AD-A237 511III i' iu I lB tI! I II.°!i"AD-E402 211

Contractor Report ARAED-CR-91008

ANALYSIS OF NITROMETHANE

William R. HerreraSouthwest Research InstituteSan Antonio, TX 78228-0510

William 0. SealsProject Engineer

June 1991

U.S. ARMY ARMAMENT RESEARCH, DEVELOPMENT ANDS! ENGINEERING CENTER

Armament Engineering DirectorateA -'Picatinny Arsenal, New Jersey

US ARMYARMIAMENT MUNtI IONShCHEMICAL.COMMANn

ARMAMENT RDF CENTFR

Approved for public release: distribution is unlimited.

REPRODUCED FROM 91-03227BESTAVAILABLEcoPY jlli liii CiiI

The views, opinions, and/or findings contained in thisreport are those of the author(s) and should not beconstrued as an official Department of the Army position,policy, or decision, unless so designated by otherdocumentation.

The citation in this report of the names of commercialfirms of commercially available products or systems doesnot constitute official endorsement by or approval of theU.S. Government.

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0 Ithe Iortm for ro.,..wo instructions. searching exisrting data sources, gathering and maintaining the dataro r-f V.r, -1 d,.r.. orII, 011-i~on Pr ,infrma,Io n t,*-Irot m.rrrsrrr r:rrdin. this b~urden *%ifimais or arny Ohotto asetiottth Iscolection of information,including suggestionh fortoducingthis burden.

roW~~~~~ Ion, I. ,, 0 ,r,,.for ,,r,r fIorlrtkr mrrOn p-'r.sorr, nrdtlr~po,!%. 1215 JnIr^r., Dwoerdh~hay, Su,:* 1204. rItngton, VA 2

220

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1. AGENG.' USE ONLY ('Leavo blank) 2 REPORT DATE 3. REPORT TYPE AND DATES COVEREDJune 1991 Final, 6/12/90 to 7/31/90

4. TITLE AND SUBTITL.E 5. FUNDING NUMBERS

MIGRAD SYSTEM IMPROVED SAFETY AND PRODUCIBILITY INTH-E MANUFACI LJRING OF PYROTrECHNIC MIXTURES DAAA21 -88-D-0021

6. AUTHOR(S)William R. Holrrera, Southwest Research InstituteWilliam 0. Seals, ARDEC

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATIONSouthwest Research Institute ARDEC, AED REPORT NUMBERSan Antonio, TX 78228-0510 ATTN: Energetics and Warheads Div

ATTN: SMCAR-AES-MPicatinny Arsenal, NJ 07806-5000

9. SPONSOR INGIMONITOR ING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORINGARDEC IMDAGENCY REPORT NUMBER

STINFO BrATTN: SMCAR-IMI-l Contractor Report ARAED-CR-91 008Picatinny Arsenal, NJ 07806-5000

11. SUPPLEMENTARY NOTES

120. DISTRIBUTION/AVAILABILITY STATEMENT j12b. DISTRIBUTION CODE

Approved for public release: distribution is unlimited.j

13. ABSTRACT (Maximum n200 words)

Samples were taken at random from 60 barrels of nitromethane which were stored at Yuma Proving Groundsand sent 1o Southwest Research Institute for analyses. The nitromethane content was determined for eachalong with contaminate analyses for nitroethane, 2-nitropropane, water, and metals. The results indicated thefollowing:

Component Percent

Nitromethane 98 or greaterNitroethane 1.1 or less2-Nitropropane 0.2 or lessWaler 0. 11 or lessMetals Trace (less than 10 ppb)

14. SUBJECT TERMS 15. NUMBER OF PAGESNitromethane; Nitroethane; FTIR; Karl Fischer; Volitiles; Semivolites; Mallinckrodt gas 61chromatography; Atomic absorption 16. PRICE CODE

7, SECURITY CLASSIFICAT ION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACTOF REPORT O HSPG FASRC

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED SAR --I Standard Form 298 (Rev. 2-89)NSN 1540-01-280-5500 Prescribed by ANSI Std. Z39-1 298-102

CONTENTS

Page

Introduction 1

Procedures and Results 2

Discussion 6

Appendixes

A FTIR Comparison Spectra 7B FTIR Spectra of Samples 13C Volatile Analyses 25

Distribution List 47

TABLES

1 FTIR analysis for percent nitromethane 2

2 GC/MS analysis for volatile contaminants 3

3 GC/MS analysis for semivolatile contaminants in selected nitromethane samples 3

4 Karl Fischer analysis of nitromethane samples 4

5 Metals analysis of nitromethane samples 4

6 Computation of various analysis of nitromethane samples 5

ETI

Avealability 00od*

Mvi fdf orDist Sp.imsail

1. INTRODUCTION

Originally, the-Government had purchased and stored 60 barrels of nitromethane at the YumaProving Grounds for use in the TEXS system. This system required that the materials be housed inthe all-purpose storage area. DOD has classified nitromethane as a Class 4, mass detonating materialand not suitable for storage in the all-purpose area. This restriction resulted in the rejection ofnitromethane as a candidate for the TEXS system.

These barrels have been exposed under varying degrees of environmental conditions andchanges. Contamination and degradation to the nitromethane may have occurred during the storageperiod. An analysis is required to determine whether the material has deviated dramatically from the

specifications furnished by the supplier. This analysis will determine whether the stored nitromethaneis suitable for use in another application.

Samples of nitromethane were taken at random from the 60 barrels of stored nitromethane.These samples were taken from the top, middle, and bottom to ascertain the uniformity ofnitromethane composition. Replicate samples of each were analyzed in the following manner forthese components and contaminates that may be present:

Component Analytical Method

Nitromethane FTIR

Nitroethane GC/Mass Spectroscopy

2-Nitropropane GC/Mass Spectroscopy

Water Karl Fischer

Metals AA Graphite Furnace

FTIR - Fourier transform infraredGC - gas chromatograpyAA - atomic absorption

ii1

2. PROCEDURES AND RESULTS

Analysis of nitromethane was performed by FTIR. SwRI received a 99%+ sample ofnitrometh,•ie that was certified by Angus Chemical. An FTIR analysis was performed and the resultscompared to the Chem Sources 98%+ sample used during the program. The results confirmed thepurity level of the Chem Sources sample. The results are given in Table 1 and raw data are foundin Appendix A.

"TABLE 1. FTIR ANALYSIS FORPERCENT NITROMETHANE

Sample % Nitromethane

Y1-B 99.6

Y1-M 98.3

Y1-T 100.0

Yl-MM 99.3

Al-B 99.3

A1-M 99.9

Al-MM 99.0

Ni-B 100.2

N1-M 9.9.5

N1-T 99.5

Standard 98%

B BottomM MiddleT TopMM Middle mixed

The FTIR spectra of the neat nitromethane samples were compared to that of the Mallinckrodtsample and found to be virtually identical. Computer subtraction of the Mallinckrodt sample fromthe other samples failed to show any gross contaminant. It was concluded that any impurities presentwere only in low concentration.

4a-

Weighed quantities of each 'of the samples were dissolved in carbon tetrachloride to make 25mL total volume. A solution prepared similarly from Chem Service nitromethane (98.0%) wasutilized as a standard. This standard was used due to the higher degree of purity of the material. Thenitromethane concentration of the samples was determined by comparing absorption intensities at 657cm1 in a se,led liquid cell. The 657 cm-1 absorption is specific for nitromethane and is unaffectedby., nitroethane and 2-nitropropane. The precision was estimated to be ca. ±1 nitromethane.

2

An overlay, offset comparison Spectta of Y1-M and the Chem Service 98% standard is givenin Appendix A. The two spectra are identical except for a few insignificant peaks in the 800-830range. The spectra for all the samples are included in Appendix B.

Analysis of volatile compounds other than nitromethane was performed using GC/MS. Theresults for nitroethane and 2-nitropropane are given in Table 2 and raw data are found in AppendixC.

TABLE 2. GC/MS ANALYSIS FORVOLATILE CONTAMINANTS

S% Composition

Sample Nitroethane 2-Nitropropane

YI-B 0.9 -0.1

Y1-M 0.9 -0.1

Yl-T 0.8 -0.1

Y1-MM 0.9 -0.1

Al-B -0.1__ -0.1

A1-M -0.1 -0.1

Al-MM -0.4 J0.2N1-T -0.1 -0.1

N1-M -0.1 -0.1

N1-B 1.1 J -0.1

See legend Table 1.

Analysis for semivolatile compounds was performed using GC/MS. Two samples wereselected for analysis. The results are given in Table 3.

TABLE 3. GC/MS ANALYSIS FOR SEMIVOLATILE CONTAMINANTSIN SELECTED NITROMETHANE SAMPLES

Sample Y1-M Sample N1-MComponent ppm ppm

Paraldehyde 70.0 38.0

2-Pentanone-4-methyl 42.0 0.0

Total other unknowns 13.4 2.9

% Total Semivolatiles 0.01% 0.004%

See legend Table 1.

3

No single semivolatile contaminant was feornd to have a concentration >0.007%.

Karl Fischer analyses were perfornmed to assay the water content of each of the samples. Theresults can be compared to standard 95% nitromethane sample from Mallinckrodt. The results aregiven in Table 4.

TABLE 4. KARL FISCHER ANALYSIS OF

NITROMETHANE SAMPLES

Sample ppm HO %

Standard 1,370 0.14

Y1-T 629 .0.06

"YlIMM 697 0.07

YI-M 1077 0.11

YI-B 693 0.07

NI-T 705 0.07

NI-M 506 0.05

Ni-B 432 0.04

A1-M 549 0.05

A1-MN.I 589 0.06

Al-B 590 0.06

See legend Table 1.

The average percent water. of the samples was 0.06.

Metals contamination analysis was performed on a Perkin-Elmer 5000 graphite furnace atomicabsorption spectrophotometer. Calibration standards were made up in methanol and samples werediluted 1:1 in methanol before analysis. A methanol blank was run with each sample set. No solventcontamination was observed.

The results are presented in Table 5.

TABLE 5. METALS ANALYSIS OF NITROMETHANE SAMPLES

ppb

Sample Cu [ Fe Ni

Standard <1.0 <2.0 <5.0

YI-T 8.2 <4.0 <10.0Y1-MM 9.0 <4.0 <10.0YI-M.0 <4.0 <10.0

TABLE 5. METALS ANALYSIS OF NITROMETHANE SAMPLESppb

Sample [ Cu Fe, Ni

Y1-B . 6.6 <4.0 ... <10.0

N1-T J 6.6 <4.0 <10.01-M 6.6 <4.0 <10.0

Ni-. 5.8 <4.0 <10.0

Al-MM 9.8 <4.0 <10.0A1-M 8.0 <4.0 <10.0Al-B 9.8 <4.0 <10.0See legend Table 1. -

A compendium of all the analytical results are given in Table 6.

TABLE 6. COMPUTATION OF VARIOUS ANALYSIS ON NITROMETHANE SAMPLES

% Composition

MetalContaminants

Sample Nitromethane H20 Nitroethane 2-Nitropropane Semivolatiles (ppb)

YI-B 99.6 0.07 0.9 -0.1 <10

YI-M 98.3 0.11 0.9 -0.1 0.01 <10

YI-T 100.0 0.06 0.8 -0.1 <10

Y1-MM 99.3 0.07 0.9 -0.1 <10

Al-B 99.3 0.06 -0.1 -0.1 <10

A1-M 99.9 0.05 -0.1 -0.1 <10

Al-MM 99.0 0.06 0.4 0.2 <10

N1-B 100.2 0.04 1.1 -0.1 <10N1-M 99.5 0.05 -0.1 -0.1 <0.01 <10

N1-T 99.5 0.07 -0.1 -0.1 <10

See legend Table 1.

U..

3. DISCUSSION

A high degree-of purity of nitromethane was found for all the samples. The FTIR analysisshowed that all the samnples had a concentration of 98% or greater nitromethane. This finding isbased on th assumption that the Chem Service nitromethane standard used for comparison is of 98%purity. Other peaks in the FTIR spectra were of insufficient prominence to quantify, so alternateanalytical techniques were utilized to identify the other compounds present.

Analysis of other volatile and semivolatiles, especially nitroethane and 2-nitropropane, wasaccomplished utilizing GC/MS. It was ascertained that all the samples contained 1.1% or less ofnitroethane and 0.2% or less of 2-nitropropane. All other peaks in the volatile analysis weresignificantly less prominent indicating much lower concentrations of any other volatile contaminants.

The semivolatile analysis yielded only trace quantities of contamination of the nitromethane.Only two samples were selected for analysis due to the similarity of the samples preceding analysisand the small percentage of unaccounted for components. Quantification ct contaminants wasaccomplished by subtracting the effects of the nitromethane. It is possible that a higher percentageof paraldehyde is present due to the elution interference of the solvent, but the results of the prioranalysis make this unlikely.

Karl Fisher water analysis yielded results of 0.11% water or less. This is consistent with theresults of the metals analysis, which showed only trace amounts of metals contamination. Fornitromethane to be corrosive to a steel container, the H20 concentration must exceed 0.2%. The H20concentration was below iis limit; hence, there was no or little interaction with the containers.

Sampling procedures did not accompany the samples. The method used to sample the barrelscould have an effect on the analytical findings. It will be important in the future to ensure that astandard method of sampling is used, preferably a technique that yields a representative sample fromeach of the layers within a single drum of nitromethane.

It will also be necessary to establish a chain-of-custody record to ensure proper handling ofthe samples from the field to the analyst. Such a record could help to facilitate understanding anygross contamination that appears, that are not accounted for in future analysis.

Two possible explanations exist for the discrepancy between the original reported purity ofthe nitromethane, and the purity found in this program. First, during telephone conversations withAngus Chemical, the origii a1 shipment of nitromethane was certified at 96%+. This designationcommonly results in product which is percentage points higher. Second, and most probable, if a pointsampling procedure was utilized, as opposed to a cross-sectional sampling procedure, then a higherdegree of homogeneity would result. Point sampling techniques miss any differences in product dueto stratification.

6

APPENDIX A

FTIR COMPARISON SPECTRA

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FTIR SPECTRA OF SAMPLES

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APPENDIX C

VOLATILE ANALYSES

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