UOP 1015-2017 Determination of Trace Oxygenates in Polymer Grade Ethylene & Propylene by Gas Chromatography Mass Spectrometry.pdf

1、 IT IS THE USERS RESPONSIBILITY TO ESTABLISH APPROPRIATE PRECAUTIONARY PRACTICES AND TO DETERMINE THE APPLICABILITY OF REGULATORY LIMITATIONS PRIOR TO USE. EFFECTIVE HEALTH AND SAFETY PRACTICES ARE TO BE FOLLOWED WHEN UTILIZING THIS PROCEDURE. FAILURE TO UTILIZE THIS PROCEDURE IN THE MANNER PRESCRIB

2、ED HEREIN CAN BE HAZARDOUS. SAFETY DATA SHEETS (SDS) OR EXPERIMENTAL MATERIAL SAFETY DATA SHEETS (EMSDS) FOR ALL OF THE MATERIALS USED IN THIS PROCEDURE SHOULD BE REVIEWED FOR SELECTION OF THE APPROPRIATE PERSONAL PROTECTION EQUIPMENT (PPE). COPYRIGHT 2017 UOP LLC. All rights reserved. . Nonconfiden

3、tial UOP Methods are available from ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. The UOP Methods may be obtained through the ASTM website, www.astm.org, or by contacting Customer Service at serviceastm.org, 610.832.9555 FAX, or 610.832.9585

4、 PHONE. Determination of Trace Oxygenates in Polymer Grade Ethylene & Propylene by Gas Chromatography Mass Spectrometry UOP Method 1015-17 Scope This method is for determining trace oxygenated components in high purity polymer grade ethylene and propylene gas or liquid using a gas chromatograph equi

5、pped with a mass spectrometer run in selected ion monitoring mode. The specific instrument is preconfigured and is capable of determining typical impurities in polymer grade ethylene or propylene, however this method only outlines the procedure for determining the specific oxygenates 2-butanol, acet

6、one, acetaldehyde, ethanol, isopropanol, methanol, methyl tert-butyl ether, n-propanol, n-butanol and tert-butanol. Some components co-elute but are readily extracted by unique ions. The lower limit of quantitation for each component is 0.05 mol-(or mass-) ppm. References UOP Method 999, “Precision

7、Statements in UOP Methods,” www.astm.org Wasson ECE Instrumentation, Application 460-SP instrument manual Wasson ECE Instrumentation, Dynamic Blender instrument manual Outline of Method The method requires the use of a dedicated gas chromatographic mass spectrometer system that is configured for aut

8、omated analysis which is capable, via valving and an on-board vaporizer, of determining impurities in polymer-grade ethylene or propylene gas or liquid. For the trace oxygenate analysis, a reproducible sample volume is injected into a gas chromatograph (GC) that is equipped with a polar fused silica

9、 capillary column (Figure 1, column 2), a mass spectrometer detector, and control and quantitation software. The concentrations of individual oxygenates are determined by a multi-point external standard calibration curve for each component that represents the area of each selected ion versus its con

10、centration, analyzed under identical conditions and injection volumes. Significance and Use High purity ethylene and propylene are used as feedstocks for production of polyethylene and polypropylene, respectively. The quality of the monomer is critical to successful polymerization. The presence of t

11、race amounts of certain impurities can have detrimental effects on the catalyst and product yields. This test method is suitable for setting specifications, for use as an internal quality control tool, and for use in development or research work. 2 of 13 1015-17 Apparatus References to catalog numbe

12、rs and suppliers are included as a convenience to the method user. Other suppliers may be used. Analyzer Wasson-ECE Instrumentation Application 460-SP “GC/MS Analysis of Impurities in Polymer-grade Propylene”, other vendors also supply similar systems. Confirm with the selected vendor that the requi

13、red separations are provided for the specific sample types to be analyzed. Pre-configured systems are available from Wasson-ECE for determining only oxygenates, the application specified can determine other impurities. The Wasson-ECE analyzer includes: Chromatographic column, 60 meters, PLOT, part#

14、60 m 2358, Wasson-ECE Instrumentation Chromatographic column, 60 meters, polar, part# 60 m 2318, Wasson-ECE Instrumentation Gas chromatograph, capable of multiple temperature ramping, built for capillary column chromatography utilizing a split injection system with electronic pressure control (EPC),

15、 having a glass injection port insert. Three channels of additional electronic pressure control is required. Agilent Technologies, Model 7890. Mass Spectrometer Detector, capable of selected ion monitoring and equipped with inert EI source, performance turbo pump, ion gauge controller kit and data s

16、ystem. Agilent Technologies, Model 5977B. On-board Vaporizer, converts LPG to the gas phase prior to injection, Wasson-ECE Instrumentation Clamp, for ring stand and sample cylinders, Fisher Scientific Cat. No. 02-217-000 Clamp holder, for ring stand and clamp, Fisher Scientific Cat. No. 02-217-005 D

17、ata System, for computerized instrument control of data acquisition and data reduction, ChemStation, Agilent Technologies. Dynamic Blender with mass flow controller, model DB302, Wasson-ECE Instrumentation Flowmeter, Mass/VLM, Agilent Technologies, Model ADM 2000. Leak detector, gas, Fisher Scientif

18、ic, Cat. No. 0.-251-702 Tubing, Sulfinert, .030-in ID x 1/16-in OD, Cat# 29230, Restek Tubing, translucent, FEP Teflon, 3.2-mm (1/8-inch) OD, 1.6-mm (1/16-inch) ID, 3450 kPa (500 psi), Thomas Scientific, Cat. No. 9567K20 Regulator, helium, two-stage, high purity, delivery pressure range 30 to 700 kP

19、a (4 to 100 psi), Matheson Tri-Gas, Model 3122-580, Cat. No. SEQ3122A580, 2 required Regulator, nitrogen, two-stage, high purity, delivery pressure range 30 to 700 kPa (4 to 100 psi), Matheson Tri-Gas, Model 3122-580, Cat. No. SEQ3122A580 Regulator, Eight component oxygenate blend, two-stage, high p

20、urity, delivery pressure range 30 to 1700 kPa (0 to 250 psi), Matheson Tri-Gas, Model 3810-350, Cat. No. SEQ3816A350 Regulator, acetaldehyde blend, two-stage, high purity, delivery pressure range 30 to 1700 kPa (0 to 250 psi), Matheson Tri-Gas, Model 3810-350, Cat. No. SEQ3816A350 Ring stand, with r

21、ectangular base, 140- x 229- mm with 610- mm rod, Fisher Scientific, Cat. No. 14-679Q 3 of 13 1015-17 Reagents and Materials References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Calibration blends, Gas, quantitative, one containin

22、g acetone, n-butanol, sec-butanol, ethanol, methanol, n-propanol, isopropanol, and methyl tert-butyl ether at the 3 mol-ppm level in helium, one containing acetaldehyde at the 3 mol-ppm level in helium, and one containing tert-butanol at the 3 mol-ppm level in helium, local supply. Gas purifier, for

23、 carrier gases, to remove moisture, VICI Mat/Sen, Cat. Nos. P100-1(helium), P300-1(nitrogen), local supply. Helium, UHP, 99.9995% minimum purity, total hydrocarbons less than 0.5 ppm as methane, local supply. Nitrogen, zero gas, 99.99% minimum purity, total hydrocarbons less than 0.5 ppm as methane,

24、 local supply. Procedure The analyst is expected to be familiar with general laboratory practices, the technique of gas chromatography, mass spectrometry and the equipment being used. Dispose of used reagents, materials, and samples in an environmentally safe manner according to local regulations. S

25、ampling Obtain the sample by following the procedures described in ASTM Practice D 1265, “Sampling Liquefied Petroleum (LP) Gases (Manual Method),” ASTM Practice D 5287, “Automatic Sampling of Gaseous Fuels,” UOP Method 516, “Sampling and Handling of Gasolines, Distillate Fuels, and C3-C4 Fractions,

26、” or other reliable technique. Chromatographic Technique 1. Follow the instrument site preparation checklist provided by the manufacturer and arrange for installation by the manufacturers service engineer to establish recommended operating conditions as listed in Table 1. The Wasson-ECE analyzer com

27、es with on-site installation and training by a Wasson-ECE engineer in the continental U.S., inquire with Wasson-ECE for other locations. 2. Install the gas purifier in the supply line between the carrier gas source and the carrier gas inlets on the gas chromatograph. Column life is significantly red

28、uced if the gas purifier is not used. Replace the gas purifier at intervals determined by good laboratory practice. An indicating oxygen trap may be placed downstream of the gas purifier. When the indicator shows one-half used, replace both the gas purifier and the indicating trap. 3. When a major c

29、hange is made to the system, such as the power to the GCMS is interrupted, the GCMS needs to be tuned in accordance with the manufacturers instructions. A new calibration curve should then be established. Operating Conditions It is recommended to use the manufacturer operating conditions for this an

30、alysis to produce the required sensitivity and chromatographic separations equivalent to those shown in the Total Ion Chromatogram as shown in Figure 2. 4 of 13 1015-17 Table 1 Recommended Operating Conditions Carrier gas helium Mode constant flow Flow rate 1.5 mL/min Head pressure 8.2 psig 40C Line

31、ar velocity 31.4 cm/sec 40C Split flow 15 mL/min Injection port temperature 200C On-board Vaporizer temperature 80C Column temperature program Initial temperature 40C Initial time 6 min Programming rate 15C/min Final temperature 150C Final time 3 min Detector Ion Source EI Source temperature 230C Qu

32、ad temperature 150C Transfer line temperature 280C Fixed Electron energy 70 eV Acquisition Type SIM Sample size 1.0 mL, repeatable Gas Samples and Blends 1. Choose and load appropriate method for gas sample analysis, ensuring valve 1 is in the on position to bypass the on-board vaporizer, see Figure

33、 1. 2. Connect the sample cylinder or calibration blend cylinder to the sample inlet with Sulfinert tubing and purge the system with the gas to be analyzed for 20 seconds. Stop the flow, allow 5 to 10 seconds for the pressure to equilibrate, and start the analysis. If connecting the dynamic blender

34、to the system, significantly more time (about 60 seconds) should be used to purge the inlet due to the decreased flow rate. The stop flow technique is described however constant flow while injecting can also be used, especially when using the dynamic blender. The technique which provides the best pr

35、ecision between multiple injections should be used. 3. Identify each sample component by matching retention time and target ion as listed in Table 2. Record the area of each target ion from the extracted ion chromatogram. A typical total ion chromatogram is shown in Figure 2 for reference. Retention

36、 times of components may be influenced by the amount of propylene or diluent in the calibration blend or sample. 4. Repeat steps 1 and 2 for each sample until the peak areas from each run do not deviate by more than 10%. Liquid Petroleum Gas (LPG Stream Samples) 1. Place the LPG sample cylinder in a

37、 vertical position in a hood or well-vented area. If the cylinder has an outage tube, the outage tube must be at the top. Briefly open the bottom valve to check 5 of 13 1015-17 that no water or sediment is present in the LPG. If water or sediment is determined to be present, discontinue the analysis

38、 and obtain a clean sample. LPG samples are usually contained in a cylinder having valves on both ends or, in some cases, a cylinder where one of the valves is connected to an eductor tube. If the sample cylinder contains an eductor tube, invert the cylinder and briefly open the valve not connected

39、to the eductor tube to check that no water or sediment is present. See Figure 3 for diagram of common LPG cylinders. 2. Pressurize the LPG cylinder containing the sample (or blend) to approximately 1400 to 2068 kPa gauge (200 to 300 psig) with nitrogen or helium. 3. Mount the cylinder securely on a

40、ring stand in a vertical position. If the cylinder has an outage tube, the outage tube fitting must be at the top. Connect the bottom valve to the liquid sample inlet tubing. If the cylinder is fitted with an eductor tube, connect the eductor tube outlet to the sample injection inlet tubing in such

41、a manner that the eductor tube is sampling liquid LPG. The connecting tubing between the cylinder and the liquid sample inlet must be as short as possible. 4. Choose and load appropriate method for LPG sample analysis, ensuring valve 1 is in the off position and the vaporizer is in line with the inl

42、et of the system. Refer to Figure 1. 5. Ensure that the back pressure restrictor valve is closed. 6. Fully open the bottom valve or eductor valve of the sample cylinder. 7. Partially open the back pressure restrictor to permit LPG flow through the sampling system. 8. Continue the flow until the flow

43、 emitting from the liquid sample vent is liquid and no bubbles are observed through translucent Teflon tubing. CAUTION: Inspect the translucent tubing regularly. Replace at first signs of wear or kinking. Pressure rating on the translucent tubing must be rated higher than pressure on sample or blend

44、 cylinder. 9. Stop the sample flow by closing the back pressure restrictor valve. 10. With the back pressure restrictor valve closed monitor the gas vent bubbler and wait 1 minute to ensure vaporized sample has flushed the sample loop. 11. Stop the flow, allow 5 to 10 seconds for the pressure to equ

45、ilibrate, and start the analysis, the integrator and the column temperature programming sequence. 12. Close the LPG cylinder valve and open the back pressure valve to vent the sampling system. 13. Identify each sample component by matching retention time and target ion as listed in Table 2. Record t

46、he area of each target ion from the extracted ion chromatogram. A typical total ion chromatogram is shown in Figure 2 for reference. Retention times of components may be influenced by the amount of propylene or diluent in the calibration blend or sample. 14. Repeat steps 4 through 13 for each sample

47、 until the peak areas from each run do not deviate by more than 10%. Typically, 3-5 times when instrument is run daily. Calibration A calibration curve is required to relate the detector response of the selected specific ion of each component to mol-ppm, as listed in Table 2 for target ions. Each ca

48、libration curve is generated by the analysis of gas calibration blends as described under Chromatographic Technique in triplicate and 6 of 13 1015-17 plotting the average area of each selected ion versus its concentration. Three or more component concentration levels are required to generate the plo

49、t. The different calibration levels can be obtained using the specified gas standard and the Wasson dynamic blender. See Appendix for the steps needed to use the blender. The calibration blend concentrations should bracket the expected concentration of the samples to be analyzed and not have a range of more than 2 orders of magnitude. Determine experimentally how long the calibration curve is valid, typically more than 2 months for the instrument specified if no major change were made to the system. A linear regression model sho