Synthesis and purification of radioactive fatty acylcarnitines of high specific activity

Micromole quantities of radiolabeled fatty acylcarnitines of high specific activity were synthesized by a simple one-step, one-pot acylation of [3H]carnitine in the presence of the respective fatty acid and acid chloride. The acylated product was isolated in high yield and high purity using liquid-liquid partitioning with isopropanol:hydrochloric acid:heptane (4:1:12 v/v) followed by butanol extraction. Product recovery was 91% for octanoyl[3H]carnitine and 90% for palmitoyl[3H]carnitine and contamination of both products with carnitine was less than 1%. The method is simple and fast, and results in high yields of pure fatty acylcarnitine in micromole scale.