Quantitative of crude fat (Soxhlet extraction)

, objective: to learn
principles and methods for determining crude fat content by sochi extraction method. , principle:
so-called coarse fat, fat, free fatty acids, wax, phospholipids, sterols and pigments and other fat-soluble substances.
soxhlet fat extractor is a re-distillation device (Figure 2-1), which is connected by a dipping tube, a small burner and a condensation tube. On both sides of the leaching tube are rainbow
straw
and airtrain, with samples of the filter paper bucket (bag) placed in the leaching tube. Solvent (ether) is found in a small can,
heating
after the solvent steam through the trachea to the condensation tube, condensate solvent drip into the leaching tube, immersion samples. The solvent in the leaching tube accumulates more and more, when the liquid surface reaches a certain height, the solvent and the crude fat dissolved in the solvent flow through the siphon tube into the small can. The solvent flowing into the small can be gasified due to heat, the gas to the condensation tube and condensation and drip into the leaching tube, so repeatedly extracted back distillation, the sample of crude fat extracted and brought to the small burner. Finally, the solvent in the small can be steamed, dried, the weight of the small can beoech increased, that is, the crude fat content in the sample. , Equipment and
Reagents
: 1. Equipment:
(1) wheat bran and other animal and plant materials.
(2) filter paper. (3) Soc extractor (one set).
(4) Analyze
balance
. (5)
the
water bath
(6)
dry
pan. (7) Iron frame.
(8) rubber tube. (9) All-in-one clip.
(10) drying box. Hair dryer.
2. Reagents:
waterless ether: commercially available waterless ether often still has moisture, need to be treated and used, the treatment method is as follows:
(1) water-rich ether, can be put in the ether without water calcium chloride (about 1/3 of the total volume), 1 to 2 days later,
filtration
, water bath distillation, collection of 36 degrees C distillate. Add an appropriate amount of metal sodium
(1)
to this distillate (to be pressed into sodium strips with a sodium press or cut into thin slices with a knife), distilled after 1-2 days, to collect 36 degrees C distillate, that is, no water ether.
(2) less moisture ether, can be added to every 500g ether 30g-50g waterless sodium sulfate or metal sodium, 1 to 2 days after distillation, collection of 36 degrees C distillate. , operation steps:
1. The washed Sauer extractor vial is penciled at the grinding port number, 103-105 degrees C baked for 2 hours
(2)
, removed, cooled in the dryer. Analyze balance weighing and record it.
2. Using the analytical balance, the dry sample is called about 2g (accurate to 4 bits after the sub-point). Samples need to be shredded, through 40 mesh sieve holes, wrapped in filter paper
(3)
and placed in the leaching tube.
3. Pour 1/2-2/3 in a weighed small
(4)
a waterless ether. Connect the parts of the Sotheton extractor, the thermostat bath heating distillation 2-4 hours (sample fat content is high, should be appropriately extended time)
(5)
. Control the water bath temperature, 3-5 times per hour distillation is more suitable
(6)
.
4. After extraction, when the ether is fully flowing into the small charred bottle, remove the filter paper bag and distill it back once to wash the leaching tube. Continue heating, pour out the ether in the leaching tube before approaching the upper end of the siphon pipe without flowing into the small can. If ether is still left in the small can, continue to heat and evaporate until the solvent in the small can begrase is basically steamed, stop heating, remove the small burner, blow the remaining ether out of the bottle with a hair dryer
(7)

At the same time, bake for half an hour in a 103-105C
oven
and remove the fat content of the sample by adding weight from the small cans to cool to room temperature in the dryer and weigh it.
, according to the same method, with non-packed samples of filter paper bags to do blank determination.
fat is determined, the small canister needs to be soaked with 2% sodium hydroxide alcohol, and then washed and dried with soap to preserve.
Note: This experiment should pay attention to fire prevention, ether is flammable, avoid open fire heating, at the same time pay attention to the extractor at all connections whether the air leakage, and condensation tube condensation effect is good, so as not to a large number of ether vapor escape.attached
water measurement
take flat weighing bottle
(8)
2, wash, use a pencil at the grinding point to make a good mark, put 103-105 degrees C oven baking for 2 hours, moved into the dryer, cold to room temperature (about 10-15 minutes), weighing (accurate after the 4th place after the small point, the same below). Using weighing bottles weighing weight, each called crushed sample (wheat bran) 2g, while baking at 103-105 degrees C for 2 hours, remove the dryer cooling, weighing. Bake so repeatedly until the constant weight
(9)
, press to calculate the water content of the sample.
note:
1. When baking samples, the cap of the weighing bottle must be opened and rested on the mouth of the weighing bottle so as not to evaporate water, but it is not necessary to remove the lid, otherwise it is easy to get dirty and wrong.
2. When cooling and weighing, the cap of the weighing bottle should be covered, called important quickly, the water absorbent in the dryer needs to be fresh, otherwise the sample will absorb moisture, or even increase the weight.
3, throughout the operation process, should keep the weighing bottle clean, can not be taken directly by hand.(1) Metal sodium in water explosion, should be noted. You can't take it directly by hand! Using the metal sodium strip (pieces), the outer yellow substance can be washed with xylene, then immersed in kerosene and stored in a sealed container.
(2) empty solichi extractor small burners (and empty weighing bottles) baked at 103-105 degrees C for 2 hours, i.e. constant weight.
(3) filter paper bag must be wired to ensure that the sample does not leak, preferably with a special filter paper bucket, mouth plug to skimmed cotton. When the sample pack (bucket) is placed in the leaching tube, its height must not exceed the maximum height of the ether surface.
(4) the amount of ether loaded, should be in the distillation process in the small flake has the appropriate amount of ether presence, such as found in the small flake fat color darkened (like charred), the solvent is too small or the temperature is too high.
(5) heated with a water bath, but the water used needs to be cleaned (with distilled water), after extraction, such as stains on the outside of the small can, should be washed clean, and then baked weighing.
(6) re-distillation speed should not be too fast, otherwise the sample fat is not easy to dip completely. Too slow is not economical. As for the amount of extraction time, and the sample dosage, fat content and particle size, the sample amount and extraction time used in this experiment is only suitable for determining wheat bran.
(7) the small amount of ether left in the small flake must be exhausted in the ventilation area and then put into the oven, otherwise it is prone to accidents.
(8) If using a high-type weighing bottle, sample moisture is not easy to dry should often mix samples, for this can be placed in the bottle, baking and weighing together. When weighing bottles with flat type, the sample should also be thinly tiled to the bottom of the bottle, not too much.
(9) the criteria for measuring constant weight should be based on the valid number of each experiment, the difference between the last two weights of this experiment is not more than 10 mg.