Improved Salting Out Extraction-Preconcentration Method for the Determination ofNitroaromatics and Nitramines in Water

摘要

An improved salting-out extraction-preconcentration, RP-HPLC-UV protocol for thedetermination of nitroaromatics and nitramines in water was developed. The method involves saturating a 760-mL water sample with NaCl and extracting with acetonitrile (ACN). Collected extracts are then preconcentrated and solvent exchanged to water via a Kuderna-Danish evaporator. Analysis involves solute focusing by introducing an 1100-mL sample onto a LC-8 column eluted with water, MeOH and THF (70.7:27.8:1.5V/V/V) at 2.0 mL/min followed by UV detection at 254 nm. A direct injection RP-HPLC-UV water method was developed concurrently, employing the same separation and detection techniques. Both methods are applicable for simultaneous determination of RDX, TNB, DNB, TNT, 2,4-DNT, 2,6-DNT, 2-Am-DNT and 4-Am-DNT, and HMX (salting out only) with reporting limits ranging from 0.006 to 0.27 micrograms/L for the salting-out method and 0.12 to 1.07 micrograms/L for the direct injection method. The salting-out extraction procedure is suitable for determination of HMX, RDX, TNT, 2,4-DNT and 2,6-DNT at concentrations below the health advisory and water quality criteria proposed by the USEPA and Oak Ridge National Laboratory.