Wolfgang Petrich

Vibrational spectroscopy as a routine tool for the quantitative analysis of serum

Mid-infrared and Raman spectroscopy together with multivariate data analysis offers the potential to be applied to clinical laboratory analysis due to their reagent-free nature, the speed of analysis and the possibility of obtaining a variety of information from a single measurement. In what we believe to be among the largest studies on mid-infrared and Raman spectroscopy for the analysis of multiple analytes in serum, samples from 247 donors have been analyzed with the emphasis on reproducibility. In an independent validation, root-mean-square errors of prediction (RMSEP) ranged from 328 mg/dL for the quantification of protein (mean concentration: 7008 mg/dL) using mid-infrared spectroscopy to 1.1 mg/dL for uric acid (mean concentration: 5.3 mg/dL) in the case of Raman spectroscopy. Both techniques deliver similar performances. We also performed first steps towards determining system precision and accuracy. In a fivefold measurement of 5 randomly chosen samples from this study, precision and accuracy range from 4% to 16% and from 4% to 29%, respectively. However, when considering the physiological and pathological range of concentrations of analytes, vibrational spectroscopy might open the path towards less expensive and more rapid multiparameter analysis of small sample volumes in those cases, in which moderate accuracy is permissible.