The mycotoxin contamination levels were also determined by an optimized HPLC-FLD method. 124 fungal isolates belonging to four different genera were recovered with Aspergillus and Penicillium as predominant fungi, with an incidence of 66.1% and 15.3%, respectively. In functional foods Aspergillus niger section (57.1%) was isolated more frequently, followed by Aspergillus flavi section (50.0%) and Aspergillus ochraceus section (21.4%), with the most contaminated samples being Coix seeds. Similar fungal presence and frequency were encountered in spice with A. niger section group (60.0%) and A. flavi section (40.0%) as main fungi. Cumin and Pricklyash peel samples showed the highest fungal contamination. Four functional foods and three spices were found to be positive at low levels for mycotoxins including aflatoxin B1 (up to 0.26μg/kg) and ochratoxin A (OTA) (5.0μg/kg). The more frequently detected mycotoxin was AFB1 (16.7%).

Development of a sensitive and reliable high performance liquid chromatography method with fluorescence detection for high-throughput analysis of multi-class mycotoxins in Coix seed

As an edible and medicinal plant, Coix seed is readily contaminated by more than one group of mycotoxins resulting in potential risk to human health. A reliable and sensitive method has been developed to determine seven mycotoxins (aflatoxins B1, B2, G1, G2, zearalenone, α-zearalenol, and β-zearalenol) simultaneously in 10 batches of Coix seed marketed in China. The method is based on a rapid ultrasound-assisted solid-liquid extraction (USLE) using methanol/water (80/20) followed by immunoaffinity column (IAC) clean-up, on-line photochemical derivatization (PCD), and high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD). Careful optimization of extraction, clean-up, separation and detection conditions was accomplished to increase sample throughput and to attain rapid separation and sensitive detection. Method validation was performed by analyzing samples spiked at three different concentrations for the seven mycotoxins. Recoveries were from 73.5% to 107.3%, with relative standard deviations (RSDs) lower than 7.7%. The intra- and inter-day precisions, expressed as RSDs, were lower than 4% for all studied analytes. Limits of detection and quantification ranged from 0.01 to 50.2 μg kg(-1), and from 0.04 to 125.5 μg kg(-1), respectively, which were below the tolerance levels for mycotoxins set by the European Union. Samples that tested positive were further analyzed by HPLC tandem electrospray ionization mass spectrometry for confirmatory purposes. This is the first application of USLE-IAC-HPLC-PCD-FLD for detecting the occurrence of multi-class mycotoxins in Coix seed.

One-step extraction for gas chromatography with flame photometric detection of 18 organophosphorus pesticides in Chinese medicine health wines.

An easy, rapid and selective gas chromatography with flame photometric detection (GC-FPD) method was established for simultaneously determining 18 organophosphorus pesticides (OPPs) in 80 Chinese medicine (CM) health wines. This method was based on a simple one-step extraction procedure using a little solvent without any further cleanup steps. The optimized extraction solvent for the pesticides is acetone:dichloromethane (1:1, V/V) with extraction recovery of 79.0-109.1% and relative standard deviation (RSD) of 0.36-12.68%, respectively. The limits of detection (LODs) of the established GC-FPD method for all investigated pesticides ranged from 1 to 15ngmL(-1) and limits of quantification (LOQs) from 4 to 50ngmL(-1). Out of all 80 CM health wines, 18 OPPs were found in 8 samples at low concentrations of 8.2-37.9ngmL(-1). These pesticides were successfully confirmed by GC-MS. This is the first report of determining OPPs in CM health wines, providing references for monitoring the quality of CM health wine in routine analysis.

Gas chromatography with flame photometric detection of 31 organophosphorus pesticide residues in Alpinia oxyphylla dried fruits.

A simple, rapid and effective gas chromatography-flame photometric detection method was established for simultaneous multi-component determination of 31 organophosphorus pesticides (OPPs) residues in Alpinia oxyphylla, which is widely consumed as a traditional medicine and food in China. Sample preparation was completed in a single step without any clean-up procedure. All pesticides expressed good linear relationships between 0.004 and 1.0 μg/mL with correlation coefficients higher than 0.9973. The method gave satisfactory recoveries for most pesticides. The limits of detection varied from 1 to 10 ng/mL, and the limits of quantification (LOQs) were between 4 and 30 ng/mL. The proposed method was successfully applied to 55 commercial samples purchased from five different areas. Five pesticide residues were detected in four (7.27%) samples. The positive samples were confirmed by gas chromatography with tandem mass spectrometry (GC-MS/MS).

Streamlined pretreatment and GC-FPD analysis of multi-pesticide residues in perennial Morinda roots: a tropical or subtropical plant.

In this study, a simple and rapid multi-pesticide residues analytical method has been developed and evaluated for simultaneous identification and quantification of 30 organophosphorus pesticides (OPPs) present at trace levels in perennial Morinda roots. Samples were firstly extracted and cleaned up with a streamlined method (modified QuEChERS), and then detected by gas chromatography with flame photometric detector (GC-FPD). For accurate quantification, representative matrix-matched calibration curves were applied to compensate matrix effects. Reasonable linearity was found in the concentration ranges of 0.04 and 1.28 μg mL(-1), with correlation coefficients r better than 0.9921 (0.9921-0.9998). The limits of detection (LODs) were between 0.005 and 0.02 μg mL(-1) for all investigated pesticides, while the limits of quantification (LOQs) were in the range of 0.01-0.04 μg mL(-1), below the regulatory maximum residue limits (MRL) suggested. Acceptable quantitative recoveries of 75.01-118.89% (96.0% on average) were achieved with relative standard deviations (RSD) varying from 0.89% to 9.80% (5.39% on average) at three different concentration levels of 0.05, 0.1 and 1.0 mg kg(-1). Out of all 40 batches of real samples, only fenitrothion was found in two samples, which was successfully confirmed by GC-MS. Based on these results, this analytical method has been proven to be fast, robust, accurate, selective, sensitive and easy to operate in the analysis of multiple pesticide residues in Morinda roots. Meanwhile, it also draws attention to the need of pesticide monitoring programs in local soils.

HPLC fingerprint analysis combined with chemometrics for pattern recognition of ginger

Abstract Context: Ginger, the fresh rhizome of Zingiber officinale Rosc. (Zingiberaceae), has been used worldwide; however, for a long time, there has been no standard approbated internationally for its quality control. Objective: To establish an efficacious and combinational method and pattern recognition technique for quality control of ginger. Methods: A simple, accurate and reliable method based on high-performance liquid chromatography with photodiode array (HPLC-PDA) detection was developed for establishing the chemical fingerprints of 10 batches of ginger from different markets in China. The method was validated in terms of precision, reproducibility and stability; and the relative standard deviations were all less than 1.57%. On the basis of this method, the fingerprints of 10 batches of ginger samples were obtained, which showed 16 common peaks. Coupled with similarity evaluation software, the similarities between each fingerprint of the sample and the simulative mean chromatogram were in the range of 0.998–1.000. Then, the chemometric techniques, including similarity analysis, hierarchical clustering analysis and principal component analysis were applied to classify the ginger samples. Results and conclusion: Consistent results were obtained to show that ginger samples could be successfully classified into two groups. This study revealed that HPLC-PDA method was simple, sensitive and reliable for fingerprint analysis, and moreover, for pattern recognition and quality control of ginger.

Multi-elements determination in medical and edible Alpinia oxyphylla and Morinda officinalis and their decoctions by ICP-MS

Contents of twenty elements (Mg, K, Ca, Na, Fe, Al, Zn, Ba, Mn, Cu, Mo, Cr, Ni, As, Se, Cd, Hg, Tl, Pb and V) in two medical and edible plant species, Alpinia oxyphylla and Morinda officinalis were simultaneously determined by inductively coupled plasma-mass spectrometry (ICP-MS) method after microwave digestion with HNO3-H2O2 (6:1, v/v) as the digestion solvent. Certified standard reference material Poplar leaf was used to assess the accuracy of the method. The greatest contents of Mg, K, Ca, Al, Fe and Na were found in dried Alpinia oxyphylla and Morinda officinalis samples. The contents of five heavy metals including Pb, Cd, As, Hg and Cu in Alpinia oxyphylla did not exceed the limits. The contents of Pb in 76.67% samples and Cd in two batches of Morinda officinalis samples exceeded the limits set by Chinese Pharmacopeia. The contents of the selected elements in different parts (leaves, stems, roots and fruits) of Alpinia oxyphylla varied considerably. The highest concentrations of Mg, Ca, Mn and Se were found in the leaves of Alpinia oxyphylla, at the same time, while, the contents of 9 elements including Cd, Cr, Cu, As, Pb in the roots were the highest. The transfer ratios of selected elements from both species of herbs into their decoctions were reduced. Especially for the heavy metals, the transfer ratios were below 30% except As (79.73%) in Morinda officinalis. The results showed that decoction of the samples may reduce the intake of heavy metals.

Simultaneous analysis of multiple mycotoxins in Alpinia oxyphylla by UPLC-MS/MS

In this study, a reliable and fast method for the simultaneous quantitation of 11 mycotoxins in Alpinia oxyphylla was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLCMS/ MS). Three different extraction procedures (solid-liquid extraction, solid-phase extraction and modified QuEChERS) were evaluated. Solid-liquid extraction was fast and easy, and also provided the best recovery rate for all mycotoxins, compared to the other extraction procedures. Some crucial factors, including extraction solvent, time and temperature, were carefully optimised. Significant matrix effects were offset using matrix-matched calibration. Under these optimised conditions, our detection approach showed a good, linear dynamic range with correlation coefficients (R2) above 0.9958. The limit of quantification ranged from 0.1 to 20 μg/kg. Accuracy was determined in a selected matrix using blank samples spiked with the target mycotoxins at three different concentration levels. The rec...

Simultaneous Analysis of Iridoid Glycosides and Anthraquinones in Morinda officinalis Using UPLC-QqQ-MS/MS and UPLC-Q/TOF-MSE

Morinda officinalis is an important herbal medicine and functional food, and its main constituents include anthraquinone and iridoid glycosides. Quantification of the main compounds is a necessary step to understand the quality and therapeutic properties of M. officinalis, but this has not yet been performed based on liquid chromatography/tandem mass spectrometry (LC-MS/MS). Analytes were extracted from M. officinalis by reflux method. Ultrahigh-performance liquid chromatography coupled with a triple quadrupole mass spectrometry (UPLC-QqQ-MS) using multiple reaction monitoring (MRM) mode was applied for quantification. Fragmentation pathways of deacetyl asperulosidic acid and rubiadin were investigated based on UPLC with quadrupole time-of-flight tandem mass spectrometry (Q/TOF-MS) in the MSE centroid mode. The method showed a good linearity over a wide concentration range (R2 ≥ 0.9930). The limits of quantification of six compounds ranged from 2.6 to 27.57 ng/mL. The intra- and inter-day precisions of the investigated components exhibited an RSD within 4.5% with mean recovery rates of 95.32–99.86%. Contents of selected compounds in M. officinalis varied significantly depending on region. The fragmentation pathway of deacetyl asperulosidic and rubiadin was proposed. A selective and sensitive method was developed for determining six target compounds in M. officinalis by UPLC-MS/MS. Furthermore, the proposed method will be helpful for quality control and identification main compounds of M. officinalis.