Objective: To develop and analytically validate a gas chromatography-mass spectrometry (GC-MS) method for the quantification of lactulose, rhamnose, xylose, 3-O-methylglucose, and sucrose in canine serum.
Sample population: Pooled serum samples from 200 dogs. Procedures-Serum samples spiked with various sugars were analyzed by use of GC-MS. The method was analytically validated by determination of dilutional parallelism, spiking recovery, intra-assay variability, and interassay variability.
Results: Standard curves ranging from 0.5 to 500 mg/L for each sugar revealed a mean r(2) of 0.997. The lower detection limit was 0.03 mg/L for lactulose, rhamnose, xylose, and methylglucose and 0.12 mg/L for sucrose. The observed-to-expected ratios for dilutional parallelism had a mean +/- SD of 105.6 +/- 25.4% at dilutions of 1:2, 1:4, and 1:8. Analytic recoveries for the GC-MS assays of sugars ranged from 92.1% to 124.7% (mean +/- SD, 106.2 +/- 13.0%). Intra-assay coefficients of variation ranged from 6.8% to 12.9% for lactulose, 7.1% to 12.8% for rhamnose, 7.2% to 11.2% for xylose, 8.9% to 11.5% for methylglucose, and 8.9% to 12.0% for sucrose. Interassay coefficients of variation ranged from 7.0% to 11.5% for lactulose, 6.4% to 9.4% for rhamnose, 6.8% to 13.2% for xylose, 7.0% to 15.9% for methylglucose, and 5.5% to 9.4% for sucrose.
Conclusions and clinical relevance: The GC-MS method described here was accurate, precise, and reproducible for the simultaneous measurement of sugar probes in canine serum.