Determination of polycyclic aromatic hydrocarbons (PAHs) in Yerba-mate herbal drink

Yerba-mate (Y-M), known as llex-paraquariensis is traditional South American herbal drink that is consumed as an aqueous extract from the Y-M leaves. This drink is thought to have long-term health benefits and thus it has recently gained more popularity. However, health hazards of polyaromatic hydrocarbons (PAHs) deposited in Y-M during drying process has been linked to the development of different types of cancer in particular oesophageal cancer. The current study developed and validated an extraction and analytical method to determine the presence of one of the PAH compounds, namely; benzo(b)fluoranthene [Bbf] as an indicator for the PAH(s) occurrence in Y-M in commercial samples of the dried leaves. Since the expected level of contamination with this compound is at trace level thus a sensitive and selective analytical method was needed. Gas Chromatography-Mass Spectrometry GC-MS method was developed using selected ion monitoring (SIM) with split-less mode focusing on 126 ion and 252 ion (main) for [Bbf]. The content of [Bbf] using different extraction methods was found in a range 0.02 to 0.09 μg/g. GC-MS results indicated a good repeatability of the peak area with strong correlation and linearity between mean peak area and concentration from the calibration curve. Soxhlet extraction using hexane as a solvent gave the highest yield of [Bbf] concentration. However, ultrasonic extraction using hot distilled water as a solvent is recommended as it better simulates the way of making and drinking.