AOAC Final Action Methods in 2019

Figure 2016.13D. Chromatogram of a toddler formula sample. Lut = Lutein, Zea = zeaxanthin, Apo = apocarotenal, AC = α-carotene, and BC = β-carotene.

where C ApoStock  = concentration of apocarotenal stock solution calculated in H(b) and 1/100 = dilution of stock solution to working solution. ( d ) Calculate the concentration of apocarotenal, in μg/100 mL, in the apocarotenal intermediate solution, E ( d ): C ApoInterm = C ApoStock × (3/50) where C ApoStock = concentration of apocarotenal stock solution calculated in H ( b ) and 3/50 = dilution of stock solution to intermediate solution. ( e ) Calculate the concentration of each carotenoid analyte (e.g., lutein, C LutIntermed ) in the all- trans form, in μg/100 mL, in the mixed carotenoid intermediate solution, E ( e ): C LutInterm = C LutStock × (V Stock /V MC ) where C LutStock = concentration of lutein stock solution calculated in H ( b ); V Stock = volume of carotenoid stock solution, E ( a ), used; V MC = total volume of mixed carotenoid intermediate solution.

( 3 )  Reference standard purity (P) .—Calculate the purity of each reference standard: P = SP × CP × 100 where 100 = factor for converting decimal to percent. ( b ) Calculate the concentration of each carotenoid (e.g., lutein, C LutStock ) in the all- trans form (in μg/100 mL) in each standard stock solution, E(a) : C LutStock = (W Lut /V Stock ) × (P Lut /100) × 1000 × 100 whereW Lut = weight of lutein used to make the stock solution in mg; V Stock = volume of the stock solution in mL; P Lut = reference standard purity of all- trans lutein calculated in H(a) ( 3 ); 100 = conversion from percent to decimal; 1000 = conversion of milligrams to micrograms; 100 = conversion from μg/mL to μg/100 mL . ( c ) Calculate the concentration of apocarotenal, in μg/100 mL, in the apocarotenal working solution, E(c) :

C ApoWS = C ApoStock × (1/100)

Figure 2016.13E. Chromatogram of an RTF adult nutritional sample. Lut = Lutein, Apo = apocarotenal, AC = α-carotene, and BC = β-carotene.

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