Drug treatment adherence is one of the biggest issues in tuberculosis (TB) treatment. Including DOTS (Directly Observed Treatment, Short-course) program, many programs for TB cases have yielded marginal success and the new drug resistance varieties of TB persist. During the 1960s, researchers have projected naphthoquinone-mercuric chloride (N-M) test as the single most way to objectively track the presence of isoniazid (INH) in urine and hence treatment adherence. INH is metabolised by cytochrome P450s and usually cleared from body within 8 h. Hence, the typical INH levels in biological fluids are within 1-5 μg/ml. The N-M test practically works at 10-50 μg/ml and the authors developed the sodium polyacrylate (SPA) as a solid surface to improve detection limit of INH by 6-10 fold. The modification involves absorbing the reagents of N-M test on the SPA surface and lyophilised material is directly used for diagnosis. The dry beads can detect 1-2 μg/ml of INH in saliva. The test performed with spiked as well as clinical samples and the results have good correlation. This new test has a realistic chance of tracking the TB treatment adherence remotely and in that direction a system was projected for implementation.

Pesticide residue in fruits & vegetables is one of the key issues affecting the export of rural products in India. Pesticide exposure or intake causes major nervous system problems in children. The solutions to quantitate them in field are rare and the pesticide residue detection in the parts per billion (ppb) ranges is challenging. Except ELISA, none of the existing methods can detect pesticide residues in ppb range in the field. We employed a new approach of concentrating field samples and used sodium polyacrylate (SPA) as water absorbing material. The SPA beads concentrate the field samples and obtained a sub ppb range detection using an existing FPIA system and could improve overall sensitivity by 10-100 fold. The developed assay can be done in few seconds. We have used three pesticides 2,4-D, atrazine and methyl parathion with 0.1, 0.5 and 3 ppb detection limit respectively. We developed a simple field ready FPIA device and used sodium poly acrylate (SPA) in this biochemical FPIA to enhance sensitivity. Our tests with spiked field samples offers a possibility of using SPA concentration assisted FPIA in field. This study will have far reaching applications of both qualitative & quantitative analysis chemical analytes in field samples.