[Nucleosides-based identification model for Fritillariae Cirrhosae Bulbus].

A high performance liquid chromatography( HPLC) method was established for the fast,and precise determination of ten nucleosides in Fritillariae Cirrhosae Bulbus and its counterfeits. Then multivariate statistical analyses,such as clustering analysis,principal component analysis( PCA),and Fisher' s linear discriminant analysis( LDA),were conducted to establish a discriminant function model for an integrated analysis. The results indicated that data acquisition time of a single sample was shortened within 16 min by the HPLC method. In the range of 5-1 000 mg·kg~(-1),the mass concentrations of all nucleosides exhibited good linear relationships with the corresponding peak areas( R2> 0. 999). The spiked recoveries were in the range of 93. 83%-108. 9% with RSDs of0. 12%-1. 3%( n = 5). The limit of quantitation( LOQ) was 0. 98-4. 13 mg·kg~(-1). As revealed by the clustering analysis,Fritillariae Cirrhosae Bulbus and the counterfeits could be discriminated into two clusters based on the content of nucleosides. Fisher's LDA could achieve this discrimination,while PCA dimension reduction failed. The accuracy of the discriminant function model established on the screened characteristic indicators reached 97. 5%. The present study proposed a new identification method of Fritillariae Cirrhosae Bulbus with one-dimensional indicators,which is simple,accurate,and reliable. It can provide a scientific basis for further optimizing the identification techniques for Fritillariae Cirrhosae Bulbus and inspiration for quality control strategy development of Chinese medicinal materials.

A simple and effective method to discern the true commercial Chinese cordyceps from counterfeits.

The Chinese cordyceps, a complex of the fungus Ophiocordyceps sinensis and its species-specific host insects, is also called "DongChongXiaCao" in Chinese. Habitat degradation in recent decades and excessive harvesting by humans has intensified its scarcity and increased the prices of natural populations. Some counterfeits are traded as natural Chinese cordyceps for profit, causing confusion in the marketplace. To promote the safe use of Chinese cordyceps and related products, a duplex PCR method for specifically identifying raw Chinese cordyceps and its primary products was successfully established. Chinese cordyceps could be precisely identified by detecting an internal transcribed spacer amplicon from O. sinensis and a cytochrome oxidase c subunit 1 amplicon from the host species, at a limit of detection as low as 32 pg. Eleven commercial samples were purchased and successfully tested to further verify that the developed duplex PCR method could be reliably used to identify Chinese cordyceps. It provides a new simple way to discern true commercial Chinese cordyceps from counterfeits in the marketplace. This is an important step toward achieving an authentication method for this Chinese medicine. The methodology and the developmental strategy can be used to authenticate other traditional Chinese medicinal materials.

Optimization of a multi-residue method for 101 pesticides in green tea leaves using gas chromatography–tandem mass spectrometry

ABSTRACT A method for analysis of 101 pesticide residues in tea leaves was developed and validated for the first time. Pure acetonitrile was used as extraction solvent rather than acetonitrile after matrix hydration based on the amount of co-extracts and recoveries performance. During clean-up procedure, primary-secondary amine/graphitized carbon black (500 mg) was selected, which exhibited outstanding properties in clean-up capabilities and recoveries of pesticides comparing to primary-secondary amine/graphitized carbon black (250 mg), NH2-Carbon and TPT absorbents. The method was validated employing gas chromatography coupled to tandem mass spectrometry at the spiked concentration levels of 0.050 and 0.100 mg kg−1. For most of the targeted pesticides, the percent recoveries range from 70 to 120%, with relative standard deviations <20%. The linear correlation coefficients (r 2) were higher than 0.99 at concentration levels of 0.025–0.250 mg kg−1. Limits of quantification ranged from 1.1 to 25.3 µg kg−1 for all pesticides. The developed method was successfully applied to the determination of pesticides in tea leaf samples.

A multi-residue method for the determination of pesticides in tea using multi-walled carbon nanotubes as a dispersive solid phase extraction absorbent.

A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method using multi-walled carbon nanotubes (MWCNTs) as a dispersive solid phase extraction (d-SPE) absorbent was established for analysis of 78 pesticide residues in tea. A 6 mg MWCNT sample was selected as the optimised amount based on the distribution of pesticide recoveries and clean-up efficiency from 6 mL acetonitrile extracts. The matrix effects of the method were evaluated and matrix-matched calibration was recommended. The method was validated employing gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) at the spiked concentration levels of 0.05, 0.1 and 0.15 mg kg(-1). For most of the targeted pesticides, the percent recoveries range from 70% to 120%, with relative standard deviations (RSDs) <20%. The linear correlation coefficients (r(2)) were higher than 0.99 at concentration levels of 0.025-0.500 mg kg(-1). In this study, MWCNTs were proved to be a promising d-SPE absorbent with excellent cleanup efficiency, which could be widely applied for the analysis of pesticide residues.

[Determination: of citrus red 2 in navel orange by ultra performance liquid chromatography-tandem mass spectrometry].

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method was developed for the determination of citrus red 2 (CR2) in navel orange. The sample was extracted with acetonitrile, cleaned-up by an NH2 solid phase extraction cartridge. Then, the analyte was separated on a Waters Acquity UPLC BEH C18 column (50 mm x 2.1 mm, 1.7 microm) in gradient elution with the mobile phases of water and acetonitrile. The separated compounds were detected with a Waters Xevo TQ MS tandem quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI+). The linearity of the method was good (r2 = 0.996 5) over the concentration range from 0.1 to 100 microg/L for CR2. The limit of detection (LOD) was 0.05 microg/kg, and the limit of quantification (LOQ) was 0.1 microg/kg. The average recoveries of CR2 at the three levels of 1.0, 10.0 and 100.0 microg/kg were between 84.2% and 94.0% with the relative standard deviations (RSDs) between 2.86% and 10.15%. Finally, a total of 18 navel orange samples randomly collected from different markets were detected by the proposed method, and two samples contained CR2. The sensitivity, accuracy, and precision of this method can meet the requirements of the CR2 analysis.