DLTDP?
ΒΗΤ DSTDP
Column: Poragel A Solvent: THF @ 1 ml/min Sample: Polymer additive mixture Detector: Differential refractometer
Only the liquid chromatographer knows for sure. 114.1 122.4 153.3 Elution Volume, Milliliters
Identifying unknown compounds with closely matching IR spectra used to be one of the knottiest problems in analytical chemistry. Combining liquid chromatography with IR, however, makes the solution a routine operation. Take the two spectra shown above. They represent two compounds (distearylthiodipropionate and dilaurylthiodipropionate) that would be extraordinarily difficult to differentiate by traditional methods. But the ALC-100 fast liquid chromatograph will separate them for you by molecular size differences. And provide you with the ultra-pure fractions you need to do subsequent IR testing for functionaf group identification. In addition, the response of the ALC-100's detector is a measure of the concentration of each compound present. Together, the two techniques give you accurate molecular structure confirmation: a sort of poor man's mass spectrometer. Circle No. 83 on Readers' Service Card
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ANALYTICAL CHEMISTRY
Far from being a limited technique, the combination of LC and IR lends itself to a diversity of analytical applications associated with the identification of unknown compounds, reaction products and by-products, additives, and impurities. A recent paper 1 on the subject discusses a variety of these problems and amply demonstrates how well the LC/IR technique solves them. If you'd like more information, write us for a copy of the above-mentioned paper. We have some literature on the latest advances in fast liquid chromatography that you might also find interesting. Waters Associates, Inc., 61 Fountain Street, Framingham, Mass. 01701.
'"Analytical Synergism: Gel Permeation Chroma tography + Infrared Spectrometry Attack Complex Organic Mixtures." H. L. Spell, Dow Chemical Company, presented at ASTM E-19 committee, Cincinnati, Ohio, Sept. 25, 1968.
WATERS ASSOCIATES
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