Determination of amino acids in jams, fruits and pharmaceutical preparations by gas chromatography using trifluoroacetylacetone and ethylchloroformate as derivatizing reagents
A gas chromatography (GC)-flame ionization detection procedure was used to determine amino acids in a pharmaceutical preparation (Aminess N tablets), jams (apple, mango, strawberry and mixed fruit), juices (lemon and orange) and a vegetable (kundru). Free amino acids were extracted as aqueous or aqueous–methanol solutions and hydrolyzed by acid treatment with 6 M hydrochloric acid. GC was performed after pre-column derivatization with trifluoroacetylacetone and ethylchloroformate using an HP-5 column (30 m × 0.32 mm id). The complete separation of 19 amino acids was repeatable with a relative standard deviation, in terms of retention time and peak height/peak area, within 3.8%. The limits of detection were in the range 0.1–0.2 μg mL−1. Differences in the concentrations of both free and acid hydrolyzed amino acids were observed in the various jams, fruit juices and vegetables.