Stormmcleod9429

A method was established for the determination of 64 pesticide residues in shellfish using accelerated solvent simultaneous extraction and purification coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS). The target compounds were extracted from shellfish using 90% (v/v) acetonitrile aqueous solution with 60% of the pool volume at 85℃ via a single cycle of accelerated solvent extraction. The extracts were synchronously purified with primary secondary amine (PSA) and graphitized carbon black (GCB) added to the extracting cell. After concentration, the target compounds were detected by GC-MS/MS in the multiple reaction monitoring (MRM) mode, and quantified by using the external standard method. Under the optimized conditions, good linearities were obtained for the 64 pesticides in the range of 10.0-1000 μg/L, with coefficients of determination greater than 0.989. The limits of quantification for the method were between 2.0 μg/kg and 10.0 μg/kg. At four spiked levels (5.0, 10.0, 100 μg/kg, and the LOQ level) in clam, the recoveries of all the pesticides were between 69.4% and 129.7%, with the relative standard deviations varying from 0.7% to 16.0% (n=6). The method is simple, repeatable and sensitive, and it is suitable for the screening of various pesticide residues in shellfish products.A rapid method for the determination of five organophosphorus flame retardants (OPFRs) in textile wastewater was established by dispersive liquid-liquid microextraction (DLLME) based on solidification of floating organic drop (SFO) coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The analytes were extracted from the water samples by SFO-DLLME, which was performed using a mixture of an extraction solvent that was less dense than water, 1-undecanol, and a dispersive solvent, methanol. The influences of the SFO-DLLME parameters on the extraction efficiencies were studied. 1-Undecanol (extraction solvent, 400 μL) and methanol (dispersive solvent, 300 μL) were added to textile wastewater (containing 2 g NaCl) with pH between 6 and 9, and the solution was shaken for 2 min. Under optimum conditions, the linear ranges of the proposed method were from 2 μg/L to 100 μg/L with correlation coefficients (R2) above 0.99 for all the analytes. The limits of detection (S/N=3) ranged from 2 μg/L to 5 μg/L. The precision of the method was evaluated in terms of repeatability; the relative standard deviations varied from 2.7% to 11.2% (n=6). The relative recoveries ranged from 71.6% to 117.6% for all analytes. Only 3 of the 11 selected samples were tested positive for OPFRs, and the total concentrations of OPFRs in them were in the range of 2.6-3.4 μg/L. Hence, this method is accurate, environmentally friendly, fast, and convenient for the routine analysis of OPFRs in textile wastewater.A method based on dispersive solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry (DSPE-HPLC-MS/MS) was developed for the simultaneous determination of five analytes scutellarein, 4'-hydroxywogonin, norwogonin, baicalein, and wogonin in healthy product tablets. The samples were extracted with 10 mL acetone and purified on 75 mg C18. JAK inhibitor The types and dosages of the extracted solvents and adsorbents were optimized. The results showed that these five analytes exhibited good linear relationships in their respective linear ranges. The correlation coefficients (r) were more than 0.99. The detection limits and quantitative limits were 0.5-40 μg/kg and 2.0-120 μg/kg, respectively. Recovery tests were carried out using three kinds of health product tablet matrices. The concentrations were one, five, and ten times the quantitative limit. The average recovery of these five targets was 83.1% to 106.5%, with relative standard deviations (RSDs) ranging from 0.97% to 4.52%. This method is easy to operate, and it shows high sensitivity and good reproducibility. Thus, it is suitable for the simultaneous determination of the target compounds in health tablets.An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established for the quantitative detection of bovine lactoferrin in dairy products. The samples were treated by degreasing and tryptic hydrolysis. Proteins of bovine lactoferrin and peptides were identified using ultra performance liquid chromatography-quadrupole/electrostatic orbitrap-high resolution mass spectrometry (UPLC-Q/Exactive-HRMS) and analyzed by Protein Pilot software. Eight species-specific marker peptides of bovine lactoferrin were identified by comparison of the basic local alignment search tool (BLAST) with the Uniprot database. Three markers with high response strength and stability were chosen for further quantitative research by UPLC-triple quadrupole mass spectrometry (QqQ-MS). The method showed a good linear relationship within its own range. The limits of detection and limits of quantification were 0.023-0.041 and 0.077-0.137 mg/kg, respectively. The observed recoveries were in the range of 93.8%-103.9%. The intra-day and inter-day RSDs were lower than 8.8% and 9.5%, respectively. This method presents various advantages such as strong anti-interference, high sensitivity and reproducibility, and it is suitable for the quantitative analysis of bovine lactoferrin in dairy products.An analytical method was established for the determination of 15 lipid regulators in fish meat by QuEChERS combined with ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry (UPLC-Q/Orbitrap-MS). The samples were purified by optimized QuEChERS methods. The amounts of the adsorbent materials (primary secondary amine (PSA) (20, 60, 100, 140 and 180 mg), C18 (40, 100, 160, 220 and 280 mg) and sodium acetate (0.2, 0.6, 1.0, 1.4 and 1.8 g)) were optimized by the response surface method to obtain the best purification effect. The target compounds were separated on an XBridge-C18 column (100 mm×2.1 mm, 3.5 μm) using acetonitrile-0.1% (v/v) formic acid aqueous solution (containing 1.5 mmol/L ammonium acetate) as the mobile phases by a gradient elution program. Qualitative and quantitative analysis of the target compounds were performed in the full scan and secondary mass spectrometry scan (dd-MS2) modes with positive and negative ionization. The target compounds showed good linear relationships in their respective ranges, with correlation coefficients (R2) greater than 0.