Validation of isotope dilution surface‐enhanced Raman scattering (IDSERS) as a higher order reference method for clinical measurands employing international comparison schemes

Isotope dilution surface‐enhanced Raman scattering (IDSERS) was established as a higher order reference measurement method for clinical measurands in international comparison schemes and in direct comparison with established mass spectrometric methods. IDSERS represents the most accurate and precise quantitative Raman technique and is capable of providing SI‐traceable amount‐of‐substance measurements. IDSERS has now been validated by participation in two international ring trials organized within the framework of the Metre Convention on the determination of biomarkers in human serum. The concentration of creatinine has been measured in two human serum samples supplied by the study organizer. The results obtained by IDSERS agree excellently with the data reported by participating national metrology institutes using mass spectrometry, and the associated uncertainties are within the claimed limits of equivalence. The performance and applicability of IDSERS were thereby convincingly demonstrated. This has led to the approval of the method as a higher order reference measurement procedure, which is now listed in a publicly accessible database maintained by the International Bureau of Weights and Measures (BIPM). Copyright © 2013 John Wiley & Sons, Ltd.