No abstract

Although the current literature has recorded many reports of identifying components from herbal preparations, all of them were largely limited to target components. This paper provides a novel and generally applicable approach to identifying nontarget components from herbal preparations, based on the use of liquid chromatography ion trap time-of-flight mass spectrometry (LC/MS-IT-TOF). A simple program was originally developed for searching the common diagnostic ions from all experimentally generated ions. The components sharing the exact same ions (mass error < 5 mDa) were classified into a family. All families were then connected into a coherent network by the bridging components that are present in two or more families. With the benefit from such a network, it is feasible to sequentially characterize the structures of all diagnostic ions once a single component has been de novo identified. The structures of the diagnostic ions could then be used as "a priori" information for selecting the exact candidates containing the substructures of the corresponding diagnostic ions from the primary database hits. This strategy enables a nearly 7-fold narrowing of the database hits and thus substantially enhances the analytical efficiency and sharpness. With the use of such an approach, 43 out of 53 components incorporated into the network have been successfully identified from the test herbal preparation. For the rest, components failed to be identified using this approach; a complementary approach to screening by sequential loss of specific chemical groups, proposed from the accurate mass differences between fragments, was established to narrow the database hits. All of the 87 peaks detected have been successfully identified by combining the use of both approaches except failed to differentiate some isomers. The presently developed approach and methodology would be useful for the identifications of complicated nontarget components from various complex mixtures such as herbal preparations, biological, and environmental samples.

Vitamins are a class of essential nutrients in the body; thus, they play important roles in human health. The chemicals are involved in many physiological functions and both their lack and excess can put health at risk. Therefore, the establishment of methods for monitoring vitamin concentrations in different matrices is necessary. In this review, an updated overview of the main pretreatments and determination methods that have been used since 2010 is given. Ultrasonic assisted extraction, liquid–liquid extraction, solid phase extraction and dispersive liquid–liquid microextraction are the most common pretreatment methods, while the determination methods involve chromatography methods, electrophoretic methods, microbiological assays, immunoassays, biosensors and several other methods. Different pretreatments and determination methods are discussed.

No abstract

Arbuscular mycorrhizal fungi (AMF) play an essential role in complex ecosystems. However, the species diversity and composition of AMF communities remain unclear in semi-arid mountains. Further, it is not well understood if the characteristics of AMF community assemblies differ for different habitat types, e.g., agricultural arable land, artificial forest land, natural grassland, and bush/wood land. Here, using the high-throughput technology by Illumina sequencing on the MiSeq platform, we explored the species diversity and composition of soil AMF communities among different habitat types in a semi-arid mountain (Taihang Mountain, Mid-western region of China). Then, we analyzed the effect of nutrient composition and soil texture on AMF community assembly. Our results showed that members of the Glomus genera were predominated in all soil types. The distance-based redundancy analysis indicated that the content of water, available phosphorus, and available potassium were the most crucial geochemical factors that significantly affected AMF communities (p < 0.05). The analysis of the soil texture confirmed that AMF diversity was negatively correlated with soil clay content. The comparison of AMF diversity among the various habitat types revealed that the artificial forest land had the lowest AMF diversity in comparison with other land types. Our findings suggest that there were differences in species diversity and composition of soil AMF communities among different habitat types. These findings shed new light on the characteristics of community structure and drivers of community assembly in AMF in semi-arid mountains, and point to the potential importance of different habitat types on AMF communities.