Measuring Ochratoxin A Concentrations in Coffee Beverages with Immunoaffinity Columns and Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry

This study developed and validated a method for measuring concentrations of ochratoxin A (OTA) in coffee beverages, not coffee beans. The new method involved extraction using immunoaffinity columns and ultra-performance LC (UPLC)-MS/MS using isotope-dilution techniques. The combination of a fused-core column and UPLC significantly shortened chromatographic time to 3 min compared to reported UPLC methods. The method was sensitive, with an LOD and LOQ of 0.52 and 1.73 pg/mL, respectively. Quantitative intraday (n = 4) and interday (n = 4) biases and RSD were both below 15%. The OTA levels in 40 samples of freshly brewed coffee from chain stores, 24 samples of canned ready-to-drink coffee, and 6 beverages made from instant coffee granules ranged from 1.60 to 93.2 pg/mL (90% positive), 6.00 to 131 pg/mL (100% positive), and 21.8 to 59.0 pg/mL (100% positive), respectively. Based on published tolerable daily intake, men and women in Taiwan should consume no more than 6.3 and 5.1 fifteen gram packages of instant coffee per day, respectively. Specific suggestions were not made for brewed coffee and canned coffee because of their large variation in OTA concentrations. This study should be more relevant to actual human exposure than those studying OTA in green, roasted, and ground coffee beans alone.