Accuracy Spectrophotometric Determination of pH for Sea Water

用分光光度法准确测定了海水的pH值。以百里酚蓝为pH指示剂，用分光光度法实现了分析物溶液pH的测定。利用了数字化光谱提供的冗余数据。使用电子表格软件计算pH值及其统计误差。统计上，海水pH测量的光度误差估计为&lt；正负&0.00015个pH单位。由于百里酚蓝的K_a值受误差的限制，在25ﾟC时，该方法的总准确度为&lt；正负&gt；0.00072，盐度在0-40*之间。PH测量的一个经常被忽视的方面是，在高离子强度的样品中，玻璃电极的pH读数的可靠性较低。光谱方法的使用可以绕过一些困难。准确、可靠地测定海水的pH值对于揭示海洋中的化学过程是必不可少的。目前，我正在将这种方法扩展到开发一种新的光学pH传感器。

The pH of sea water was accurately determined from spectrophotometric measurement. The measurement of pH of the analyte solution was achieved by the spectrophotometric method using thymol blue as a pH indicator. Advantage was taken of the redundant data available with digitized spectra. The calculations of pH and its statistical errors were performed using the spreadsheet software. Statistically photometric errors of the pH measurement of sea water was estimated to be <plus-minus>0.00015 pH units. Because of limited by errors in the K_a evaluation of thymol blue, the overall accuracy of this method was <plus-minus>0.00072 pH at 25ﾟC,and salinities between 0 to 40 *. One aspect of pH measurement often ignored is the low reliability of glass electrode pH reading at high ionic strength sample. The use of spectral method can circumvent some of the difficulties. Accurate and reliable determination of the pH of sea water is necessary for the reveal of chemical process in the ocean. Currently, I am extending this approach to development of a new optical pH sensor.