Enantioselective comprehensive two-dimensional gas chromatography. A route to elucidate the authenticity and origin of Rosa damascena Miller essential oils

The analysis of Bulgarian and Turkish Rosa damascena Miller essential oils was performed by flow modulated comprehensive two-dimensional gas chromatography using simultaneous detection of the second columneffluent by flame ionization and quadrupole ma…



Thousand-Fold Volumetric Concentration of Live Cells with a Recirculating Acoustofluidic Device

Analytical ChemistryDOI: 10.1021/acs.analchem.5b01944



Fingerprint analysis, multi-component quantitation, and antioxidant activity for the quality evaluation of Salvia miltiorrhiza var. alba by high-performance liquid chromatography and chemometrics

Salvia miltiorrhiza Bge. var. alba C.Y. Wu and H.W. Li has wide prospects in clinical practice. A useful comprehensive method was developed for the quality evaluation of Salvia miltiorrhiza var. alba by three quantitative parameters: high-performance …



Combination of quantitative analysis and chemometric analysis for the quality evaluation of three different frankincenses by ultra high performance liquid chromatography and quadrupole time of flight mass spectrometry

Frankincense has gained increasing attention in the pharmaceutical industry because of its pharmacologically active components such as boswellic acids. However, the identity and overall quality evaluation of three different frankincense species in dif…



The effects of molecular collisions between the mobile phase and the solute in gas-solid chromatography

In chromatographic processes, molecular collisions between the mobile phase and the solute result in the transfer of kinetic energy. Based on these interactions, the relationship between the gauge pressure of the carrier gas at the column inlet and th…



The Poisson distribution and beyond: methods for microfluidic droplet production and single cell encapsulation

Lab Chip, 2015, Advance ArticleDOI: 10.1039/C5LC00614G, Critical ReviewDavid J. Collins, Adrian Neild, Andrew deMello, Ai-Qun Liu, Ye AiIn recent years there has been an explosion of methods for encapsulating cells in droplets. This review examines the…



Direct Identification of Rituximab Main Isoforms and Subunit Analysis by Online Selective Comprehensive Two-Dimensional Liquid Chromatography–Mass Spectrometry

Analytical ChemistryDOI: 10.1021/acs.analchem.5b01578



Voltammetric Characterization of Ion–Ionophore Complexation Using Thin Polymeric Membranes: Asymmetric Thin-Layer Responses

Analytical ChemistryDOI: 10.1021/acs.analchem.5b02355



Merging drops in a Teflon tube, and transferring fluid between them, illustrated by protein crystallization and drug screening

Lab Chip, 2015, Accepted ManuscriptDOI: 10.1039/C5LC00726G, PaperAlexander Feuerborn, Aishah Prastowo, Peter Cook, Edmond WalshThe ability to manipulate drops with small volumes has many practical applications. Current microfluidic devices generally ex…



Correction: Microfluidic pumping, routing and metering by contactless metal-based electro-osmosis

Lab Chip, 2015, Advance Article
DOI: 10.1039/C5LC90090E, Correction
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Xiaotong Fu, Nicholas Mavrogiannis, Steven Doria, Zachary Gagnon
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Paper diagnostic device for quantitative electrochemical detection of ricin at picomolar levels

Lab Chip, 2015, Advance ArticleDOI: 10.1039/C5LC00731C, PaperJosephine C. Cunningham, Karen Scida, Molly R. Kogan, Bo Wang, Andrew D. Ellington, Richard M. CrooksA paper analytical device for quantitative electrochemical detection of ricin a chain is r…



High-Speed Scanning Electrochemical Microscopy Method for Substrate Kinetic Determination: Application to Live Cell Imaging in Human Cancer

Analytical ChemistryDOI: 10.1021/acs.analchem.5b01269



High-Speed Scanning Electrochemical Microscopy Method for Substrate Kinetic Determination: Method and Theory

Analytical ChemistryDOI: 10.1021/acs.analchem.5b01268



Determination and validation of psammaplin A and its derivatives in rat plasma by liquid chromatography–tandem mass spectrometry and its application in pharmacokinetic study

Publication date: 1 September 2015
Source:Journal of Chromatography B, Volume 1000
Author(s): Jae-Young Lee, Mee Yeon Lee, Min Woo Ha, Tae Hyung Won, Hyun-Jong Cho, Jongheon Shin, Hyeung-geun Park, Dae-Duk Kim
A liquid chromatography–tandem mass (LC–MS/MS) method was developed for the determination of psammaplin A (PsA) and its newly synthesized derivatives (PsA 107, PsA 109, and PsA 123) in rat plasma using bupropion as an internal standard (IS). The plasma samples were deproteinized with acetonitrile. Chromatographic separation was performed on hydro-RP column (75×2.0mm, 80Å, 4μm) with isocratic elution using 5mM ammonium formate buffer/acetonitrile (30:70, v/v) at a flow rate of 0.4mL/min and the total run time was 5min. Mass spectrometric detection was performed with positive electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode. The ion transitions monitored were m/z 663.2→331.0, 687.2→343.1, 587.3→293.1, 563.3→281.0, and 240.0→184.0 for PsA, PsA 107, PsA 109, PsA 123, and IS, respectively. All analytes showed good linearity over the concentration range of 5.00–5000ng/mL (r2≥0.994). The lower limit of quantification was 5ng/mL for PsA and its three PsA derivatives. Within- and between-run precisions (relative standard deviation, RSD) were less than 9.66% and accuracy (relative error, RE) ranged from −9.34% to 7.25%. Established method was successfully applied to the investigation of pharmacokinetic properties of PsA and its derivatives in rats after intravenous administration at a dose of 2mg/kg.



Simultaneous determination of ten compounds in rat plasma by UPLC-MS/MS: Application in the pharmacokinetic study of Ma-Zi-Ren-Wan

Publication date: 1 September 2015
Source:Journal of Chromatography B, Volume 1000
Author(s): Dong-Dong Hu, Quan-Bin Han, Linda Li-Dan Zhong, Yan-Hong Li, Cheng-Yuan Lin, Hing-Man Ho, Man Zhang, Shu-Hai Lin, Ling Zhao, Tao Huang, Hong Mi, Hong-Sheng Tan, Hong-Xi Xu, Zhao-Xiang Bian
Ma-Zi-Ren-Wan (MZRW) is a classic Chinese formula which has been used to treat human constipation in China for over 2000 years. In order to make good and rational use of this formula in the future, this paper presents the first attempt to track the pharmacokinetic features of MZRW in rat using rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Ten chemical components of MZRW, namely, rhein, emodin, aloe emodin, hesperidin, naringin, amygdalin, albiflorin, paeoniflorin, magnolol and honokiol, were simultaneously determined in rat plasma after a single oral administration (10g/kg body weight) of MZRW to rats. Geniposide and liquiritin were used as internal standards. The separation was performed on a Waters ACQUITY BEH C18 column (100mm×2.1mm, 1.7μm). The detection was conducted by multiple-reaction monitoring (MRM) in negative ionization mode. Two highest abundant MRM transitions without interference were optimized for each analyte. This method was well validated in terms of linearity, precision, accuracy, recovery, matrix effect and stability. All calibration curves had good linearity (r2>0.995) over the concentration range from 3.9 to 125.0ng/mL for emodin, 3.9–500.0ng/mL for amygdalin, 2.0–4000.0ng/mL for naringin and hesperidin, 3.9–2000.0ng/mL for magnolol, 7.8–2000.0ng/mL for rhein and 3.9–4000.0ng/mL for albiflorin, paeoniflorin, aloe emodin and honokiol. The intra-day and inter-day precision (relative standard deviation) was within 15%, the accuracy (relative error) ranged from −13.6% to 15.1%, and the lower limit of quantification in plasma ranged between 2.0ng/mL and 7.8ng/mL. Extraction recovery, matrix effect and stability were satisfactory. The validated method was successfully applied to a pharmacokinetic study of these ten compounds after oral administration of MZRW to rats. The pharmacokinetic parameters of each compound can facilitate clinical studies in the future.



Following the enzymatic digestion of chondroitin sulfate by a simple GPC analysis

Publication date: 23 July 2015
Source:Analytica Chimica Acta, Volume 885
Author(s): Carla Silva, Ramon Novoa-Carballal, Rui L. Reis, Iva Pashkuleva
We describe the use of gel permeation chromatography (GPC) setup with four size exclusion columns for analysis of enzymatically digested glycosaminoglycans (GAGs). This setup provides information about the molecular weight (Mw) and concentration of all species (low and high Mw) present in the digests in a single measurement. The data about the fraction with high Mw (often omitted in the analysis of GAG digests) provide direct evidence about the mechanisms of action of the enzymes. We proved the feasibility of this methodology by applying it to chondroitin sulfate (CS) substrates with different molecular weight and sulfation pattern and using different enzymes (hyaluronidase and chondroitinase). NMR analysis of the obtained digests fractionated by ultrafiltration confirmed the results obtained by GPC setup and reveal further details about the degradation mechanisms: (i) both enzymes preferentially attack 4-sulfated chondroitin and (ii) additionally to the well documented endolytic activity of hyaluronidase we also observed a low lyase activity for this enzyme reflected in the detected minor exolytic breakage. Finally, we demonstrate that CS with medium molecular weight (12–60kDa) which is sulfated mainly at 6-position can be obtained in good yields by enzymatic digestion and following ultrafiltration.

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Poly(N-vinylimidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids

Publication date: 23 July 2015
Source:Analytica Chimica Acta, Volume 885
Author(s): Dieter Schemeth, Jean-Christophe Noël, Thomas Jakschitz, Matthias Rainer, Richard Tessadri, Christian W. Huck, Günther K. Bonn
In this study we report the novel polymeric resin poly(N-vinyl imidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids. The monomer to crosslinker ratio and the porogen composition were optimized for isolating phenolic acids diluted in acetonitrile at normal phase chromatography conditions, first. Acetonitrile serves as polar, aprotic solvent, dissolving phenolic acids but not interrupting interactions with the stationary phase due to the approved Hansen solubility parameters. The optimized resin demonstrated high loading capacities and adsorption abilities particularly for phenolic acids in both, acetonitrile and aqueous solutions. The adsorption behavior of aqueous standards can be attributed to ion exchange effects due to electrostatic interactions between protonated imidazole residues and deprotonated phenolic acids. Furthermore, adsorption experiments and subsequent curve fittings provide information of maximum loading capacities of single standards according to the Langmuir adsorption model. Recovery studies of the optimized polymer in the normal-phase and ion-exchange mode illustrate the powerful isolation properties for phenolic acids and are comparable or even better than typical, commercially available solid phase extraction materials. In order to prove the applicability, a highly complex extract of rosemary leaves was purified by poly(N-vinyl imidazole/ethylene glycol dimethacrylate) and the isolated compounds were identified using UHPLC–qTOF-MS.

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Occurrence of oleic and 18:1 methyl-branched acyl chains in lipids of Rhodobacter sphaeroides 2.4.1

Publication date: 23 July 2015
Source:Analytica Chimica Acta, Volume 885
Author(s): Sara Granafei, Ilario Losito, Simona Salivo, Peter Q. Tranchida, Luigi Mondello, Francesco Palmisano, Tommaso R.I. Cataldi
The fatty acids (FAs) composition of lipids extracted from Rhodobacter sphaeroides 2.4.1 was investigated by gas chromatography–mass spectrometry (GC–MS) analysis of the corresponding FA methyl esters (FAMEs), obtained through trans-esterification of the original lipid species. A GC stationary phase based on a highly polar ionic liquid (IL) was selected, aimed to enhance the separation of isomeric FAMEs with particular emphasis on positional and geometrical isomers of monounsaturated 16:1 and 18:1 fatty acyl chains. The occurrence of 18:1 cis-Δ9 (oleic) acid, a positional isomer of the well-known and most predominant 18:1 cis-Δ11 (cis-vaccenic) acid, has been demonstrated here for the first time. Furthermore a methyl branched 18:1 FA was also identified and its structure tentatively assigned as 11-methyl-Δ12-octadecenoic acid (most likely as trans isomer). The unprecedented observation about 18:1 cis-Δ9 FA occurrence in R. sphaeroides 2.4.1 is, even indirectly, supported by a biosynthetic pathway postulated with the aid of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The concurrent presence of 16:1 cis-Δ7 and 18:1 cis-Δ9 FAs suggested the existence of parallel and/or complementary processes to those invoked for the formation of most common 16:1 cis-Δ9 and 18:1 cis-Δ11 FAs. A further route was hypothesized for the trans FAs biosynthesis in wild-type cells of R. sphaeroides.

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Determination of organophosphate flame retardants and plasticizers in lipid-rich matrices using dispersive solid-phase extraction as a sample cleanup step and ultra-high performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry

Publication date: 23 July 2015
Source:Analytica Chimica Acta, Volume 885
Author(s): Shaogang Chu, Robert J. Letcher
A fast, robust and highly sensitive analysis method for determination of trace levels of organophosphate ester (OPE) flame retardants and plasticizers in lipid-rich samples was presently developed, and based on ultra-high performance liquid chromatography-tandem mass spectrometry coupled to a positive atmospheric pressure chemical ionization source (UHPLC-MS/MS-APCI(+)). The target OPEs in the sample were extracted from the biota samples, such as egg and liver, by ultrasonic extraction, and cleaned up further by dispersive solid phase extraction (d-ESP). As a result, background contamination was largely reduced. Different dispersive ESP sorbents were tested and primary secondary amine (PSA) bonded silica sorbents showed the best recoveries for these target OPEs. The recoveries obtained were in the range 54–113% (RSD<17%), with method limits of quantification (MLOQs) ranging between 0.06 and 0.29ng/g in egg, and 0.05 and 0.50ng/g w.w. in liver sample. The matrix effects (MEs) associated with using APCI(+) and ESI(+) sources were investigated. APCI(+) showed much less ion suppression than ESI(+) for the determination of these OPEs. For egg and liver samples, the APCI(+) ME values ranged from 40% to 94%, while ESI(+) ME values ranged from 0% to 36%. Although APCI(+) was used for the determination of OPEs, the ionization mechanism might mainly be a thermospray ionization process. This UHPLC-MS/MS-APCI(+) method showed good response linearity for calibration (R2>0.99). The proposed method was applied to real environmental bird egg and fish samples, where several OPE were quantifiable and different OPE patterns was observed between samples.

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Diastereo- and enantioseparation of a Nα-Boc amino acid with a zwitterionic quinine-based stationary phase: Focus on the stereorecognition mechanism

Publication date: 23 July 2015
Source:Analytica Chimica Acta, Volume 885
Author(s): Federica Ianni, Andrea Carotti, Maura Marinozzi, Gloria Marcelli, Alessandro Di Michele, Roccaldo Sardella, Wolfgang Lindner, Benedetto Natalini
A chiral chromatography method enabling the simultaneous diastereo- and enantioseparation of Nα-Boc-N4-(hydroorotyl)-4-aminophenylalanine [Boc-Aph(Hor)-OH, 1] was optimized with a quinine-based zwitterionic stationary phase. The polar-ionic eluent system consisting of ACN:MeOH:water—49.7:49.7:0.6 (v/v/v) with formic acid (4.0mM) and diethylamine (2.5mM), allowed the successful separation of the four acid stereoisomers: αd,d-/d,l-1=1.08; αd,l-/l,d-1=1.08; αl,d-/l,l-1=1.40.According to the in-house developed synthetic procedure and the recorded electronic circular dichroism spectra, the following stereoisomeric elution order was readily established in the optimal chromatographic conditions: d,d-1<d,l-1<l,d-1<l,l-1.With the aim of better understanding the molecular basis of the retention behaviour of the four stereoisomers in the employed chromatographic system and conditions, a computational protocol consisting in molecular dynamics simulations was applied. The use of the three descriptors INTER (in kcalmol−1, encoding for the interaction energy between the selector SO unit and the whole system), INTER_SA (in kcalmol−1, encoding for the interaction energy between SO and the sole selectand SA), and SELF (in kcalmol−1, encoding for the conformational energy of SA relative to its minimum energy registered by the collected snapshots) revealed the active role of achiral sub-structural elements of the chiral stationary phase and eluent components in the overall stereorecognition mechanism.

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