Alkalinity determination by potentiometry - intercalibration using three different methods
Alkalinity determination by potentiometry - intercalibration using three different methods
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DOI：
10.7773/cm.v26i1.573
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发表时间：
2000-03
期刊：
影响因子：
0.7
通讯作者：
L. Mintrop;F. F. Pérèz-F.;M. González-Dávila;J. Santana-Casiano;A. Körtzinger
中科院分区：
文献类型：
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作者：
L. Mintrop;F. F. Pérèz-F.;M. González-Dávila;J. Santana-Casiano;A. Körtzinger
从北大西洋（加那利群岛地区）的不同深度采集海水样本，并分配给三个不同的实验室，用于测定滴定碱度。通过电位滴定法进行分析，包括在封闭电池中滴定，在开放电池中滴定和两个终点酸添加法。精密度是从重复测量的平均标准差中获得的样品重现性，单个实验室的精密度在0.45和0.90 µmol kg（-1）之间。准确度，这里是指一个实验室的值与所有三个实验室的平均值的偏差，大多数低于1 µmol kg（-1），从未超过样品值的0.1%。一旦使用经认证的参考物质（CRM）校准各个方法，所有实验室和所有样品的平均标准偏差为0.87 µmol kg（-1）。如果没有CRM校准，平均标准偏差将增加到2.8 µmol k（-1）。结论是，目前高精度的碱度测量方法校准标准物质能够达到类似的准确度，总溶解无机碳库仑法的测量，因此允许精确测定海洋二氧化碳系统通过使用两个测量参数。
Seawater was sampled from different depths in the North Atlantic Ocean (Canary Islands region) and distributed among three different labs for the determination of titration alkalinity. Analysis was performed by potentiometric methods, involving titration in a closed cell, titration in an open cell and a two end-point acid addition method. The precision, which is the sample reproducibility taken from the mean standard deviation for replicate measurements, was between 0.45 and 0.90 µmol kg(-1) for the individual labs. Accuracy, here taken as the deviation for the values of a lab from the mean of all three, was mostly below 1 µmol kg(-1) and never exceeded 0.1% of the sample value. Mean standard deviation for all labs and all samples was 0.87 µmol kg(-1), once the individual methods were calibrated using certified reference material (CRM). Without CRM calibration, the mean standard deviation would increase to 2.8 µmol k(-1). The conclusion is that current high precision methods for alkalinity measurements calibrated with CRMs are able to reach similar accuracy as the measurement of total dissolved inorganic carbon by coulometry and therefore allow for the precise determination of the oceanic carbon dioxide system by using the two measured parameters.