1. SensorLab, Department of Chemistry; University of Western Cape; Private Bag X17 Bellville 7535 South Africa
2. Department of Chemical Science and Technology; Technical University of Kenya; P.O Box 52428 - 00200 Nairobi Kenya.
3. Department of Biological and Chemical Sciences; University of the West Indies; Cave Hill Campus, P.O. Box 64 Bridgetown BB11000 Barbados.