Fiber Optic Sensor Research To Detect Heavy Metal Based On The Spectral Color Rendering Method

Nowadays, due to the fact that the lake and the soil in nature are continuously polluted,it shows a more and more serious phenomenon that heavy metal content in drinking water, food and vegetables exceeds the provided standard and it has a great impact on human health. Fast and accurate detection of heavy metal content in diet can directly and effectively decrease the damage on human. The main traditional detecting methods for heavy metals include spectrophotometry, atomic absorption and stripping voltammetry, which have the strengths with low detection limit, high sensitivity, but these methods require complex sample pretreatment, difficult operation of large-scale instrument, long testing time, and can't realize fast online sample testing. The number of food samples is so large, so it's important to develop a rapid and accurate testing technology.In this paper, a fast fiber optic sensor for accurately measuring chromium ion concentration is reported. Also we elaborate structure construction of the sensor,method for preparing original detection, detection of the specific process. The sensor uses absorption spectral intensity to indirectly detect chromium ion concentration.The principle is that fuchsia, which origins from the chromogenic reaction between diphenylcartazide and hexavalent chromium, gradually deepens with the concentration increase of six valence chromium ion. Color film, which is plated on the surface of optical fiber, shows amaranth with hexavalent chromium complex. The experimental results show that the spectral intensity positively correlates with chromium ion concentration over the range from 0.01 mg/L to 0.1 mg/L. The method shows that the detectable limit is 0.01 mg/L, that the operating time is within 10 min,and that detection rate is 96%. This sensor has many advantages, such as easy operation, fast detection speed, low detection cost, and easy to meet the detection conditions. Meanwhile, detection sensitivity reaches detection limits of the national drinking water health standard, which is very suitable for screening a large number of samples.