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Aflatoxins B/G and Ochratoxin A in Tea



Tea is one of the best known and most popular hot drinks along with coffee. The most famous are the real teas, „black tea“ and „green tea“, both made from leaves of the tea plant (Camellia sinensis). There is also a wide range of tea-like products such as fruit and herbal teas in different compositions. With more than 2 million tons of tea harvested in 2017, which corresponds to around 40 % of the total, China is by far the world‘s largest tea producer.

The harvested blossoms and leaves of the tea plant are dried before further processing and then exported for the most part. Mycotoxins can form during this drying process or under incorrect storage conditions. These are toxic to humans and lead to health damage or even death. For this reason there are EU-wide regulations and controls which set the limit value for mycotoxins and thus ensure high product quality.

Two in one - Combined immunoaffinity column Afla-OtaCLEAN

Aflatoxins B/G and Ochratoxin A are naturally occurring mycotoxins and are formed by fungi when products are stored moist or incorrectly. They are often found together in many food and feed products. In order to facilitate extraction and halve the working time, it is advisable to examine the extracts for several mycotoxins in a single step.

For this reason LCTech offers the combined immunoaffinity column Afla-OtaCLEAN for the simultaneous clean-up of aflatoxin B1, B2, G1, G2 and ochratoxin A. Since LCTech produces both, the clean-up columns and the antibodies, extensive quality tests throughout the entire production process ensure high product quality. On the following page you will find a processing protocol with the use of an Afla-OtaCLEAN immunoaffinity column.

Processing Protocol

Homogenise 10 g of tea and add 2 g sodium chloride to the sample. Then extract the mixture trough 100 mL methanol/water (80/20 (v/v)) and 50 mL n-hexane, to remove essential oils and fat. To ensure high extraction efficiencies, perform the extraction for at least 30 minutes. Use the n-hexane free phase for the further processing.

Filter the raw extract and dilute 2 mL with 12 mL PBS (contains 8 % Tween). Afterwards load the sample (14 mL, corresponding to 0.2 g matrix) onto an Afla-OtaCLEAN immunoaffinity column. 

Wash the column with 10 mL of deionized water, the washing solution is used to rinse out the template vessel before applied onto the columns to remove residule matrix from the column. Elute the column with 2 mL methanol. Make sure that the column bed is incubated with methanol for 5 minutes in order to ensure a fully denaturation of the antibodies and release of the toxin.

Find more details, recovery rates, HPLC-conditions and chromatograms here.

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