Rapid and simple determination of inulin in biological fluids by high-performance liquid chromatography with light-scattering detection

We report a new high-performance liquid chromatography method developed for measuring inulin in plasma and urine using ion moderated partition chromatography and evaporative light-scattering detection. Samples are deproteinized with a zinc acetate and phosphotungstic acid solution and added with melezitose as an internal standard. The chromatographic separation is carried out in 16 min at a flow-rate of 0.6 ml/min using deionized water as the mobile phase. Within-run precision, measured at four different concentrations (0.050 mg/ml, 0.150 mg/ml, 0.300 mg/ml and 1.200 mg/ml), ranges from 1.7 to 3.4% in plasma and from 1.5 to 3.5% in urine. Similarly, between-run precision is in plasma from 2.0 to 4.3% and in urine from 2.0 to 4.4%. Analytical recovery ranges from 97.9 to 100.1% in plasma and from 99.1 to 99.7% in urine, respectively. Detection limit (signal-to-noise ratio=3) is 5 μg/ml both in plasma and urine. The method is simple, sensitive, without interference due to hexoses or drugs commonly taken by patients with renal diseases, and offers the advantage of measuring inulin without previous hydrolysis of the molecule.