Spectrophotometric determination of pH and alkalinity in seawater using pH indicator dyes.

在海洋碳系统的研究中，pH值的精确测定是必不可少的。使用pH电极的方法不足以达到该目的。我们已考虑使用染料法进行pH值测量。近年来分光光度计的发展使其应用成为可能。对分光光度计系统作了进一步的改进。该系统可在2.5秒内测量出吸附量曲线。精确度为0.0001吸光度。用该系统对70 ml海水样品进行测定，其精密度为<plus-minus>0.001pH单位。1994 ~ 1999年，将一步滴定法与溴酚蓝分光光度法相结合，改进了碱度测定方法，并成功地应用于研究船（Hakuho Maru）的实际海水样品中。精度达到<plus-minus>0.001mue

In the study of the oceanic carbon system, the precise determination of pH is essentially necessary. The method using a pH electrode is insufficient for the purpose. We have considered to use a dye method for the pH measurement. Recent development in the spectrophotometer makes possible the application. We have made further improvement for the spectrophotometer system. The system can measure the adsorbance curve within 2.5 sec. with an accuracy of 0.0001 of absorbance. Using the system and seawater sample of 70ml, we have the precision of <plus-minus>0.001 pH unit. The method have been successfully applied to the actual seawater samples on board the research vessel, Hakuho Maru in 1994-199Alkalinity determination is improved by combining a single-step titration and the spectrophotometric pH determination using Bromophenol Blue. We have the precision of <plus-minus>0.001mue