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Keywords
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clonazepam, nitrazepam, hydrophobic deep eutectic solvent, microextraction, saliva
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Abstract
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In this study, a 96-well microplates-based spectrophotometer with the aid of
the partial least squares (PLS) approach was used for the simultaneous determination
of more common benzodiazepines, clonazepam, and nitrazepam, in
human saliva samples. For this purpose, a hydrophobic deep eutectic solvent
(DES) based on choline chloride and 1-phenylethanol in the mole ratio of 1:4 was
prepared and utilized in the ultrasound-assisted emulsification-microextraction
(USAEME) method followed by back-extraction to retrieve the drugs from the
DES phase to 200 μL of 0.1 M NaOH solution. Central composite design (CCD)
in combination with the desirability function was used for multi-response optimization
of different parameters and the optimum values were found to be:
pH 2.06; DES volume, 247.1 μL; NaCl, 1.55% (w/v); sonication time, 5.33 min.
The DES-based USAEME method showed wide linear ranges of 0.1–6 and 0.2-
8 μg/mL and good limits of detection of 0.02 and 0.05 μg/mL for clonazepam
and nitrazepam, respectively. Furthermore, the method was successfully used
for determining the drugs in human saliva samples.
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