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Abstract
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The thiocyanate ion is a biomarker for exposure to environmental tobacco smoke. We used a simple solidphase
extraction method based on a nickel–aluminumlayered double hydroxide (Ni–Al LDH) nano-sorbent
for the extraction of trace amounts of thiocyanate from biological samples, followed by gas
chromatography with flame ionization detection. The extraction is based on the adsorption of
thiocyanate anions on the Ni–Al nitrate LDH and/or their exchange with the nitrate anions in the LDH
interlayer. Several parameters affecting the extraction performance (pH, the amount of nano-sorbent,
the eluent type and volume, the sample loading flow-rate and the sample volume) were investigated
and optimized. Under the optimized experimental conditions, good linearity was achieved from 0.6 to
80 ng mL1 thiocyanate. The limit of detection and relative standard deviation for the thiocyanate ion
were 0.2 ng mL1 and 4.6%, respectively. The method was successfully applied to monitoring
thiocyanate in human saliva and serum samples. It was confirmed that the thiocyanate concentration in
saliva noticeably increased after smoking.
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