Open tubular capillary ion chromatography with online dilution for small ions determination in drinks

This work aims to develop a more robust, easy-to-use, low-pressure, and cost-effective nonsuppressed open tubular capillary ion chromatography (NS-OTIC) approach with online dialysis for small ions determination in drinks. The fabricated device was applied for two selected columns, including poly(butadiene-maleic acid) on a 50-mu m bore and AS18 Latex on 25-mu m bore fused silica capillaries, for the separation of mixed cations (Na+, K+, Ca2+, Mg2+) and mixed anions (Cl-, Br-, NO2-, NO3-), respectively. High concentrations of ions (up to 100 mM) level can be directly introduced into the NS-OTIC system without an off-line (manual) dilution step. The linear relationship of the peak area and concentration of model ions can be obtained with a resolution > 1.1. The repeatability of the peak area for both OTIC columns was < 6% RSD. Juice and tea samples were successfully analyzed with % recoveries of 77-112 and 90-119 for cation and anion determinations, respectively.

Automated summary

This work presents the development of a robust, easy-to-use, low-pressure, and cost-effective NS-OTIC approach for small ion determination in drinks. The fabricated device successfully separated mixed cations and mixed anions, with high concentrations of ions directly introduced into the system without dilution. The linear relationship between the peak area and concentration of model ions was obtained, and good repeatability was achieved. Juice and tea samples were analyzed with satisfactory recoveries.