1、TRACE DESORBENT IN C10-C18MOLEX PRODUCTS BY GCUOP Method 863-01SCOPEMolexis an adsorptive separation process that separates normal paraffins from branched chain andcyclic hydrocarbons.This method is for determining trace amounts of Molex desorbent (n-pentane, isooctane, p-xylene) in C10-C18Molex pro
2、ducts. The lower limit of detection for n-pentane and isooctane is 5 mass-ppm. Early elutingMolex product may cause interference at the p-xylene site. Therefore, the lower limit of detection for p-xylene can be as high as 50 mass-ppm.OUTLINE OF METHODA repeatable sample volume is injected into a gas
3、 chromatograph that is equipped with a fused silicacapillary column internally coated with dimethyl polysiloxane, and a flame ionization detector. Theconcentrations of the desorbent components are determined by the external standard method of quantitation,wherein, the peak areas of the desorbent com
4、ponents in the sample are compared to the peak areas ofdesorbent components in a calibration blend.APPARATUSReferences to catalog numbers and suppliers are included as a convenience to the method user. Othersuppliers may be used.Balance, readability 0.1-mgChromatographic column, 50 m of 0.20-mm ID f
5、used silica capillary, internally coated to a filmthickness of 0.5-m with cross-linked dimethyl polysiloxane, Agilent Technologies, Cat. No. 19091-SGas chromatograph, capable of temperature ramping, built for capillary column chromatography utilizinga glass injection port insert, and equipped with a
6、 flame ionization detector that will give a minimumpeak height response of 10 times the background noise for 5 mass-ppm isooctane when operated at therecommended conditions. Agilent Technologies, Model 6890IT IS THE USERS RESPONSIBILITY TO ESTABLISH APPROPRIATE PRECAUTIONARY PRACTICES AND TODETERMIN
7、E THE APPLICABILITY OF REGULATORY LIMITATIONS PRIOR TO USE. EFFECTIVE HEALTH ANDSAFETY PRACTICES ARE TO BE FOLLOWED WHEN UTILIZING THIS PROCEDURE. FAILURE TO UTILIZE THISPROCEDURE IN THE MANNER PRESCRIBED HEREIN CAN BE HAZARDOUS. MATERIAL SAFETY DATA SHEETS(MSDS) OR EXPERIMENTAL MATERIAL SAFETY DATA
8、 SHEETS (EMSDS) FOR ALL OF THE MATERIALS USED INTHIS PROCEDURE SHOULD BE REVIEWED FOR SELECTION OF THE APPROPRIATE PERSONAL PROTECTIONEQUIPMENT (PPE). COPYRIGHT 1985, 2001 UOP LLCALL RIGHTS RESERVEDUOP Methods are available through ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoh
9、ocken PA 19428-2959,United States. The Methods may be obtained through the ASTM website, www.astm.org, or by contacting Customer Service atserviceastm.org, 610.832.9555 FAX, or 610.832.9585 PHONE2 of 6863-01Gas purifier, hydrogen, used to remove oxygen from the carrier gas, Mat/Sen, Fisher Scientifi
10、c, Cat. No.P200-1Integrator, electronic, for obtaining peak areas, ChemStation, Agilent TechnologiesLeak detector, gas, Alltech Associates, Cat. No. 21-250Recorder (optional), used to supplement integrator plotRegulator, air, two-stage, high purity, Matheson Gas Products, Model 3122-590Regulator, he
11、lium, two-stage, high purity, Matheson Gas Products, Model 3122-580Regulator, hydrogen, two-stage, high purity, Matheson Gas Products, Model 3122-350Sample injector, syringe or injector capable of injecting a reproducible 2-L volume of sample. Use of anautomatic injection system (autosampler) is str
12、ongly recommended, Agilent Technologies, Model 7683REAGENTS AND MATERIALSReferences to catalog numbers and suppliers are included as a convenience to the method user. Othersuppliers may be used.Air, zero-gas, total hydrocarbons less than 2 ppm as methaneHelium, zero-gas, total hydrocarbons less than
13、 0.5 ppm as methaneHydrogen, zero-gas, 99.95% minimum purity, total hydrocarbons less than 0.5 ppm as methaneIsooctane (2,2,4-trimethylpentane), 99% minimum purity, Acros Organics, Cat. No. 42456-5000n-Undecane, 99% minimum purity, Acros Organics, Cat. No. 14066-5000p-Xylene, 99% minimum purity, Acr
14、os Organics, Cat. No.15877-5000PROCEDUREChromatographic Technique1. Install the gas purifier in the supply line between the carrier gas source and the carrier gas inlet on thegas chromatograph Column life is significantly reduced if a gas purifier is not used.2. Install the column in the gas chromat
15、ograph. CAUTION: Hydrogen gas leakage into the confined volume of the column oven can cause a violentexplosion. It is, therefore, mandatory to check for leaks each time a connection is made and periodicallythereafter.3. Establish the recommended operating conditions as given in Table 1. Other condit
16、ions may be used provided they produce the required sensitivity and chromatographicseparations equivalent to those shown in the Typical Chromatogram (Figure).3 of 6863-014. Program the column oven to 250C and maintain this temperature until a stable baseline has beenobtained at the required sensitiv
17、ity.5 Cool the column oven to a stabilized 50C.Table 1Recommended Operating ConditionsCarrier gas hydrogenColumn head pressure 100 C,Constant pressure 105 kPa gauge (15 psig)Equivalent flow 0.7 mL/minEquivalent linear velocity 25 cm/secInjection port temperature 250 CColumn temperature programInitia
18、l temperature 50 CInitial time 0 minProgramming rate A 4 C/minIntermediate temperature 120 CIntermediate time 0 minProgramming rate B 20 C/minFinal temperature 230 CFinal time 38 minDetectorTemperature 275 CHydrogen flow rate* 30 mL/minAir flow rate* 400 mL/minMakeup helium flow rate* 30 mL/minSampl
19、e size2.0 L_* Consult the manufacturers instrument manual for suggested flow rates.6. Inject 2.0 L of sample into the gas chromatograph and start the integrator and the column ovenprogramming sequence.7. Identify the desorbent components using the Typical Chromatogram as a guide (Figure).Calibration
20、Quantitative results are based on the injection of a repeatable volume of a sample and of a referenceblend. Absolute response factors are used to relate the peak area of the desorbent components to mass-ppm.Since n-pentane is quite volatile, and it has about the same detector response as isooctane,
21、the isooctane inthe blend is used to calibrate for both n-pentane and isooctane in the sample; p-xylene in the blendcalibrates for p-xylene in the sample.4 of 6863-011. Prepare, following ASTM Method D 4307, one or more calibration blends containing isooctane andp-xylene in n-undecane at the concent
22、rations expected in the samples.2. Analyze the blend in triplicate as described under Steps 6 and 7, Chromatographic Technique.Average the peak areas for each desorbent component from the three runs. The peak areas from each of the three runs should not deviate from the average by more than 2%. Ifgr
23、eater deviation is found, check equipment and technique, and make further runs until the requiredrepeatability is obtained.3. Calculate the response factor for each desorbent component as follows:MFP= (1)where:F = absolute response factor for desorbent componentM = concentration of desorbent compone
24、nt in the blend, mass-ppmP = average peak area for the desorbent component in the blendCALCULATIONSCalculate the concentration of the total amount of each desorbent component in the sample as follows:Molex desorbent component, mass-ppm = FS (2)where:F = absolute response factor for the component (us
25、e the isooctane factor for n-pentane)S = peak area for the component in the sampleReport results to the nearest 1 mass-ppm.PRECISIONThe GC used to perform the precision study was equipped with an autoinjector. Precision statements weredetermined using UOP Method 999.ASTM and UOP RepeatabilityA neste
26、d design was carried out for determining Molex desorbent components in Molex product with twoanalysts in one laboratory. Each analyst carried out tests on two separate days, performing two tests eachday for each sample. The total number of tests for each constituent was 16. The precision data aresum
27、marized in Table 2. Two tests performed by the same analyst on the same day should not differ by morethan the ASTM allowable difference with 95% confidence. Two tests performed in one laboratory bydifferent analysts on different days should not differ by more than the UOP allowable difference with 9
28、5%confidence.The data in Table 2 are a short-term estimate of repeatability. When the test is run routinely, a controlstandard and chart should be used to develop a better estimate of the long-term repeatability.5 of 6863-01ReproducibilityThere is insufficient data to calculate the reproducibility o
29、f the test at this time.Table 2ASTM and UOP Repeatability, mass-ppmASTM Repeatability UOP RepeatabilityCompoundMeanConc.Within-Day esdAllowableDifferenceWithin-Lab esdAllowableDifferenceSample 1n-Pentane 8 0.32 1.3 0.29 1.1Isooctane 8 0.25 1.0 0.26 1.0p-Xylene 9 0.50 2.0 0.50 2.0Sample 2n-Pentane 73
30、 0.38 1.5 1.0 5.Isooctane 73 0.56 2.2 0.56 2.2p-Xylene 77 0.52 2.1 0.52 2.0TIME FOR ANALYSISThe elapsed time for one analysis is 1.3 hour. The labor requirement is 0.3 hour.REFERENCESASTM Method D 4307, www.astm.orgUOP Method 999, “Precision Statements in UOP Methods”SUGGESTED SUPPLIERSAcros Organic
31、s, Fisher Scientific, 711 Forbes Ave., Pittsburgh, PA 15219 (412-562-8300)Agilent Technologies, 2850 Centerville Rd., Wilmington, DE 19808-1610 (302-633-8000)Alltech Associates, Inc., 2051 Waukegan Rd., Deerfield, IL 60015 (847-948-8600) Fisher Scientific, 711 Forbes Ave., Pittsburgh, PA 15219 (412-562-8300) Matheson Gas Products, P.O. Box 85, East Rutherford, NJ 07073 (201-933-2400)6 of 6863-01FigureTypical ChromatogramMolex Product
