BACKGROUND: 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 (NO 3 − ), nitrite (NO 2
−) and bromate (BrO 3 − ) ions in some selected plants and tea samples using capillary electrophoresis and a Box-Behnken response surface design for method optimization.RESULTS: 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 ∼m, 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. CONCLUSION: 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.
A quick method for the simultaneous determination of nitrate, nitrite and bromate ions in tea infusions using capillary zone electrophoresis was developed. A three‐factor full factorial design was applied for the determination of optimal conditions. Prior to the full factorial analysis, a number of experiments were conducted. A 50 mM phosphate buffer solution with pH 3.5 was selected. A capillary temperature of 40 °C, −20 kV applied voltage, 61.5 cm total capillary length (53.5 cm effective length) with 50 μm i.d., and 50 mbar injection pressure for 30 s were used. The limits of detection for nitrate, nitrite, and bromate were 0.60, 0.99, and 2.14 mg/L, respectively. The anions could be detected by the method with good resolution within 7 min with average spike recovery ranging between 91.6 and 105.5% (n = 3).
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