A novel salicylic acid optical fibre probe fabrication

Optical fibre salicylic acid (SA) sensor is fabricated based on immobilisation of ferric(III) nitrate on Dowex-50x8. SA forms a stable purple complex with immobilised Fe3+ at pH 2.1 with a response time of 10 min. The reflectance spectra of the sensor were measured by using an optical fibre spectrophotometer. The results showed this SA sensor has a maximum reflectance at 786 nm. The useful dynamic response range from 2.0 × 10−2 to 5.0 × 10−1 g/L. The complex is stable for more than 24 h. A good reproducibility (0.9%) of measurement was obtained with this probe.