Standard Reference Material 2881 - National Institute of Standards ...

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TABLE OF CONTENTS1. Introduction2. Preparation, Initial Characterization, and Bottling3. Bottle-to-Bottle Homogeneity Testing4. Discussion of the Certification Method Developed for SRM 28815. Mass Axis Calibration Procedure6. Signal Axis Calibration Procedure7. Experimental Method for the Calibration of the Signal Axis8. Data Analysis Methods9. Experimental Results10. Discussion of Type A Uncertainties11. Discussion of Type B Uncertainties12. Discussion of Certified Values13. ConclusionsAcknowledgementsReferencesFiguresTablesAppendix A SRM Certificate3
1. IntroductionThe certification of the absolute molecular mass distribution (MMD) of an n-octyl-initiated,proton-terminated, low mass, atactic polystyrene (PS) by matrix-assisted laser desorptionionization time-of-flight mass spectrometry (MALDI-TOF MS) is fully described. This polymerhas been designated Standard Reference Material (SRM) 2881. The material constituting SRM2881 was prepared commercially for the NIST Polymers Division specifically for use as anarrow-distribution polymer standard. Anticipated uses include calibration of massspectrometers and size exclusion chromatographs (SEC) in accordance with various internationalstandards (described below), as well as any other application where quantitative knowledge ofthe entire MMD is necessary. The work described here, and in related references, provides ameans to create absolute molecular mass distribution standards of any low mass, narrowpolydispersity polymer including proprietary materials.This work is the culmination of a multi-year effort that required development of newmethods in sample preparation 1 , numerical instrument optimization 2 , and unbiased dataanalysis 3-5 . This report mainly covers the final uncertainty determination and discusses aTaylor’s expansion methodology to certify the absolute MMD of polydisperse samples.2. Preparation, Initial Characterization, and Bottling2.1 SynthesisThe polystyrene used for this SRM was prepared commercially by Scientific PolymerProducts, Inc. (Ontario, NY) by anionic polymerization of styrene initiated with n-octyl lithium(FMC Lithium, Gastonia, NC) and terminated with a proton. From the preparation chemistry, weexpected the polymer to be atactic polystyrene of the form:CH 3 -(CH 2 ) 7 -[CH 2 -CHPh] n -CH 2 -CH 2 -Ph [2.1]where Ph refers to the pendant phenyl group. The material was received in the form of a clean,white powder.4
Page 1 and 2: NISTIR 7512A Report on the Certific
Page 3: ABSTRACTThe certification of an abs
Page 7 and 8: BHT), was used as the solvent. The
Page 9 and 10: anticipated to be a useful material
Page 11 and 12: sample using a separate method, or
Page 13 and 14: 6.0. Signal Axis Calibration Proced
Page 15 and 16: 6.2 Mathematical Model for Gravimet
Page 17 and 18: Here Q is a function of all the exp
Page 19 and 20: Let us consider this final equation
Page 21 and 22: GGexpTAexpTBGG0TA0TB=⎧⎨1+⎩0(
Page 23 and 24: were also used in this experiment:
Page 25 and 26: The matrix was all-trans retinoic a
Page 27 and 28: educes the data set to groups of th
Page 29 and 30: atios of the two sets of data is ag
Page 31 and 32: An analysis of variance (ANOVA) 5 w
Page 33 and 34: 11. Discussion of Type B Uncertaint
Page 35 and 36: Two other methods were used to chec
Page 37 and 38: certified by this method with the u
Page 39 and 40: References1. S. D. Hanton, I. Z. Hy
Page 41 and 42: Figures1. MALDI-TOF mass spectra of
Page 43 and 44: Figure 242
Page 45 and 46: Figures 5 (inset) and 6 (main)44
Page 47 and 48: Figure 946
Page 49 and 50: Tables1. Q/k 0 with its estimated u
Page 51 and 52: Table 2Instrument Parameter Optimal
Page 53 and 54: 103 10840.42 0.0063 8.93 % 14.72 %
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99 10423.86 0.0139 0.0008 93.9 %100
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INSTRUCTIONS FOR USEStorage: The SR
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REFERENCES[1] See ASTM D5296 05 “
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