FTIR spectroscopy as a tool to detect contamination of rocket (Eruca sativa and Diplotaxis tenuifolia) salad with common groundsel (Senecio vulgaris) leaves.

BACKGROUND: Rocket is a popular salad vegetable used all over the world and it has many health benefits. However, like with all plant material, there exists a danger of contamination with toxic substances. In the case of rocket, contamination with groundsel has occurred. Groundsel is a common weed in rocket crops, and it contains very toxic pyrrolizidine alkaloids. In our study infrared spectroscopy was used to distinguish groundsel samples from rocket leaves. Infrared spectroscopy is a very simple analytical technique; however, some specific conditions are more easily implemented in industrial environment than others. Some of these conditions and parameters of infrared spectroscopy were explored in detail. RESULTS: We tested for the influence of different parameters of attenuated total reflectance and transmission infrared method. Our results show that a 100 % correct classification can be obtained under conditions most suitable for industry: using fresh samples and parameters that enable fast spectral measurement. CONCLUSION: Infrared spectroscopy is a fast and easy-to-use method that has been shown to be able to differentiate between rocket and groundsel leaves. Therefore, it could be further studied for implementation in the safety control of rocket salads. © 2016 Society of Chemical Industry.

Herbal tea identification using mid-infrared spectroscopy.

Herbal teas and other herbal preparations are becoming more and more popular, and it is essential to ensure their quality. Quality control methods that are simple, fast, and of low cost are needed by the producers and by inspections. Infrared spectroscopy coupled with multivariate mathematical methods has been shown to be useful for the identification and characterization of plant samples. In this work, we developed a method for the identification of herbal drugs in different herbal teas. 100 one-component herbal teas were first used to build an identification algorithm, which showed 100 % correct classification. In the next validation step, 13 samples from 7 herbal mixtures were analyzed, confirming high accurate results for classification. The influence of using different number of components in the principal component analysis is also explored. Infrared spectroscopy coupled with analysis of variance, principal component analysis, and discriminant analysis was shown to be highly applicable for quality control procedures.

Differences among Epilobium and Hypericum species revealed by four IR spectroscopy modes: transmission, KBr tablet, diffuse reflectance and ATR.

INTRODUCTION: Quality control of dried plant material in assessments of suitability of herbal medicinal products is of extreme importance. Commonly used procedures for identification of species are time consuming and expensive. The development of multivariate statistical methods has enabled application of vibrational spectroscopy for establishing plant species membership. OBJECTIVE: To determine which infrared spectroscopy mode gives most informative spectra for plant species identification. METHODOLOGY: Different modes of infrared spectroscopy were applied for investigation of differences among Epilobium and Hypericum species: diffuse reflectance (DR), attenuated total reflectance (ATR), direct transmission of whole leaves and KBr tablet transmission with comminuted leaves. The same chemometrical methods were applied to all spectra. The informative wave numbers were chosen by one-way analysis of variance. Afterwards the colinearity was reduced with principal component analysis. In the final step the species identification was determined with discriminant analysis. RESULTS: Transmission and diffuse reflectance mode did not give satisfactory results. Best results for discrimination among Epilobium species were obtained with ATR mode (98%), while best results for Hypericum species were obtained with KBr transmission mode (97%). This might be explained by the morphological properties of the two genera. Epilobium species differ in distribution and morphology of trichomes on the surface of the leaves. Hypericum species differ in structures and secondary metabolites in the interior of the leaves. CONCLUSION: For best results in using infrared spectroscopy for plant species identification in quality control, the morphological properties of plant material should be taken into consideration.