AOAC Official Method 896
|
ID： |
BEED10A87C1A4A98BE9EB99C080BCB16 |
|
文件大小(MB)： |
0.18 |
|
页数： |
1 |
|
文件格式： |
|
|
日期： |
2024-7-31 |
|
购买： |
文本摘录（文本识别可能有误，但文件阅览显示及打印正常，pdf文件可进行文字搜索定位）：
33.2.21,AOAC Official Method 896.01,Lactose in Milk,Polarimetric Method,First Action 1896,Final Action,A. Reagents,(a) Acid-mercuric nitrate solution. —Dissolve Hg in twice its,weight HNO3 and dilute with 5 volumes H?O. Or—,(b) Mercuric iodide solution. —Dissolve 33.2 g KI and 13.5 g,HgCl2 in 200 mL CH3COOH and 640 mL H2O.,(c) Phosphotungstic acid solution, 5%. —Dissolve 5 g PTA in,95 mL water.,B. Determination,Weigh 65.8 g (2 normal weight) milk into each of 2 volumetric,flasks, 100 and 200 mL, respectively. To each flask add 20 mL,acid-Hg(NO3)2 solutionor 30 mL HgI2 solution. To 100 mL flask,add 5%phosphotungstic acid solution to mark, and to the 200 mL,flask add 15 mL 5% phosphotungstic acid solution and dilute to,mark with H2O. Shake both flasks frequently during 15 min, filter,through dry filter, and polarize. (It is preferable to read solution,from 200 mL flask in 400 mm tube to reduce error of reading; solution,from 100 mL flask may be read in200 mmtube.) Calculate,% lactose in test portion as follows: (1) Subtract reading of solution,from 200 mL flask (using 400 mm tube) from reading of solution,from 100 mL flask (using 200 mm tube); (2) multiply,difference by 2; (3) subtract result from reading of solution,from 100 mL flask; (4) divide result by 2.,References: Analyst 21, 182(1896).,JAOAC 25, 603(1942); 27, 232(1944).,CAS-63-42-3 (lactose),. 2000 AOAC INTERNATIONAL……
……