| Summary: | An SPE followed by HPLC-DAD method to analyze pharmaceuticals with
acethylcholinesterase activity in water samples was developed.
Acetylcholinesterase (AChE) inhibitors have been used to treat less severe
dementias such as Alzheimer�s disease. In this study, five AChE inhibitors
pyridostigmine, galathamine, neostigmine, eserine, and donepezil were selected as
target compounds. A HPLC/DAD method with ion pair chromatography
technique was used for detection and separation of the target compounds. Effects
of the pH of the mobile phase and ion pair reagents in the mobile phase were
studied. Chromatographic separation was achieved using reversed-phase
SymmetryShield column using gradient system with mobile phase consisting of
H2O/ACN (99:1, v/v) as mobile phase A with 10 mM sodium 1-hexanesulfonate
and 0.1% HAc. The HPLC/DAD method was linear between concentrations of 5
to 100 ng/μL. The IDL and IQL ranged from 0.50 to 1.25 ng/μL and 1.5 to 3.0
ng/μL, respectively. SPE was used to extract and clean up the water samples. An
extraction model was conducted with fortification experiments in spiked pure
water, tap water, and wastewater samples. The recovery rate of all target
substances using WCX cartridge was high for pure and tap water. The application
of extraction method of 5 target substances in wastewater sample was divided into
2 parts: Oasis WCX (6 mL, 500 mg) for PYR the extraction and Oasis HLB (6
mL, 200 mg) for GAL, NEO, ESE and DON. The recovery rates of GAL, NEO,
ESE and DON using Oasis HLB from wastewater at spiking levels of 50, 125 and
250 μg/L were in the range of 93.3 to 105.8% with RSD values that ranged
between 1.0 and 12.1%. The recovery rates of PYR using Oasis WCX from
wastewater samples at the spiking levels of 100 μg/L were 95.5 (210 nm) and
105.2% (270 nm) and RSDs were 7.2 and 2.6%, respectively. The MQL for GAL,
NEO, ESE and PYR (at 210 nm) in wastewater was reached for a concentration of
50 μg/L and DON at concentration of 25 μg/L.The developed SPE and
HPLC/DAD method is applicable for quantification of the five target compounds
in water samples in a concentration range > 50 μg/L and assumable lower for
DON (> 25 μg/L).
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