Discriminating authentic Nostoc flagelliforme from its counterfeits by applying alternative ED-XRF and FTIR techniques.

Nostoc flagelliforme is an edible blue-green algae belonging to the Nostocaceae family. It is recognised as a Chinese delicacy in south-eastern Asia and is widely consumed. Due to its high economic value and diminishing supply, as a result of overharvesting, counterfeits have often been found in the retail markets. Methods involving microscopy and histochemistry were conventionally applied to differentiate the authentic N. flagelliforme from its counterfeits. In this paper, we report an alternative analytical approach, using a combination of non-destructive energy dispersive X-ray fluorescence (ED-XRF) and Fourier-transform infrared (FTIR) spectroscopy, to achieve the objective of authentic N. flagelliforme verification. In view of the scarcity of this Chinese delicacy, such a non-destructive methodology would be ideal to preserve the integrity of the sample and yet provide a means to discriminate between authentic and counterfeit samples.