Ask The Expert Webinar Series Explosives by HPLC, LC/MS and LC/MS/MS Karla Buechler Corporate Technical Director August 2, 2016
Presentation Outline A Historical Overview of Explosive Chemicals An Introduction to the Chemistry and types of Explosives Explosive Chemicals in the Environment How are Explosives Regulated? Analytical Methodologies Method 8330B vs 8321 A Perchlorate Discussion An ISM Discussion TestAmerica s Capabilities
History of Explosive Chemical Discoveries Chinese alchemist discovered first explosives in 9 th century. Roger Bacon (1220-1292) made black powder from saltpeter, sulfur and charcoal. In 1353, Berthold Schwarz invented the gun. In 1845, Schonbein made nitrocellulose (NC). In 1860, Major Schultz made a stable NC powder. Nitroglycerin (NG) was discovered in 1846 by Ascanio Sobrero.
Cont. History of Explosive Chemistry Discoveries du Pont de Nemours in 1858 began production of sodium nitrate. Commercial production of gun powder. Alfred Nobel mixed NG with silica and patented dynamite in 1867. 1884, a smokeless gun powder was developed as a mixture of (NC) and ether and alcohol, by Vieille.
What are Explosives? A reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly 2 Functional Classes of Explosives 1) High Release large of amounts of energy when detonated. Primary Used to start explosions (Lead azide and Lead styphnate). Secondary Main charge TNT and RDX. 2) Low Burn at steady speed and detonate only under extreme conditions.
Chemical Classes of Explosive Compounds Nitroaromatics Nitrate esters C-NO 2 C-O-NO 2 TNT PETN RDX C-N-NO 2 Cyclic nitramines
Explosive Aromatics (TNT, DNT, TNB) Desirable features include stability and low sensitivity to high temperature Used in military munitions and in civilian mining Relatively safe to manufacture TNT is toxic Degradates are routinely analyzed GC and GCMS are inadequate IC, LC and LCMS are preferred
Explosive Esters (NC, NG, PETN, EGDN) All except NC are highly sensitive All are toxic NC primarily used in smokeless powder NG main component of dynamite PETN used as a detonator EGDN additional ingredient in dynamite No degradation products of concern GC and GCMS are inadequate IC, LC and LCMS are preferred
Explosive Nitramines (RDX and HMX) Very important military explosive Resistant to heat High chemical stability Explosive power much greater than TNT Often used in mixtures Very shock sensitive Very toxic Concern about metabolites GC and GCMS are inadequate IC, LC and LCMS are preferred
RDX/HMX Metabolites and Degradation Products Why do we care? Persistence in the environment Human body can transform RDX/HMX into metabolites We know little about their toxicity We need reliable analytical techniques in order to remediate these chemicals
Insensitive Munitions (DNAN, NTO and NQ) Do not react violently save lives and materials In 2013, US Army approved the use of IM Used to replace or supplement RDX, HMX and TNT Potential release to the environment We need analytical methods USS Enterprise January 15, 1969 Flight deck accident
Other Explosive Chemicals White Phosphorus incendiary purposes, burns spontaneously in air Tetracene used in ammunition primers to provide stability Nitroguanidine - high explosive like TNT Perchlorate rocket propellants, consumer products NDMA liquid rocket fuels Nitrocellulose First smokeless powder
Other Explosive Methods White Phosphorus Modified 8141 GC with NP detector Tetracene Method 8331 LC/UV or PDA detector Nitroguanidine Modified Method 8330 unique polarity Perchlorate Method 8321 or 6850/60 IC or LC with MS/MS NDMA Method 521, 1625 or 625. All GC/MS techniques. Nitrocellulose Modified Method 353.2
Explosive chemicals in the Environment Production, storage, and disposal of explosives and propellants at military installations and manufacturing facilities Discharge of contaminated manufacturing waste streams into rivers or ground water, Burial of obsolete munitions, Training exercises increase the availability of explosives to the environment. Environmental analytical methods were needed to
Explosives Regulations RDX, TNT, and 1,3-DNB listed in UCMR2 NDMA included in UCMR2 RDX & DNTs included on DoD MERIT list
Additional Regulatory Guidance RSEPA- Range Sustainability Environmental Program Assessment RCA Range Condition Assessment CRE Comprehensive Range Evaluation SRO Sustainable Range Oversight during a CERCLA response
Desirable Method Characteristics Explosives compounds are unique GC and GCMS work poorly Linearity IC Precision LC IC MS Accuracy Sensitivity Selectivity Robustness LC MS LC MSMS
8330B - Primary Method for Explosive Residue Analysis Developed by USACE CRREL laboratory in late 1980 s Updated to 8330B in November 2006 Originally for RDX, HMX, Tetryl, NB, DNT, TNT General use all purpose method EPA Method 8330 HPLC/UV, confirmation by LCMS allowed
Pros and Cons of Method 8330B Pros of HPLC/UV Fairly simple technique Moderately inexpensive Reasonably rugged and quick Cons of HPLC/UV Prone to false positives Lack of sensitivity No complex matrices Limited analyte list
Advantages of Method 8321 vs 8330B Sample preparation very similar to 8330B Mass spectrometer reduces interferences MS/MS mode is available Second column conf. not necessary Analyte list can be significantly extended
Advantages of LC/MS/MS Specificity/Selectivity - A target analyte s response is highly characteristic of its identity. LC/MS/MS analyses are 10 to 100 times better at filtering interferences than conventional instrumentation Sensitivity - Softer ionization than Electron Impact (EI) GCMS allows for thermally labile analytes to be detected Ruggedness improved reproducibility for a wide variety of parameters and matrices and improved productivity 21
LC/MS/MS Electrospray Ionization 22
Perchlorate IC vs LC/MS/MS EPA Methods 314.0 and SW 846-9058 Both use Ion Chromatography Limitations Solution Insufficient sensitivity, selectivity and robustness LC/MS, LC/MS/MS, IC/MS, IC/MS/MS Method 8321, Method 6850 or Method 6860 All our MS/MS methods Better sensitivity less affected by ionic strength Definitive selectivity
Chasing Sources of Uncertainty Field sample collection Lab subsampling Sample extraction Instrumental analysis
Surface Soil from Military Training Range What? Explosives Where? < 2 mm particles Particle interior & exterior Nugget effect? Expected to be high due to particulate nature of the analytes Pictures from USACE-Alan Hewitt 25
26 Incremental Sampling Systematic Random Design Random starting locations in first grid Increment collection point
Surface Soil from Military Training Range One Decision Unit (DU) USACE-Alan Hewitt 27
Explosives Sample Preextraction Steps Goal - We need a small representative sample of a larger sample. Drying Disaggregation Sieving Milling Subsampling 28
Air Drying of Soil Samples High boiling analytes 29
Disaggregation & Sieving Mechanical chopping #10 Sieve Mortar & Pestle 30
Soil Sample Milling Puck mill grinding Smaller, better mixed particles Picture from USACE-Alan Hewitt 31
Subsampling 2 D slabcake subsampling 32
Technical Summary Study allowed for the comparison of a number of factors that affected the reproducibility of results. Factor A Factor B Comments Field collection techniques Discrete, box, and wheel Avg RSD = 115% ISM Avg RSD = 22% ~5x better precision with ISM Laboratory subsampling and milling 8330A Avg RSD = 22% 8330B Avg RSD = 6% ~3x better precision with ISM 33
Advantages of ISM Advantages Better spatial coverage Higher Sample Mass Optimized processing Effects Includes high & low conc. in proper proportions Reduces errors associated with processing and analysis Representative subsamples Fewer non-detects Simplifies statistical analysis More consistent data More confident decision 34
Project Experience Federal Program Support US Army Corps of Engineers US Navy US Air Force USGS DOE Example Project Locations Redstone Arsenal Ft. McClellan Ravenna Arsenal Avon Park Pueblo Chemical Depot Iowa AAP China Lake NAWS Picatinney Arsenal Benicia Arsenal Dugway Proving Ground Jefferson Proving Ground Alleghany Ballistics Lab Indian Head NSWC JACADs Weldon Springs Pantex
TestAmerica Capabilities 3 laboratories accredited by DoD ELAP for 8330B: Burlington, Denver, Sacramento LC/UV LC/MS LC/MS/MS Dedicated ISM facilities More than 25 years at each lab with explosives analysis
Capabilities for Complex Matrices 37
Future Concerns Need methods for insensitive munitions Need to expand analyte lists for existing methods Need to develop clean up techniques for complex matrices
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