26 Apr 2010
DEVELOPING DETECTION METHODS FOR ANTIBIOTICS
During the second year of the research the focus within WP2b (antibiotics) has been on the development and evaluation of immunoreagents and the construction of dipstick based screening tests for the rapid screening of antibiotics in foods including the optimised Tetrasensor®, Sulfasensor®, combined malachite green and leucomalachite green sensor and the multi-sensor for honey by partner Unisensor (Liege, Belgium). An alternative format electrochemical immunosensor (ECIMS) for sulfonamide analysis has also been developed at Applied Molecular Receptors group, CSIC, (Barcelona, Spain) and evaluated as a rapid laboratory based screening test.The optimised Tetrasensor® dipstick assay for class specific detection of the tetracycline family in a range of commodities including animal feeds, urine and cooked/ processed meats. The performance of the new Tetrasensor assay has been evaluated and found to have an enhanced detection capability of ≤20 μg kg^-1 in all commodities. The Sulfasensor® employs an antibody capable of detecting 10 key sulfonamide drugs at or below the target detection level of 25 μg kg^-1 in honey. The protocol includes a rapid acid hydrolysis step to effectively liberate the bound sulfonamide residues from the sugar component. Both the Sulfasensor® and the ECIMS have been found to compare well to conventional chemical analysis (LC-MS/MS) using a range of incurred honey materials.A prototype MG/LMG dipstick has been constructed incorporating a specific antibody as the biological recognition element. Preliminary findings indicate that the dipstick in combination with a solid phase extraction based concentration step is capable of detecting residue levels around the EU Minimum Required Performance Limit (MRPL) of 2 μg kg^-1 in fish (Figure 1). This is the first reported dipstick applicable the for the screening of MG/LMG at trace levels in fish. Insert figure 1 about here.The multi-sensor assay for the simultaneous screening of generic sulfonamides, fluoroquinolones, tylosin and chloramphenicol is currently under development at Unisensor. These analytes are found to be among the most commonly detected and problematic in retail honey samples. The preliminary results from the prototype dipstick in buffer show the assay is capable of the simultaneous detection of the four target classes/ analytes (Figure 2). 
Insert figure 2 about here.
Information supplied by Sara Stead, Fera, UK, WP2c Leader and Benoit Granier, Unisensor, Be, WP2c Deputy
Source : CONffIDENCE