Use absorbances at 440 nm and then convert this to absorbance at 620 nm and subtract from the absorbance at 620 nm to determine the absorbance at 620 due to Vitamin A. Carotenoid Absorbance at 440nm Vitamin A Absorbance at 620 nm Carotenoid (mg/ml) Vitamin A mg/cuvette (sample) x x x x x x x x x x xUse absorbances at 440 nm and then convert this to absorbance at 620 nm and subtract from the absorbance at 620 nm to determine the absorbance at 620 due to Vitamin A. Carotenoid Absorbance at 440nm Vitamin A Absorbance at 620 nm Carotenoid (mg/ml) Vitamin A mg/cuvette (sample) x x x x x x x x x x x