Determination of iohexol and iothalamate in serum and urine by capillary electrophoresis.

Estimation of glomerular filtration rate (eGFR) is essential to assess kidney function. Iodine containing contrast agents detection by HPLC has been proposed as a safe alternative for inulin or radioactive compounds. However, HPLC is a time-consuming and labour-intensive method. The aim of this study was to develop an assay for iohexol and iothalamate using capillary electrophoresis (CE). Iohexol and iothalamate were directly analysed by CE in serum and urine, using photometric detection (246 nm). Serum peak height was proportional to iohexol and iothalamate concentrations. Detection limits for iohexol and iothalamate were 10 mg/L and 5 mg/L. Limits of quantification were 13.0 mg/L and 15.0 mg/L. Within-run CVs were 4.9% and 6.5%; between-run CVs 3.1-9.9% and 3.8-13.7%. A good correlation was observed between CE and HPLC: y = 1.1703 x + 5.017 (iohexol) and y = 0.7807 x + 11.01 (iothalamate) [y = concentration obtained by CE (mg/L), x = concentration obtained by HPLC (mg/L)]. In addition, CE allowed to determine urinary iohexol concentration. Although the detection limit for CE was higher than for HPLC, CE can still be used for eGFR determination. Advantages of this high throughput method are the absence of sample pretreatment and a minimal sample volume requirement. This article is protected by copyright. All rights reserved.