Determination of Solvent Extractable Subs – Leather Accessories

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This SOPs is intended for the determination of substances which are extractable in Dichloromethane or petroleum Hydrocarbon Solvent 40/46 in all types of leather.


APPARATUS

  • Desiccator.
  • Filter Paper thimbles
  • Oven  – 102 ± 2°C
  • Soxhlet extraction apparatus.
  • Extraction Flask- 250 ml


REAGENTS

  • Dichloromethane or Petroleum Hydrocarbon Solvent 40/60.


PROCEDURE

  • Sample the leather specimen to grounded form in leather mill machine.
  • Dry the extraction flask for half an hour at 102°C. Cool for about 20 min in a Desiccator and weigh.
  • Weigh accurately about 10±0.1 gm of leather from test portion.
  • Press the leather evenly into the filter paper thimble and cover the leather with a thin layer of grease- free cotton wool.
  • Place it in a Soxhlet extractor with the tarred flask.
  • Start the extraction of the soluble with the Dichloromethane solvent.
  • After at least 30 changes of solvent, distill the solvent from the flask, containing the extractable matter.
  • Dry the extract in the oven for 4h at 102°C.
  • If drops of water are visible, add 1 to 2 ml of ethyl alcohol, and dry again for sometime at 102°C.
  • Weigh after cooling for 30 minutes in a Desiccator.
  • If redrying results in a further weight reduction of more than 10 mg, continue drying up to a maximum of 8 h.


CALCULATION


Calculate the extractable substances in leather as follows:


Extractable substances, percent by weigh=100 x W2 / W1


Where,
         W2= weight in g of the extract,
         W1=weight in g of the material taken for the test.

PERMISSIBLE ERROR –


The result of a duplicate determination shall not differ from one another by more than 0.2 percent calculated on the original weight of the material taken for the test.



REFERANCE: – IS 582 [LC 4]-1970 – methods of chemical testing of leather.



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