A novel ion chromatography tandem mass spectrometry (IC-MS/MS) method for the determination of chlorate and prechlorate in freshly brewed coffee

Abstract Coffee is one of the most popular beverages in the world. A sensitive and fast method has been established and validated to measure chlorate and perchlorate in freshly brewed coffee beverages based on ion chromatography tandem mass spectrometry (IC-MS/MS) in this study. After the extraction with water and protein precipitation with acetonitrile, the samples were purified with MCX columns and then separated on an ion chromatographic column (250 mm × 2.1 mm) by using a gradient program of 0.4 mol/L methylamine aqueous solution and acetonitrile as mobile phase. Multiple reactions monitoring (MRM) model was used to obtain the sufficient sensitivity for the method, and the isotope internal standards, potassium 18O3-chlorate and potassium 18O4-perchlorate, were applied for the calibration. The validation results provided good linearity in the range of 25.0∼1000 μg/L for chlorate and 6.25∼250 μg/L for perchlorate. The recovery rates were 84.6%∼99.8% for chlorate and 99.7%∼112% for perchlorate in six different kinds fancy coffee samples at three known concentration levels and the relative coefficients were lower than 8%. The limit of quantification of method was 15.0 μg/L, 1.50 μg/L for chlorate and perchlorate, respectively. Finally, the method was applied in the measurement of two chlorine oxides in the retail freshly brewed coffee products from local coffee shops in Nanjing. The concertation of chlorate and perchlorate in coffee indicated the widespread of chlorate and perchlorate in these beverages. The established method was sensitive and suitable for the detection of chlorate and perchlorate in coffee products.