Capillary liquid chromatographic fingerprint used for discrimination of Zingiber montanum from related species

Fingerprint analysis using capillary liquid chromatography (CLC) has been developed for discrimination of Zingiber montanum (ZM) from related species, for example Z. americans (ZA) and Z. zerumbet (ZZ). By comparing the fingerprint chromatograms of ZM, ZA, and ZZ we could identify ZM samples and discriminate them from ZA and ZZ by using their marker peaks. We also combined CLC fingerprint with multivariate analysis, including principal-component analysis (PCA) and canonical variate analysis (CVA); all three species were discriminated successfully. This result indicates that CLC fingerprint analysis in combination with PCA and CVA can be used for discrimination of ZM samples from samples of related species.

Radical polymerization of methyl methacrylate with 2,2,3-triphenylpropanoic acid as an initiator

An unsymmetrical compound, 2,2,3-triphenylpropanoic acid (TPPA), was successfully prepared from phenyllithium, 1,1-diphenylethylene (DPE), gas carbon dioxide (CO₂), and aqueous standard solution of hydrochloric acid with LiCl deprivation. Characterization of the compound was performed by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. The polymerization of methyl methacrylate (MMA) was performed in the presence of TPPA at 95 °C. The free radicals obtained were characterized by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS). Gel permeation chromatography (GPC) traces of the average molecular weight of poly(MMA) (PMMA) showed a series of translations with increasing time. The average molecular weight of PMMA indicated narrow polydispersity, and an approximately linear relationship was found between ln ([M]₀/[M]) and polymerization time.

Metabolomic profiling of mice urine and serum associated with trans-trans 2, 4-decadienal induced lung lesions by liquid chromatography-mass spectrometry

Metabolomics has become an important tool in clinical research and the diagnosis of human disease. Intratracheal instillation of trans-trans 2,4-decadienal (tt-DDE), a major component in cooking oil fumes, has been demonstrated to cause lung lesions in mice at 8 weeks after treatment. The objective of this study was to identify any changes in metabolite profiles associated with the development of tt-DDE-induced lung lesions. Using a metabolomics strategy involving a liquid chromatography–mass spectrometry-based approach in conjunction with principal component analysis and confirmation by liquid chromatography triple quadrupole tandem mass spectrometry, we have demonstrated that the amino acid profiles of the urine and serum of tt-DDE-treated mice are changed. Ten amino acids were significantly reduced in serum of tt-DDE-treated mice at 8 weeks after treatment. Our results suggest that amino acid profiles may be useful as an early indicator of the presence of tt-DDE-induced lung lesions.

Monitoring subcellular biotransformation of N-l-leucyldoxorubicin by micellar electrokinetic capillary chromatography coupled to laser-induced fluorescence detection

Development of prodrugs is a promising alternative to address cytotoxicity and nonspecificity of common anticancer agents. N-l-leucyldoxorubicin (LeuDox) is a prodrug that is biotransformed to the anticancer drug doxorubicin (Dox) in the extracellular space; however, its biotransformation may also occur intracellularly in endocytic organelles. Such organelle-specific biotransformation is yet to be determined. In this study, magnetically enriched endocytic organelle fractions from human uterine sarcoma cells were treated with LeuDox. Micellar electrokinetic chromatography with laser-induced fluorescence detection (MEKC-LIF) was used to determine that 10 % of LeuDox was biotransformed to Dox, accounting for ～43 % of the biotransformation occurring in the post-nuclear fraction. This finding suggests that endocytic organelles also participate in the intracellular biotransformation of LeuDox to Dox.

Chromatography-bioluminescence coupling reveals surprising bioactivity of inthomycin A

By employing a novel technique for the direct coupling of a bacterial bioassay with chromatography, we discovered a gyrA promotor active compound in myxobacterial extracts and elucidated the structure directly without any isolation step. As a result, we identified inthomycin A as the bioactive substance. Our method is based on a whole-cell bioluminescent reporter gene assay coupled with thin-layer chromatography for primary hit detection and with liquid chromatography (LC)/mass spectrometry or LC/NMR for dereplication and structure elucidation. Previously, inthomycin A has been isolated from Streptomycetes and was associated with the inhibition of cellulose biosynthesis and herbicidal activity. Thus, our findings support the basic principle that completely different microbial phyla are able to synthesize the same natural product. Moreover, our results indicate that inthomycin A affects bacterial DNA supercoiling, which reveals an unexpected bioactivity for this compound. These results can possibly promote further investigation of the biosynthesis as well as the biological activity of inthomycins and related natural products.

Establishing Drug Resistance in Microorganisms by Mass Spectrometry

A rapid method to determine drug resistance in bacteria based on mass spectrometry is presented. In it, a mass spectrum of an intact microorganism grown in drug-containing stable isotope-labeled media is compared with a mass spectrum of the intact microorganism grown in non-labeled media without the drug present. Drug resistance is determined by predicting characteristic mass shifts of one or more microorganism biomarkers using bioinformatics algorithms. Observing such characteristic mass shifts indicates that the microorganism is viable even in the presence of the drug, thus incorporating the isotopic label into characteristic biomarker molecules. The performance of the method is illustrated on the example of intact E. coli, grown in control (unlabeled) and ¹³C-labeled media, and analyzed by MALDI TOF MS. Algorithms for data analysis are presented as well.

Derivatization of pinacolyl alcohol with phenyldimethylchlorosilane for enhanced detection by gas chromatography–mass spectrometry

A derivatization procedure for the qualitative gas chromatography–mass spectrometry (GC-MS) analysis of pinacolyl alcohol (PA) that employs phenyldimethylchlorosilane (PhDMClS) and the promoter N-methylimidazole is described. While PA, underivatized, can be detected using conventional gas chromatographic methods, its polarity and low boiling point make its detection in complex matrices challenging. The silylation procedure described herein generates a PA-derivative exhibiting an increased on-column retention time, thus shifting its GC-MS signal away from commonly encountered, volatile, interfering analytes. Derivatized PA could be distinguished from other PhDMClS-derivatized isomeric alcohols by its unique retention time and mass spectrum. The derivatization was demonstrated to perform well in the GC-MS analysis and identification of PA in samples from Proficiency Tests administered by the Organisation for the Prohibition of Chemical Weapons (OPCW).

Interaction of mercury(II) ions with immobilized apo-metallothioneins studied by scanning electrochemical microscopy combined with surface plasmon resonance

Scanning electrochemical microscopy (SECM) was combined with surface plasmon resonance (SPR) and applied for in-situ monitoring of the incorporation of Hg²⁺ by apo-metallothionein (apo-MT) immobilized on the SPR substrate. Hg²⁺ was anodically stripped from the Hg-coated SECM Pt tip and sequestered by apo-MT upon its diffusion to the SPR substrate. The high sensitivity of the SPR instrument enabled the detection of the change in the composition and structure of apo-MT molecules that was induced by the metal sequestration of Hg²⁺. The SPR response revealed that the saturation co-ordination number of Hg²⁺ binding to apo-MT was 18. Moreover, an unexpected collapse of the structure of MT was observed when the stoichiometric ratio of Hg²⁺/MT was ~70, and the structure cannot be further altered even by adding a large excess of Hg²⁺. This collapse was also confirmed by Raman spectroscopy. The results are potentially useful for a deeper understanding of the detoxification mechanism of MT to mercury ion.

Multidimensional nano-HPLC coupled with tandem mass spectrometry for analyzing biotinylated proteins

Multidimensional high-performance liquid chromatography (HPLC) is a key method in shotgun proteomics approaches for analyzing highly complex protein mixtures by complementary chromatographic separation principles. Here, we describe an integrated 3D-nano-HPLC/nano-electrospray ionization quadrupole time-of-flight mass spectrometry system that allows an enzymatic digestion of proteins followed by an enrichment and subsequent separation of the created peptide mixtures. The online 3D-nano-HPLC system is composed of a monolithic trypsin reactor in the first dimension, a monolithic affinity column with immobilized monomeric avidin in the second dimension, and a reversed phase C18 HPLC-Chip in the third dimension that is coupled to a nano-ESI-Q-TOF mass spectrometer. The 3D-LC/MS setup is exemplified for the identification of biotinylated proteins from a simple protein mixture. Additionally, we describe an online 2D-nano-HPLC/nano-ESI-LTQ-Orbitrap-MS/MS setup for the enrichment, separation, and identification of cross-linked, biotinylated species from chemical cross-linking of cytochrome c and a calmodulin/peptide complex using a novel trifunctional cross-linker with two amine-reactive groups and a biotin label.

Electrochemical immunoassay for subgroup J of avian leukosis viruses using a glassy carbon electrode modified with a film of poly (3-thiophene boronic acid), gold nanoparticles, graphene and immobilized antibody

We have modified a glassy carbon electrode (GCE) with a film of poly(3-thiophene boronic acid), gold nanoparticles and graphene, and an antibody (Ab) was immobilized on its surface through the covalent bond formed between the boronic acid group and the glycosyl groups of the Ab. Subgroup J of avian leukosis viruses (ALV-J) were electrochemically determined with the help of this electrode. There is a linear relationship between the electron transfer resistance (R _et) and the concentration of ALV-J in the range from 527 to 3,162 TCID₅₀?mL^?1 (where TCID₅₀ is the 50?% tissue culture infective dose). The detection limit is 210 TCID₅₀?mL^?1 (at an S/N of 3), and the correlation coefficient (R) is 0.9964. The electrochemical immunoassay showed good selectivity, stability and reproducibility.

Simultaneous chromatography and electrophoresis: two-dimensional planar separations

Single-dimension separations are routinely coupled in series to achieve two-dimensional separations, yet little has been done to simultaneously exploit multiple dimensions during separation. In this work, simultaneous chromatography and electrophoresis is introduced and evaluated for its potential to achieve two-dimensional separations. In simultaneous chromatography and electrophoresis, chromatography occurs via capillary action while an orthogonal electric field concurrently promotes electrophoresis in a second dimension. A novel apparatus with a dual solvent reservoir was designed to apply the concurrent electric field. Various compounds were used to characterize the apparatus and technique, i.e., vitamins, amino acids, and dyes. Improved separation is reported with equivalent analysis times in comparison to planar chromatography alone. The feasibility of simultaneously employing chromatography and electrophoresis in two dimensions is discussed.

Structural Analysis of Guanylyl Cyclase-Activating Protein-2 (GCAP-2) Homodimer by Stable Isotope-Labeling, Chemical Cross-Linking, and Mass Spectrometry

The topology of the GCAP-2 homodimer was investigated by chemical cross-linking and high resolution mass spectrometry. Complementary conducted size-exclusion chromatography and analytical ultracentrifugation studies indicated that GCAP-2 forms a homodimer both in the absence and in the presence of Ca²⁺. In-depth MS and MS/MS analysis of the cross-linked products was aided by ¹⁵ ? N-labeled GCAP-2. The use of isotope-labeled protein delivered reliable structural information on the GCAP-2 homodimer, enabling an unambiguous discrimination between cross-links within one monomer (intramolecular) or between two subunits (intermolecular). The limited number of cross-links obtained in the Ca²⁺-bound state allowed us to deduce a defined homodimeric GCAP-2 structure by a docking and molecular dynamics approach. In the Ca²⁺-free state, GCAP-2 is more flexible as indicated by the higher number of cross-links. We consider stable isotope-labeling to be indispensable for deriving reliable structural information from chemical cross-linking data of multi-subunit protein assemblies.

Microfluidic robotic device coupled with electrochemical sensor field for handling of paramagnetic micro-particles as a tool for determination of plant mRNA

The expression of genes responsible for the biosynthesis of stress proteins corresponds to the exposition of an organism to abiotic and/or biotic stress. We utilize two types of paramagnetic particles for isolation of total mRNA from early somatic embryos of Norway Spruce (Picea abies /L./ Karst.) and maize plants (Zea mays L.) treated with cadmium(II) ions. The paramagnetic particles were evaluated for analysis of real samples, and poly-adenine was used as a model mRNA. Various approaches (from non-automatic to fully automatic) were tested in terms of handling the particles.

Rapid on-site TLC–SERS detection of four antidiabetes drugs used as adulterants in botanical dietary supplements

A novel facile method has been established for rapid on-site detection of antidiabetes chemicals used to adulterate botanical dietary supplements (BDS) for diabetes. Analytes and components of pharmaceutical matrices were separated by thin-layer chromatography (TLC) then surface-enhanced Raman spectroscopy (SERS) was used for qualitative identification of trace substances on the HPTLC plate. Optimization and standardization of the experimental conditions, for example the method used for preparation of silver colloids, the mobile phase, and the concentration of colloidal silver, resulted in a very robust and highly sensitive method which enabled successful detection when the amount of adulteration was as low as 0.001 % (w/w). The method was also highly selective, enabling successful identification of some chemicals in extremely complex herbal matrices. The established TLC–SERS method was used for analysis of real BDS used to treat diabetes, and the results obtained were verified by liquid chromatography–triple quadrupole mass spectrometry (LC–MS–MS). The study showed that TLC–SERS could be used for effective separation and detection of four chemicals used to adulterate BDS, and would have good prospects for on-site qualitative screening of BDS for adulterants.

Rapid comprehensive characterization of crude oils by thermogravimetry coupled to fast modulated gas chromatography–single photon ionization time-of-flight mass spectrometry

Comprehensive multi-dimensional hyphenation of a thermogravimetry device (i.e. a thermobalance) to gas chromatography and single photon ionization–time-of-flight mass spectrometry (TG–GC×SPI–MS) has been used to investigate two crude oil samples of different geographical origin. The source of the applied vacuum ultraviolet radiation is an electron beam pumped rare gas excimer lamp (EBEL). The soft photoionization favors the formation of molecular ions. Introduction of a fast, rapidly modulated gas chromatographic separation step in comparison with solely TG–SPI–MS enables strongly enhanced detection especially with such highly complex organic matrices as crude oil. In contrast with former TG–SPI–MS measurements, separation and identification of overlying substances is possible because of different GC retention times. The specific contribution of isobaric compounds to one mass signal is determined for alkanes, naphthalenes, alkylated benzenes, and other compounds.

Immobilized purine nucleoside phosphorylase from Schistosoma mansoni for specific inhibition studies

The parasite Schistosoma mansoni (Sm) depends exclusively on the salvage pathway for its purine requirements. The enzyme purine nucleoside phosphorylase (PNP) is, therefore, a promising target for development of antischistosomal agents and an assay for screening of inhibitors. To enable this, immobilized SmPNP reactors were produced. By quantification of hypoxanthine by liquid chromatography, kinetic constants (K _M) for the substrate inosine were determined for the free and immobilized enzyme as 110 ± 6.90 μmol?L ^?1 and 164 ± 13.4 μmol?L ^?1 , respectively, indicating that immobilization did not affect enzyme activity. Furthermore, the enzyme retained 25 % of its activity after four months. Non-Michaelis kinetics for the phosphate substrate, and capacity for P_i-independent hydrolysis were also demonstrated, despite the low rate of enzymatic catalysis. Use of an SmPNP immobilized enzyme reactor (IMER) for inhibitor-screening assays was demonstrated with a small library of 9-deazaguanine analogues. The method had high selectivity and specificity compared with screening by use of the free enzyme by the Kalckar method, and furnished results without the need for verification of the absence of false positives.

Development of monolith-based stir bar sorptive extraction and liquid chromatography tandem mass spectrometry method for sensitive determination of ten sulfonamides in pork and chicken samples

A highly sensitive method was developed for the simultaneous determination of ten sulfonamides in pork and chicken samples by monolith-based stir bar sorptive extraction (SBSE) coupled to high-performance liquid chromatography tandem mass spectrometry. The samples were freeze-dried and extracted by acetonitrile, then enriched and further extracted by SBSE which was based on poly(vinylphthalimide-co-N,N-methylenebisacrylamide) monolith (SBSE-VPMB) as coating. To achieve optimum extraction performance of SBSE for sulfonamides, several parameters, including pH value and ionic strength in the sample matrix and extraction and desorption time, were investigated in detail. Under the optimal conditions, the limits of detection (S/N?=?3) for target sulfonamides were 1.2–6.1 ng/kg in pork and 2.0–14.6 ng/kg in chicken, respectively. Real samples spiked at the concentration of 0.5 and 5.0 μg/kg showed recoveries above 55 % and relative standard deviations below 12 %. At the same time, the extraction performances of target sulfonamides on SBSE-VPMB were compared with other SBSE based on porous monolith and commercial SBSE.

Bioactivity fingerprint analysis of cyclooxygenase-2 ligands from radix Aconiti by ultrafiltration–UPLC–MSn

A novel fingerprinting method, bioactivity fingerprint analysis, based on an ultrafiltration–ultraperformance liquid chromatography–multistage tandem mass spectrometry (UPLC–MS ⁿ ) method is proposed for the quality control of herbal medicines from the bioactivity viewpoint concerning the efficacy of herbal medicines. The bioactivity fingerprints reflecting the anti-inflammatory activities of radix Aconiti and radix Aconiti preparata were established. With use of ultrafiltration UPLC–MS ⁿ , 11 cyclooxygenase-2 ligands from radix Aconiti preparata and 14 cyclooxygenase-2 ligands from radix Aconiti were found after incubation with cyclooxygenase-2. Twelve of the cyclooxygenase-2 ligands were identified by the ultraperformance UPLC–MS ⁿ method. The enrichment factor of each peak in the bioactivity fingerprint was calculated and was demonstrated to be characteristic, which makes bioactivity fingerprint analysis for the quality control of herbal medicines possible from the viewpoint of their bioactivities.

Mass spectrometry characterisation of fatty acids from metabolically engineered soybean seeds

Improving the quality and performance of soybean oil as biodiesel depends on the chemical composition of its fatty acids and requires an increase in monounsaturated acids and a reduction in polyunsaturated acids. Despite its current use as a source of biofuel, soybean oil contains an average of 25 % oleic acid and 13 % palmitic acid, which negatively impacts its oxidative stability and freezing point, causing a high rate of nitrogen oxide emission. Gas chromatography and ion mobility mass spectrometry were conducted on soybean fatty acids from metabolically engineered seed extracts to determine the nature of the structural oleic and palmitic acids. The soybean genes FAD2-1 and FatB were placed under the control of the 35SCaMV constitutive promoter, introduced to soybean embryonic axes by particle bombardment and down-regulated using RNA interference technology. Results indicate that the metabolically engineered plants exhibited a significant increase in oleic acid (up to 94.58 %) and a reduction in palmitic acid (to <3 %) in their seed oil content. No structural differences were observed between the fatty acids of the transgenic and non-transgenic oil extracts.