Preparation of cain
I. The purpo and requirements
1. Master to u the centrifuge;
2. Master prepared from milk cain in the principles and methods.
II. The experimental principle实事求是的含义
Cain is protein phosphorus, but also the heterogeneous mixture, rich in Tyr, Met, Gys, (Gys) 2, pI equal to 4.7 to 4.8, insoluble in ethanol.
The experimental u when in the isoelectric point of the principle of minimum solubility, the milk's pH to 4.7, the cain will precipitate out. Sediment washed with ethanol to remove lipid impurities, you get pure cain
III. Equipment and reagents
1. Equipment
a. Centrifuges禁用笔记本触摸板
b. Filtration system(Buchner funnel);
c. Constant temperature heating device
2. Reagent
a. pH4.7 acetic acid - sodium acetate buffer (0.2mol/L) 30ml
b. Milk 30ml
大别山石窟风景区c.95% ethanol
IV. Methods of operation
1. The 30ml milk heated to 40℃, stirring slowly add heated to 40 ℃, pH4.7 acetic acid - sodium acetate buffer, 30ml (with a precision pH meter or pH paper and adjusted to pH 4.7).
海绵粉扑 To have mixed suspension cooled to room temperature, centrifuge (4000 rpm / min) centrifugation for 5 minutes, remove the supernatant, the crude products obtained cain.
2. The precipitate washed once with water, centrifugation for 5 min (4000 r / min), discard the supernatant.
3. Add 30ml of ethanol in the precipitation, stirring a moment, put all the suspension transferred to Buchner funnel filtration.
4. The precipitate on the surface of the dish open, to get pure cain.
什么是干垃圾5. Accurately weighed to calculate concentration and yield.
V. The experimental results and analysis快乐的童年时光
1. The experimental results
Data of the measurement is shown in the following table.
The amount of milk(mL) | 幼儿园天气预报Cain(g) | Measured values(g/L) | The theoretical value(g/L) | Yield（%） |
30 广元凉面 | 2.0 | 66.7 | 35 | 190.5 |
| | | | |
End of the experiment to be cain yield was 190.5%, far greater than 100%, which is derived from the experimental proof of cain in the more impurities. Impurities which may be: water, ethanol and milk in some of the impurities.
2. The experimental analysis
a. Washed precipitate, when washed only once, did not completely wash out the impurities, so that the product is still more residual impurities, the results of this error is caud by one of the reasons.
b. After the filtration, did not u ethanol - ether mixture washed precipitate, not in the final precipitate washed with ether, resulting in the final product contains fat-soluble substances, alcohol, water and other impurities, which is the result of errors caud by one of the reasons.
c. No air-dried, during the experiment, water and ethanol in the product is not completely evaporated.
d. Buchner funnel in the transfer of diment from the pan to the surface when a small amount of diment left in the Buchner funnel and filter paper, and a small amount of precipitation is lost, leading to the result of error.
