UOP 673-2012 Linear Alkylbenzene Isomer Distribution in Detergent Alkylate by GC.pdf

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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. 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 THE APPROPRIATE PERSONAL PROTECTION EQUIPMENT (PPE). COPYRIGHT 1968, 1985, 1988, 2006, 2012 UOP LLC.

3、All rights reserved. Nonconfidential UOP Methods are available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, USA. The UOP Methods may be obtained through the ASTM website, www.astm.org, or by contacting Customer Service at serviceastm.org, 610.832.9

4、555 FAX, or 610.832.9585 PHONE. Linear Alkylbenzene Isomer Distribution in Detergent Alkylate by GC UOP Method 673-12 Scope This method is for determining the isomer distribution in C15 through C20 mono-substituted linear alkylbenzenes (LABs). The 6-phenyltridecane and 7-phenyltridecane isomers are

5、not resolved from each other and are determined as a composite. The lower limit of detection for a single component is 0.1 mass-%. Components other than linear alkylbenzenes are not normally determined by this method; however, an estimate of the total LAB content of the sample may be obtained by mea

6、suring the components present in the sample other than the LABs. A calculation is included to determine the number average molecular weight of the LABs in the sample, if needed. Reference UOP Method 999, “Precision Statements in UOP Methods,“ www.astm.org Outline of Method The sample to be analyzed

7、is injected into a gas chromatograph that is equipped with a fused silica capillary column. The mass-% distribution of LABs is obtained by the internal normalization technique of quantitation wherein the peak areas of the LABs are normalized to 100%. By summing the non-LAB components, an estimate of

8、 the linearity of the detergent alkylate may be obtained. Apparatus References to catalog numbers and suppliers are included as a convenience to the method user. Other suppliers may be used. Chromatographic column, 30 m of 0.32-mm ID fused silica capillary, internally coated to a film thickness of 0

9、.25 m with DB-17 bonded (50%-phenyl)-methylpolysiloxane, Agilent Technologies, Cat. No. 123-1732 Gas chromatograph, temperature programmable, built for capillary column chromatography, utilizing a split injection system having a glass injection port insert and equipped with a flame 2 of 7 673-12 ion

10、ization detector (FID), Agilent Technologies, Model 7890A, with autosampler capable of injecting a repeatable 0.2-L volume of sample, Agilent Technologies, Model 7693A Data system, electronic, for obtaining peak areas. This device must integrate areas at a sufficiently fast rate so that narrow peaks

11、 typically resulting from the use of a capillary column can be accurately measured. Agilent Technologies, ChemStation. Leak detector, gas, Grace Davison, Cat. No. 60229 Regulator, air, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-590 Regulator,

12、 hydrogen, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-350 Regulator, nitrogen, two-stage, high purity, delivery pressure range 30-700 kPa (4-100 psi), Matheson Tri-Gas, Model 3122-580 Reagents and Materials References to catalog numbers and s

13、uppliers 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 Gas purifier, for hydrogen, to remove oxygen and moisture from carrier gas, VICI Mat/Sen, Cat. No. P200-1, and (optional) indicating oxygen trap, Res

14、tek, Cat. No. 22010, see Procedure, Chromatographic Technique, Step 1 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 Syringe, replacement, for recommended sample inj

15、ector, 10-L, Agilent Technologies, Cat. No. 5181-1267 Vials, autosampler, for recommended sample injector, with caps, Agilent Technologies, Cat. No. 5182-0864 Procedure The analyst is expected to be familiar with general laboratory practices, the technique of gas chromatography, and the equipment be

16、ing used. Dispose of used reagents, materials, and samples in an environmentally safe manner according to local regulations. Chromatographic Technique 1. 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 sig

17、nificantly reduced 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. 2.

18、Install the fused silica capillary column in the gas chromatograph according to the column and gas chromatograph manufacturers instructions. CAUTION: Hydrogen leakage into the confined volume of the column oven can cause a violent explosion. Therefore, it is mandatory to check for leaks each time a

19、connection is made and periodically thereafter. 3 of 7 673-12 3. Establish the recommended operating conditions as given in Table 1. Different conditions may be used provided they produce the required sensitivity and chromatographic separations equivalent to those shown in the Typical Chromatogram (

20、see Figure). 4. Program the column oven to 250C (see Table 1) and maintain this temperature until a stable baseline has been obtained at the required sensitivity. Table 1 Recommended Operation Conditions Carrier gas hydrogen Mode constant flow Flow rate 1.4 mL/min flow rate Column head pressure 140C

21、 38 kPa gauge (5.5 psig) Linear velocity 32.5 cm/sec Split flow rate 280 mL/min Injection port temperature 240C Column temperature program Initial temperature 140C Initial time 0 min Programming rate 1C/min Final temperature 170C Final hold timea 5 min Detector flame ionization Detector temperature

22、240C Hydrogen flow rateb 30 mL/min Air flow rateb 300 mL/min Makeup gas nitrogen Makeup flow rateb 30 mL/min Sample size 0.2 L aThe final hold time may need to be adjusted to ensure that all heavies elute and response returns to baseline. If heavy components continue to elute for an extended period,

23、 the column temperature may be raised rapidly to up to 250C to shorten the total analysis time. This increase in column temperature must be started after a flat baseline is established following the elution of the LABs. bConsult the manufacturers instrument manual for suggested flow rates. 5. Cool t

24、he column oven to a stabilized 140C. 6. Inject nominally 0.2 L of the sample and immediately start the data system and column temperature programming sequence. The use of an autosampler automates the injection of the sample into the GC, starts the data system, and the GC oven program simultaneously.

25、 7. Identify the components by comparing the chromatogram obtained to the Typical Chromatogram shown in the Figure. The LAB peaks are identified in Table 2. To ensure accuracy, the chromatographic baseline must be straight, without drift, from beginning to end. The parameters of the integrator must

26、also be adjusted so that a continuous, straight baseline is followed, and the integrator must separate the areas defined as the LAB with a perpendicular drop, not a tangent skim. 8. Determine the area of each LAB peak. If an estimate of the linearity of the detergent alkylate is desired, sum the are

27、as of all the non-LAB peaks. 4 of 7 673-12 Table 2 LAB Components Peak No. Component Peak No. Component 1 2 3 4 5 6 7 8 9 10 5-Phenylnonane 4-Phenylnonane 3-Phenylnonane 2-Phenylnonane 5-Phenyldecane 4-Phenyldecane 3-Phenyldecane 2-Phenyldecane 6-Phenylundecane 5-Phenylundecane 14 15 16 17 18 19 20

28、21 22 23 6-Phenyldodecane 5-Phenyldodecane 4-Phenyldodecane 3-Phenyldodecane 2-Phenyldodecane 7- therefore, no response factors are required. Calculate the isomer distribution of the LABs, to the nearest 0.1 mass-%, using Equation 1. Component, mass-% = S E 100 )1( where: E = peak area of each linea

29、r alkylbenzene isomer S = sum of all recorded LAB peak areas 100 = factor to convert to mass-% If an estimate of the linearity of the detergent alkylate is desired, calculate the estimated linearity using Equation 2. Estimated linearity, mass-% = T S 100 (2) where: S = sum of all recorded LAB peak a

30、reas T = sum of all recorded LAB peak areas and non-LAB peak areas 100 = factor to convert to mass-% If the average molecular weight of the LABs in the sample is desired, calculate the number average molecular weight of the LABs in the sample using Equation 3. Number average molecular weight of the

31、LABs in the sample =n1i iiGM100 (3) where: 5 of 7 673-12 Gi = molecular weight of component i, see Table 3, g/mol i = each component Mi = mass-% of component i n = number of components 100 = conversion from mass-% Table 3 Molecular Weights of LABs, g/mol Phenylnonane 204.35 Phenyldecane 218.38 Pheny

32、lundecane 232.41 Phenyldodecane 246.44 Phenyltridecane 260.46 Phenyltretradecane 274.49 Precision Precision statements were determined using UOP Method 999 from precision data obtained using an autosampler. Repeatability and Site Precision A nested design was carried out for determining LAB isomer d

33、istribution in a detergent alkylate sample with two analysts in one laboratory. Each analyst carried out tests on two separate days, performing two tests on each day. The total number of tests for each component was eight. The precision data are summarized in Table 4. Two tests performed by the same

34、 analyst on the same day should not differ by more than the repeatability allowable difference with 95% confidence. Two tests performed in one laboratory by different analysts on different days should not differ by more than the site precision allowable difference with 95% confidence. The data in Ta

35、ble 4 are a short-term estimate of repeatability and site precision. When the test is run routinely, a control standard and chart should be used to develop a better estimate of the long-term intermediate precision. Reproducibility There is insufficient data to calculate the reproducibility of the te

36、st at this time. Time for Analysis The elapsed time for one analysis is 0.7 hour. The labor requirement is 0.3 hour. Suggested Suppliers Agilent Technologies, 2850 Centerville Rd., Wilmington, DE 19808-1610, USA (302-633-8000) Grace Davison Discovery Sciences, 2051 Waukegan Rd., Deerfield, IL 60015

37、, USA (847-948-8600) Matheson Tri-Gas, 166 Keystone Drive, Montgomeryville, PA 18936, USA (215-648-4000) Restek, 110 Benner Circle, Bellefonte, PA 16823, USA (814-353-1300) VICI Mat/Sen, 7806 Bobbitt, Houston, TX 77055, USA (713-688-9345) 6 of 7 673-12 Table 4 Repeatability and Site Precision, m

38、ass-% Repeatability Site Precision Component Mean Conc. Within- Day esd Allowable Difference Within- Lab esd Allowable Difference 5-Phenyldecane 2.58 0.004 0.01 0.006 0.04 4-Phenyldecane 2.46 0.004 0.02 0.005 0.02 3-Phenyldecane 3.04 0.014 0.08 0.019 0.08 2-Phenyldecane 4.46 0.009 0.03 0.012 0.05 6-

39、Phenylundecane 2.99 0.021 0.08 0.030 0.12 5-Phenylundecane 5.90 0.008 0.03 0.010 0.04 4-Phenylundecane 5.61 0.005 0.02 0.005 0.02 3-Phenylundecane 6.91 0.008 0.03 0.010 0.04 2-Phenylundecane 9.62 0.016 0.06 0.022 0.09 6-Phenyldodecane 5.04 0.004 0.01 0.006 0.04 5-Phenyldodecane 5.18 0.004 0.01 0.004

40、 0.01 4-Phenyldodecane 4.88 0.004 0.02 0.005 0.02 3-Phenyldodecane 6.08 0.004 0.01 0.004 0.01 2-Phenyldodecane 8.51 0.005 0.02 0.005 0.02 7- & 6-Phenyltridecane 5.84 0.005 0.02 0.005 0.02 5-Phenyltridecane 4.05 0.003 0.01 0.004 0.01 4-Phenyltridecane 3.73 0.005 0.02 0.005 0.02 3-Phenyltridecane 4.65

41、 0.007 0.03 0.009 0.03 2-Phenyltridecane 6.75 0.023 0.09 0.106 0.65 7-Phenyltetradecane 0.08 0.007 0.03 0.111 0.21 6-Phenyltetradecane 0.28 0.004 0.01 0.004 0.01 5-Phenyltetradecane 0.31 0.011 0.04 0.015 0.06 4-Phenyltetradecane 0.28 0.008 0.03 0.011 0.04 3-Phenyltetradecane 0.32 0.008 0.03 0.011 0.04 2-Phenyltetradecane 0.48 0.015 0.06 0.017 0.08 7 of 7 673-12