Soils, tandem extractions

The development of methods of analysis of tria2ines and thek hydroxy metabohtes in humic soil samples with combined chromatographic and ms techniques has been described (78). A two-way approach was used for separating interfering humic substances and for performing stmctural elucidation of the herbicide traces. Humic samples were extracted by supercritical fluid extraction and analy2ed by both hplc/particle beam ms and a new ms/ms method. The new ms /ms unit was of the tandem sector field-time-of-flight/ms type. 

Specifically for triazines in water, multi-residue methods incorporating SPE and LC/MS/MS will soon be available that are capable of measuring numerous parent compounds and all their relevant degradates (including the hydroxytriazines) in one analysis. Continued increases in liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) sensitivity will lead to methods requiring no aqueous sample preparation at all, and portions of water samples will be injected directly into the LC column. The use of SPE and GC or LC coupled with MS and MS/MS systems will also be applied routinely to the analysis of more complex sample matrices such as soil and crop and animal tissues. However, the analyte(s) must first be removed from the sample matrix, and additional research is needed to develop more efficient extraction procedures. Increased selectivity during extraction also simplifies the sample purification requirements prior to injection. Certainly, miniaturization of all aspects of the analysis (sample extraction, purification, and instrumentation) will continue, and some of this may involve SEE, subcritical and microwave extraction, sonication, others or even combinations of these techniques for the initial isolation of the analyte(s) from the bulk of the sample matrix. 

In another example, a multiresidue method using HPLC/ESI-MS was developed to determine six imidazolinone herbicides in five different soil types. Good recoveries (80-120%) and adequate sensitivity at the 2.0 ngg level were obtained for the compounds investigated. In the method, a 50-g soil sample was extracted for 1 h in 0.5N NaOH solution. A portion of the extract was acidified, to precipitate the humic acids, and the supernatant was then loaded on to a preconditioned trifunctional Cig SPE cartridge and eluted with ethyl acetate. Further cleanup was achieved using a tandem strong anion-exchange (SAX)-SCX SPE combination. Analytes were eluted... 

Schltisener MP, Spiteller M. Bester K. Determination of antibiotics from soil by pressurized liquid extraction and liquid chromatography-tandem mass spectrometry. J. Chromatogr. A 2003 1003 21-28. 

Barron L, Tobin J, Pauli B (2008) Multi-residue determination of pharmaceuticals in sludge and sludge enriched soils using pressurized liquid extraction, solid phase extraction and liquid chromatography with tandem mass spectrometry. J Environ Monit 10 353-361... 

Pyle and Marcus [ 102] achieved low ppb detection limits for the determination of organochlorine insecticides in soil using accelerated solvent extraction followed by gas chromatography ion trap tandem mass spectrometry. Richter et al. [103] showed that accelerated solvent extraction gave essentially equivalent recoveries of chlorinated dibenzo-p-dioxins and dibenzofurans from soil compounds to Soxhlet extraction, but in less time and using much less solvent. 

Tso J, Dutta S, Inamdar S, Aga DS. Simultaneous analysis of free and conjugated estrogens, sulfonamides, and tetracyclines in runoff water and soils using solid-phase extraction and liquid chromatography—tandem mass spectrometry. J Agri Food Chem 2011 59(6) 2213-22. 

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