Method for detecting ascorbic acid
An ascorbic acid and lysine modification technology, which is applied in the field of electrochemistry, can solve the problems of complicated operation steps, expensive instruments, unfavorable rapid analysis, etc., and achieves the effects of good selectivity, low cost and convenient detection device.
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Embodiment 1
[0016] Example 1 Preparation of silver-doped poly-L-lysine modified electrode
[0017] A glassy carbon electrode was used as the working electrode, a saturated calomel electrode was used as the reference electrode, and a platinum wire was used as the counter electrode in a three-electrode system containing 1.00×10 -3 mol / L of L-lysine, 3.00×10 -4 In the solution of mol / L silver nitrate, 0.05mol / L nitric acid and 0.10mol / L potassium nitrate, in the potential range of -0.4~2.6V, let it stand still for 5s, and use cyclic voltammetry to scan at a scanning speed of 60mV / s 10 cycles to obtain a silver-doped poly-L-lysine modified electrode.
[0018] The principle of the silver-doped poly-L-lysine modified electrode prepared under the above-mentioned optimal conditions for detecting ascorbic acid is as follows:
[0019] figure 1 The cyclic voltammetry curve (1 to 10 means scanning 1 to 10 circles) of the silver-doped poly-L-lysine modified electrode was prepared under the optimal ...
Embodiment 2
[0021] Embodiment 2 directly measures 8.00×10 -4 mol / L ascorbic acid
[0022] The silver-doped poly-L-lysine modified electrode prepared in Example 1 was put into a phosphate buffer solution of pH=3.0 as a supporting electrolyte, and the phosphate buffer solution was composed of Na 3 PO 4 , NaH 2 PO 4 、Na 2 HPO 4 Composition, the concentration of each substance is 0.1moL / L, using H 3 PO 4 Adjust the pH to 3.0, and after standing still for 14s, in the potential range of -0.6 ~ 0.8V, use cyclic voltammetry at a scanning speed of 160mV / s to detect 8.00×10 -4 mol / L ascorbic acid solution for scanning determination, and then measure a series of ascorbic acid solutions containing known concentrations, and draw a standard curve.
[0023] According to the standard curve, the concentration of ascorbic acid obtained by using the oxidation peak current was 8.112×10 -4 mol / L, with a relative standard deviation of 1.4% from the true value.
Embodiment 3
[0024] Embodiment 3 standard addition method measures the ascorbic acid of unknown concentration
[0025] According to the conditions of Example 2, the modified electrode prepared in Example 1 was placed in a solution containing unknown concentration of ascorbic acid for measurement, and 2.00×10 -3 After mol / L ascorbic acid, measure again.
[0026] The test results showed that the concentration of ascorbic acid in the unknown sample was 4.15×10 -4 mol / L, the recovery rate measured by the standard addition method was 98.21%.
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