Improved method for rapid determination of vitamin A in small samples of breast milk by high-performance liquid chromatography.

Employing a short, potassium hydroxide (KOH) saponification (25 min) and rapid extraction with n-hexane-toluene (1:1) and a <4-min retention time, a convenient, rapid, accurate and precise determination of vitamin A in breast milk was developed. The recovery rate was 102.3 +/- 2.5% and the small relative standard deviation (intra-assay 1.9%, inter-assay 2.3%) resulted in high precision. The amount of breast milk needed is very low (1 ml) which makes the method suitable for the use in free field studies with large sample sizes. The simple extraction and separation steps allow a high throughput screening under routine laboratory conditions.