Mojonnier Method (AACC 30-10)
Diethyl Ether
Description: colourless liquid with sweet odour.
Risk: danger, caus irritation, harmful if swallowed or inhaled, extremely flammable, highly volatile.
Precautions: keep away from heat, keep in tightly clod container. U with adequate ventilation or in fumehood. Wash thoroughly after handling. In ca of fire, u alcohol foam, dry chemical, carbon dioxide - and flush spill area with water spray to reduce vapours.
Spillages: wear breathing apparatus and full protective clothing, shut off ignition sources, stop leak if possible. U water spray to reduce vapours.
Disposal: Take up with sand and place in clean container, leave in fumehood for vapours to evaporate before disposing of sand.
Apparatus a) Water bath b) 50mL beaker 两成语c) Mojonnier fat extraction apparatus d) Steam bath e) Drying oven f) Centrifuge |
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Reagents Ethyl alcohol (95%) Hydrochloric acid solution (25mL concentrated HC1 plus 11mL water) Diethyl ether, free from residue on evaporation Petroleum ether – boiling point between 400C and 600C 35% w/w ammonium hydroxide 2% phenolphthalein合同类别 |
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Petroleum Ether 40 怎样注册qq邮箱oC - 60 oC序号排序规则
Description: clear, colourless liquid with hydrocarbon odour.
Risk: extremely flammable, caus irritation, avoid breathing vapour, keep away from heat and keep in tightly clod container.
Precautions: u in fumehood where possible or with adequate ventilation and general laboratory protective equipment.
Spillages: wear suitable protective gear, shut off ignition sources, take up with sand or other non-combustible absorbent material.
Disposal: place into container and in fumehood so solvent can evaporate before later disposal. Flush area with lots of water.
Preparation of flour, bread or baked cereal products
a) Place 2 g flour in a 50 mL beaker, add 2 mL ethyl alcohol and stir to moisten all particles. Moistening of the sample with alcohol prevents lumping on addition of acid. Add 10 mL HCl and mix well. Set beaker in a boiling water bath and stir at frequent intervals for 30-40 minutes. Cool. Add 10 mL ethyl alcohol and mix.
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b) Transfer mixture to a Mojonnier fat extraction tube. Rin beaker into the extraction tube with 25 mL diethyl ether in three portions. Stopper the tube and rock gently for about 1 minute.
Preparation of Dairy Products
a) 年会节目速成Weigh accurately sufficient sample to give between 0.3 and 0.7 g of extracted fat into a dry Mojonnier tube (e.g. 10 mL milk; 1-2 g milk powder). Make up to 10 mL if necessary with water, and shake to dissolve or blend.
b) Add 2 mL ammonium hydroxide and mix well in the lower bulb. Place in a 60 C water bath for about 5 minutes and swirl occasionally. Cool. Add 2-4 drops phenolphthalein.
c) Add 10 mL of ethyl alcohol and mix by allowing the liquid to flow backwards and forwards between the two bulbs; avoid bringing the liquid too near the neck of the tube. The complete extraction of the fat is dependent on satisfactory mixing at each stage.
Mojonnier fat extraction procedure (all samples)梦见蜘蛛是什么意思
a) Add 25 mL of diethyl ether, stopper the tube and rock gently for about 1 minute.
b) Remove the stopper, add 25 mL petroleum ether, using the first few mL to rin the stopper and the neck of the tube, allowing the washings to run into the tube.
c) Replace the stopper, again wetted with water, rock carefully for 30 conds and centrifuge Mojonnier tubes for 2 minutes at 600 rpm.
d) Examine the tube to e if the interface of the liquid is in line with the upper junction of the neck of the tube. If it is below this, it should be raid by the addition of a little water run down the side of the tube.
e) Remove the cork and carefully decant as much as possible of the organic solvent layer into a pre-weighed conical flask by gradually bringing the cylindrical bulb of the tube into a horizontal position. Place conical flask on a steam bath in the fumehood to evaporate off the ethers while the next extraction is carried out.
f) Add 5 mL ethyl alcohol to the Mojonnier tube and mix. This helps prevent emulsions forming and is in accordance with the AOAC method.
g) Repeat the extraction using 15 mL of diethyl ether and 15 mL of petroleum ether (steps a to e). Add the cond extract into the same flask as ud in step (e).
h) Evaporate all the solvents from the flask using a steam bath. There should be no smell of ether remaining in the flask (DANGER! If there are ether vapours remaining in the flask, there is a risk of explosion if it is placed in an air oven). If possible, leave the flasks overnight in the fumehood to remove all solvent traces. Dry the flask in the oven at 100 C for ~90 minutes. Allow the flask to cool to room temperature before weighing the flask and recording the fat content extracted from the sample. Do not u a desiccator.
