DL-Carnitine → (3-Carboxy-2-oxopropyl)trimethylammonium chloride

The reaction product was passed through a column of cation exchange resin Dowex AG 50W-X8 of 20×200 mm. This column had been previously brought to the H+ form by washing with 350 ml of 10% HCl and then with 500 ml of water. After introduction of the sample, the column was washed with 400 ml of water and then eluted with a 1-normal ammonia solution. The fraction discharged from the column between 150 ml and 225 ml, after the beginning of the elution with ammonia, was collected. By carnitine acetyltransferase titration, it was found to contain 1.48 g of carnitine. The sample was then evaporated in vacuo, re-dissolved into water (15 ml) and evaporated again. The carnitine base was converted to the hydrochloride by addition of 8 ml of a 1-normal HCl solution and evaporated again. The deliquescent product was dissolved into 75 ml of an anhydrous mixture of 3 parts of acetone with 2 parts of ethanol. 210 ml of acetone at 0° C. was added and the solution was stored at -9° C. for 12 hours. The crystals were collected, washed with ether and dried under vacuum. 0.91 g of carnitine was obtained. The final product was titrated with carnitine acetyltransferase and found to contain 89.5% of L-carnitine hydrochloride. It was obtained with an aggregate yield of 57% with respect to dehydrocarnitine hydrochloride.