Jd. Vargo, DETERMINATION OF SULFONIC-ACID DEGRADATES OF CHLOROACETANILIDE AND CHLOROACETAMIDE HERBICIDES IN GROUNDWATER BY LC MS/MS/, Analytical chemistry (Washington), 70(13), 1998, pp. 2699-2703
An analytical method is presented which permits qualitative and quanti
tative analysis of sulfonic acid degradates of three chloroacetanilide
herbicides (acetochlor, alachlor, and metolachlor) and one chloroacet
amide herbicide (dimethenamid) in groundwater at trace levels with det
ermination by LC/MS/MS. The analytes were isolated from groundwater by
solid-phase extraction (SPE). The final samples were analyzed by reve
rsed-phase HPLC: with MS/MS detection utilizing a pneumatically assist
ed, and heat-assisted electrospray interface (TurboIonSpray). Unique p
recursor/product ion pairs were obtained in the MS/MS mode which permi
tted conclusive identification of each analyte, even when the analytes
coeluted. Quantification was performed by generation of an external c
alibration curve. Excellent linearity was obtained over a calibration
range from 0.25 to 10 ng injected on-column, with all linear correlati
on coefficients exceeding 0.999. Method performance for this analytica
l procedure was validated by analyzing groundwater samples fortified a
t levels of 0.1, 1, and 50 ppb. The average recovery at each fortifica
tion level for each analyte exceeded 89%, Excellent method precision w
as demonstrated with percent relative standard deviations of less than
10% for all analytes at all fortification levels.