EPA Method 310A Determination Of Residual Hexane Through Gas Chromatography
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ID： |
C787A311B5AD45DA884772224EEA7FB5 |
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文件大小(MB)： |
0.02 |
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页数： |
7 |
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文件格式： |
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日期： |
1998-5-13 |
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购买： |
文本摘录（文本识别可能有误，但文件阅览显示及打印正常，pdf文件可进行文字搜索定位）：
1,METHOD 310A - DETERMINATION OF RESIDUAL HEXANE THROUGH GAS,CHROMATOGRAPHY,1.0 SCOPE AND APPLICATION,1.1 This method is used to analyze any crumb rubber or,water samples for residual hexane content.,1.2 The sample is heated in a sealed bottle with an,internal standard and the vapor is analyzed by gas,chromatography.,2.0 SUMMARY OF METHOD,2.1 This method, utilizing a capillary column gas,chromatograph with a flame ionization detector,determines the concentration of residual hexane in,rubber crumb samples.,3.0 DEFINITIONS,3.1 The definitions are included in the text as needed.,4.0 INTERFERENCES,4.1 There are no known interferences.,5.0 SAFETY,5.1 It is the responsibility of the user of this procedure,to establish safety and health practices applicable to,their specific operation.,6.0 EQUIPMENT AND SUPPLIES,6.1 Gas Chromatograph with a flame ionization detector and,data handling station equipped with a capillary column,30 meters long.,6.2 Chromatograph conditions for Sigma 1:,6.2.1 Helium pressure: 50# inlet A, 14# aux,6.2.2 Carrier flow: 25 cc/min,6.2.3 Range switch: 100x,6.2.4 DB: 1 capillary column,2,3,6.3 Chromatograph conditions for Hewlett-Packard GC:,6.3.1 Initial temperature: 40EC,6.3.2 Initial time: 8 min,6.3.3 Rate: 0,6.3.4 Range: 2,6.3.5 DB: 1705 capillary column,6.4 Septum bottles and stoppers,6.5 Gas Syringe - 0.5 cc,7.0 REAGENTS AND STANDARDS,7.1 Chloroform, 99.9+%, A.S.C. HPLC grade,8.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE,8.1 A representative sample should be caught in a clean 8,oz. container with a secure lid.,8.2 The container should be labeled with sample,identification, date and time.,9.0 QUALITY CONTROL,9.1 The instrument is calibrated by injecting calibration,solution (Section 10.2 of this method) five times.,9.2 The retention time for components of interest and,relative response of monomer to the internal standard,is determined.,9.3 Recovery efficiency must be determined once for each,sample type and whenever modifications are made to the,method.,9.3.1 Determine the percent hexane in three separate,dried rubber crumb samples.,9.3.2 Weigh a portion of each crumb sample into separate,sample bottles and add a known amount of hexane,(10 microliters) by microliter syringe and 20,4,microliters of internal standard. Analyze each,by the described procedure and calculate the percent,recovery of the known added hexane.,9.3.3 Repeat the previous step using twice the hexane level,(20 microliters), analyze and calculate the percent,recovery of the known added hexane.,9.3.4 Set up two additional sets of samples using 10,microliters and 20 microliters of hexane as before,but add an amount of water equal to the dry crumb,used. Analyze and calculate percent recovery to show,the effect of free water on the results obtained.,9.3.5 A value of R between 0.70 and 1.30 is acceptable.,9.3.6 R shall be used to correct all reported results for,each compound by dividing the measured results of,each compound by the R for that compound for the same,sample type.,10.0 CALIBRATION AND INSTRUMENT SETTINGS,10.1 Calibrate the chromatograph using a standard made by,injecting 10 μl of fresh hexane and 20 μl of chloroform,into a sealed septum bottle. This standard will be 0.6,wt.% total hexane based on 1 gram of dry rubber.,10.2 Analyze the hexane used and calculate the percentage of,each hexane isomer (2-methylpentane, 3-methylpentane,n-hexane, and methylcyclo-pentane). Enter these,percentages into the method calibration table.,10.3 Heat the standard bottle for 30 minutes in a 105EC,oven.,10.4 Inject about 0.25 cc of vapor into the gas,chromatograph and after the analysis is finished,calibrate according to the procedures described by the,instrument manufacturer.,11.0 PROCEDURE,11.1 Using a cold mill set at a wide roller gap (125-150,mm), mill about 250 grams of crumb two times to,homogenize the sample.,11.2 Weigh about 2 grams of wet crumb into a septum bottle,ppmhexane,’(AhexanexRhexane)/(AisxRis),5,and cap with a septum ring. Add 20 μl of chloroform,with a syringe and place in a 105EC oven for 45,minutes.,11.3 Run the moisture content on a separate portion of the,sample and calculate the grams of dry rubber put into,the septum bottle.,11.4 Set up the data station on the required method and,enter the dry rubber weight in the sample weight field.,11.5 Inject a 0.25 cc vapor sample into the chromatograph,and push the start button.,11.6 At the end of the analysis, the data station will print,a report listing the concentration of each identified,component.,11.7 To analyze water samples, pipet 5 ml of sample into the,septum bottle, cap and add 20 μl of chloroform. Place,in a 105EC oven……
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