Salting-Out Solvent Extraction Method for Determining Low Levels ofNitroaromatics and Nitramines in Water

摘要

A protocol was developed for determining low levels of nitroaromatics in groundwater. Sample preparation employs salting-out extraction with acetonitrile and NaCl, further preconcentration of extract by solvent evaporation on a Kuderna-Danish concentrator, dilution of the concentrate with water, and filtration through a 0.5-micrometers Millex-SR filter. Separation is achieved using reversed-phase high-performance liquid chromatography with an LC-8 (3.3 cm) column using a 70.7/27.8/1.5 (v/v/v) water-methanol-THF eluent, and determination is obtained on a UV detector at 254 nm. This procedure provides far lower detection limits than the earlier protocol, which involved direct injection onto an LC-18 (25 cm) column eluted with 50/50 (v/v) methanol-water. The new method is capable of simultaneously determining RDX, TNB, DNB, TNT, 2,4-DNT, 2,6-DNT, 2-Am-DNT in less than five minutes, with reporting limits ranging from 0.02 to 0.84 micrograms/L. Analytical recovery averaged greater than 95%. Keywords: Explosives analysis, Nitramines, Nitroaromatics, Salting-out extraction, Water analysis. (js)