Determination of the Explosive HMX in Soil - Coursework Example

The method is commercially designed for RDX and HMX testing for concentrations between 1-20mg/kg in soil samples, Marshall & Oxley (2008). EPA method 8510’s procedure adheres to the following steps; Extract soil sample with acetone If inorganic nitrates and nitrites are present the soil extract is then pasted through an ion exchange resin for their removal The Nitramines and Nitrate esters are then acidified and mixed with zinc dust, passed through reactants of target analytes of zinc dust A color then is developed using NitriVer3 powder pillow, which ranges from pink to deep red depending on the concentration of RDX/HMX in the mixture.

Using a spectrophotometer, absorbance is then measured of the treated extract at designated wavelengths and the concentration of RDX/HMX of the unknown sample estimated by comparison to a known standard. Interferences of the sample analysis can be caused by the presence of solvents, reagents, glassware and other processing hardwares present in the soil sample. Hence, the soil samples must be rendered free of these materials by using specific selection of reagents and solvent purification using distillation process in an all glass system following guidelines on cleaning of glassware().

Chemical related explosives such as nitroguanidine (NQ), nitroglycerine (NG), nitrocellulose (NC), tetryl and pentaeythritol tetra nitrate (PETN) can cause pink color to develop if found present in the soil sample. In the absence of RDX and HMX on the pink color does not develop in the presence of Trinitroluence, Dinitrobenzene, 2, 6-Dinitrotoluene, Trinitrobenzene and 2, 4-Dinitrotoluene. Human matter present in the soil will cause a yellow colored extract but this precipitates during acidification leaving the extract cloudy interfering with the accurate determination of absorbance, Taibah University (2012).

Other than the common laboratory glassware such as beakers, test tubes etc., the equipment used in this procedure include: A commercial testing product, EnSys RDX soil testing system that specify the apparatus and materials necessary for test completion Spectrophotometer capable of reading absorbance of 507-510 nm Top loading or mechanical balance for weighing samples to -/+ 0.1g Spectrophotometer cuvettes two or more of 25ml and 2.5cm path length Alternatively; Analytical balance Wide mouth bottles of 125ml Glass volumetric pipettes ranging from 0.

5ml – 25.0ml Graduated cylinders 10ml and 100ml Glass volumetric flasks 100ml and 250ml Filter units 0.45 or 0.5µm Syringes Spatula Vacuum desiccator – For preparing calibration standards in a fixed laboratory and storage of zinc dust Ion exchange tubes Alumina-A, 3ml Automatic pipet -500µl equipped with tips Measuring spoon for zinc dust Wrist action shaker Vials -40ml amber glass equipped with solid caps Reagents and standards; Acetone, CH3COCH3 Distilled water Analytical standards(RDX and HMX analytical standards) Stock standard solution Working standard solution Calibration solution Q2.

Draw a cause and effect (fishbone) diagram to indicate the contributions to the uncertainty in the result for RDX in soil. Taibah University (2012) Reagent Humic matter Linearity Temperature Calibration Temperature Standard Sampling Standard Volume Temperature Extraction procedure