The reagent-free multicomponent analysis of components in urine using mid-infrared spectroscopy possesses many attractions. A population of 67 individual urine samples from children and adults, collected over 24 h, was analyzed for urea, creatinine, uric acid, glucose, total protein, phosphate, and sulfate by using clinical reference methodology. The urine pH value was potentiometrically measured by a glass electrode. Partial least-squares (PLS) calibration models were calculated over optimized, component-specific ranges from attenuated total reflection spectra of the urine samples measured by a micro-Circle cell. Apart from glucose and total protein, for which the spread in urine sample concentrations was too small, calibrations were successful for metabolites such as urea, creatinine, and uric acid. Additionally, concentrations of sulfate and phosphate anions, which show significant mid-infrared absorption bands, could also be quantified. The acid secreted with the urine influences the equilibrium between di- and monobasic phosphate in this biofluid, which is used as the spectroscopic basis for the pH assay presented here. The analytical performance of the reference methods is discussed with regard to evaluating the limitations of the spectroscopic assay. Additionally, aqueous solutions of individual urine components with a spread of concentrations similar to those found in native urine samples were analyzed by using PLS calibrations.

PDF Article

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
Login to access OSA Member Subscription