Mori V, Bertotti M
Instituto de Quimica, Universidade de São Paulo, São Paulo SP 05599-970, Brazil.
Talanta. 1998 Nov;47(3):651-8. doi: 10.1016/s0039-9140(98)00121-0.
The construction of a wall-jet cell with amperometric detection using a set of disc electrodes whose radii ranged from 5 to 750 mum has been proposed. The influence of some experimental parameters like flow rate and electrode radius on hydrodynamic voltammograms recorded for a 0.5 mmol dm(-3) potassium ferrocyanide solution also containing 0.1 mol dm(-3) KCl has been discussed. Some considerations regarding the current signals obtained from flow injection experiments using both a 5- and a 750-mum radius platinum electrode were carried out in order to achieve the lowest limit of detection, a value of 0.03 mumol dm(-3) ferrocyanide being calculated by using the 5-mum radius microelectrode as amperometric detector. The wall-jet cell has been used in the determination of nitrite in saliva by quantifying the triiodide formed in the reaction of the analyte with excess iodide in acidic medium. A 12.5-mum platinum disc microelectrode maintained at +0.2 V vs. Ag/AgCl was used as amperometric detector. Peaks obtained in fiagrams after injection of diluted saliva to the carrier stream containing 0.1 mol dm(-3) sulphuric acid and 20 mmol dm(-3) potassium iodide were compared to an analytical curve obtained in the same conditions (r(2)=0.997) for a nitrite concentration in the range 1-10 mumol dm(-3). The concentration of nitrite in the saliva sample after the appropriate correction for dilution was found to be 2.3 ppm (0.05 mmol dm(-3)), in a good agreement with results obtained by using a standard spectrophotometric procedure (2.5 ppm). The limit of detection of the method was calculated as 0.2 mumol dm(-3), and the reproducibility was checked by measuring the peak current for 19 injections of 10 muM nitrite, the standard deviation being 3.7%.
有人提出构建一种采用一组半径范围为5至750μm的圆盘电极进行安培检测的壁流池。还讨论了一些实验参数，如流速和电极半径对在含有0.1 mol dm⁻³ KCl的0.5 mmol dm⁻³亚铁氰化钾溶液中记录的流体动力学伏安图的影响。为了实现最低检测限，对使用半径为5μm和750μm的铂电极进行流动注射实验获得的电流信号进行了一些考量，使用半径为5μm的微电极作为安培检测器计算得出亚铁氰化物的检测限为0.03μmol dm⁻³。壁流池已用于通过定量分析物在酸性介质中与过量碘化物反应形成的三碘化物来测定唾液中的亚硝酸盐。使用相对于Ag/AgCl保持在 +0.2 V的12.5μm铂圆盘微电极作为安培检测器。将稀释唾液注入含有0.1 mol dm⁻³硫酸和20 mmol dm⁻³碘化钾的载流后在图表中获得的峰与在相同条件下（r² = 0.997）亚硝酸盐浓度在1 - 10μmol dm⁻³范围内获得的分析曲线进行比较。对稀释进行适当校正后，唾液样品中亚硝酸盐的浓度为2.3 ppm（0.05 mmol dm⁻³），与使用标准分光光度法获得的结果（2.5 ppm）非常吻合。该方法的检测限计算为0.2μmol dm⁻³，并通过测量10μM亚硝酸盐的19次进样的峰电流来检查重现性，标准偏差为3.7%。
