Determination of vitamin A in liver and liver-containing products using narrow-bore normal, phase HPLC

Abstract

Vitamin A concentrations in livers of fattening animals and liver-containing products may reach much higher values than was assumed up to now. This effect may be caused by animal feed, which is usually supplemented with vitamins. To support this supposition, 57 liver samples of different species of animals, 97 liver sausages and 106 samples of liver-containing infant food were analysed. For isolation of retinol from the sample matrix the sample was saponified for 16 h under a nitrogen atmosphere at room temperature. Retinol was extracted from the saponification solution by using disposable cartridges. For chromatographic determination a normal-phase HPLC system using a narrow-bore analytical column and a photodiode array detector was used. It was possible to separate all-trans-retinol from other isomers. The identity of the peaks could be confirmed by recording the UV spectra.--The results of the retinol contents found in the analysed samples ranged from 11.6 to 160.7 mg/100 g in liver, from 1.4 to 31.1 mg/100 g in liver sausages and from 0.5 to 3.8 mg/100 g in infant food containing between 5 and 11% liver. By consuming liver-containing meals frequently a multiple amount of the recommended dietary intake ranging from 0.375 mg for infants to 0.8 mg for adults may be taken up. Also the recommended daily intakes of the Deutsche Gesellschaft für Ernährung can be exceeded.--The carry-over effect of daily vitamin A consumption of pigs and their liver vitamin A was investigated by parallel determination of the retinol content in the liver after slaughtering and the vitamin A content in the pig-feed during the fattening period. A clear correlation between their daily vitamin A intake and the resulting retinol content in the livers was found.