Determination of retinol, antioxidant vitamins and homocysteine in skin puncture blood.

For determination of the vitamin status via mass screening, simple and rapid methods are required. Additionally, blood samples should be obtained using simple and low invasive sampling techniques. To fulfill this existing methods have been modified to analyze retinol, tocopherols, beta-carotene, vitamin C and homocysteine in 20 microliters plasma. Blood samples were obtained via skin punctures. HPLC measurements were carried out with isocratic separation and precolumn derivatization. Intra and interday variation coefficients were below 8% and regression coefficients better than 0.99 for all measurements. The difference between venous and capillary samples were < 5%. In conclusion, the methods employed proved satisfactory for the determination of important nutritional parameters in blood samples obtained via skin punctures. These methods are therefore well suited for mass screening, especially under field conditions in developing countries.