1、Designation: E 755 94 (Reapproved 2003)Standard Test Method forDicumyl Peroxide, Assay (Liquid Chromatography)1This standard is issued under the fixed designation E 755; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the assay of dicumyl peroxide2in commercially available refined grades of dicumyl peroxide.Tec
3、hnical grades can also be assayed, provided that impuritiesthat interfere chromatographically are absent (see Note 1).These materials nominally contain approximately 99 and 92 %of dicumyl peroxide, respectively.NOTE 1In the assay of technical grade dicumyl peroxide, errors arepossible if the product
4、 contains an impurity that elutes with the sameretention time as the internal standard. A chromatogram obtained underthe test conditions minus the internal standard will determine whether aninterference situation exists in the assay of a particular technical gradeproduct. If an impurity is noted, an
5、d its retention time is slightly differentfrom that of the internal standard, the interference can often be eliminatedby the use of a column known to have a high plate count.1.2 Review the current material safety data sheets (MSDS)for detailed information concerning toxicity, first aid proce-dures,
6、and safety precautions.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practi
7、ces and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 7.2. Referenced Documents2.1 ASTM Standards:3D 1193 Specification for Reagent WaterE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing
8、 of Industrial ChemicalsE 682 Practice for Liquid Chromatography Terms and Re-lationshipsE 685 Practice for Testing Fixed-Wavelength PhotometricDetectors Used in Liquid ChromatographyE 300 Practice for Sampling Industrial Chemicals3. Summary of Test Method3.1 A solution of sample and internal standa
9、rd in methanolis chromatographed on a reversed-phase ODS column using85/15 methanol/water as the mobile phase and an ultraviolet(UV) detector at 254 nm. The percent of dicumyl peroxide inthe sample is determined by the internal standard technique,using the peak height ratios of standard and sample c
10、hromato-grams.4. Significance and Use4.1 This test method provides a means for determining thepercent of dicumyl peroxide in technical and refined grades ofthis material. This test method is specific for dicumyl peroxide.No interference is encountered from dimethylbenzyl alcohol,acetophenone, or oth
11、er minor impurities normally associatedwith commercial dicumyl peroxide.5. Apparatus5.1 Liquid Chromatograph, equipped with a 254-nm UVdetector, an injection valve, and an isocratic solvent deliverysystem capable of operating to a gage pressure of 3000 psi (21MPa). The detector should be equipped wi
12、th an attenuatorswitch to change the sensitivity range as required.5.2 Recorder, 0 to 10-mV range, or an electronic integratorwith printer-plotter, or both.5.3 Chromatographic Column, reversed-phase C-18, 250 by4.6-mm inside diameter, containing octadecyldimethylsilanechemically bonded to spherical,
13、 5-m microparticulate silica.4NOTE 2Commercial HPLC columns vary in physical dimensions,degree of substrate loading, and size and type of support material. Somemodification in the operating parameters may be required to achieveoptimum separation for these reasons.5.4 Guard Column, reversed-phase C-1
14、8, 12.5 by 4.0 mm,with an inline filter.41This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.02 on Product Standards.Current edition approved Dec. 15, 1994. Published February 1995. Originallypubli
15、shed as E 755 80. Last previous edition E 755 90.2Dicumyl Peroxide; peroxide, bis (1-methyl-1-phenyethyl) C18H22O2; CASRegistry No. 80-43-3.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volum
16、e information, refer to the standards Document Summary page onthe ASTM website.4The commercial guard and analytical columns found to be most satisfactory foruse with this test method are Zorbax Rx-18, Part Nos. 820764.914 and880967.9002, respectively, available from Mac Mod, 127 Commons Court, Chadd
17、sFord, PA 19317. This column was selected for its separation characteristics andlinear response of the dicumyl peroxide and internal standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.5 Precision Sample Injection Valve, with
18、a 10-L loop andfiller port.5.6 Syringe, 250-L capacity.5.7 Sample Filter, consisting of a syringe and 0.2-m filterassembly to remove microparticulate matter from the preparedsample solution.55.8 Glass Bottles, 4 oz, with polyethylene-lined screw caps.6. Reagents6.1 WaterPrepare ASTM Type II reagent
19、water in accor-dance with Specification D 1193, or distill deionized water.Filter through a 0.2-m, Nylon-66 filter, and store in a glasscontainer. Alternatively, commercial multicartridge systemsthat produce water meeting or exceeding the requirements ofType II can be used.6.2 Methanol, chromatograp
20、hic grade, distilled in glass.6.3 Methanol-Water Mobile Phase, 85:15Mix 8.5 vol-umes of methanol with 1.5 volumes of water.6.4 Di-n-Heptyl Phthalate, purified.66.5 Dicumyl Peroxide, RecrystallizedTransfer 25.0 g ofcommercial refined dicumyl peroxide into a 100-mL Erlenm-eyer flask. Add 8.0 mL of met
21、hanol, and gently warm thesolution in a water bath while swirling to effect completesolution. Cool to 0C in an ice bath. Transfer the contents to amedium-porosity sintered glass crucible and vacuum filter.Allow air to pass through the filter for 10 to 15 min to dry theperoxide. Repeat the crystalliz
22、ation twice using approximately1 mL of methanol solvent for every3gofperoxide. Place therecrystallized dicumyl peroxide in a tightly capped bottle, andstore in a refrigerator (see Section 7).7. Safety Precautions7.1 Small quantities of solid or molten dicumyl peroxidecan be handled safely at tempera
23、tures up to 55C. Dicumylperoxide should not be heated above 55C because the rate ofperoxide decomposition increases rapidly with increasing tem-peratures above this point.7.2 A recirculating water bath or a water bath that has beenpreheated to the desired temperature and removed from theheat source
24、should be used for warming vessels containingdicumyl peroxide. Electrically heated water baths should notbe used since they may cause localized hot spots. Other sourcesof heat considered unsafe for warming containers of dicumylperoxide include ovens, hot plates, open flames, and directsteam.7.3 Orga
25、nic peroxides may ignite violently in contact withan open flame or electrical spark. These heat sources must beavoided for this reason.8. Sampling8.1 Prior to sampling technical and refined grades of di-cumyl peroxide, it is essential that the sample be blendedthoroughly after melting. This is best
26、accomplished by placingthe container in a 55C water bath. After the sample has meltedcompletely, mix thoroughly by swirling or stirring beforewithdrawing the sample for analysis (see 7.1-7.3). See Note 3.NOTE 3Refer to Practice E 300 for guidelines on sampling.9. Procedure9.1 Preparation of Standard
27、 Dicumyl Peroxide Solution:9.1.1 To the nearest 0.1 mg, weigh 0.40 6 0.05 g ofrecrystallized dicumyl peroxide and 0.20 6 0.05 g of di-n-heptyl phthalate (internal standard) into a tared 4-oz glassbottle.9.1.2 Add 100 mL of methanol, and mix well until thesample and internal standard have dissolved c
28、ompletely.9.1.3 Filter the solution through a 0.2-m filter, collectingthe filtrate in clean 17-mL vials equipped with PTFE-linedcaps. Cap the vials and store in a cool, dark location. Thissolution should be used within 36 h, after which time a freshsolution should be prepared. Gradual peroxide decom
29、positionwill cause a change in the internal standard/dicumyl peroxidepeak height ratio.9.2 Preparation of Sample Solution:9.2.1 To the nearest 0.1 mg, weigh 0.40 6 0.05 g of melteddicumyl peroxide sample and 0.20 6 0.05 g of di-n-heptylphthalate (internal standard) into a tared 4-oz glass bottle.9.2
30、.2 Add 100 mL of methanol, and swirl until the sampleand internal standard have dissolved completely.9.2.3 Filter a portion of the solution through a 0.2-m filter,collecting the filtrate in a 17-mL vial equipped with a PTFE-lined cap. Cap the vial and store in a cool, dark location. Thissolution sho
31、uld be used within 36 h, after which time a freshsolution should be prepared. Gradual peroxide decompositionwill cause a change in the internal standard/dicumyl peroxidepeak height ratio.9.3 Calibration:9.3.1 Adjust the liquid chromatograph in accordance withthe following parameters, and allow the i
32、nstrument to equili-brate until a stable baseline is obtained.Column oven 40CDetector UV, 254 nmMobile phase methanol:water, 85:15Flow rate 1.0 mL/minRecorder chart speed 0.5 cm/minNOTE 4The parameters given above apply to a liquid chromatographequipped with a Zorbax Rx-18 C-18 reversed-phase column
33、, 4.6-mmdiameter by 25 cm in length. Other columns may require some modifi-cation in the flow rate or mobile phase composition (see Note 2).NOTE 5See Practice E 682 for liquid chromatography terms andrelationships. See Practice E 685 for testing fixed-wavelength photometricdetectors.9.3.2 When the c
34、olumn is in equilibrium with the mobilephase, flush the sample loop with approximately 250 L of thestandard dicumyl peroxide solution and inject a 10-L aliquot.Typical retention times for dicumyl peroxide and di-n-heptylphthalate are 9 and 20 min, respectively.9.4 Analysis of Sample:9.4.1 Immediatel
35、y after obtaining the chromatogram of thestandard solution, flush the sample loop with approximately250 L of the prepared sample solution, and inject a 10-L5Waters Associates Sample Clarification Kit, Catalog No. 26870, has been foundto be satisfactory for this purpose.6Di-n-heptyl phthalate, Lancas
36、ter Synthesis, Cat. No. 5396, has been found to besatisfactory for use as an internal standard.E 755 94 (2003)2aliquot. A typical chromatogram of technical grade dicumylperoxide obtained under the conditions outlined in 9.3.1 isshown in Fig. 1.10. Calculation10.1 Measure the heights of the dicumyl p
37、eroxide anddi-n-heptyl phthalate peaks in the chromatogram of the stan-dard solution.10.2 Calculate the response factor, FC, for dicumyl peroxideas follows:FC5WC3 HISWIS3 HC(1)where:FC= response factor,WC= weight of standard dicumyl peroxide, g, see 9.1,WIS= weight of di-n-heptyl phthalate, g, see 9
38、.1,HIS= peak height of di-n-heptyl phthalate, andHC= peak height of dicumyl peroxide in standard.10.3 Measure the heights of the dicumyl peroxide anddi-n-heptyl phthalate peaks in the chromatogram of the samplesolution.10.4 Calculate the percent of dicumyl peroxide present inthe sample as follows:Wt
39、 % dicumyl peroxide 5WIS3 HC3 FC3 100WS3 HIS(2)where:FC= response factor, see 10.2,WIS= weight of di-n-heptyl phthalate, g, see 9.2,WS= weight of sample, g, see 9.2,HIS= peak height of di-n-heptyl phthalate, andHC= peak height of dicumyl peroxide in sample.11. Report11.1 Report the percentage of dic
40、umyl peroxide to thenearest 0.1 %.12. Precision and Bias12.1 PrecisionThe following criteria should be used forjudging the acceptability of the results (Note 6):12.1.1 Repeatability (Single Analyst)The standard devia-tion for a single determination has been estimated to be0.418 % absolute at 14 DF.
41、The 95 % limit for the differencebetween two such runs is 1.3 % absolute.12.1.2 Laboratory Precision (Within-Laboratory, BetweenDays, Formerly Called Repeatability)The standard deviationof results (each the average of duplicates), obtained by thesame analyst on different days, has been estimated to
42、be 0.30 %absolute at 7 degrees of freedom. The 95 % limit for thedifference between two such averages is 0.8 % absolute.12.1.3 Reproducibility (Multilaboratory)The standard de-viation of results (each the average of duplicates), obtained byanalysts in different laboratories, has been estimated to be
43、0.58 % absolute at 6 degrees of freedom. The 95 % limit for thedifference between two such averages is 1.6 % absolute.NOTE 6The above precision estimates are based on an interlaboratorystudy performed in 1992 on one sample containing approximately 99 %dicumyl peroxide. One analyst in each of seven l
44、aboratories performedduplicate determinations on each of two different days for a total of 28determinations.7Practice E 180 was used in developing these precisionstatements.7Supporting data are available from ASTM Headquarters. Request RR: E15-1023.FIG. 1 Typical Chromatogram of Technical Grade Dicu
45、myl PeroxideE 755 94 (2003)312.2 BiasThe bias of this test method has not beendetermined due to the unavailability of suitable referencematerials.13. Keywords13.1 assay; dicumyl peroxide; HPLC; liquid chromatogra-phy; peroxidesASTM International takes no position respecting the validity of any paten
46、t rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision a
47、t any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your commen
48、ts will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted
49、by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E 755 94 (2003)4
