Traceability Research on Dendrobium devonianum Based on SWATHtoMRM.

SWATHtoMRM technology was used in this experiment to further identify and trace the sources of Dendrobium devonianum and Dendrobium officinale produced in the same area using TOF and MS-MRM. After the conversion of the R package of SWATHtoMRM, 191 MRM pairs of positive ions and 96 pairs of negative ions were obtained. Dendrobium devonianum and Dendrobium officinale can be separated very well using the PCA and PLS-DA analysis of MRM ion pairs; this shows that there are obvious differences in chemical composition between Dendrobium devonianum and Dendrobium officinale, which clearly proves that the pseudotargeted metabolomics method based on SWATHtoMRM can be used for traceability identification research. A total of 146 characteristic compounds were obtained, with 20 characteristic compounds in Dendrobium devonianum. The enrichment pathways of the characteristic compounds were mainly concentrated in lipids and atherosclerosis, chagas disease, fluid shear stress and atherosclerosis, proteoglycans in cancer, the IL-17 signaling pathway, the sphingolipid signaling pathway, diabetic cardiomyopathy, arginine and proline metabolism, etc., among which the lipid and atherosclerosis pathways were more enriched, and 11 characteristic compounds affected the expression levels of IL-1, TNFα, CD36, IL-1ß, etc. These can be used as a reference for research on variety improvement and active substance accumulation in Dendrobium devonianum and Dendrobium officinale.

Simultaneous Determination and Health Risk Assessment of Four High Detection Rate Pesticide Residues in Pu'er Tea from Yunnan, China.

Four pesticides with a high detection rate in Pu'er tea have been determined by a QuEChERS (quick, easy, cheap, effective, rugged, safe) method with multiwalled carbon nanotubes (MWCNTs), and combined ultrahigh-performance liquid chromatography-triple quadrupole linear ion trap-tandem mass spectrometry (UHPLC-QTRAP-MS/MS). MWCNs have been compared with other common purification materials, and found to be superior. The matrix effect was systematically studied, and the results show that the MWCNs can quickly and effectively reduce matrix interference values, which were in the range from -17.8 to 13.8. The coefficients (R2) were greater than 0.99, with the limit of quantification ranging from 0.1 to 0.5 µg/kg, and the recovery rate ranging from 74.8% to 105.0%, while the relative standard deviation (RSD) ranged from 3.9% to 6.6%. A total of 300 samples, taken from three areas in which Yunnan Pu'er tea was most commonly produced, tested for four pesticides. The results show that the detection rate of tolfenpyrad in Pu'er tea was 35.7%, which is higher than other pesticides, and the lowest was indoxacarb, with 5.2%. The residual concentrations of chlorpyrifos, triazophos, tolfenpyrad and indoxacarb ranged from 1.10 to 5.28, 0.014 to 0.103, 1.02 to 51.8, and 1.07 to 4.89 mg/kg, respectively. By comparing with China's pesticide residue limits in tea (GB 2763-2021), the over standard rates of chlorpyrifos, tolfenpyrad, and indoxacarb were 4.35%, 0.87% and 0%, respectively. The risk assessment result obtained with the hazard quotient (HQ) method shows that the HQ of the four pesticides was far less than one, indicating that the risk is considered acceptable for the four pesticides in Pu'er tea. The largest HQ was found for tolfenpyrad, 0.0135, and the smallest was found for indoxacarb, 0.000757, but more attention should be paid to tolfenpyrad in daily diets in the future, because its detection rate, and residual and residual median were all relatively high.

Determination of new generation amide insecticide residues in complex matrix agricultural food by ultrahigh performance liquid chromatography tandem mass spectrometry.

Eight new generation amide insecticide residues analysis by multiwalled carbon nanotubes (MWCNs) cleanup, combined with QuEChERS and ultrahigh performance liquid chromatography tandem mass spectrometry has been developed and successfully applied in complex matrix such as orange, celery, onion, litchi, mango, shallot, chives, avocado, garlic. The matric effect of MWCNs is optimized and compared with ordinary cleanup materials. The results show that the performance of MWCNs is fine and effectively reduce matrix interference. Through chemical structure skeletons analyzed, chlorantraniliprole, bromoantraniliprole, and cyantraniliprole can cause same product ions of m/z 286.0 or 177.1 in the ESI+ mode, then tetrachlorantraniliprole and cyclaniliprole can produce collective ions of m/z 146.9 in the ESI- mode. The coefficients (R2) were greater than 0.9990, the limit of quantification ranges from 0.03 to 0.80 µg/kg, the recovery rate ranges from 71.2 to 120%, and the relative standard deviation (RSD) ranges from 3.8 to 9.4%. The method is fast, simple, sensitive, and suitable for the rapid determination of amide pesticides in complex matrix agricultural food.

The level variation of Nε-(carboxymethyl)lysine is correlated with chlorogenic acids in Arabica L. Coffee beans under different process conditions.

Nε-(carboxymethyl) lysine (CML) is universally used as a marker of the occurrence of advanced glycation end products (AGEs) in foods. This study investigated the level changes of CML, chlorogenic acids (CQAs), lysine (Lys), fat and pH in coffee during roasting. The CML level went up slowly in the first 10 mins, then declined sharply during the next 2 mins, and kept increasing constantly in the following baking time, while the lowest CML level was obtained by roasting at 235 °C for 12 mins. The three CQAs isomers had different efficacy in affecting the levels of CML and other factors, indicating the CQAs isomers may play an important role in influencing the CML level. So it might be possible to regulate the formation of CML and gain better coffee quality via adjusting the levels of CQAs in baking process. This study provided important enlightenment on CML control during coffee baking.

[Rapid determination of multiple prohibited and restricted veterinary drug residues in fish and shrimp by ultra high performance liquid chromatography-tandem mass spectrometry].

A method was established for the rapid determination of 28 prohibited and restricted veterinary drugs of five classes (sulfonamides, quinolones, chloramphenicols, nitrofurans metabolites and triphenylmethane) in fish and shrimp by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) coupled with simultaneous extraction and purification. After optimizing the sample pretreatment methods and chromatographic conditions, the samples were hydrolyzed with hydrochloric acid. The five kinds of residual drugs were simultaneously extracted with acetonitrile after nitrofuran metabolites derivatized with 2-nitrobenzaldehyde. The extraction solutions were dehydrated with sodium chloride and salted out. The acetonitrile layer was purified with n-hexane and concentrated to near dryness. The residues were dissolved in 1.0 mL methanol. Then, the solutions were purified by dispersive solid phase extraction with C18, N-(n-propyl)ethylenediamine (PSA) and amino bonded silica gel (NH2) sorbents. The residues were separated on a ZORBAX C18 chromatographic column (50 mm×2.1 mm, 1.8 µm). The MS data were acquired in positive and negative multiple reaction monitoring (MRM) modes, and quantitated by the isotope internal standard method. With this approach, the linear relationships of the 28 veterinary drugs were good. The linear correlation coefficients were greater than 0.99. The limits of detection and limits of quantification were in the range of 0.1-0.8 µg/kg and 0.3-2.7 µg/kg, respectively. The average recoveries at three spiked levels (1, 5, and 20 fold of the LOQs) were 70.0%-120% with relative standard deviations of 0.9%-10.0%. The method is simple, rapid, accurate and sensitive, and it is suitable for the rapid determination of various prohibited and restricted drugs in fish and shrimp.

[Simultaneous determination of antibiotics and triphenylmethanes veterinary drug residues in fish and shrimp by dispersive solid phase extraction purification-ultra high performance liquid chromatography-tandem mass spectrometry].

A method was established to rapidly determine 20 kinds of veterinary drug residues including three catagories of antibiotics (sulfonamides, quinolones, and chloramphenicols) and two kinds of triphenylmethanes (malachite green (MG) and leucomalachite green (LMG)) in fish and shrimp, based on dispersive solid phase extraction purification-ultra high performance liquid chromatography-tandem mass spectrometry. The samples were first hydrolyzed using a dipotassium hydrogen phosphate solution, and then extracted using acetonitrile. Afterward, the extraction solution was dehydrated and salted out with sodium chloride and condensed to nearly dry using a rotating evaporator. This residue was dissolved in 1.0 mL methanol. The resulting solution was purified by dispersive solid phase extraction method with C18 and PSA sorbents, and filtered through a filter. The target compounds were separated employing a ZORBAX C18 column. The mass spectrometer datas were acquired by multiple reaction monitoring (MRM) of positive and negative modes and quantitated applying the isotope internal standard method. The 20 veterinary drugs showed a good linear relationship in the range of 0.2-300 µg/L. The limits of detection and the limits of quantification were 0.1-0.6 and 0.3-1.8 µg/kg, respectively, while the correlation coefficients were greater than 0.99. The average recoveries at the three spiked levels (1, 5, and 20 times of quantitative limits) ranged between 72.5%-118%, with the relative standard deviations of 1.9%-9.8%. The advantages of method include a simple pretreatment, a high detection efficiency, and a low cost. Moreover, it is suitable for the simultaneous determination of multiple veterinary drug residues in fish and shrimp.

Determination of Enantiomeric Excess by Solid-Phase Extraction Using a Chiral Metal-Organic Framework as Sorbent.

Metal-organic frameworks (MOFs) have recently attracted considerable attention because of their fascinating structures and intriguing potential applications in diverse areas. In this study, we developed a novel method for determination of enantiomeric excess (ee) of (±)-1,1'-bi-2-naphthol by solid-phase extraction (SPE) using a chiral MOF, [Co(l-tyr)]n(l-tyrCo), as sorbent. After optimization of the experimental conditions, a good linear relationship between the ee and the absorbance of the eluate (R² = 0.9984) was obtained and the standard curve was established at the concentration of 3 mmol L-¹. The ee values of (±)-1,1'-bi-2-naphthol samples can be rapidly calculated using the standard curve after determination of the absorbance of the eluate. The method showed good accuracy, with an average error of 2.26%, and is promising for ee analysis.

[Determination of six amide herbicide residues in soil by QuEChERS-gas chromatography-mass spectrometry].

A method was developed for the determination of six amide herbicides, such as acetochlor, alachlor, metolachlor, metazachlor, butachlor and pretilachlor, by QuEChERS-gas chromatography-mass spectrometry. The soil samples were extracted by 10 mL acetonitrile, 10 mL deionized water and 4 g sodium chloride, then purified with 50 mg N-propyl ethylenediamine (PSA), 50 mg C18, 10 mg graphitized carbon black (GCB) and 100 mg MgSO4. Low-polar silica capillary column HP-5MS was used. The extracts were detected by electron impact ionization (EI) source in the selected ion monitoring (SIM) mode. The results showed that good linearities were obtained with the mass concentrations of the six amide herbicides in the range of 0.01-1.00 mg/L, and their correlation coefficients ranged from 0.9996 to 1.0000. Under the condition of adding contents of 0.025, 0.10 and 0.50 mg/kg, the average recoveries of the six amide herbicides ranged from 92.0% to 108%, and the relative standard deviations were 1.64%-8.25%. The limits of detection (LODs) were 0.002-0.006 mg/kg and the limits of quantification (LOQs) were 0.005-0.02 mg/kg. Comparing with the gas chromatography-electron capture detection (GC-ECD) which used to detect the amide herbicides, this method can improve the anti-interference ability, and get better separation of the six amide herbicides. The method has the advantages of simplicity, rapidity, and application value.

A 3D Homochiral MOF [Cd2(d-cam)3]•2Hdma•4dma for HPLC Chromatographic Enantioseparation.

Up to now, some chiral metal-organic frameworks (MOFs) have been reported for enantioseparation in liquid chromatography. Here we report a homochiral MOF, [Cd2(d-cam)3]·2Hdma·4dma, used as a new chiral stationary phase for high-performance liquid chromatographic enantioseparation. Nine racemates of alcohol, naphthol, ketone, and base compounds were used as analytes for evaluating the separation properties of the chiral MOF packed column. Moreover, some effects such as mobile phase composition, column temperature, and analytes mass for separations on this chiral column also were investigated. The relative standard deviations for the resolution values of run-to-run and column-to-column were less than 2.1% and 3.2%, respectively. The experimental results indicate that the homochiral MOF offered good recognition ability, which promotes the application of chiral MOFs use as stationary phase for enantioseparation.

[Determination of 41 pesticide residues in vegetables by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry].

A multiresidue analytical method for the rapid determination of 41 pesticide residues in vegetables was developed by using QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), including recessive pesticides, banned pesticides and pesticides with restrict use, plant growth regulators and some other pesticides with high detection rates. The vegetable sample was extracted by 1% (v/v) acetic acid-acetonitrile, cleaned-up by primary secondary amine (PSA) and injected for analysis. The positive and negative ion modes and multiple reaction monitoring (MRM) mode were used in the analysis, and the analytes were quantified by the external standard method. Under the conditions of optimized QuEChERS, chromatography and mass spectrometry, the 41 pesticides showed good linearities in the range of 1.0 µg/L to 100 µg/L, with the correlation coefficients (r2) higher than 0.999. The limits of detection of the method were 0.003 µg/kg to 1.00 µg/kg. The average recoveries of the 41 pesticides in different matrices were in the range of 74.1%-120.4% with the relative standard deviations from 2.8% to 11.9%. The method has the advantages of rapidity, simplici- ty, high sensitivity and better purification effect. It is suitable for the rapid determination of the common pesticides in vegetables, and it provides a strong guarantee for the risk assessment of the quality and safety of vegetables.

[Determination of amantadine and rimantadine residues in egg and chicken samples by dispersive solid phase extraction purification-ultra high performance liquid chromatography-tandem mass spectrometry].

A method was developed for the determination of residual amantadine and rimantadine in eggs and chickens by dispersive solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry. Egg and chicken samples were extracted with ammonia water-acetonitrile (2:98, v/v). The extraction solution was dried to 1 mL under nitrogen, and then purified by dispersive solid phase extraction method with C18 and NH2 sorbents. After purification, the extraction solution was filtered through a filter. The target compounds were analyzed by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) on a ZORBAX C18 column using a mixture of 1 mmol/L ammonium acetate solution (containing 0.1% (v/v) formic acid) and methanol as mobile phases with gradient elution. The mass spectrometer was operated under multiple reaction monitoring (MRM) mode in positive mode. The good linearities were obtained for amantadine and rimantadine at a concentration range of 0.15-10.0 µg/L. The limits of detection for amantadine and rimantadine were all 0.05 µg/kg, and the limits of quantification were 0.20 µg/kg. The recoveries of amantadine and rimantadine in eggs and chickens at three spiked levels (0.2, 1.0 and 2.0 µg/kg) age of 89%-108% with the relative standard deviations of 5.0%-8.6%. The results demonstrated that the method is suitable for the determination of amantadine and rimantadine in eggs and chickens.

Chiral recognition of a 3D chiral nanoporous metal-organic framework.

Some racemates including alcohol, ketone, flavone, phenol, base, and amide racemates etc. were successfully separated by using a 3D chiral nanoporous metal-organic framework (MOF) as a new chiral stationary phase in HPLC. The experimental results show that the chiral MOF possesses excellent recognition ability for various racemates, and indicate that enantioseparation on the chiral MOF column is practicable.