Li Hangqian, Wang Shu, Zheng Shulu, Fang Tengyue, Shu Huilin, Xu Yi, Guo Xianghui, Achterberg Eric P, Zhan Liyang, Ma Jian
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, People's Republic of China; College of the Environment and Ecology, Xiamen University, Xiamen, 361102, People's Republic of China; Marine Biogeochemistry, Chemical Oceanography, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, 24148, Germany.
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, People's Republic of China; School of Resources and Environmental Engineering, Hefei University of Technology, Hefei, 230009, People's Republic of China.
Talanta. 2024 Oct 1;278:126532. doi: 10.1016/j.talanta.2024.126532. Epub 2024 Jul 11.
The development of field-deployable methods and instruments for the measurement of pH and other carbonate parameters is important for the assessment of the marine carbon cycle, ocean acidification and marine carbon dioxide removal techniques. In this study, a high-precision fully automated integrated syringe-pump-based environmental-water analyzer for pH (iSEA-pH) was developed. The pH is determined spectrophotometrically using purified indicator dye with a high precision (better than ±0.001) and high frequency (3.5 min/sample). For the short-term analysis, the measurement frequency was 18 h, which revealed pH = 7.8148 ± 0.0005 (n = 104) for aged surface seawater (S = 35) from the western Pacific. For long-term analysis, the measurement frequency was 2 h for 4 days, and the results showed that pH = 7.8148 ± 0.0010 (n = 200). Three commonly used pH indicators (meta-cresol purple, thymol blue and phenol red) were purified with improved flash chromatography procedures. The autonomous iSEA-pH can automatically correct for the influence of temperature, salinity and other factors on pH measurements to achieve rapid and accurate on-site measurements, which meet the "climate" goal of the Global Ocean Acidification Observing Network (uncertainty is ±0.003). Three identical iSEA-pH systems were developed and successfully applied in mesocosm experiments and several coastal and open ocean cruises with excellent in field performance.
开发用于测量pH值和其他碳酸盐参数的可现场部署的方法和仪器，对于评估海洋碳循环、海洋酸化和海洋二氧化碳去除技术至关重要。在本研究中，开发了一种基于集成注射泵的高精度全自动环境水pH分析仪（iSEA-pH）。使用纯化的指示剂染料通过分光光度法测定pH值，具有高精度（优于±0.001）和高频率（3.5分钟/样品）。对于短期分析，测量频率为18小时，结果显示西太平洋老化表层海水（S = 35）的pH值为7.8148±0.0005（n = 104）。对于长期分析，测量频率为4天内每2小时一次，结果显示pH值为7.8148±0.0010（n = 200）。通过改进的快速色谱法纯化了三种常用的pH指示剂（间甲酚紫、百里酚蓝和酚红）。自主的iSEA-pH可以自动校正温度、盐度和其他因素对pH测量的影响，以实现快速准确的现场测量，满足全球海洋酸化观测网络的“气候”目标（不确定度为±0.003）。开发了三个相同的iSEA-pH系统，并成功应用于中尺度实验以及几次沿海和远洋航行，现场性能优异。
