Characterization of meta-Cresol Purple for spectrophotometric pH measurements in saline and hypersaline media at sub-zero temperatures.
Characterization of meta-Cresol Purple for spectrophotometric pH measurements in saline and hypersaline media at sub-zero temperatures.
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DOI：
10.1038/s41598-017-02624-0
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发表时间：
2017-05-30
影响因子：
4.6
通讯作者：
Achterberg EP
中科院分区：
文献类型：
--
作者：
Loucaides S;Rèrolle VMC;Papadimitriou S;Kennedy H;Mowlem MC;Dickson AG;Gledhill M;Achterberg EP
极地水域和海冰卤水中准确的pH测量要求pH指示剂染料具有接近零和零下的温度和高盐度。本文报道了一种纯间甲酚紫pH指示剂的物理和化学特性，适用于在盐度(S)35-100时和冰点(T)-298.15 K(25 °C)之间的海水和保守海水中的pH测量。在这个温度和盐度范围内，使用提纯的单环戊二烯和一种新型的恒温分光光度装置，可以根据在这些扩展条件下的单环戊二烯的表征，通过直接测量天然样品中染料的吸光度比R来计算总标度上的pH。在这些扩展的条件下，提纯的单环戊二烯的摩尔吸光系数和− 的温度和盐度的关系由下列函数描述：E 1 = −0.004363 + 3.598 × 10−5 T，E 3/e 2 = −0.016224 + 2.42851 × 10−4 T + 5.05663 × 10−5(S − 35)和− =−319.8369 + 0.688159 S−0.00018374 S 2 + (10508.724 − 32.9599 S + 0.059082S 2)T−1 + (55.54253 − 0.101639 S)ln T −0.08112151T。这项工作使微通道蛋白的表征超出了目前在天然海水中可用的278.15 K ≤ T ≤ 308.15 K和20 ≤ S ≤ 40的范围，从而可以在极地系统中进行高质量的PHT测量。
Accurate pH measurements in polar waters and sea ice brines require pH indicator dyes characterized at near-zero and below-zero temperatures and high salinities. We present experimentally determined physical and chemical characteristics of purified meta-Cresol Purple (mCP) pH indicator dye suitable for pH measurements in seawater and conservative seawater-derived brines at salinities (S) between 35 and 100 and temperatures (T) between their freezing point and 298.15 K (25 °C). Within this temperature and salinity range, using purified mCP and a novel thermostated spectrophotometric device, the pH on the total scale (pHT) can be calculated from direct measurements of the absorbance ratio R of the dye in natural samples as Based on the mCP characterization in these extended conditions, the temperature and salinity dependence of the molar absorptivity ratios and − of purified mCP is described by the following functions: e 1 = −0.004363 + 3.598 × 10−5 T, e 3/e 2 = −0.016224 + 2.42851 × 10−4 T + 5.05663 × 10−5(S − 35), and − = −319.8369 + 0.688159 S −0.00018374 S 2 + (10508.724 − 32.9599 S + 0.059082S 2) T−1 + (55.54253 − 0.101639 S) ln T −0.08112151T. This work takes the characterisation of mCP beyond the currently available ranges of 278.15 K ≤ T ≤ 308.15 K and 20 ≤ S ≤ 40 in natural seawater, thereby allowing high quality pHT measurements in polar systems.