RESUMO
In the presence of silver ion, Mn2+ could be electro-oxidized to potassium hypermanganate in phosphoric acid solution, which could effectively react with pyrocatechol in acid solution and luminol in sodium hydroxide solution to produce chemiluminescence. On the basis of this, a novel indirect approach for the detection of Mn2+ was established. The effect of silver ions on the electrochemical oxidation of Mn2+was studied. when 1. 5 ×10-5 mol/L Ag+ and 0. 01 mol/L phosphoric acid solution were used in the process of electrochemical oxidation, the CL intensity could be up to the maximum value after the above solution was electrolyzed for 2 min. The relation of CL intensity and Mn2+concentration in the solutions at different pH and the selectivity were also investigated. when the pyrocatechol was used as luminescent reagent in the acidic medium, the CL intensity was linearly to the Mn2+concentration in the range of 1. 82×10-7-7. 27×10-5 mol/L with excellent selectivity. Common ions had little interferences in the determination of Mn2+. The method was successfully applied to the determination of Mn2+ in surface water and drinking water with satisfactory results.
RESUMO
Objective To study the method and conditions of determination of niclosamide in water. Methods Niclosamide was extracted by mixed extractent, then striped by NaOH. Niclosamide in NaOH solution was determined with dual-wavelength photometry. Results The recovery of niclosamide was 93%. The linear ranger was 0-4. 0 g/m3 and the detectable limit for niclosamide was 0. 042 7 g/m3. The apparent molar absorptivity was 1. 26 ?105 L/(mol?cm). Conclusion Extraction photometry is suitable for determination of niclosamide in water in the field.