Simultaneous Sensitive Determination of Eight Collagen-Related Bone Turnover Biomarkers in Diverse Clinical Samples by HPLC with Fluorescent Derivatization

Abstract

The suitability of HPLC with fluorescent derivatization for simultaneous determination of eight collagen-related bone turnover biomarkers, 4-hydroxy-l-proline (OHP), pyridinoline (PYD), hydroxylysine (Hyl), deoxypyridinoline, and their glycosides, galactosyl-Pyd (Gal-Pyd, GP), galactosyl-glucosyl-Pyd, β-1-galactosyl-O-hydroxylysine (Gal-Hyl, GH), and α-1,2-glucosyl-galactosyl-O-hydroxylysine (GGH), in diverse clinical samples was investigated. 5-Carboxyfluorescein succinimidyl ester (CFSE) was chosen as the fluorescent labeling reagent. Various parameters affecting derivatization and separation were optimized. Under optimal conditions, maximum derivatization could be achieved in 25 min at 30 °C, and complete baseline separation could be completed within 25 min, with relative standard deviation values for corrected peak areas less than 3.5 % for intraday assay and 4.2 % for interday assay, respectively. The limits of detection were determined to be 0.1–1.7 nM, which are well below the expected concentrations in the real samples. The method has been used for the quantitative determination of eight target analytes in various clinical samples, including cell cultures of normal human osteoclast, preosteoblast, osteoclastoma cells and serum and urine fluids from patients with fracture, osteitis fibrosa, or osteoclastoma as well as healthy subjects, with spiked recoveries of 96–103 %. This original application of HPLC–fluorescence detection represents a powerful tool for investigating the dynamics of metabolic imbalance of these biomarkers for bone turnover under physiological and pathophysiological conditions.