Journal of Chromatography A, 1025 (2004) 125–132 Physico-chemical measurements of CL-20 for environmental applications Comparison with RDX and HMX Fanny Monteil-Rivera, Louise Paquet, Stéphane Deschamps, Vimal K. Balakrishnan, Chantale Beaulieu, Jalal Hawari ∗ Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Que., H4P 2R2 Canada Abstract CL-20 is a polycyclic energetic nitramine, which may soon replace the monocyclic nitramines RDX and HMX, because of its superior explosive performance. Therefore, to predict its environmental fate, analytical and physico-chemical data must be made available. An HPLC technique was thus developed to measure CL-20 in soil samples based on the US Environmental Protection Agency method 8330. We found that the soil water content and aging (21 days) had no effect on the recoveries (>92%) of CL-20, provided that the extracts were kept acidic (pH 3). The aqueous solubility of CL-20 was poor (3.6 mg l -1 at 25 ◦ C) and increased with temperature to reach 18.5 mg l -1 at 60 ◦ C. The octanol–water partition coefficient of CL-20 (log K OW = 1.92) was higher than that of RDX (log K OW = 0.90) and HMX (log K OW = 0.16), indicating its higher affinity to organic matter. Finally, CL-20 was found to decompose in non-acidified water upon contact with glass contain- ers to give NO 2 - (2 equiv.), N 2 O (2 equiv.), and HCOO - (2 equiv.). The experimental findings suggest that CL-20 should be less persistent in the environment than RDX and HMX. © 2003 Elsevier B.V. All rights reserved. Keywords: Octanol–water partition coefficients; Solubility; Soil; CL-20; RDX; HMX; Nitramines; Explosives 1. Introduction Past and present high-scale manufacturing, use, and dis- posal of explosives have resulted in severe environmental contamination [1]. Explosives such as the cyclic nitramines, RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) (Fig. 1), are toxic to various terrestrial and aquatic receptors [2,3], and the provision of chemical and analytical data on their transport and transformation mechanisms in soil has been the subject of extensive study. Due to their high energy content, polynitropolyaza-caged compounds seem more attractive than the presently used RDX and HMX. A typical energetic chemical of this family is 2,4,6,8,10,12-hexanitro-2,4,6,8, 10,12-hexaazatetracyclo[5.5.0.0 5,9 .0 3,11 ]dodecane or hexa- nitrohexaazaisowurtzitane (HNIW), commonly known as CL-20 (Fig. 1), which was synthesized by Nielsen [4] and later adopted by Thiokol for pilot scale production [5]. Because of its superior ballistic, detonation and explosive performance, CL-20 may soon replace RDX and HMX. ∗ Corresponding author. Tel.: +1-514-4966267; fax: +1-514-4966265. E-mail address: jalal.hawari@cnrc-nrc.gc.ca (J. Hawari). However, to limit the consequences of its use, the environ- mental fate, transport and impact of CL-20 should first be thoroughly understood. Prediction of the environmental fate (transport and trans- formation) of a new chemical such as CL-20 requires accu- rate analysis of the compound and its degradation products in both water and soil samples. The stability of the compound while being manipulated and analyzed should be well char- acterized. Moreover, physico-chemical parameters such as the octanol–water partition coefficient (K OW ), the aqueous solubilities and the soil sorption coefficients (K d ) must be- come known in order to foresee both bioaccumulation in ter- restrial and aquatic biota and migration through subsurface soil that causes groundwater contamination [6]. CL-20 is a relatively new compound and most of its physico-chemical parameters have yet to be determined. The objectives of the present study were threefold: first, to provide the reader with an optimized analytical method to quantify CL-20 in aqueous and soil matrices; second, to make data available on its aqueous solubility at different temperatures (5–60 ◦ C) as well as its octanol/water partition and soil sorption coef- ficients; and finally, to provide insight into the stability of CL-20 in water. 0021-9673/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2003.08.060