Polyvinyl polypyrrolidone

It is also possible to fractionate wine anthocyanins on the basis of their degree of polymerization on a hand-packed column consisting of polyvinyl-polypyrrolidone, silica gel G, and silica 60. The free anthocyanins elute in the first fraction (methanol-HCl 999 1), slightly polymerized anthocyanins in the second fraction (formic acid-water 1 1), and the condensed polymeric forms are eluted in 100% formic acid. The absorbance of the three fractions is read spectrophotometrically (538 nm for the first fraction and 525 nm for the second and third fractions) and their relative proportions may thus be calculated. This test is a very good indicator of the age of a wine the younger the wine the higher the absorbance of the first fraction due to the presence of anthocyanin monomers conversely, the absorbance of the third (polymerized) fraction will be greatest in older wines. 

PMR spectroscopy has been applied to the characterisation of a wide range of homopolymers including PMMA [286-289], PVC [290-294], PS [293, 295, 296], polyvinyl ethers [297-300], polyacrylic acid [301], poly(methyl-a-chloroacrylate) [302], carboxy terminated polybutadiene [303], poly(a-methyl styrene) [304], natural rubber [305-307], chlorinated polyisobutylenes [308], sulfonated PS resins [309, 310], polyvinyl phenyl ether [311], lactone polyester [312], chlorinated PVC [313], PC [314], poly 1,3 butadiene [315], poly-2-allyl phenyl acrylate [316], poly(4-methyl-pentene-1) [317], polymethacrylic acid [318], PP [296], cyclic ethers [319], polymethacrylonitrile [320], poly(a-methyl styrene) tetramer [321], PEG [322], PE [289], polyacrylamide [311], polymethylacrylamide [323], polypyrrolidone [324], polychloroprene [325], phenol formaldehyde resins [326, 327], Nylon 66 [328], polyvinylidene fluoride [329], polyvinyl formate [330], polyacrylonitrile [331], epoxy resins [332], allyl biguanide [333], poly(2-isopropyl-2-oxazollines) [334] and trehalose vinyl benzyl ether [335]. 

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