Schauer Andrew J, Schoenemann Spruce W, Steig Eric J
IsoLab, Department of Earth and Space Sciences, University of Washington, Seattle, WA, 98195, USA.
Rapid Commun Mass Spectrom. 2016 Sep 30;30(18):2059-69. doi: 10.1002/rcm.7682.
Water isotope analysis for δ(2) H and δ(18) O values via laser spectroscopy is routine for many laboratories. While recent work has added the δ(17) O value to the high-precision suite, it does not follow that researchers will routinely obtain high precision (17) O excess (Δ(17) O). We demonstrate the routine acquisition of high-precision δ(2) H, δ(17) O, δ(18) O, d, and Δ(17) O values using a commercially available laser spectroscopy instrument.
We use a Picarro L2140-i cavity ring-down spectroscopy analyzer with discrete liquid injections into an A0211 vaporization module by a Leap Technologies LC PAL autosampler. The instrument is run in two modes: (1) as recommended by the manufacturer (default mode) and (2) after modifying select default settings and using alternative data types (advanced mode). Reference waters analyzed over the course of 15 months while running unknown samples are used to assess system performance.
The default mode provides precision for δ(2) H, δ(17) O, δ(18) O, d, and Δ(17) O values that may be sufficient for many applications. When using the advanced mode, we reach a higher level of precision for δ(2) H, δ(17) O, δ(18) O, d, and Δ(17) O values (0.4 mUr, 0.04 mUr, 0.07 mUr, 0.5 mUr, and 8 μUr, respectively, where mUr = 0.001 = ‰, and μUr = 10(-6) ) in a shorter amount of time and with fewer syringe actuations than in the default mode. The improved performance results from an increase in the total integration time for each injected water pulse.
Our recommended approach for routine δ(2) H, δ(17) O, δ(18) O, d and Δ(17) O measurements with the Picarro L2140-i is to make use of conditioning vials, use fewer injections (5 per vial) with greater pulse duration (520 seconds (s) per injection) and use only the first 120 s for δ(2) H measurements and all 520 s for δ(17) O and δ(18) O measurements. Although the sample throughput is 10 unknowns per day, our optimal approach reduces the number of syringe actuations, the effect of memory, and the total analysis time, while improving precision relative to the default approach. Copyright © 2016 John Wiley & Sons, Ltd.
许多实验室通过激光光谱法对δ(2)H和δ(18)O值进行水同位素分析已成为常规操作。虽然最近的工作已将δ(17)O值纳入高精度测量范围，但这并不意味着研究人员能常规获得高精度的(17)O过量值（Δ(17)O）。我们展示了使用商用激光光谱仪常规获取高精度δ(2)H、δ(17)O、δ(18)O、d和Δ(17)O值的方法。
我们使用Picarro L2140 - i腔衰荡光谱分析仪，由Leap Technologies LC PAL自动进样器将离散液体注入A0211汽化模块。该仪器以两种模式运行：(1)按照制造商推荐的模式（默认模式）；(2)在修改某些默认设置并使用替代数据类型后（高级模式）。在运行未知样品的15个月期间对参考水进行分析，以评估系统性能。
默认模式下δ(2)H、δ(17)O、δ(18)O、d和Δ(17)O值的精度对许多应用可能已足够。使用高级模式时，我们在更短时间内、通过比默认模式更少的进样针操作，使δ(2)H、δ(17)O、δ(18)O、d和Δ(17)O值达到更高精度水平（分别为0.4 mUr、0.04 mUr、0.07 mUr、0.5 mUr和8 μUr，其中mUr = 0.001 =‰，μUr = 10(-6)）。性能的提升源于每个注入水脉冲的总积分时间增加。
我们推荐的使用Picarro L2140 - i进行常规δ(2)H、δ(17)O、δ(18)O、d和Δ(17)O测量的方法是，使用预处理小瓶，减少进样次数（每个小瓶5次），增加脉冲持续时间（每次进样520秒），δ(2)H测量仅使用前120秒，δ(17)O和δ(18)O测量使用全部520秒。尽管每天的样品通量为10个未知样品，但我们的最佳方法减少了进样针操作次数、记忆效应和总分析时间，同时相对于默认方法提高了精度。版权所有© 2016 John Wiley & Sons, Ltd.
