Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
Electrophoresis. 2018 Nov;39(22):2864-2871. doi: 10.1002/elps.201800274. Epub 2018 Sep 25.
The search for biosignatures on spaceflight missions requires in situ instrumentation capable of highly selective and sensitive organic analyses. To this end, CE-LIF is a uniquely promising technique, capable of determining the type, abundance, and chirality of amino acids present in environmental samples at nanomolar concentrations. However, this type of assay requires several reagents that have not yet been used on spaceflight missions. A key concern, particularly for future missions to Europa, is the survivability of these critical components for CE separation and LIF detection under high levels of radiation. Here we present an investigation of the chemical stability of the reagents and associated fused silica capillary after a total ionizing dose of 300 krad, exceeding the predicted total ionizing dose for the potential Europa Lander Mission payload by two-fold. Neither the fused silica capillary nor the fluorescent dye (5-carboxyfluorescein succinimidyl ester) showed significant change in performance following irradiation. Following the irradiation of the pre-mixed background electrolyte, both migration time and resolution were affected. However, when the reagents (sodium tetraborate, sodium taurocholate, and γ-cyclodextrin) and the acetonitrile solution were irradiated separately and mixed afterwards, there was no change in the separation performance.
在太空飞行任务中寻找生物特征需要能够进行高度选择性和灵敏的有机分析的原位仪器。为此，CE-LIF 是一种非常有前途的技术，能够在纳摩尔浓度的环境样本中确定存在的氨基酸的类型、丰度和手性。然而，这种类型的测定需要几种尚未在太空飞行任务中使用的试剂。一个关键问题，特别是对于未来前往欧罗巴的任务，是这些关键组件在高水平辐射下对 CE 分离和 LIF 检测的生存能力。在这里，我们研究了在 300 krad 的总离子剂量下，试剂和相关的熔融石英毛细管的化学稳定性，这超过了潜在的欧罗巴着陆器任务有效载荷的预计总离子剂量的两倍。熔融石英毛细管和荧光染料（5-羧基荧光素琥珀酰亚胺酯）在辐照后均未显示出性能的显著变化。在辐照预混合背景电解质后，迁移时间和分辨率都受到影响。然而，当单独辐照试剂（四硼酸钠、牛磺胆酸钠和γ-环糊精）和乙腈溶液，然后混合时，分离性能没有变化。
