Worldwide proficiency test for routine analysis of [delta] super(2)H and [delta] super(18)O in water by isotope-ratio mass spectrometry and laser absorption spectroscopy

• Published in: Rapid communications in mass spectrometry Vol. 26; no. 15; pp. 1641 - 1648
• Main Authors: Wassenaar, LI, Ahmad, M, Aggarwal, P, Duren, M, Poltenstein, L, Araguas, L, Kurttas, T
• Format: Journal Article
• Language: English
• Published: 01.08.2012
• Subjects: Absorption spectroscopy; Hydrology; Lasers; Mass spectrometry; Mathematical analysis; Reproduction; Routines
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/rcm.6270

RATIONALE The interpretation of stable hydrogen and oxygen isotope data in isotope hydrology relies on accurate, high-precision analytical measurements of the super(2)H: super(1)H and super(18)O: super(16)O ratios in liquid H sub(2)O samples. METHODS A synthesis of the International Atomic Energy Agency (IAEA) worldwide proficiency test for analytical laboratories conducting routine analysis of [delta] super(2)H and [delta] super(18)O values in water (WICO2011) by isotope-ratio mass spectrometry (IRMS) and laser absorption spectroscopy (LAS) technology has been carried out. RESULTS This test revealed that >96% of the 160 laboratory submissions provided acceptable results within plus or minus 2ppt for [delta] super(2)H values and plus or minus 0.2ppt for [delta] super(18)O values of the established reference values for four test waters, and no difference in outcomes based on IRMS vs. LAS technology was found for good performing laboratories. CONCLUSIONS The leading cause of outliers appeared to be improper calibration or compromised storage of laboratory standard and primary reference waters; hence the importance of judicious storage of lab standards cannot be understated. The deprecated practice of single standard normalization was identified as a problem for some laboratories. We further recommend that laboratories strive to report parsimonious long-term precisions based upon control standards, and to improve quantification and correction for LAS instrumental drift and inter-sample carryover effects. Copyright [copy 2012 John Wiley & Sons, Ltd.