A variety of additives (e.g., stabilizers) are present in explosive formulations which need to be verified during manufacture, trouble-shooting or re-certification for continued use. ANALYZE Inc. is a certified “user of explosives” by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). ANALYZE has assayed a variety of constituents in energetic formulations by chromatography, spectroscopy and calorimetry.
The client would like to re-certify a batch of material for continued use by ensuring the stabilizer (ethyl centralite) has remained above the manufacturer specified lower level.
The concentration of ethyl centralite in an energetic materials matrix was determined using high performance liquid chromatography (HPLC).
HPLC is an analytical technique which is used for separation of a wide variety of organic compounds according to their interaction with the selective stationary phase while a solution is being pumped through a chromatography column. The separated compounds are identified qualitatively based on their residence or retention time while passing through the chromatography column and UV-VIS absorbance spectrum. The concentration of the additives is proportional to the integrated signal intensity at a given wavelength which defines the eluting peak.
Analyses were conducted using an Agilent HPLC system fitted with an auto-sampler, diode array UV-VIS detector and Chemstation software. A high purity ethyl centralite reference standard was acquired and a calibration curve was constructed.
The chromatogram acquired of the solvent extraction of the energetic material is shown in the figure.
The ethyl centralite elutes with a retention time of 5.1 minutes and had a measured loading above the expected lower concentration level. A matrix spike recovery of the target analyte was 96%.
An additional major component was detected at 3.1 minutes. If this compound was not an expected ingredient of the formulation and of interest to the client (e.g., degradation product), additional analyses (LC-MS) utilizing the Agilent 6230 TOF-MS could have been performed to identify the unknown component.
Conclusion and Benefit to the Customer
ANALYZE was able to determine the loading of the ethyl centralite in the formulation which allowed the customer to re-certify the lot of energetic material.