| dc.description.abstract | In this work a multiresidue method for the determination of three antiemetic drugs
(ondansetron, metoclopramide and bromopride) in a sediment sample was developed
and validated. Sediment samples were collected at 10 locations at the main campus
of the Federal University of Santa Maria (UFSM), the first point being before the main
UFSM stream enters the university and the last when the stream is no longer part of
the university area. Quantification was performed with liquid chromatography coupled
to mass spectrometry (LC-MS, quadrupole). Salting-out-assisted microextraction
(SILLME) was the selected method for this study. The following extraction solvents
were evaluated: acetone, acetonitrile, ethyl acetate, isopropyl alcohol, methanol,
ethanol and a mixture of these in the proportion of 1:1 (v/v). The best recoveries were
achieved using a mixture of ethyl acetate and acetone. The following salts were
evaluated: anhydrous magnesium sulfate, magnesium sulfate heptahydrate,
ammonium chloride, potassium phosphate, ammonium formate, sodium chloride,
ammonium sulfate, anhydrous sodium sulfate, calcium carbonate, potassium
hydrocarbon and hydrocarbon of calcium dihydrate. The use of anhydrous sodium
sulfate provided the best results for all substances. The main factors more affecting
the extraction of analytes were identified using the Plackett-Burman design containing
16 experiments and 3 center points. In this way, the sample mass, the proportion of
the solvent mixture, the pH of the water, the amount of water, the mass of salt, the
stirring time in both steps and the centrifugation time were optimized. Finally, the
method was optimized using a central rotational composite design. The following
conditions were selected: 0.5 g of sample, 5 mL of water at pH 9.5, 2.0 g of salt and a
final step of stirring for 3.5 min, plus 5 min for centrifugation. The supernatant was
removed, evaporated under flowing water at 40°C and resuspended in 1 mL of
methanol acidified with 1% formic acid for analysis by LC-MS. All analytes were
present at concentrations below the limits of quantification. The developed method was
suitable for the three drugs and the method proved to be suitable for the detection and
quantification of the three antiemetic drugs in complex matrices, such as sediment,
allowing the detection of at least one of the investigated analytes. | |
