Paper spray ionization mass spectrometry for rapid quantification of illegal beverage dyes

A rapid method is described for quantification of six illegal colorants in beverages, i.e., soft beverages, energy beverages, alcoholic beverages, teas, and fruit juices. Paper spray (PS) ionization combined with tandem mass spectrometry (MS/MS) allowed detection of particular dyes in times of less than 1 min per sample. Samples where diluted in methanol and isotopically-labeled internal standards were utilized to obtain linear responses over ranges of two or three orders of magnitude. The LODs were below 1.5 ng mL(-1) and LOQs were below 5 ng mL(-1). Quality control experiments gave accuracies that ranged between 80% and 120%. Matrix effects were evaluated for different samples but had little effect given the use of the dilution method.