Dual-column Switching Ion Chromatography for the Simultaneous Determination of Inorganic Cations and Anions (particularly Thiocyanate) in Human Urine and Saliva Samples to Identify Smokers Types

Abstract

An ion chromatography (IC) have been developed for the simultaneous determination of inorganic cations (Na+, NH4+, K+, Mg2+, and Ca2+) and inorganic anions (PO43−, Cl−, NO3−, and SCN−) using a single pump, a single eluent and a single detector. The method is based on column switching means allows anions and/or cations could be determined in a single analysis system. While one ion-exchange column is being operated, the other ion-exchange column is being conditioned, i.e., the columns are always ready for analysis at any time. When the combination of 10 mM tartaric acid was used as the eluent, and operated at eluent flow rate of 0.5 mL/min, five cations and four anions could be separated on the cation-exchange column and the anion-exchange column, respectively. The separation of cations was completed within 15 min, whereas the separation of anions was completed within 40 min. The detection limits was calculated at S/N = 3 were 3.10–12.14 ppb (µg/L) for the cations and 16.00–88.10 ppb for the anions. The relative standard deviations of the all ions were less than 4.81%, 6.30%, and 6.22% for peak height, peak area, and retention time, respectively. The developed technique was successfully applied to the simultaneous determination of inorganic cations and anions in human saliva and urine samples.