Revsbech Niels Peter, Thamdrup Bo, Dalsgaard Tage, Canfield Donald Eugene
Department of Biological Sciences, Microbiology, Aarhus University, Aarhus, Denmark.
Methods Enzymol. 2011;486:325-41. doi: 10.1016/B978-0-12-381294-0.00014-6.
Until recently, it has not been possible to measure O(2) concentrations in oxygen minimum zones (OMZs) with sufficient detection limits and accuracy to determine whether OMZs are anoxic or contain 1-2 μM O(2). With the introduction of the STOX (switchable trace oxygen) sensor, the level for accurate quantification has been lowered by a factor of 1000. By analysis with STOX sensors, O(2) can be prevented from reaching the sensing cathode by another cathode (front guard cathode), and it is the amplitude in signal by polarization/depolarization of this front guard that is used as a measure of the O(2) concentration. The STOX sensors can be used in situ, most conveniently connected to a conventional CTD (conductivity, temperature, and depth analyzer) along with a conventional oxygen sensor, and they can be used for monitoring O(2) dynamics during laboratory incubations of low-O(2) media such as OMZ water. The limiting factors for use of the STOX sensors are a relatively slow response, with measuring cycle of at least 30 s with the current design, and fragility. With improved procedures for construction, the time for a complete measuring cycle is expected to come down to about 10 s.
直到最近，要在海洋低氧区（OMZs）中测量氧气（O₂）浓度，使其检测限和准确度足以确定这些区域是缺氧的还是含有1-2微摩尔/升的O₂，一直是不可能的。随着可切换痕量氧气（STOX）传感器的引入，准确量化的水平降低了1000倍。通过使用STOX传感器进行分析，另一个阴极（前保护阴极）可防止O₂到达传感阴极，并且正是这个前保护阴极极化/去极化产生的信号幅度被用作O₂浓度的度量。STOX传感器可以原位使用，最方便的是与传统的氧气传感器一起连接到常规的CTD（电导率、温度和深度分析仪）上，并且它们可用于在低氧介质（如海洋低氧区水）的实验室培养过程中监测O₂动态。使用STOX传感器的限制因素是响应相对较慢，当前设计的测量周期至少为30秒，以及易碎性。随着构建程序的改进，完整测量周期的时间预计将降至约10秒。
