AOAC Final Action Methods in 2018

( c )  Calibration curve .—Make a calibration curve using either weighted linear or quadratic regression with correlation coefficients of at least 0.9995 from at least five standards prepared from intermediate standard solution, including a blank (Std0). Six suggested concentrations of the standard solution (Std1–Std6) shown in Table 2011.14K and expressed in mg/kg. ( d )  Test portion analysis .—Analyze test solutions using an ICP- AES instrument calibrated with the working standard solutions. Insert a working standard or other suitable quality control solution every 10 test portions to monitor for instrument drift. The inclusion of a digestion blank, a sample duplicate, and known reference materials is highly encouraged. F. Calculations The concentration ( C ) of each element, in mg/kg, is calculated as follows:

obtained from instrument; V = volume (mL) of the test solution after being made up (i.e., 50 mL for MDC and 100 mL for MDO); F  = dilution factor of the test solution; and m = weight of the test portion (g). References: J. AOAC Int . 95 , 177(2012) (First Action, Food) J. AOAC Int . 102 , 1845(2019)

DOI: 10.5740/jaoacint.19-0073 (Final Action, Milk and Milk Products, Infant Formula, Adult Nutritionals) AOAC SMPR 2014.004 (Minerals and Trace Elements in Infant Formula and Adult/Pediatric Nutritional Formula) J. AOAC Int . 98 , 1042(2015) DOI: 10.5740/jaoac.int.SMPR2014.004

Posted: 2013 (First Action, Food); March 2019 (Final Action pre- publication; method extension to include milk, dried milk, butter, cheese, whey, dried whey, infant formula, and adult nutritionals); November 2019 (Final Action publication; method extension to include milk, dried milk, butter, cheese, whey, dried whey, infant formula, and adult nutritionals)

F V a C ××

=

m

where C = concentration in the test portion sample (mg/kg); a = concentration (mg/L) of the element in the digest solution as

© 2019 AOAC INTERNATIONAL