A novel method for the determination of dried saliva spots (DSS) based on UHPLC-MS/MS for three α-dicarbonyl compounds: An application in the saliva of diabetes patients

α-Dicarbonyl compounds (α-DCs) in human saliva are closely associated with diabetes, but their inherent instability presents challenges for sample transportation and detection. This study introduces a novel approach for the simultaneous detection of three α-DCs—3-deoxyglucoside (3-DG), glyoxal (GO), and methylglyoxal (MG)—in dried saliva spots using 4,5-dimethyl-1,2-phenylenediamine (DMPD) derivatization combined with UHPLC-MS/MS. 5.0 mm diameter double-circle qualitative filter paper was selected as the substrate for dried saliva, with optimal extraction conditions involving two 3-minute extractions. Chromatographic separation was performed on a CSH™ C18 column (2.1 × 50 mm, 1.7 μm) via gradient elution, utilizing a mobile phase consisting of 0.1 % formic acid in water and 0.1 % formic acid in acetonitrile. The entire separation process was completed within a 5.0 min timeframe. The linearity of 3-DG and GO in the concentration range of 0.10–12.5 μM, and MG in the range of 0.24–31.25 μM. (R² ≥ 0.9994). Intra- and inter-day precision yielded RSD values ranging from 0.59 % to 5.78 %, with average recoveries between 99.78 % and 108.50 %. The detection limits were 0.85–12.85 fmol. This method was applied to analyze dried saliva samples from 44 healthy volunteers (HVs) and 46 diabetic patients (DPs), revealing significant differences (p < 0.001) in the concentrations of 3-DG, GO, and MG between HVs and DPs. The research outcomes validate the practicality of α-DCs in dried saliva samples as prospective biomarker candidates for diabetes, while introducing an innovative methodology for their utilization in clinical settings.