AOAC SPIFAN Nutrients ERP Review (March 14, 2019)

2016.13 (Jan. 2019) Carot-02 MLT Report FOR ERP USE ONLY DO NOT DISTRIBUTE

and not by more than 10% for lycopene. Use the average of the points from the two curves bracketing the samples for calculations. (5) Representative sample chromatograms are shown in Figures C – E . H. Calculations (a) Determine the purity of lutein, β-carotene, and lycopene standards by first determining the spectrophotometric purity and then the chromatographic purity of each. The overall purity is calculated as the product of the two measured purities (1) Spectrophotometric purity (SP) .—Measure each standard measuring solution, E(b) , against the appropriate solvent blank at its absorbance maximum (444 nm for lutein in MTBE, 450 nm for β-carotene in MTBE, and 471 for lycopene in n-hexane). Calculate the spectrophotometric purity of each reference standard as the observed absorbance over the expected absorbance: SP = (Abs MS × V Total × 1000)/(E 1%,1cm × V Stock × C W ) where Abs MS = absorbance of the standard measuring solution; V Total = total volume of standard measuring solution made, in mL; 1000 = factor for g to mg; E 1%,1cm = extinction coefficient [lutein in MTBE: 2589 at 444 nm (18); β-carotene in MTBE: 2588 at 450 nm (18); lycopene in hexane: 3450 at 471 nm (17)]; V Stock = volume of standard stock solution used, in mL; C W = stock concentration by weight, in mg/100 mL; spectrophotometric purity is typically greater than 0.90 (i.e., 90%). (2) Chromatographic purity (CP). —Inject standard working solutions, E(c) , at least 3 times. The CP is calculated as: CP = (area of the all- trans -carotenoid peak)/(sum of areas of all relevant peaks)

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