LCGC The Peak - April 2008 - (Page 24)

24 THE PEAK APRIL 2008 Table II: Method validation data Spiked level (µg/g) OTC 0.05 0.1 0.15 92.3 (2.1) 89.2 (1.8) 88.8 (1.7) 0.9998 0.031 0.1025 0.1061 Recoverya CTC 84.9 (2.3) 83.5 (2.1) 83.8 (2.0) 0.9997 0.044 0.1034 0.1073 TC 93.4 (3.1) 91.0 (2.6) 90.4 (2.8) 0.9998 0.024 0.1043 0.1094 rb QLc CC d CC e a Data are expressed as averages (%, n 5 6). Values in parentheses are RSDs (n 5 6). b Mean of three determinations using spiked prawn samples for calibration curves; range of concentration was 0.1 – 1.0 µg/mL; r is the correlation coefficient. c Quantification limit (µg/g). d Decision limit (µg/g) and edetection capability (µg/g) by the EU regulation 2002/657/EC. fering peaks, their symmetrical natures and their short retention times was obtained using Column A and an isocratic mobile phase of 0.1 mol/L citric acid with a flow-rate of 1.0 mL/min and a column temperature of 45 °C. The HPLC analysis accomplished optimum separation within 4 min and also enabled the multiple sequential injections, without the risks of interfering late-eluting peaks. Under the low-pH environment of the mobile phase and raised column temperature, the short length (35 mm) and carbon contents 4% in the column were necessary to obtain the findings. Columns B, C, and D provided significantly rounded peaks of all the target compounds throughout the examined condition ranges. Column C had difficulty separating OTC, TC and CTC, and the interferences of the resulting sample extract. The target compounds were not eluted from columns E and F. There was no interference from prawn extract with the elution of OTC, CTC and TC, respectively (Figure 1). In the present HPLC system, separation and quantification were achieved in a mere 5 min for each run without requiring precolumn washing after the analysis. Method Validation Table II summarizes the main validation parameters. The accuracy, precision, lin-

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LCGC The Peak - April 2008 Contents LC3LC: Comprehensive Two-Dimensional Liquid Chromatography Split Injections in Gas Chromatography: How to Reduce Inlet Discrimination A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns Industry News Events Education

LCGC The Peak - April 2008

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