A QuEChERS-type
method without matrix interference was designed
and developed to determine organophosphorus pesticide residues in
edible vegetable oils, based on dispersive solid-phase extraction
with cleanup using UiO-66 as sorbent. Microporous UiO-66 directly
and selectively adsorbed organophosphorus pesticides and excluded
interfering compounds. Clean analytes were obtained by elution and
analyzed using gas chromatography–tandem mass spectrometry.
The dispersive solid-phase extraction conditions (amount of adsorbent,
extraction time, desorption solvent volume, and elution time) were
optimized. The limits of detection of the pesticides in vegetable
oils were 0.16–1.56 ng/g. Under optimized conditions, the average
pesticide recoveries were 81.1–113.5%. The intraday and interday
relative standard deviations for analyte recovery were <8.2 and
<13.9%, respectively. Thus, the method is reliable and could detect
organophosphorus pesticide residues in edible vegetable oils. Furthermore,
UiO-66 can be easily recycled and reused at least 10 times, reducing
the cost of analysis.
A new method for the determination of six plant growth regulators, 3-indolylacetic acid, 3-indolepropionic acid, 2-naphthoxyacetic acid, 2,4-dicholrophenoxyacetic acid, 1-naphthlcetic acid, and methyl naphthalene-1-acetate, in pears was established by liquid chromatography with electrospray ionization mass spectrometry. In this study, a microwave-assisted extraction technique was first applied for the determination of plant growth regulators in fruit and three cleanup techniques were, respectively, investigated for the purification of pear samples. The chromatographic separation was performed on a Diamonsil C18 column by using 0.01 mol/L formic acid/ammonium formate buffer solution (pH 3.5)/methanol (35:65, v/v) as the mobile phase with a flow rate of 0.7 mL/min in 1:1 split mode. The LODs ranged from 0.3 to 1.9 μg/kg. Under optimized conditions, the average recoveries (five replicates) for six plant growth regulators (spiked at 0.01, 0.05, and 0.5 mg/kg) ranged from 78.9 to 118.0%, and the RSDs were 1.4-10.3%.
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