AOAC RI ERP E-Book - DS DF

C. Reagents

(a) EthanolEtOH 95 % v/v. or Industrial Methylated Spirits (IMS). Industrial Methylated Spirits made up of: ethanolEtOH 84.8333 (w%), 85.952 (v%); water 5.6571 (w%), 4.524 (v%); 2-propanol 4.9118 (w%), 5.0000 (v%); methanol 4.5979 (w%), 4.524 (v%). Can be prepared by mixing 5 volumes of 2 propanol with 95 volumes of denatured ethanol formula SDA-3A [ ( 100 volumes of 95% ethanolEtOH combined with 5 volumes of methanol ].). (b) EthanolEtOH (or IMS), 78 % .— Place 179 mL water into 1-L volumetric flask. Dilute to volume with 95 % ethanolEtOH or IMS. Mix. (c) Acetone , reagent grade. (d) Stock PAA plus AMG powder.— PAA (40 KU/g) plus AMG (17 KU/g) as a freeze-dried powder mixture. Note: One Unit of AMG activity is the amount of enzyme required to release one mole of D -glucose from soluble starch per minute at 40°C and pH 4.5; one Unit of PAA activity is the amount of enzyme required to release one mole of p -nitrophenyl from Ceralpha reagent per minute at 40°C and pH 6.9; AOAC Method 2002.01). PAA/AMG preparations should be essentially devoid of -glucanase, -xylanase and detectable levels of free D -glucose. Stable for > 4 years at −20°C. (e) PAA (4 KU/5 mL)/AMG (1.7 KU/5 mL).— Immediately before use, dissolve 1 g of PAA/AMG powder in 50 mL of sodium maleate buffer (50 mM, pH 6.0 plus 2 mM CaCl 2 ) and stir for approx. 5 min. Store on ice during use. Use on the day of preparation. [ Alternatively: Some individuals are allergic to powdered PAA and/or AMG. In this instance, engage an analyst who is not allergic to prepare the powdered enzymes as an ammonium sulphate suspension as follows: gradually add 5 g of PAA/AMG powder mix (PAA 40 KU/g plus AMG 17 KU/g ; reagent 4 C(d ) to 70 mL of cold, distilled water in a 200 mL beaker on a magnetic stirrer in a laboratory hood and stir until the enzymes are completely dissolved (approx. 5 min). Add 35 g of granular ammonium sulphate and dissolve by stirring. Adjust the volume to 100 mL with ammonium sulphate solution (50 g/100 mL) and store at 4 o C. (This preparation contains PAA at 2 KU/mL and AMG at 0.85 KU/mL). Stable at 4 o C for 3 months]. AOAC Research Institute ERP Use Only

Method updated 2008--08-10 This copy printed 22 August 2017

10