LCGC The Peak - April 2008 - (Page 25)

APRIL 2008 THE PEAK 25 earity and quantification limit (QL) are well within “acceptable criteria” for the residue analysis that the Codex set-up (20). The decision limits (CC , 5%) and detection capabilities (CC , 5%) calculated according to the EU regulation decision (2002/657/EU) (21) are shown in Table II. Specificity: The application of the proposed procedure to 18 blank samples from different species (Japanese Tiger, Black Tiger, and Shiba Prawn) demonstrated that no interference was present around the retention times for OTC, CTC, and TC in any of the samples examined. Robustness: Some HPLC chromatographic parameters were performed using a spiked (0.15 g/g of each compound) prawn sample obtained under the established procedure. Changes of 5% of the flow-rate, the HPLC column temperature and the citric acid concentration of the mobile phase had no effect on the peak areas, whereas the variations in the retention times were obtained with both the flow-rate and the column temperature. Normal retention times for OTC, TC, and CTC were 1.59, 2.24, and 3.63 min, respectively. At 5% the flow-rate, the three retention times were decreased ranging between 1.1 and 3.8% and at 5%, the times were increased, ranging between 4.4–7.1%. By changing the column temperature by 5%, the decreasing retention times obtained were 1.0–7.8%, however, no significant variations were observed with 5%. During these studies, all the target compounds were separated. Keynotes TCAs are widely used in aquaculture and antibiotics and could be present in seafood for human consumption. A fast and solvent-free method to analyse TCAs in prawn was developed. The total analysis time, including the sample preparation and chromatography stages, was less than 15 min for each sample. The use of a PDA detector means this technique can be routinely used in laboratories in developing countries where MS may not be readily available. Selectivity: The PDA detector is an easy way to confirm peaks and enable the determination of OTC, CTC, and TC by their retention times and spectra. The OTC, CTC, and TC peak spectra obtained from the sample were practically identical to those of the standards. Because of the high absorbance of OTC, CTC and TC and the satisfactory purification method, UV detection ( 200–380 nm) is possble at trace levels using PDA. It is, therefore, instructive to demonstrate purification effectiveness of the sample preparation. The present HPLC system made it unnecessary to use MS, which is very expensive, to analyze the target compounds. Cost/time performances: The time and budget required for the analysis of one sample were 15 min and roughly 1.25 for

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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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