Alachlor ethanesulfonic acid

In a study that included comprehensive spatial and temporal sampling, 70% of the total herbicide concentration in water from the Mississippi River Basin was from transformation products [39]. Other studies in the United States have documented similar results. For example, in 1993, the annual load of alachlor ethanesulfonic acid was almost 500 metric t whereas, the annual load of alachlor was less than 50 metric t [40]. 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

Figure 7 Formation of ethanesulfonic acid and oxanilic acid metabolites from the reaction of a chloroacetanilide herbicide (alachlor) with glutathione and other enzymes (Field and Thurman (1996) reproduced hy permission of American Chemical Society from Environ. Sci. Technol, 1996, 30, 1413-1417).

Thurman, E. M., Eerrer, I., and Parry, R., Accurate mass analysis of ethanesulfonic acid degradates of acetochlor and alachlor using high performance liquid chromatography and time-of-flight mass spectrometry, J. Chromatogr. A, 957, 3-9, 2002. 

R.A. Yokley, L.C. Mayer, S.-B. Huang, J.D. Vargo, Analytical method for the determination of metolachlor, acetochlor, alachlor, dimethenamid, and their corresponding ethanesulfonic and oxanillic acid degradates in water using SPE and LC-ESI-MS-MS, Anal. Chem., 74 (2002) 3754. 

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