Rank: Newbie Groups: Member
Joined: 8/28/2019(UTC) Posts: 28 Points: 84 Location: New York
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kansas1412, I received your samples and tested them with the Biuret test for proteins as well as the burn and microscopic test. I received three different fibers. One white, one green, one red. The white fiber burned like cotton. It flared and didn't self extinguish and smelled of burning paper. The other 2 samples where too small to burn test. I ran the Biuret test twice. The first time with 10 percent NaOH to dissolve the fiber and 4 percent CuSO4 to react with any peptide in solution indicating a protein. ( Note: Silk and wool contain proteins, cotton and synthetic do not). The first test was negative. A positive test is where the light blue copper sulfate solution turns purple. I noted the fibers were still visible in the NaOH after 2 hours. I'm not sure the fibers dissolved. I increased the NaOH from 10 percent to 40 percent and put the new samples in a water bath at 160F for 24 hours. The red thread dissolved completely the green only partly dissolved. None of the samples turned a classic purple of a positive Biuret test but the green and red fibers reacted to different degrees. In the image labeled final the beaker on the left is unreacted CuSO4. The next beaker is a know wool. The first test tube is the red fiber. The right test tube is the green fiber. The pictures don't do the colors justice but the small beaker and the left test tube have a distinct purple hue where the right test tub is cobalt blue. I can't say with certainty but the red fiber may contains protein. The green fiber is inconclusive. Moving to microscopic both the green and red fibers show very fine floss similar to silk and does not indicate courser wool. All said I can't confirm but it is possible it contains silk This test process still needs refinement. I haven't found any literature specific to testing rug fibers. I suspect that the dyes in the carpet may interfere with the classic color change of the Biuret test. File Attachment(s): ChefAndy attached the following image(s):
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