Statistical optimization for determination of trace amounts of RDX in matrix of HMX using GC-ECD

Abstract

1,3,5,7-Tetranitro-1,3,5,7-tetrazocane (HMX) is one of the most powerful military explosives that is produced by means of Bechmann method. Simultaneous, 1,3,5-rinitroperhydro-1,3,5-triazine (RDX) as a by-product is produced in this method that affect on the purity and sensitivity of HMX. Using a simple and fast technique is important for determination of trace amounts of RDX in the HMX matrix. The technique of gas chromatography-electron capture detector (GC-ECD) was proposed for these reasons. Because the presence of several parameters in the proposed technique, the experimental design methods of factorial and central composite were used for the experiments of screening and optimization, respectively. The parameters of oven programming, injection volume, injection temperature, carrier gas flow rate, and detector temperature were used in experiments of screening. The analysis of variance and Pareto plots showed that the injection temperature and carrier gas flow rate must be optimized among the parameters. After the screening and optimization of the studied parameters, the selected conditions were oven programming 10 °C min−1, injection volume 1 μL, injection temperature 250 °C, carrier gas (N2) flow rate 3 mL min−1, and detector temperature 300 °C. The calibration curve and detection limit of the optimized method were 10–90 and 1.8 mg L−1, respectively, of RDX in matrix of HMX. The relative standard deviation of the measurement was 1.89%. Finally, the RDX recovery percentages in HMX matrix in the three spiked samples were also calculated.