Document DDv8yyDj7NDXez61GnnM7p2vM

DETERMINATION OF RESIDUAL VINYL CHLORIDE MONOMER IN VINYL RESINS METHOD NUMBER WC-326-G-1 ISS * E 1 PURPOSE DA fjctober 15, 1975 This is a method for determining small amounts of residual vinyl chloride monomer present in vinyl resins. The resin sample is dis solved in a suitable solvent and is analyzed by means of a gas chroma tographic technique utilizing a backflush mode. The method is appli cable to polyfvinyl chloride), vinyl chloride-vinyl acetate copoly mers and other vinyl resins in which there are no volatiles capable of interfering with the determination. It resolves vinyl chloride from the major impurities found in vinyl resins and can be quanti tated with proper calibrations. 2 EQUIPMENT AND REAGENTS 2a Gas chromatograph, Hewlett-Packard (F and M) Model 5750 or equi valent, equipped with a hydrogen flame ionization detector. 2b Backflush valve, Bendix 8-port sliding plate valve or equivalent. 2c Tetrahydrofuran, reagent grade 2d Balance with accuracy to 0,01 gram 2e Fritted glass sparger, fine 3 INSTRUMENT PARAMETERS : PLAINTIFF'S ( i ; I _EXHIBIT Instrument Hewlett-Packard (F and M) Model 5750 or equivalent, equipped with hydrogen flame ionization detector Column 20 feet x 1/8-inch stainless steel tubing packed with 20 percent TERGITOL E-35 on Chromosorb W AW, 60/80 mesh Backflush valve Bendix, 8 port sliding plate valve or equivalent UCC - 109541 CONFIDENTIAL WC-326-G-1 p2 of 9 Temperatures Column Injection port Detector 70C isothermal 100C (maximum) 300C Carrier gas helium Flows Helium carrier a) inject b) backflush gas 40 cc/minute 40 cc/minute Hydrogen 20 psi at cylinder heat Compressed air 40 psi at cylinder head Sample size 40 microliters Electrometer Range Attenuation 1 8 Approximate elution time Vinyl Chloride 2.8 minutes 4 SCHEMATIC OF FLOW SYSTEM A schematic of the flow system utilizing the Bendix 8-port sliding plate valve is shown in Figure 1. 5 PROCEDURE 5a Analyze the tetrahydrofuran (THF) prior to preparing any samples or calibration standards using the parameters listed in Section 3. A backflush valve has been incorporated into the system to facilitate the analysis. Four minutes after the sample injec tion, the column is backflushed and vented to the atmosphere thus preventing the solvent from reaching the detector. A backflush time of 10-15 minutes should be sufficient to elute the solvent. After the backflush period, return the valve to its original position. The base line should be allowed to equili brate before injecting another sample. NOTE 1: An alternative backflush technique can be'employed which""significantly reduces the analytical time required to elute the solvent from the column and reestablish a stable base line. In this procedure, a four-foot section of the twenty-foot an alytical column is employed as a precolumn, with the remaining sixteen-foot section functioning as the analytical column. The columns may be connected to the backflush valve as described in Section 2b of this method or to a 6-port rotary valve. Flow schematic diagrams for both valves are shown in Figures 4 and 5. ucc 109542 WC-326-G-1 p3 of 9 The sample of vinyl chloride monomer in THF is carrieddirectly in the 4' precolumn from the heated injection port with the backflush valve in the Inject position. After approximately 1.0 minute, the VCM monomer elutes from the precolumn into the analytical column. The valve is then switched to the Backflush position to flush the THF (which remains in the precolumn) to vent. 5b Compare the THF chromatogram with those shown below. If the scan is comparable to A, the THF will have to be sparged with nitrogen at a medium flow rate for approximately 2 hours in an effort to remove the interfering peak. Reanalyze the sparged THF to determine if it is acceptable. If the scan is comparable to B, the THF should be acceptable for use in the analysis. interfering peak minutes 5c Accurately weigh one gram of the resin to be analyzed into a 6-dram vial** containing 9 grams of THF. Cap the vial and shake to effect solution. Analyze the sample using the parameters listed in Section 3 and follow the above instructions for the backflush. ** A glass vial and a phenolic cap equipped with a polyethylene liner are used to insure gas retention. 5d Measure the peak height of the vinyl chloride peak in milli meters. The area can also be measured using an acceptable technique (e.g. planimeter, automatic integrator, computer, etc.). 6 CALIBRATION Prepare solution mixtures of varying amounts of vinyl chloride iu THF to cover the expected ppm range of concentration, obtain the gas chromatogram for each sample using the parameters listed in Section 3. Prepare a chart plotting the peak height (or area) ob tained from the chromatogram of each sample versus the known concen tration to establish a relative detector response. See Figure 2 for typical calibration curve. ucc 109543 CONFIDENTIAL WC-326-G-1 p4 of 9 7 CALCULATIONS 7a Determine the monomer content in the test solution from the cal ibration chart. Apply the peak height (or area) of the monomer obtained from the chromatographic scan of the test solution to the calibration curve and read the corresponding concentration in parts per million (ppm). 7b The concentration value obtained from the calibration curve is total monomer in the solution. In order to convert the data to monomer concentration based on total resin, the value must be multiplied by a factor of 10. 8 GAS CHROMATOGRAM A gas chromatogram is attached as Figure 3 showing the response for 1.3 ppm vinyl chloride. 9 LIMIT OF DETECTABILITY The lower limit of analytical detectability as defined using poly (vinyl chloride) and vinyl chloride-vinyl acetate copolymers has been shown to be<0.2 ppm. 10 REPORT Full identification of sample Identification of the test method Vinyl Chloride Monomer, ppm. Analyst and Date UCC - 109544 CONFIDENTIAL WC-326-G-1 p5 of 9 FIGURE 1 SCHEMATIC OF FLOW SYSTEM UTILIZING THE BENDIX 8-PORT SLIDING PLATE VALVE "BACKFLUSH" UCC - 109545 CONFIDENTIAL ' '-326-G-l p6 of 9 FIGURE 2 TYPICAL GAS CHROMATOGRAPHIC CALIBRATION CURVE ppm VINYL CHLORIDE VS AREA IN TETRAHYDROFURAN WC-326-G-1 p7 of 9 FIGURE 3 GAS CHROMATOGRAM OF VINYL RESIN WITH 1.3 PPM VINYL CHLORIDE MONOMER D e te cto r response Time, minutes ucc 109547 CONFIDENTIAL WC-326-G-1 p8 of 9 FIGURE 4 Schematic of Flow System Utilizing Bendix 8-Port Sliding Plate Valve etcctor # ucc - 109548 CONFIDENTIAL  * FIGURE 5 SCHEMATIC OF FLOW SYSTEM UTILIZING THE VALCCT6-PORT ROTARY VAI.VE WC-326-G-1 p9 of 9 $