Capillary electrophoretic method for the simultaneous determination of nitrate, nitrite and bromate ions in some...

Teas and traditional herbs are taken as health remedies in most cultures worldwide. Plants often used in the manufacture of teas and herbal remedies can comprise carcinogenic contaminates, such as nitrates, nitrites and bromate ions. In the present study, a quick method was applied for the simultaneous determination of nitrate (NO₃ ^- ), nitrite (NO₂ ^- ) and bromate (BrO₃ ^- ) ions in some selected plants and tea samples using capillary electrophoresis and a Box-Behnken response surface design for method optimization.

Optimal conditions of 60 mmol L^-1 phosphate buffer solution at pH 3.5, a capillary temperature of 40 °C, applied voltage of -22.5 kV, total capillary length of 61.5 cm (effective length 53.5 cm) with capillary internal diameter of 50 μm, and an injection pressure of 50 mbar for 30 s were selected. The limits of detection for nitrate, bromate and nitrite were 0.49, 1.25 and 0.11 mg L^-1 , whereas linearity values were determined as 0.998, 0.996 and 0.999, respectively.

A quick and easy applicable method was developed and the detection of the anions was achievable within 6 min of analysis. From the studied samples (cherry stalk, a dry mixed herbal tea; cherry stalk, dry sticks; dry pomegranate flower; dry olive leaves; and black tea), dry pomegranate flower (13.10 ± 0.62 mg L^-1 ) and cherry stalk, dry mix herbal tea (13.10 ± 0.62 mg L^-1 ) had the highest nitrate content. © 2021 Society of Chemical Industry.