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Handbook of Size Exclusion Chromatography and Related ...

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compared to anormal product. By comparing the raw chromatograms <strong>of</strong> any lots<br />

<strong>of</strong> product to acontrol, the abnormal lot <strong>of</strong> product can be easily identified.<br />

4.1.2 Determining Percent Active Polymer in Solution Product<br />

Figure 7a shows the chromatograms obtained using an RI single detector for five<br />

low MWAM/AA solutions. The injected mass <strong>of</strong> the five solutions varies from<br />

9.48 10 26 to1.90 10 24 g.Acalibration curve that relates the injected mass<br />

<strong>and</strong> total area <strong>of</strong> the polymer peak for the five solutions is shown in Fig. 7b.<br />

Utilizing the calibration constant (4.90 10 210 g/unit area) obtained from<br />

Fig. 7b, the active polymer in the copolymer sample has been determined to be<br />

30.2%. This is about 0.6% higher than the expected value (29.6%).<br />

4.1.3 Determining the Molecular Weight Reduction <strong>and</strong> Mass Loss<br />

<strong>of</strong> Degraded Polymer<br />

Figure8showsSECchromatograms<strong>of</strong>75/25wt%AM/AAcopolymertreatedat<br />

various conditions (44). The 4000 ppm solution treated in an autoclave at 3508C<br />

<strong>and</strong>2400 psipressurehasabout82% M wreduction<strong>and</strong>about71%massloss.This<br />

masslosscanbedeterminedfromthereduction<strong>of</strong>areaforthedegradedpolymerin<br />

Figure 8 <strong>Size</strong>exclusionchromatograms<strong>of</strong>A75/25 wt%AM/AAcopolymer treatedat<br />

various conditions (4000 ppm solution). (Courtesy <strong>of</strong> Millipore Corporation, Billerica,<br />

Massachusetts, U.S.A.)<br />

© 2004 by Marcel Dekker, Inc.

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