Liquid chromatography-tandem mass spectrometry quantification of acetamiprid and thiacloprid residues in butterbur grown under regulated conditions.

An analytical method was developed to quantify the residual levels of the neonicotinoid insecticides, acetamiprid and thiacloprid, in field-incurred butterbur samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Samples were extracted with acetonitrile and partitioned with dichloromethane. After partitioning, purification was conducted using a Florisil® cartridge. Linearity of a matrix-matched calibration curve of the two compounds over a concentration range of 0.004-0.4µg/g was excellent, with determination coefficients (R2)≥0.9998. The limits of detection (LOD) and quantitation (LOQ) for both acetamiprid and thiacloprid were 0.0006 and 0.002mg/kg, respectively. The average recoveries for acetamiprid and thiacloprid at two spiking levels (0.02 and 0.1mg/kg, i.e., 10×LOQ and 50×LOQ) were between 78.23 to 82.17%, with relative standard deviations (RSDs)≤7.22%. The method was successfully applied to field-incurred samples treated with a commercial pesticide product, either once (zero or 7 days before harvest) or twice (0 and 7, 7 and 14, or 14 and 21 days before harvest). The highest and lowest residues were obtained for the 7 and 0 days' treatment and the 21 and 14 days' treatment, respectively. The developed method is simple and accurate and can be extrapolated to other leafy vegetables.

The medical plant butterbur (Petasites): analytical and physiological (re)view.

Butterbur (Petasites) is an ancient plant which has been used for medical and edible purposes with its spasmolytic agents. However, toxic alkaloid content of the plant limits its direct usage. The paper covers the pyrrolizidine alkaloids (PAs) and butterbur themes in detail in order to display the outline of alkaloid-free plant extract production for medical and edible purposes. The toxic PAs and medicinal constituents of the plant are described with emphasis on analytics, physiological effects and published patent data on alkaloid free extract production. The analytics is based on several commonly used analytical methods including liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry and enzyme linked immunoassay analysis of PAs and N-oxides based on published literature data of butterbur. The analyses of major medicinal constituents of butterbur are given and the physiological effects of these compounds have been discussed to attract attention to the importance of alkaloid-free extract production. The concentration distributions of the medicinal constituents and toxic PAs in different parts of the plant and the outcomes of the published patent data provide comprehensive information for proper plant raw-material selection and production of alkaloid-free butterbur extracts. The review is intended to guide researchers interested in medical plant extracts by providing comprehensive data on the medical plant butterbur and its chemical constituents.

The impact of altitude and simulated herbivory on the growth and carbohydrate storage of Petasites albus.

We tested the hypothesis that higher respiratory losses caused by higher temperatures in the lowlands, compared to montane sites, prevent growth of the montane hemicryptophyte Petasites albus (Asteraceae). In addition, we tested whether increased levels of herbivory enhanced carbon losses at lower elevations. Rhizomes of Petasites albus were transplanted to a montane and a lowland site. In the subsequent three growing seasons the plants were artificially defoliated to simulate mollusc herbivory. Whereas there were no altitudinal differences in the leaf number per plant, the leaf area was higher at the montane site. At the montane site, the leaf number and leaf area decreased with increasing damage, and the rhizome dry weight in the third year was much higher in the undamaged plants. In contrast, fructan concentrations in the rhizomes that were harvested at the end and at the beginning of the growing seasons were generally higher at the lowland site. No clear defoliation effects were observed on most harvest dates. The results indicate that the lower altitudinal limit of Petasites albus cannot be explained by the negative effects of higher temperatures or more leaf damage by herbivores in the lowlands, either alone or in combination. An explanation will require consideration of other site factors such as competition and possibly interactions with herbivory and carbohydrate storage.