Ultrasound-assisted Matrix Solid Phase Dispersion for the HPLC-DAD analysis of amphenicols in shrimps

Ultrasound-assisted matrix solid phase dispersive extraction was applied for the selective isolation and clean-up of three amphenicol antibiotics, chloramphenicol (CAP), thiamphenicol (TAP) and florfenicol (FFC) from shrimp. The target antibiotics were separated on a LiChroCART-LiChrospher® 100 RP-18 (5 μm, 250 × 4 mm) analytical column in less than 9 min, with isocratic elution using a mixture of 70% ammonium acetate (0.05 M) and 30% acetonitrile (v/v). Matrix Solid Phase Dispersion protocol was optimized in terms of extraction sorbent and elution solvent. Two polymer based (Oasis and Nexus) sorbents and one silica based (Lichrolut C18) were compared and different elution solvents such as methanol, acetone, acetonitrile and isopropanol were evaluated based on the achieved recovery rates as well as on the cleanup efficiency. The extraction procedure was performed with and without sonication to evaluate the impact of ultrasounds. TAP and FFC were monitored at 234 nm and CAP at 280 nm by a photodiode array detector. The method was validated according to the European Union Decision 2002/657/EC in terms of linearity, selectivity, stability, accuracy, precision and sensitivity. Detection capability values (CCb) were 64.6 μg/kg for TAP and 1046.8 μg/kg for FFC and 63.8 μg/ kg for CAP.

High-Throughput Analytical Techniques for Multiresidue, Multiclass Determination of 653 Pesticides and Chemical Pollutants in Tea—Part III: Evaluation of the Cleanup Efficiency of an SPE Cartridge Newly Developed for Multiresidues in Tea

A comparative study was conducted over three stages on the cleanup efficiency of SPE cartridge Cleanert TPT, newly developed for multigroups of pesticide residues in tea. In Stage I, different SPE cartridges C18, graphite carbon black (GCB), primary secondary amine (PSA), and amino (NH2) were purchased and combined into 12 different sequences. Through the comparative test on cleanup efficiency of 84 representative pesticides in tea, Envi-Carb GCB + PSA with a good cleanup effect was selected. In Stage II, GC/MS test results from the comparative study of the extraction efficiency of 201 pesticides spiked into green tea and Woolong tea with Cleanert TPT and Envi-Carb + PSA SPE showed that average recoveries fell within 70–110% and RSD <20% for 193 and 184 pesticides, respectively, for green tea, accounting for 96.0 and 91.0% of the total number, respectively. GC/MS/MS test results also found 193 and 184 pesticides, respectively, meeting the recovery and RSD conditions, accounting for 96.0 and 91.5%, respectively, of the total number. For Woolong tea samples, GC/MS results showed that with Cleanert TPT and Envi-Carb + PSA SPE for cleanup, there were 192 and 177 pesticides, respectively, meeting the conditions, accounting for 95.5 and 88.1% of the total number, respectively. GC/MS/MS results demonstrated that there were 195 and 184 pesticides, respectively, meeting the conditions, accounting for 97.0 and 91.5% of the total number, respectively. It was seen that Cleanert TPT was superior to Envi-Carb + PSA in cleanup efficiency, whether for green or Woolong tea samples, or GC/MS or GC/MS/MS determination. In Stage III, 61 104 results of the average content value of pesticides and RSD (two teas × two Youden pair concentrations × two kinds of SPE cartridges × two instruments × 19 tests × 201 pesticides) were derived from the 19 times stability tests over 3 months by paralleling three samples every 5 days via two instruments with two kinds of SPE cartridges for cleanup, respectively, against Youden Pair samples of the 201 incurred pesticides from green and Woolong teas. The statistical analysis found that detected values from the target pesticides of the incurred Youden pair samples showed no marked differences with cleanup by either Cleanert TPT or Envi-Carb + PSA, whether for green or Woolong tea, or GC/MS or GC/MS/MS. The test results using the two aforementioned kinds of SPE cleanup for above 93% pesticides had a tolerance less than 15%, which testifies that both cartridge cleanups met the requirement for pesticide residue analysis.