Abstract: Insects trigger plants to release volatile compounds that mediate the interaction with both pest and beneficial insects. Soybean aphids (Aphis glycines) induces soybean (Glycine max) leaves to produce volatiles that attract predators of the aphid. In this research, we describe the use of solid-phase microextraction (SPME) for extraction of volatiles from A. glycines-infested plant. Objectives were to (1) determine if SPME can be used to collect soybean plant volatiles and to (2) use headspace SPME-GC-MS approach to screen compounds associated with A. glycines-infested soybeans, grown in the laboratory and in the field, to identify previously known and potentially novel chemical markers of infestation. A total of 62 plant volatiles were identified, representing 10 chemical classes. 39 compounds had not been found in previous studies of soybean volatile emissions. 3-hexen-1-ol, dimethyl nonatriene, indole, caryophyllene, benzaldehyde, linalool, methyl salicylate (MeSA), benzene ethanol, and farnesene were considered herbivore-induced plant volatiles (HIPVs). For reproductive field-grown soybeans, three compounds were emitted in greater abundance from leaves infested with A. glycines, cis-3-hexen-1-ol acetate, MeSA and farnesene. In summary, SPME can detect the emission of HIPVs from plants infested with insect herbivores.
Abstract: Kratom is a tree planted in Southeast Asia, including Thailand, Malaysia, Myanmar (Burma) and elsewhere in the region. A long history of usage and abuse of kratom has led to the classification of kratom as a controlled substance in its native Thailand and other Southeast Asian countries. However, kratom is not controlled in the United States, and the wide availability of kratom on the Internet and in the streets has led to its emergence as an herbal drug of misuse. With the increasing popularity of kratom, efficient protocols are needed to detect kratom use. In this study, a rapid method for the analysis of kratom compounds, mitragynine and 7-hydroxymitragynine, in human urine has been developed and validated using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The chromatographic system employed a 2.6-μm 100 mm × 2.1 mm phenyl-hexyl analytical column and gradient elution with a 0.4-mL/min flow rate of water and acetonitrile as mobile phases. A triple quadrupole mass spectrometer was used as the detector for data acquisition. The analyst was the quantification software. The established method demonstrated linearity of >0.99 for both analytes, and low detection limits were obtained down to 0.002581 ng/mL for mitragynine and 0.06910 ng/mL for 7-hydroxymitragynine. The validated method has been utilized for clinical analysis of urine for the purpose of mitragynine and 7-hydroxymitragynine detection.
Abstract: A method for conducting fast and efficient gas chromatography based on short multicapillaries in straight alignment combined with atomic emission detection was developed for field analysis. The strategy enables for speciation analysis of organometallic compounds. The analytes are simultaneously ethylated and preconcentrated on a solid phase microextraction (SPME) fiber placed in the headspace over the sample for 25 min. The ethylated species are then completely separated and selectively quantified within 25 s under isothermal conditions. A new miniaturized speciation analyzer has been constructed and evaluated. The system consists of a GC injection port and a lab-made miniaturized GC unit directly coupled with miniaturized plasma excitation source. The emitted light is transferred via optical fiber and registered with a miniaturized charged coupled device (CCD) based spectrometer. Working parameters for multicapillary column gas chromatography with atomic emission detector, including carrier gas flow rate, desorption temperature, and GC column temperature, were optimized to achieve good separation of analytes. Basic investigations of the fundamental properties of 5 cm-long multicapillary column, to evaluate its potential and limitations as a rapid separation unit, are presented. The adaptation of the technique for use with a SPME system and with a multichannel element-selective plasma-emission detector is highlighted.
Abstract: The richness of bioactive compounds in plant materials encourages continuous development of separation methods and bioassays for their isolation and identification. Thin-layer chromatography-direct bioautography links separation on the adsorbent layer with biological tests performed directly on it. Therefore, the method is very convenient for searching plant constituents with biological activity, such as antibiotics. Test bacteria grow directly on a plate surface excluding places where antibacterials are located. They can be detected with reagents converted by living bacteria. TLC-DB is a high throughput method enabling analyses of many samples in parallel and the comparison of their activity. Both screening and semi-quantitative analysis is possible. The targeted compounds can be identified using spectroscopic methods, mostly mass spectrometry, that can be performed directly on a TLC plate. This paper discusses all above mentioned aspects of TLC-DB, illustrating them with literature, schemes and our own results.
Abstract: Security control is becoming a major global issue in strategic locations, such as airports, official buildings, and transit stations. The agencies responsible for public security need powerful and sensitive tools to detect warfare agents and explosives. Volatile signature detection is one of the fastest and easiest ways to achieve this task. However, explosive chemicals have low volatility making their detection challenging. In this research, we developed and evaluated fast chromatographic methods to improve the characterization of volatile signatures from explosives samples. The headspace of explosives was sampled with solid phase micro-extraction fiber (SPME). Following this step, classical gas chromatography (GC) and comprehensive two-dimensional GC (GC×GC) were used for analysis. A fast GC approach allows the elution temperature of each analyte to be decreased, resulting in decreased thermal degradation of sensitive compounds (e.g., nitro explosives). Using fast GC×GC, the limit of detection is further decreased based on the cryo-focusing effect of the modulator. Sampling of explosives and chromatographic separation were optimized, and the methods then applied to commercial explosives samples. Implementation of fast GC methods will be valuable in the future for defense and security forensics applications.
Abstract: Monolithic columns are a special type of chromatography column, which can be used for the purification of different biomolecules. They have become popular due to their high mass transfer properties and short purification times. Several articles have already discussed monolith manufacturing, as well as monolith characteristics. In contrast, this review focuses on the applied aspect of monoliths and discusses the most relevant biomolecules that can be successfully purified by them. We describe success stories for viruses, nucleic acids and proteins and compare them to conventional purification methods. Furthermore, the advantages of monolithic columns over particle-based resins, as well as the limitations of monoliths are discussed. With a compilation of commercially available monolithic columns, this review aims at serving as a ‘yellow pages’ for bioprocess engineers who face the challenge of purifying a certain biomolecule using monoliths.