Santhakumar Dhanya, Talasila Prasada Rao
The present invention relates to test strips that are photo and thermally stable, optically transparent and offer virtually specific absorptiometric sensing of nitrite in natural waters. The process of which is as follows: 1) The entrapment of xanthene dye specifically rhodamine 6G in sol-gel glass. This entrapment is done by delicate balance of coulombic interactions, hydrogen bonding and molecular imprinting effect. 2) In particular, rhodamine 6G entrapped sol-gel layers are formed by first preparing a sol by sonicating a mixture of tetraethoxsilane, water and ethanol for 30 minutes and hydrolysed to form gel by drop wise addition of hydrochloric acid. 3) This gel is further sonicated for 30 minutes after addition of dye and then aged for 15-20 h to obtain dye entrapped sol-gel glass and 4) This is then manually cast as sol-gel films on glass substrates to obtain test strips.