Optical oxalate detector based on chemical modification of a polymer film

A new, low-cost oxalate detector was developed by immobilizing a direct indicator dye in an optical sensing film for food and environmental monitoring. This detector was fabricated by binding brilliant cresyl blue (BCB) to a cellulose acetate film that had previously been subjected to an exhaustive base hydrolysis. The membrane has good durability (>4 months) and a short response time (<9 s). Oxalate can be determined for the range 0.08-3.50 μg ml−1 with 36 detection limits of 7 ng ml−1. The method is easy to perform and uses acetylcellulose as a carrier. The reagents used for activating the cellulose support are inexpensive, non-toxic and widely available.