A suggested protocol for value assignment using isotope-dilution-LC-MS/MS in reference measurement procedures – Exemplary application for ciprofloxacin in serum.

• A novel protocol for the application of isotope-dilution-LC-MS/MS in reference measurement procedures is described. • An spreadsheet file is used as an essential tool for result generation, data review and validation of series and results. • A method for the quantification of ciprofloxacin in human serum was investigated as an example. Reference measurement procedures for assigning values to calibration materials play a crucial role in the concept of metrological traceability in laboratory medicine. ISO standard 15,193 specifies the requirements for such measurement procedures, albeit in a very general terms. A standard structure of analysis series for value assignment by LC-MS/MS was developed and tested,this structure was complemented by a spreadsheet file for result calculation, metadata evaluation, and finally validation and confirmation of individual analysis runs and individual results, and measurement uncertainty evaluation. This framework was applied to a procedure for the quantification of ciprofloxacin in serum as an example. The approach of a detailed description of the analytical procedures of isotope dilution LC-MS/MS reference measurement methods together with a highly standardized spreadsheet-based method for data processing was found to be practical and efficient. The described measurement procedure for the quantification of ciprofloxacin in serum was found to be fit for purpose. A standardized, detailed procedure for the application of isotope dilution LC-MS/MS in reference measurement procedures can complement the ISO 15193 standard with respect to this particular analytical technique, which is now widely used in the context of metrological traceability in laboratory medicine. [ABSTRACT FROM AUTHOR]