Determination of the composition of ethoxylated alkylamines in pesticide formulations by high-performance liquid chromatography using ion-pair extraction detection

Characterisation of alkylamine ethoxylates (ANEOs) in commercial herbicide formulations using liquid chromatography/electrospray ionisation mass spectrometry

“…Non‐ionic surfactants, which are the most commonly used in agrochemical formulations, enable the efficient delivery of the active ingredient to the target sites required for the herbicide activity and are especially effective for foliage‐applied systemic compounds such as glyphosate 2. Commercial glyphosate formulations usually contain alkylamine ethoxylates (ANEOs) as surfactants, which are prepared by the reaction of alkylamines, derived from natural fats or oils such as coconut, laurel, tallow and soya, with ethylene oxide (EO) at high pressure and temperature 3. The distribution of the various fatty acids found in the original natural product determines the length of the alkyl chains of the resulting ANEOs.…”

“…The role of adjuvants on foliar uptake of glyphosate formulations has been widely studied 2, 4–6. In the presence of surfactants, herbicide uptake depends on at least three factors: the concentration and physicochemical properties of active ingredients, the chemical structure and concentration of surfactants and the characteristics of the leaf 3. Not all surfactants are effective in increasing the uptake of all industrial herbicides and so it is essential to know the complete composition both of the active ingredient and of the added adjuvants.…”

“…A great variety of analytical methods have been used for glyphosate determination,9 but few attempts have been made to analyse ANEOs 3, 10–12. These have involved chromatographic separation followed by fluorescence,3 evaporative light‐scattering mass detection10 or mass spectrometric11, 12 detection of the analytes.…”

“…A great variety of analytical methods have been used for glyphosate determination,9 but few attempts have been made to analyse ANEOs 3, 10–12. These have involved chromatographic separation followed by fluorescence,3 evaporative light‐scattering mass detection10 or mass spectrometric11, 12 detection of the analytes. Of these techniques, only mass spectrometry (MS) allows the simultaneous determination of both the alkyl and the ethoxymer homologues as the others require a two‐step process involving the prior separation of the alkyl homologues by reversed‐phase liquid chromatography (LC) followed by the separation of the individual oligomers by normal‐phase LC 3, 10…”

Analysis of ethoxylated fatty amines. Comparison of methods for the determination of molecular weight

“…Reversed-and normal-phase high-performance liquid chromatography (HPLC) methods have been developed for analysis of ethoxylated nonionic surfactants, most commonly for ethoxylated fatty alcohols, acids, sulfonates, and alkylphenols (8)(9)(10)(11). The one reported method applicable to ethoxylated fatty amines was limited to a mean EO content of only 15 moles owing to the ion-pair/fluorescence detection system used (12). Use of an evaporative lightscattering detector for HPLC applications allows for detection of polyalkoxylated compounds with no molecular weight limitations (13).…”