Microwave-Assisted Extraction Coupled with Gas Chromatography/Electron Capture Negative Chemical Ionization Mass Spectrometry for the Simplified Determination of Imidazolinone Herbicides in Soil at the ppb Level

Abstract

The imidazolinones are a significant new class of low-use-rate, reduced-environmental-risk herbicides for protection of a wide variety of agricultural commodities. Because of their low rates of application, residues of the imidazolinones in soil need to be monitored at the low ppb level. Current methodology for this purpose involves an exhaustive base extraction followed by a laborious, time-consuming cleanup procedure to permit analysis at the 5 ppb level. Using imazethapyr, the most widely utilized member of the class, as a representative, we have achieved not only a limit of quantitation of 1 ppb but also a greatly simplified cleanup procedure by combining microwave-assisted extraction technology with gas chromatography/electron capture negative chemical ionization mass spectrometry. On a variety of soil types covering a fortification range of 1−50 ppb, an average recovery of 92% with a standard deviation of 13% was achieved. Control soil extracts gave apparent residues of <0.2 ppb. Sample preparation time per sample was reduced from 2 h to 10 min.

Microwave oven and boiling waterbath extraction of hepatotoxins from cyanobacterial cells

“…A microwave oven has recently been used for the acid hydrolysis of microcystins -LR, -YR, -RR, -LA and nodularin to their constituent amino acids [18]. Furthermore, microwave extraction has been applied to several other compounds including £avin mononucleotides [19], herbicides [20] and amino acids [21]. Microwave extraction has also been applied to complex matrices including soil, sediments and animal tissue [22,23].…”

Rapid and simple method for extraction and determination of imidazolinone herbicides in soil

“…Th ey we re discove red and introduced by American Cyanamid. As shown in figure 1, the members of this class of herbicides have similar struct u ral fe at u res centered around the imidazolinone ring and attached aromatic system bearing a carboxylic acid moiety [5]. In general the imidazolinones are highly active against annual and perennial grasses and broad-leaved weeds when applied either pre-or postemergence.…”

Modern Extraction Techniques for Pesticide Residues Determination in Plant and Soil Samples

“…Other investigated herbicides are sulfonyl-and phenylurea herbicides (Font et al, 1998;Molins et al, 2000). The investigated fungicides were hexaconazole (Frost et al, 1997), and dimethomorph (Stout et al, 1998) From economical and practical aspects, MAE is a strong competitor to other recent sample preparation techniques. The main MAE advantages are the low temperature requirement, high extraction efficiency, complete automation, and the possibility of extracting different samples at the same time without interference.…”