Description:The present invention provides on a spot detection system by using an optical capsule containing prepared aggregated silver nanoparticles solution which makes it economically efficient, low cost, and rapid to use. The method is based on the principle of anti-aggregation of silver nanoparticles under the presence of fluoride ions in the wastewater which showed color changes from red to yellow in the optical capsule which can be observed with the naked eye. , Claims:WE CLAIMS:
1. An optical capsule-based system comprised of aggregated nanoparticles (silver, gold, titanium, copper and any other) which show on the spot colorimetric change on addition of target group of analytes (fluoride, arsenic, nitrate etc.)within 2-3 minutes.
2. The system work on change in SPR spectra of selected nanoparticles (aggregated form) on addition of target analyte and convert the aggregated nanoparticle into nanoparticles result in change of color of the solution.
3. Prepare optical capsule is highly selective, sensitive and user friendly for target analyte.
4. The method for the preparation of optical capsule for detecting target analyte comprising the following steps of:
a) Pyrocatechol (0.01M) and Sulphanilic acid (0.01) were mixed(1:1) at room temperature with continuous stirring for 15 minutes.
b) AgNO3 (0.01M) was added dropwise with continuous stirring and mixing.
c) The resulting solution was kept in dark for 24 hours. The solution turns into red indicating the end of the reaction.
d) The red color confirmed the aggregation of nanoparticles(silver, gold, titanium, copper and any other) after 24 hours and was used for colorimetric detection of target analyte (fluoride, arsenic, nitrate etc.).
e) The synthesized solution was closely packed into an optical capsule having a capacity of 2 ml and stored for months at freezing temperature before use.
5. A transparent capsule (PVC, Plastic etc.) of 2 ml was filled with aggregated nanoparticleas prepared in claim no.4 and store at 4 degree Celsius till further use.
6. Detection method involved addition of 50 microliter of sample into the above (as per claim 5.) prepared capsule. The change in color from red to yellow indicates the presence of target analyte.
7. The method give both qualitative as well as a quantitative test for the target analyte.