Rapid method to determine sphinganine/sphingosine in human and animal urine as a biomarker for fumonisin exposure

The widespread occurrence of fumonisins in maize and maize-based foods and feeds demands the development of rapid and reliable methods for the analysis of suitable biomarkers in biological fluids in order to assess human and animal exposure to these important mycotoxins. The increase in the ratio of free sphinganine/sphingosine (SA/SO) in urine has been recently proposed as a biomarker to evaluate exposure to fumonisins. The presently available method for the determination of SA and SO in biological samples is labor intensive, time consuming and insufficiently accurate. A new method has been proposed for the determination of SA and SO in human and animal urine which is more precise and accurate, and drastically reduces the number of steps during extraction and clean-up. The method is essentially based on the use of silica minicolumn clean-up of the chloroform extract from alkalinized urine. The final extract is derivatized with o-phthaldialdehyde reagent and SO and SA are determined by reversed-phase HPLC with fluorimetric detector. Urine samples spiked with SO, SA standards at concentrations ranging from 1.5 to 15 ng/ml have given mean recoveries higher than 80% and precision (coefficient of variation) lower than 10%. Detection limit for SO and SA was 0.1 ng/ml.