Objective To establish a detection method for 12 kinds of nicotine pesticides in fruits by ultra performance liquid chromatography-tandem mass spectrometry coupled with cold induced liquid-liquid extraction. Methods Fruit samples were extracted using acetonitrile, and after salting out, shaking, and centrifugation, they were subjected to freeze induced liquid-liquid extraction using acetonitrile water solution for further enrichment and purification. Combined with ultra performance liquid chromatography mass spectrometry, data was collected using a multi reaction monitoring mode, and quantified using isotope internal standard method. Results The linear range of 12 kinds of nicotine compounds was 1-500 ng/mL, and the method showed good linearity (r²>0.999). The limits of detection were 2.15-3.60 μg/kg, and the method limits of quantification were 7.11-13.01 μg/kg. The recovery rates of 12 kinds of nicotine compounds were 73.1%-126.7%, and the relative standard deviations were 3.5%-13.3%. Conclusion This method is easy to operate, has high precision, and good stability, and is suitable for screening and detecting nicotine like compounds in fruit samples.

Objective To explore the effect of stir-frying and ultramicro grinding on the quality of Crataegus pinnatifida kernel. Methods The Crataegus pinnatifida kernels produced and processed by the enterprise were used as the test materials, and the Crataegus pinnatifida kernels were treated by ordinary grinding, frying-ordinary grinding and frying-ultrafine grinding combined treatment technology, and the physical properties of surface color, surface structure, water-holding capacity, oil-holding capacity, and the changes of oxidation resistance and flavonoid release were determined. Results The Crataegus pinnatifida kernel powder treated by frying and ultrafine grinding had an increased binding capacity to water, a solubility of 35.63%, an expansion force of 3.71 mL/g, and an oil-holding capacity of 2.61 g/g. The angle of repose and slip angle were reduced to 37.12° and 43.63°, respectively. The flavonoid release rate of Crataegus pinnatifida kernel powder increased from 60.47% to 71.48%, and the oxidant resistance increased by nearly 20%, which was manifested by a increase in the scavenging rates of 2,2-diazine-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) cationic radical, 1,1-diphenyl-2- picrylhydrazyl (DPPH) radicals and hydroxyl radicals. Conclusion Therefore, the combined treatment technology of frying and ultrafine grinding is a feasible processing method for Crataegus pinnatifida kernel powder. This technology can effectively improve the physicochemical properties of Crataegus pinnatifida kernel powder and increase the total flavonoid release rate. The results of this study are helpful to enhance the market value of Crataegus pinnatifida nuclear powder and promote the sustainable development of Crataegus pinnatifida industry.

Objective To establish the detection of 172 kinds of pesticide residues in brown sugar by QuEChERS-gas chromatography-tandem mass spectrometry (GC-MS/MS). Methods The samples were fully dissolved in ultrapure water and extracted by high-speed homogenization of n-hexane, nitrogen blowing and concentration, and purified by QuEChERS method, and the data was collected in selective reaction monitoring mode by GC-MS/MS detection technology, and quantitatively detected by matrix curve and solvent curve. Results The 172 kinds of pesticides had a good linear relationship in the linear range of 10-200 ng/mL, and the linear correlation coefficient was between 0.9962 and 0.9999, the limit of quantification of the method was 0.01 mg/kg, performed 6 repeated spiked experiments at concentrations 1, 2, and 10 times the limit of quantification each, the recovery rate of spikes was between 71.0%-113.0%, and the relative standard deviation (n=6) was 0.49%-17.00%. Conclusion This method can detect hundreds of pesticides in one injection, which is fast, simple, high-throughput and economical, and is suitable for the detection of a variety of pesticide residues in brown sugar.

Objective To investigate the effects of 1-methylcyclopropene (1-MCP) and ZSM-5 nano molecular sieve blended polyethylene (PE) film on the quality and oxidative stress of Prunus persica during cold storage. Methods The 4 kinds of treatments were set up: PE packaging (P), PE packaging combined with 1-MCP (PM), PE film blended with ZSM-5 Nano molecular sieve blended polyethylene film (PN), and the combination of ZSM-5 and 1-MCP (PMN). Samples were stored at 0-2 °C for 35 days with sampling every 7 days. Texture, chromatic indexes, soluble solids content, titratable acidity, electrical conductivity, and the activities or content of polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured. Results 1-MCP and the nano molecular sieve blended polyethylene film effectively inhibited fruit softening, color change and fibrosis. On day 21, the fruit hardness in the PM and PMN groups was significantly higher than in other groups (P<0.01), while the cohesiveness of the PMN group was significantly lower than the P group on day 27 (P<0.01). Color analysis showed that the redness and yellowness changes in other treated groups were significantly reduced compared to the P group (P<0.05). Although the PMN group's fruit appeared more yellow by day 35, the over-ripening process was suppressed. In terms of physicochemical indicators, the PM and PMN groups exhibited significantly lower electrical conductivity ratio and titratable acidity lose than the P group (P<0.01), indicating that 1-MCP and the nano molecular sieve blended polyethylene film effectively slowed down the increase in cell membrane permeability and the decrease in flavor and nutrients. Physiological measurements showed that by day 35, the MDA level in the PMN group was significantly lower than in the P group (P<0.01), with delayed peak POD and PPO activities. The PMN group's PPO activity was significantly lower than the P group (P<0.01). Conclusion The combination of 1-MCP and ZSM-5 nano molecular sieve blended polyethylene film significantly alleviates color change, over-ripening, and oxidative stress in Prunus persica during cold storage, demonstrating promising application potential.

Objective To establish a rapid detection method for the simultaneous determination of 24 kinds of veterinary drug residues in pork by QuEChERS technique combined with ultra performance liquid chromatography-tandem triple quadrupole mass spectrometry (UPLC-MS/MS). Methods The samples were extracted with acidified acetonitrile, salted out by 3 g magnesium sulfate anhydrous and 2 g C₁₈ E, separated by Thermo-Fisher Hypersil GOLD aQ chromatographic column (50 mm×2.1 mm, 1.9 μm) via gradient elution of acetonitrile and 0.1% formic acid aqueous solution. The gradient elution of acetonitrile and 0.1% formic acid in aqueous solution was performed in the mode of electrospray positive ion scanning. Results The linear relationship of 24 kinds of veterinary drugs was good, and the correlation coefficients were greater than 0.9910, and the detection limit ranged from 0.2-10.0 μg/kg. The spiked recoveries varied between 70.2%-110.3%, and the relative standard deviations were 1.2%-13.8%. Conclusion The method is simple, rapid, accurate, practical, and suitable for detection of multiple veterinary drug residues in pork.

Objective To establish a rapid colloidal gold card method for the determination of fumonisin and T-2/HT-2 toxin in Triticum aestivum L. and Zea mays. Methods The limit of detection, limit of quantitative, precision and accuracy of the method were evaluated in 6 laboratories. Results The limits of detection of fumonisin and T-2/HT-2 toxin methods were 150 μg/kg and 5 μg/kg, respectively. The limits of quantitation were 450 μg/kg and 11 μg/kg, respectively. When the fumonin content in Triticum aestivum L. and corn ranged from 426.39 to 3897.22 μg/kg, the relationship between the method repeatability standard deviation S_r and reproducibility standard deviation S_R and fumonin content was obtained, namely, repeatability standard deviation S_r=1.478m^0.600 and reproducibility standard deviation S_R=4.269m^0.591. When the T-2/HT-2 toxin content in Triticum aestivum L. and Zea mays ranged from 426.39 to 3897.22 μg/kg, the relation between repeatability standard deviation S_r and reproducibility standard deviation S_R and T-2/HT-2 toxin content m was as follows: Repeatability standard deviation S_r=3.1901m^0.218, reproducibility standard deviation S_R=0.2507m^0.492 (Triticum aestivum L. matrix). Repeatability standard deviation S_r=0.8357m^0.333, reproducibility standard deviation S_R=1.1231m^0.585 (Zea mays matrix). The recoveries of fumonisin and T-2/HT-2 toxin ranged from 95.42% to 101.90% and 83.30% to 118.20% respectively. There was no significant difference between the paired t test and the standard method. Conclusion The method has good accuracy and can be widely used for rapid and quantitative determination of fumonisin and T-2/HT-2 toxin in Triticum aestivum L. and Zea mays.

Objective To analyze Cyperus esculentus by near infrared spectroscopy, and trace geographical origin of Cyperus esculentus by the identification model in chemometrics. Methods A total of 408 samples of Cyperus esculentus samples from Hebei, Hunan, Shandong, Xinjiang, and Yunnan were analyzed for provenance tracing using near-infrared spectroscopy and chemometric software, 3 kinds of spectral preprocessing methods including multiplicative scatter correction, standard normal variate transformation and standard normal variate transformation & detrending, were used respectively, and 5 kinds of recognition modes such as support vector machine (SVM), soft independent modeling of class analogy (SIMCA), orthogonal partial least squares discriminant analysis (OPLS-DA), partial least squares discriminant analysis (PLS-DA), and K-nearest neighbor algorithm (KNN) were used to identify the geographical origin. Results The modeling recognition rates of the 5 kinds of modes including SVM, SIMCA, OPLS-DA, PLS-DA, and KNN were 91.89%, 94.47%, 62.37%, 65.32%, and 100.00% respectively. The KNN was selected as the origin identification model, and the impact of different preprocessing methods, data preprocessing and sample distance on the stability of the model prediction results were analyzed in order to select the optimal model parameters. The prediction set recognition rate could reach 100.00% by using multiplicative scatter correction spectral preprocessing method, one of data preprocessing methods including UV, Pareto, automatic, or centering, and block distance as the sample distance. Conclusion The technology of near infrared spectroscopy combined with KNN mode has the advantages of fast analysis speed, simple operation, easy sample pretreatment, non-destructive, on-line qualitative and quantitative analysis, etc., and has a certain application prospect.

Objective To detect and analyze the content of As, Cd, Cr, Cu, Ni and Pb in different dried Lycium barbarum L. from Nuomuhong Farm, Chaidamu, and evaluate the health risk of heavy metals in Lycium barbarum L. via the dietary route to humans. Methods The content of 6 kinds of heavy metals in Lycium barbarum L. was determined by inductively coupled plasma emission spectrometer. The pollution degree of Lycium barbarum L. heavy metals was evaluated by single factor index, mean pollution index, pollution factor analysis and Nemero's composite pollution index. The target risk factor method was used to evaluate the health risk of single and complex heavy metal intake of Lycium barbarum L. Results The single pollution index of 6 kinds of heavy metals in Lycium barbarum L. in this area was less than 1, and the comprehensive pollution index was less than 0.7, and the mean pollution index of the lock-in freshness group was less than 0.1, which was uncontaminated, and the mean pollution index of the sun-dried, hot air dried, and hang-dried groups was less than 0.2, which was a slightly contaminated state, and among them, Cu, and Cd were the main contaminating factors. Through correlation and principal component analysis, the sources of heavy metal pollution in the drying process of Lycium barbarum L. were characterized by diversified and multiple pathways, and the heavy metal content of Lycium barbarum L. that had undergone lock-in freshness treatment and hang-dried treatment had a higher safety coefficient; the single or compound heavy metals ingested by the human body through the consumption of Lycium barbarum L. did not pose a health risk to either children or adults. Conclusion The pollution degree of heavy metal of Lycium barbarum L. in this region is low, and the content is in accordance with the limited requirement of Chinese Pharmacopoeia 2020, and there is a certain effect of different drying on the heavy metal content of Lycium barbarum L., and this test can provide a reference basis for the prevention and control of heavy metal pollution of Lycium barbarum L. in the drying system.

Objective To establish a method for the determination of nitrite content in pickles by nitroso derivative ultra performance liquid chromatography. Methods A novel and sensitive method for the determination of nitrite content was developed. This is a nitroso derivative produced based on the interaction between nitrite and antipyrine This derivative has strong absorption in 0.02 mol/L acetate buffer solution (contains 0.1% acetic acid) at a wavelength of 345 nm the nitrite content was determined by ultra performance liquid chromatography. Results Nitrite in the linear concentration range of 0.05-5.00 mg/L was determined with a limit of detection 0.01 µg/mL. The high, medium and low concentrations were spiked. The extraction recoveries ranged from 88%-96% (n=6). The relative standard deviation was the precision ranged from 2.0%-4.5%. Conclusion The method can effectively eliminate the interference of chloride ions and other anions and pigments on this experiment. The established analytical method has good sensitivity, accuracy, precision and recovery rate, and is suitable for the detection of nitrite in pickles.

Objective To develop a method for the simultaneous determination of lutein, zeaxanthin, α-carotene, and β-carotene in infant formula milk powder and natural foods by online solid phase extraction-liquid chromatography (online SPE-LC). Methods Samples were saponified with 50% potassium hydroxide solution at 70 ℃ for 15 min. Saponified solution was diluted with 70% ethanol, and after high-speed centrifugation, the supernatant was directly analyzed. A styrene-divinylbenzene copolymer-based SelectCore PSS-packed chromatographic column was chosen as the online SPE column, using 80% methanol-water as the initial loading solvent and acetonitrile/methyl tert-butyl ether as the washing solvent. A ChromCore C₃₀ column (4.6 mm×250 mm, 3 μm) was used as the analytical column, with acetonitrile-methanol (26:74, V:V, 0.4 g/L of ascorbic acid) and methyl tert-butyl ether as the mobile phase for gradient elution. The flow rate was 1.0 mL/min, and the detection wavelength was 450 nm. Results The 4 target analytes in infant formula milk powder and natural foods were well separated. Linear correlation coefficients for all target analytes were greater than 0.9999. The limit of quantification of method for lutein, zeaxanthin, α-carotene, and β-carotene were 0.77, 0.72, 0.94, and 1.40 μg/100 g, respectively. Average recovery rates of infant formula milk powder were 99.76%, 103.51%, 99.16%, and 97.92%, respectively. The relative standard deviations of method repeatability for all the analytes were less than 2.5%. Conclusion This method is accurate, reliable, and reproducible and can meet the quantitative requirements of lutein, zeaxanthin, and α-carotene, β-carotene in foodstuffs. It can be applied to the determination of real samples.