Determination of β‐carotene in plasma, blood cells and buccal mucosa by electrochemical detection

The β‐carotene concentrations in plasma, blood cells and buccal mucosal cells were determined by high‐performance liquid chromatography with electrochemical detection. This method was 1,000 times more sensitive than the conventional spectrophotometric method. Polymorphonuclear cells and red blood cells had lower β‐carotene levels than the other cells. After oral administration of 580 mg/day of all‐trans β‐carotene to human male volunteers for a week, the β‐carotene concentrations in all cell types increased at least several times above the original levels.