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

Abstract

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.

Recent developments in quantitative SERS: Moving towards absolute quantification

“…The use of isotopologues for SERS was first reported by van Duynes' group for systematic studies of single molecule detection of crystal violet [97]. For quantitative analysis, this approach is often termed isotope dilution surfaceenhanced Raman scattering (IDSERS) [98], and has been used to improve quantification between different batches of nanoparticles [99] and to effect the absolute quantification of markers in serum [100] as well as human plasma [101], and for the analysis of nicotine content in electronic cigarettes [102].…”

Towards improved quantitative analysis using surface-enhanced Raman scattering incorporating internal isotope labelling

“…The IL approach has also been carried out by Zakel and Stosch to develop a quantitative method for measuring creatinine as a biomarker in human serum. 10 This study concluded that the combination of SERS and IL had proved to be a valuable approach for clinical diagnostic measurements.…”

Step‐by‐step monitoring of a magnetic and SERS‐active immunosensor assembly for purification and detection of tau protein

“…The simplified preparation concept for a controlled formation for a SERS‐active immunosensor greatly improves the applicability of this approach and allows a larger scale implementation. Furthermore, a quantification principle will be established utilizing the isotope dilution (ID) technique, which is mostly used in mass spectrometry, but which has also been shown to work excellently when combined with Raman spectroscopy . Besides the advantages of having molecular specificity, accuracy and a high sensitivity during quantification, an ID‐SERS approach also could provide SI‐traceability of the measurement results when combined with well‐characterized reference materials.…”

“…For this purpose, so‐called reference measurement methods must be provided, which are ideally connected directly to the international system of units (SI) . It has already been demonstrated that SERS‐based methods are basically suitable for realizing the required SI‐traceability . However, the establishment of a reference measurement method to quantify extremely low concentrations of large biomarker molecules such as tau protein is still challenging and time consuming.…”