Analysis of pesticide residues in commercially available chenpi using a modified QuEChERS method and GC-MS/MS determination

To ensure the safety of the commercially available chenpi,a convenient and fast analytical method was developed for the determination of 133 pesticide residues in chenpi using gas chromatography-tandem mass spectrometry(GC-MS/MS).In this study,different extraction solvents,redissolution solvents and adsorbents were tested according to the recovery and purification effect to obtain a modified QuEChERS method.The samples were extracted with acetonitrile.During the clean-up step,octadecyl-modified silica(C18)and graphitized carbon black(GCB)were selected,and aminopropyl(NH2)was used instead of primary secondary amine(PSA)because of its weaker ion exchange capacity which had little effect on the recovery of ditalimfos.Samples were quantified by matrix-matched calibration with internal standards.All pesticides showed good linearity in the respective range,both with values of r2>0.99.The average recoveries of the pesticides spiked samples ranged from 70.0% to 112.2% with the RSDs of 0.2%–14.4%.The modified QuEChERS method was validated and applied to twenty real samples.Five pesticides were found in eight batches,but no pesticide exceeded the maximum residue limits(MRL,MRL reference to European commission).

A New Temperature Channel Selection Method Based on Singular Spectrum Analysis for Retrieving Atmospheric Temperature Profiles from FY-4A/GIIRS

Hyperspectral data have important research and application value in the fields of meteorology and remote sensing.With the goal of improving retrievals of atmospheric temperature profiles,this paper outlines a novel temperature channel selection method based on singular spectrum analysis(SSA)for the Geostationary Interferometric Infrared Sounder(GIIRS),which is the first infrared sounder operating in geostationary orbit.The method possesses not only the simplicity and rapidity of the principal component analysis method,but also the interpretability of the conventional channel selection method.The novel SSA method is used to decompose the GIIRS observed infrared brightness temperature spectrum(700-1130 cm-1),and the reconstructed grouped components can be obtained to reflect the energy variations in the temperature-sensitive waveband of the respective sequence.At 700-780 cm-1,the channels selected using our method perform better than IASI(Infrared Atmospheric Sounding Interferometer)and Cr IS(Cross-track Infrared Sounder)temperature channels when used as inputs to the neural network retrieval model.

Development and Quality Analysis of Protein Enriched Instant Soup Mix

The aim of the study was to develop protein enriched instant fish soup mix and analysis of the quality of various conditions. The study used a mechanical dryer for maintaining a constant air flow and temperature at its drying and dehydration stage. Powder was made after drying. An appropriate composition was used as an indicator. Various compositions like 75%, 65%, 55% and 45% fish powder were used as formulation 0, formulation 1, formulation 2, and formulation 3 respectively. Then these were reconstituted by boiled water for soup mix preparation. The result indicated that mixer 2 was the best composition. The finding suggested that 55% fish powder mix is the best composition for protein enriched instant soup mix. It will help to produce the instant soup mix and an alternative source of various costly animal and plant protein as a value-added material.

A validated reversed phase HPLC method for determination of process-related impurities in DHDK-loaded mPEG-PLA micelles

A new compound named DHDK was isolated from Viscum coloratum and identified as (1E,4E)-1,7-bis(4-hydroxyphenyl)hepta -1,4-dien-3-one. DHDK, a new potential anti-tumor drug, was synthesized and prepared poly(ethylene glycol)-poly(D.L-lactic acid)(mPEG-PLA) micelles due to cytotoxic effects on a range of cancer cells. A revered phase liquid chromatographyic method has been developed and validated for the determination of potential related impurities in DHDK-loaded mPEG-PLA micelles. The micelles was subjected to the stress conditions of acid, base, oxidation, thermal and photolysis. The determination was achieved on Phenomenex SynergiTM 4 μm Fusion-RP 80?(250 mm × 4.6 mm, 4 μm) with a gradient elution and the detection wavelength was set at 220 nm. Regression analysis shows as r value (correlation coefficient) of greater than 0.999 for DHDK and six potential impurities. Recoveries of impurities were found between 90.0% and 108.0%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness, which can be used for determination of related impurities in DHDK-loaded mPEG-PLA micelles.

Non-enzymatic browning path analysis of ready-to-eat crayfish(Promcambarus clarkii)tails during thermal treatment and storage

This study was carried out to reveal the browning path of ready-to-eat(RTE)crayfish tails during thermal treatment and storage using path analysis.Maillard reactions,lipid oxidation,and phenol oxidation were evaluated in combination with free radical content and FTIR analysis,and direct path coefficients as well as determination coefficients were obtained based on these parameters,such as the absorbance at 294 nm(A294),5-hydroxymethylfurfural(5-HMF),thiobarbituric acid-reactive substances(TBARS),and total phenols(TP).The result showed that the browning of seasoned RTE crayfish tails was ascribe to the synergistic effect of Maillard reaction and lipid oxidation by the order of determination coefficient.After the crayfish hepatopancreas were removed,the content of A294,5-HMF,TBARS,and TP declined more than 30%,specifically affecting the direct pathway from lipid oxidation to Maillard reaction and alleviating the browning.However,no significant change of color was observed in the group without thirteen-spices,while TBARS and free radical content increased by at least 16.7%.The removal of hepatopancreas and the control of Maillard reaction were deemed to be a good measure for inhibiting the non-enzymatic browning of RTE crayfish tails.

The impact of pH and acid-activated proteases on the decrease of immunological properties of parvalbumin from freshwater fish

Fermentation has been found as an effective method to decrease the hypersensitive reactions of consumers by freshwater fish,but the reason is not clear.Therefore,the aim of this study was to investigate the impact of pH and acid-activated proteases on the decrease of immunological properties of parvalbumin from freshwater fish,by the indicators of SDS-polyacrylamide gel electrophoresis,western blotting,enzyme-linked immunosorbent assay,surface hydrophobicity and circular dichroism.The results showed that black carp(Mylopharyngodon piceus)had the highest level of immunological properties reflected by quantitation,the content of linear epitopes and conformational epitopes of parvalbumin,and IgE-binding rate.Afterwards,purified parvalbumin from black carp was obtained with purity higher than 95%.Then,for acidification and enzyme models,it indicated that acid-activated proteases were the reason for the decrease of immunological properties.Ulteriorly,the mechanism on the level of protein structure was provided,which showed the decrease ofα-helix and the increase ofβ-turn and random coil,as well as the decrease of surface hydrophobicity had joint contribution for the breaking of conformational epitopes.This study could provide a novel guidance for the decrease of immunological properties of fish and promote fish processing industry further.