45I-21 |
Quantification of water-soluble B-vitamins using an SPR optical biosensor |
A. A. O'Kane, T. MCGRATH, J. Ferguson, S. A. Haughey, and A. Baxter. Xenosense Ltd., QUBIS, Lanyon North, Queen's University, Belfast, BT7 1NN, United Kingdom Vitamin levels in food products are monitored during quality control as part of the legislative provision concerning fortification, and to reduce wastage. The most widely used method for the determination of water-soluble vitamins is microbiological analysis based on the growth rate of vitamin dependent bacteria. This method is time consuming and often unreliable. HPLC methods are hampered by the difficulty of removing interfering compounds from the food matrix. This has led to the objective of developing methods using an optical biosensor which exploits the phenomenon of surface plasmon resonance to detect and measure biomolecular interactions at an interface on a sensor chip. The sensor monitors changes in the resonance angle which shifts when biomolecules bind to the chip surface and alter the refractive index of the surface layer. The biosensor methods are inhibition assays and detect vitamin binding proteins when they bind to the vitamin immobilised onto a sensor chip surface. The competition for binding with free vitamin molecules in the sample is measured as a change in response by the sensor. Methods have been validated for folic acid, biotin and vitamin B12, with a detection limit of 1ng/ml, 0.5ng/ml and 0.06ng/ml respectively. An example of reproducibility results between laboratories give a standard deviation of 9.1% for biotin and 8.1% for folate. Up to 40 samples can be analysed in under 12 hours in a single run. These methods are reliable and accurate in a variety of matrices including milk and soy-based infant formula, breakfast cereals and drinks. Ongoing work also includes expansion of the assay format to other vitamins including pantothenic acid and riboflavin.
Session 45I, Nutrition: General
|