Measurements of Sputum Desmosines Using Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry

Osama Albarbarawi

Department of Chemistry, Taibah University, Saudi Arabia

Dr. Osama Albarbarawi, Department of Chemistry, Taibah University, Saudi Arabia.

Keywords: Mass Spectrometry; COPD; Biomarker; Elastin Degradation; Desmosine

Abstract

An LC-MS/MS method for the absolute quantitation of total desmosine (DES/IDS) in human sputum using synthesized in house internal standard (IS: D4-IDES) was developed. The method involves acid hydrolysis, solid phase extraction (SPE) and liquid chromatographic separation and tandem mass spectrometric analysis (LC-MS/MS). The synthesized IS was characterized to ensure its suitability for the assay. The IS was found to contain at least 4 forms of deuterated IDES. D4- IDES was the most abundant derivative and its structure confirmed by mass spectrometry. The calibration curve showed good precision and accuracy from 0.05 (LLQ) to 20.0ng/mL. The intraand inter-assay precision (%CV) and accuracy (%Bias) of the assay were determined. The precision intraassay ranged from 4.76 to 23.47% and the interassay were from 1.05 to 20.15%. whereas per the accuracy intraassay ranged from 20.0 to -20.0% and the interassay were from -13.33 to -3.33%. The reference range of total DES was established in forty sputum samples and concentrations of all sputum samples fall within the reportable range of the assay. These results demonstrate that the developed method provided a sensitive, reproducible and accurate quantitation of total desmosine in human sputum samples that could be used as a biomarker for monitoring elastin degradation in respiratory diseases.

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