激光光譜同位素儀分析植物與土壤樣品會產生極大誤差！

　　國際權威刊物"Rapid Communications in Mass Spectrometry"發表最新文章，指出采用激光光譜同位素儀（無論是LGR還是Piccaro公司)分析植物與土壤樣品會產生極大誤差,建議還是采用傳統的同位素比率質譜儀才能獲得可靠的結果。該文摘要和文獻出處如下：

　　RAPID COMMUNICATIONS IN MASS SPECTROMETRY

　　Rapid Commun. Mass Spectrom. 2010； 24: 1948–1954

　　Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/rcm.4597

　　Discrepancies between isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters

　　Adam G. West1,2*, Gregory R. Goldsmith1, Paul D. Brooks3 and Todd E. Dawson1,3

　　1Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA

　　2Botany Department, University of Cape Town, Rondebosch, 7701, South Africa

　　3Center for Stable Isotope Biogeochemistry, University of California, Berkeley, Berkeley, CA 94720, USA

　　Received 7 April 2010； Revised 24 April 2010； Accepted 24 April 2010

　　The use of isotope ratio infrared spectroscopy (IRIS) for the stable hydrogen and oxygen isotope

　　analysis of water is increasing. While IRIS has many advantages over traditional isotope ratio mass

　　spectrometry (IRMS), it may also be prone to errors that do not impact upon IRMS analyses. Of

　　particular concern is the potential for contaminants in the water sample to interfere with the

　　spectroscopy, thus leading to erroneous stable isotope data. Water extracted from plant and soil

　　samples may often contain organic contaminants. The extent to which contaminants may interfere

　　with IRIS and thus impact upon data quality is presently unknown. We tested the performance of

　　IRIS relative to IRMS for water extracted from 11 plant species and one organic soil horizon. IRIS

　　deviated considerably from IRMS for over half of the samples tested, with deviations as large as 46%

　　(d2H) and 15.4% (d18O) being measured. This effect was reduced somewhat by using activated

　　charcoal to remove organics from the water； however, deviations as large as 35% (d2H) and 11.8%

　　(d18O) were still measured for these cleaned samples. Interestingly, the use of activated charcoal to

　　clean water samples had less effect than previously thought for IRMS analyses. Our data show that

　　extreme caution is required when using IRIS to analyse water samples that may contain organic

　　contaminants. We suggest that the development of new cleaning techniques for removing organic

　　contaminants together with instrument-based software to flag potentially problematic samples are

　　necessary to ensure accurate plant and soil water analyses using IRIS. Copyright# 2010 John Wiley

　　& Sons, Ltd.