UOP 976-2002 TRACE C4-C9 SATURATES IN HIGH PURITY AROMATICS BY GC.pdf

1、 COPYRIGHT 2002 UOP LLC ALL RIGHTS RESERVED Marks of other proprietors may appear incidentally in this method for purposes such as product or service identification, but no claim is made to any other proprietors mark used. UOP Methods are available through ASTM International, 100 Barr Harbor Drive,

2、PO Box C700, West Conshohocken, PA 19428-2959, United States. The 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 PHONE. TRACE C4-C9SATURATES IN HIGH PURITY AROMATICS BY GC UOP Method 976-02 SCOPE

3、 This gas chromatographic method is for determining individual and composite trace non-aromatic hydrocarbon impurities in olefin-free aromatic mixtures. C8and lower boiling paraffins and naphthenes are determined individually and then summed by carbon number and carbon type. C9non-aromatics are repo

4、rted as a composite. The method is not quantitative for C3and lower molecular weight hydrocarbons due to their volatility. The range of quantitation for each component is 1 to 2000 mass-ppm. The range of quantitation for each composite depends upon the number of components in the composite. An alter

5、native method providing similar information is UOP Method 868, Trace Saturates in High Purity Aromatics by GC. It uses a two-column system to report paraffins and naphthenes by carbon number through C10. OUTLINE OF METHOD The sample is injected into a gas chromatograph equipped with a flame ionizati

6、on detector and a fused silica capillary column, internally coated with cross-linked methyl silicone. The mass-ppm concentration of the impurities in aromatic mixtures is obtained on an absolute basis by the external standard method of quantitation, wherein the peak areas for the impurity components

7、 are compared to the peak area for a known amount of 2,2,4-trimethylpentane in the calibration blend. 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 T

8、O BE FOLLOWED WHEN UTILIZING THIS PROCEDURE. FAILURE TO UTILIZE THIS PROCEDURE IN THE MANNER PRESCRIBED HEREIN CAN BE HAZARDOUS. MATERIAL SAFETY DATA SHEETS (MSDS) OR EXPERIMENTAL MATERIAL SAFETY DATA SHEETS (EMSDS) FOR ALL OF THE MATERIALS USED IN THIS PROCEDURE SHOULD BE REVIEWED FOR SELECTION OF

9、THE APPROPRIATE PERSONAL PROTECTION EQUIPMENT (PPE). 2 of 11 976-02 APPARATUS References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Balance, readability 0.1-mg Chromatographic column, PONA, 50 m of 0.21-mm ID fused silica capillary

10、, internally coated to a film thickness of 0.5-m with cross-linked methyl silicone, Agilent Technologies, Cat. No. 19091S-001 Gas chromatograph, temperature programmable, built for capillary column chromatography, utilizing a split injection system having a glass injection port insert and equipped w

11、ith a flame ionization detector that will give a minimum peak height response of 10 times the background noise for 1 mass-ppm 2,2,4-trimethylpentane when operated under the recommended conditions, Agilent, Model 6890 Gas purifier, hydrogen purifier, Mat/Sen, Cat. No. P200-1 Integrator, or data syste

12、m, electronic, for obtaining peak areas. This device must integrate areas at a sufficiently fast rate so that narrow peaks typically resulting from use of a capillary column can be accurately measured. Regulator, air, two-stage, high purity, Matheson Gas Products, Model 3122-590 Regulator, hydrogen,

13、 two-stage, high purity, Matheson Gas Products, Model 3122-580 Regulator, nitrogen, two-stage, high purity, Matheson Gas Products, Model 3122-580 Sample injector, any syringe or injector capable of introducing a 1-L volume of sample. An automatic injection device is recommended, Agilent Technologies

14、, Model 7683. Syringe, 10-L, for sample injector, Agilent Technologies, Cat. No. 5181-1267 REAGENTS AND MATERIALS References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Air, zero gas, total hydrocarbons less than 2.0 ppm as methane

15、Hydrogen, zero gas, 99.99% minimum purity, total hydrocarbons less than 0.5 ppm as methane Nitrogen, zero gas, 99.99% minimum purity, total hydrocarbons less than 0.5 ppm as methane Pipet, Pasteur, disposable, 146-mm, Fisher Scientific, Cat. No. 13-678-20A Pipet bulb, 1-mL, Fisher Scientific, Cat. N

16、o. 13-678-9A 2,2,4-Trimethylpentane, 99.9% minimum purity, Acros Organics, Cat. No. 29572-0010 Xylenes, reagent, Acros Organics, Cat. No.42268-5000 Vial, 14.8-mL, with screw cap, Fisher Scientific, Cat. No. 03-339-21J 3 of 11 976-02 PROCEDURE Preparation of Apparatus 1. Install the gas purifier in t

17、he supply line between the carrier gas source and the carrier gas inlets on the gas chromatograph. Column life may be significantly reduced if a gas purifier is not used. 2. Install the fused silica capillary column in the gas chromatograph. CAUTION: Hydrogen carrier gas leakage into the confined vo

18、lume of the column oven can cause a violent explosion. It is, therefore, mandatory to check for leaks each time a connection is made and periodically thereafter. 3. Establish the recommended operating conditions as given in Table 1. Table 1 Recommended Operating Conditions Carrier gas hydrogen Colum

19、n head pressure 137 kPa gauge (20 psig) Equivalent flow 32C 1 mL/min Equivalent linear velocity 32.5 cm/sec Split Flow 100 mL/min Injection port temperature 250C Column temperature program Initial temperature 32C Initial time 6 min Programming rate A 5C/min Final temperature A 52C Holding time A 14

20、min Programming rate B 20C/min Final temperature B 250C Final time 10 min Detector Detector temperature 300C Hydrogen flow rate* 30 mL/min Air flow rate* 275 mL/min Makeup nitrogen flow rate* 30 mL/min Sample size 1 L *Consult the manufacturers instrument manual for suggested flow rates. 4 of 11 976

21、-02 Other conditions may be used provided they produce the required sensitivity and chromatographic separa-tions equivalent to those shown in the Typical Chromatograms (Figs. 1 and 2). 4. Program the column oven to 250C and maintain this temperature until a stable baseline has been obtained at the r

22、equired sensitivity. 5. Cool the column oven to a stabilized 32C. Chromatographic Technique 1. Inject 1.0 L of sample and immediately start the gas chromatograph and integrator. 2. Identify the components of interest by comparing the chromatogram obtained to the Typical Chromatograms, Parts 1 and 2

23、(Figs. 1 and 2) and Retention Times of Identified Components (Table 2). Sum the impurity peak areas into groups by carbon number and type: paraffin or naphthene. 3. Determine the density of the sample by ASTM Test Method D 4052, or other suitable technique. Figure 1 Typical Chromatogram, Part 1 5 of

24、 11 976-02 Calibration 1. Analyze the xylenes as described under Chromatographic Technique and confirm that there are no impurity peaks in the 2,2,4-trimethylpentane region (Peak No. 28). If there is any interference, obtain the xylenes from another source. If an impurity eluting at the retention ti

25、me of 2,2,4-trimethylpentane cannot be eliminated, analyze the xylenes every time a calibration blend is analyzed and subtract the area of the impurity from the area of the 2,2,4-trimethylpentane in the calibration blend. 2. Prepare a calibration blend as described in ASTM Test Method D 4307. 3. Tar

26、e a vial to the nearest 0.1 mg. Add approximately 10 g of xylene and record the weight. The xylene is deposited in the center of the vial with a Pasteur pipet so that the liquid does not contact the neck. 4. Add approximately 0.1 g of 2,2,4-trimethylpentane using a Pasteur pipet and quickly reweigh

27、to the nearest 0.1 mg. This solution will correspond to an approximate concentration of 1 mass-% of 2,2,4-trimethylpentane in xylenes. Figure 2 Typical Chromatogram, Part 2 6 of 11 976-02 The external standard is added to the vial while on the balance pan and deposited into the center of the liquid,

28、 not on the side of the vial. 5. Cap the vial and mix well by inverting the vial several times. Label this solution as Standard Solu-tion A. 6. Tare another vial to the nearest 0.1 mg. Add approximately 10 g of xylene and record the weight. The xylene is deposited in the center of the vial with a Pa

29、steur pipet so that the liquid does not contact the neck. 7. Add approximately 0.1 g of Standard Solution A. Record the weight to the nearest 0.1 mg. This solution will correspond to an approximate concentration of 100 mass-ppm of 2,2,4-trimethylpentane in xylenes. Standard Solution A is added to th

30、e vial while on the balance pan and deposited into the center of the liq-uid, not on the side of the vial. 8. Cap the vial and mix well by inverting the vial several times. Label this solution as Calibration Blend. This solution is stable for one month. 9. Calculate the concentration of the Calibrat

31、ion Blend using Eq. 1: where: C = concentration of 2,2,4-trimethylpentane in Calibration Blend, mass-ppm W = the weight of mixed xylenes in Calibration Blend X = the weight of 2,2,4-trimethylpentane in Standard Solution A Y = the weight of Standard Solution A in Calibration Blend Z = the weight of m

32、ixed xylenes in Standard Solution A 106 = factor to convert to mass-ppm 10. Analyze the Calibration Blend in triplicate daily as described under Chromatographic Technique when samples are analyzed. 11. Identify the 2,2,4-trimethylpentane peak and average the peak area from the triplicate runs. Peak

33、areas from each of the triplicate runs should not deviate from the average by more than 2% of the value. If greater deviations occur, make certain that there are no problems with the equipment, then make additional runs until the required repeatability is obtained on three consecutive runs. )WY)(ZX(

34、XY10C6+=)1(7 of 11 976-02 Table 2 Retention Times of Identified Components Typical Retention Time, Min Peak No. Component Identification Group 2.04 2.15 2.33 2.48 2.75 3.06 3.38 3.97 4.60 4.64 4.75 5.16 5.74 6.70 6.78 6.97 7.18 7.79 8.07 8.22 8.68 8.75 8.86 9.09 9.37 9.51 9.58 9.64 9.72 10.28 11.30

35、11.49 12.00 12.10 12.22 12.56 12.66 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Ethane site Propane Isobutane n-Butane 2,2-Dimethylpropane Isopentane n-Pentane 2,2-Dimethylbutane Cyclopentane 2,3-Dimethylbutane 2-Methylpentane 3-Methylpentane n-

36、Hexane 2,2-Dimethylpentane Methylcyclopentane 2,4-Dimethylpentane 2,2,3-Trimethylbutane Benzene 3,3-Dimethylpentane Cyclohexane 2-Methylhexane 2,3-Dimethylpentane 1,1-Dimethylcyclopentane 3-Methylhexane 1-cis-3-Dimethylcyclopentane 1-trans-3-Dimethylcyclopentane 3-Ethylpentane 1-trans-2-Dimethylcycl

37、opentane 2,2,4-Trimethylpentane n-Heptane Methylcyclohexane + 1-cis-2-Dimethylcyclopentane 1,1,3-Trimethylcyclopentane + 2,2-Dimethylhexane Ethylcyclopentane 2,5-Dimethylhexane 2,2,3-Trimethylpentane + 2,4-Dimethylhexane 1-trans-2-cis-4-Trimethylcyclopentane 3,3-Dimethylhexane C2Paraffin C3Paraffin

38、C4Paraffin C4Paraffins C5Paraffins C5Paraffins C5Paraffins C6Paraffins C5Naphthene C6Paraffins C6Paraffins C6Paraffins C6Paraffins C7Paraffins C6Naphthenes C7Paraffins C7Paraffins C7Paraffins C6Naphthenes C7Paraffins C7Paraffins C7Naphthenes C7Paraffins C7Naphthenes C7Naphthenes C7Paraffins C7Naphth

39、enes C8Paraffins C7Paraffins C7Naphthenes C7Naphthenes C8Naphthenes * C8Paraffins * C7Naphthenes C8Paraffins C8Paraffins C8Paraffins C8Naphthenes C8Paraffins 8 of 11 976-02 Typical Retention Time, Min Peak No. Component Identification Group 13.04 13.25 13.48 14.06 14.13 14.53 14.65 14.75 14.94 15.15

40、 15.21 15.37 15.83 16.17 16.37 16.47 16.66 16.92 17.42 17.61 18.38 19.34 20.15 20.78 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 1-trans-2-cis-3-Trimethylcyclopentane 2,3,4-Trimethylpentane 2,3,3-Trimethylpentane + Toluene 2,3-Dimethylhexane+ 1,1,2-Trimethylcyclopen

41、tane 2-Methyl-3-ethylpentane 2-Methylheptane 4-Methylheptane 3,4-Dimethylhexane + 3-Methyl-3-ethylpentane 1-cis-2-trans-4-Trimethylcyclopentane+ 1-cis-2-cis-4-Trimethylcyclopentane 3-Methylheptane 3-Ethylhexane + 1-cis-3-Dimethylcyclohexane + 1-cis-2-trans-3-Trimethylcyclopentane 1-trans-4-Dimethylc

42、yclohexane 1,1-Dimethylcyclohexane 1-Methyl-trans-3-ethylcyclopentane 1-Methyl-cis-3-ethylcyclopentane 1-Methyl-trans-2-ethylcyclopentane 1-Methyl-1-ethylcyclopentane 1-trans-2-Dimethylcyclohexane 1-cis-2-cis-3-Trimethylcyclopentane n-Octane + 1-cis-4-Dimethylcyclohexane + 1-trans-3-Dimethylcyclohex

43、ane Isopropylcyclopentane 1-Methyl-cis-2-ethylcyclopentane 1-cis-2-Dimethylcyclohexane n-Propylcyclopentane + Ethylcyclohexane C9Non-Aromatics Xylenes C8Naphthenes C8Paraffins C8Paraffins * C8Paraffins * C8Naphthenes * C8Paraffins C8Paraffins C8Paraffins C8Paraffins C8Paraffins C8Naphthenes C8Naphth

44、enes C8Paraffins C8Paraffins * C8Naphthenes * C8Naphthenes * C8Naphthenes C8Naphthenes C8Naphthenes C8Naphthenes C8Naphthenes C8Naphthenes C8Naphthenes C8Naphthenes C8Paraffins * C8Naphthenes * C8Naphthenes * C8Naphthenes C8Naphthenes C8Naphthenes C8Naphthenes C8Naphthenes * * Some co-eluting peaks

45、contain components belonging to different groups. Select the most appropriate group for those peaks, based upon sample characteristics. * The C9Non Aromatic group was defined in the chromatogram by analyzing known C9compounds (Fig 1 and 2). 9 of 11 976-02 12. Determine the response factor relative t

46、o the mass-ppm concentration of 2,2,4-trimethylpentane in the Calibration Blend using Eq. 2. where: A = average peak area of 2,2,4-trimethylpentane from chromatogram (Fig. 2) C = concentration of 2,2,4-trimethylpentane in Calibration Blend, mass-ppm M = response factor CALCULATIONS Calculate the con

47、centration of each impurity or group of impurities in the sample to the nearest mass-ppm using the following equation: Impurity or grouped impurities, mass-ppm = DBMSwhere: B = peak area of a specific impurity or group of impurities D = density of sample M = response factor S = density of Calibratio

48、n Blend The flame ionization detector responds equally on a mass basis to all measured impurities. REPORT Report the following impurity groups to the nearest mass-ppm: C4Paraffins C5Naphthene C5Paraffins C6Naphthenes C6Paraffins C7Naphthenes C7Paraffins C8Naphthenes C8Paraffins C9Non-Aromatics If de

49、sired, individual impurities may also be reported to the nearest mass-ppm. ACM =)2(3)10 of 11 976-02 PRECISION Precision statements were determined using UOP Method 999. An autoinjector was used for sample injection. ASTM and UOP Repeatability A nested design was carried out for determining components in two high purity aromatic samples with two analysts in one laboratory. Each analyst carried out tests on two separate days, performing two tests each day for sample A and three tests each day for Sample B. The total numb