A RAPID HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR DETERMINATION OF MELAMINE IN RENAL CALCULI

Abstract

A rapid high-performance liquid chromatograph (HPLC) technique for the determination of melamine (MEL) in renal calculi has been developed. MEL was extracted from calculi with 0.1 M sodium hydroxide. Separation was conducted on a reversed-phase C18 column with 1 mM phosphate buffer (pH 7.0)/methanol (95/5, v/v) as mobile phase. Linearity range for MEL was 0.05–50 µg mL⁻¹ and limit of detection (LOD) was 16 µg g⁻¹. The reliability of this method was validated. The content of MEL in the ten calculi was from 200 µg g⁻¹ to 339,000 µg g⁻¹. The method could be used for research on the pathogenesis of nephrolithiasis associated with the ingestion of excessive MEL.

Keywords:

• HPLC
• infant formula
• melamine
• nephrolithiasis
• renal calculi
• validation

ACKNOWLEDGMENTS

We would like to thank our colleagues of the Second Hospital of Lanzhou University for helping collect the samples from the infants. We are grateful to all members of the Medical Scientific Institute of Gansu Province for excellent technical assistance. We thank Dr. Haixiang Su (Medical Scientific Institution, Tumor Hospital of Gansu Province, Lanzhou) and Dr. Junkui Ai (Department of Urology, University of Pittsburgh, PA, USA) for critical reading of the manuscript.

Notes

W = weight of stones; V = volume of 0.1 M NaOH; C = concentration of samples.

^a Quality controls were analyzed at room temperature for 24 hr.

^b Sample solutions were analyzed at room temperature for 12 hr after being processed.

^c Stock solution was analyzed at 0–4°C for 28 d.

^d The RSD was calculated for each concentration as the percentage of standard deviation of the mean values of samples analyzed at different time intervals.

^e The accuracy of the assay was determined as the percentage of the mean value obtained at different time intervals.

*The quantity of MEL in different samples of calculi was calculated by comparing the peak areas of samples with those of external calibration standards of pure substances.