Fast Heroin and Cocaine Analysis by GC–MS with Cold EI: The Important Role of Flow Programming

A fast GC–MS method was developed based on the use of GC–MS with Cold EI. This new method was applied for the analysis of the street drugs heroin and cocaine and it enabled 2 min chromatography time and 3 min full analysis cycle time. GC–MS with cold EI provides mass spectra with enhanced molecular ions that are library compatible (with increased identification probabilities) and allows the use of short, 5 m 0.25 mm ID columns, which facilitates fast GC–MS. A central ingredient of our unique cold EI-based fast GC–MS analysis method is the use of column flow programming from 1 up to 32 ml min^?1 column flow rate. Column flow programming can reduce the analysis time by about a factor of two and unlike temperature programs of GC ovens the carrier gas flow rate can be raised and lowered very quickly (in a few seconds). The fast GC–MS with Cold EI method is demonstrated by the analysis of heroin in its street drug powder and cocaine on paper money and it can be applied for other drugs of abuse as a general fast drugs analysis method.     

Micro-pyrolysis of technical lignins in a new modular rig and product analysis by GC–MS/FID and GC × GC–TOFMS/FID

A new offline-pyrolysis rig has been designed to allow multifunctional experiments for preparative and analytical purposes. The system conditions can be set and monitored, e.g. temperature, its gradients and heat flux. Some special features include (1) high heating rates up to 120 °C/s with pyrolysis temperatures up to 850 °C at variable pyrolysis times and (2) the selection of different atmospheres during pyrolysis. A complete mass balance of products and reactants (gas, liquids and solids) by gravimetric methods and sequential chromatographic analyses was obtained.The pyrolytic behaviour and the decomposition products of lignin-related compounds were studied under different conditions: heating rates (from 2.6 °C/s up to 120 °C/s), pyrolysis temperatures at 500 °C and 800 °C in different atmospheres (N₂, H₂, and mixtures of N₂ and acetylene). Kraft lignin, soda lignin, organosolv lignin, pyrolytic lignin from pine bio-oil, residues from biomass hydrolysis and fermentation were studied.The obtained pyrolysis products were classified into three general groups: coke, liquid phase and gas phase (volatile organic compounds (VOC) and permanent gases). The liquid fraction was analysed by GC–MS/FID. In addition, comprehensive two-dimensional GC was applied to further characterise the liquid fraction. VOCs were semi-quantified by a modified headspace technique using GC–MS/FID analysis. The micro-pyrolysis rig proved to be an efficient and useful device for complex pyrolysis applications.     

A New LC–MS–MS Method for Quantitative Analysis of Adefovir,and Its Use for Pharmacokinetic Studies in Healthy Chinese Volunteers

A rapid and sensitive liquid chromatographic–tandem mass spectrometric method for analysis of adefovir in human plasma has been developed and validated. After protein precipitation and evaporation, 10 μL supernatant was injected for reversed-phase LC separation. Adefovir and the internal standard (acyclovir) were monitored in selected reaction monitoring (SRM) mode at m/z 274.10 → 256.00 and 226.10 → 152.00, respectively. The calibration plot was linear over the concentration range 0.5–100 ng mL^?1, and correlation coefficients were >0.999. Mean intra-day and inter-day accuracy ranged from 89.43 to 93.20% and from 91.40 to 95.57%, respectively, and mean intra-day and inter-day precision was between 2.40 and 7.66% and between 5.60 and 10.47%, respectively. The method was successfully applied to a Phase I pharmacokinetic study of adefovir after oral administration of adefovir dipivoxil capsules at doses of 5, 10, and 20 mg to twenty-four healthy Chinese volunteers.     

LC–MS–MS Method for Simultaneous Analysis of Abacavir and Lamivudine in Human Plasma, and Its Application to a Bioequivalence Study

A rapid and sensitive LC–MS–MS method has been developed and validated for simultaneous analysis of abacavir (ABA) and lamivudine (LAM) in human plasma. The analytes were extracted from human plasma by SPE. Nelfinavir (NEL) and emtricitabine (EMT) were used as the internal standards for ABA and LAM, respectively. An RP18 column enabled chromatographic separation of the analytes. The method involves simple isocratic chromatography and MS detection in positive-ionization mode. Validation of the method showed response was a linear function of concentration in the ranges 100.0–7000.0 ng mL^?1 for ABA and 80.0–5000.0 ng mL^?1 for LAM. At the LOQ levels, inter-run and intra-run precision were within 5.80 and 3.51%, respectively, for ABA and within 4.68 and 3.16%, respectively, for LAM. Overall recovery for ABA and LAM was 59.32 and 105.18%, respectively. Total elution time was 2 min only, which enabled quantification of more than 200 plasma samples per day. This validated method was used successfully for analysis of plasma samples from a bioequivalence study.     

A New Method for Brucine Analysis Based on Its Chemiluminescence Reaction with Potassium Permanganat

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Topological Model for Dipole–Quadrupole Polarizability and Its Application to Analysis of Discriminating Intermolecular Interactions

A simplified model for calculating the dipole and dipole–quadrupole polarizabilities A_i,jk is suggested. The model is based on the mean energy method and on the topological approximation to the bond order matrix. Pseudoinvariants of the A_i,jk tensor are calculated to evaluate the degree of molecular dissymmetry, which is responsible for the discriminating intermolecular forces. The method is illustrated by calculations for a number of chiral molecules and comparison of the calculated indices with the experimentally evaluated twisting ability of molecules during the nematic–cholesteric phase transition.     

Validated LC–MS–MS Method for Quantitative Determination of Batifiban in Human Plasma and Its Application to a Pharmacokinetic Study

Batifiban is a new platelet GPIIb/IIIa receptor antagonist. In this work, an analytical method based on liquid chromatography and electrospray ionization tandem mass spectrometry has been firstly developed and validated for the quantitative measurement of batifiban in human plasma to support the investigation of this compound. Separation of analyte and the internal standard eptifibatide was performed on a Thermo HyPURITY C18 column (150 × 2.1 mm, 5 μm) with a mobile phase consisting of formic acid 0.1% (v/v)–acetonitrile (40:60, v/v) at a flow rate of 0.25 mL min^?1. The Waters QuattroMicro API triple quadrupole mass spectrometer was operated in multiple reaction monitoring mode via positive electrospray ionization interface using the transition m/z 819.2 → m/z (623.9 + 159.4) for batifiban and m/z 833.4 → m/z (645.7 + 159.3) for IS. The method was linear over the concentration range of 2.45–5,000 μg L^?1. The intra- and inter- day precisions were less than 15% in terms of relative standard deviation, and the accuracy was within 8.5% in terms of relative error (RE). The lower limit of quantification (LLOQ) was identifiable and reproducible at 2.45 μg L^?1 with acceptable precision and accuracy. The validated method offered sensitivity and wide linear concentration range. This method was successfully applied for the evaluation of pharmacokinetics of batifiban afer single oral doses of 55, 110 and 220 μg kg^?1 batifiban to 36 Chinese healthy volunteers.     

Multi-residue Methodologies for the Analysis of Non-polar Pesticides in Water and Sediment Matrices by GC–MS/MS

Chromatographia - A multi-residue method for the analysis of non-polar pesticides by GC–MS/MS in water and sediment matrices has been successfully developed, including 33 and 27 compounds,...     

Colorimetric and Fluorimetric DNA Detection with a Hydroxystyryl–Quinolizinium Photoacid and Its Application for Cell Imaging

The combination of styryl dye properties with the acidity and strong photoacidity of the 2,2′-[(1′′-hydroxy-4′′-methyl-(E)-2′′,6′′-phenylene)]-bisquinolizinium enables the detection of DNA by distinct absorption and emission color changes and the fluorimetric detection of DNA in cells with epifluorescence and confocal fluorescence microscopy.     

Rapid Method for Simultaneous Determination of Inositol Phosphates by IPC-ESI–MS/MS and Its Application in Nutrition and Genetic Research

Inositol phosphates (InsPs) have important biological functions and multiple nutritional effects. Breeding and nutrition studies of InsPs require a simple, rapid, and accurate method for high-throughput quantification. Here, we developed an ion-pair chromatography/tandem mass spectrometry (IPC/ESI–MS/MS) method for the simultaneous separation and determination of each InsP. A highly volatile ion-pair reagent (dihexylammonium acetate, DHAA) was applied to separate InsP₁–InsP₆, which were then quantified by multiple reaction monitoring (MRM) in negative ESI mode. This method could simultaneously detect InsP₁–InsP₆ within 15 min and exhibited a wide linearity (typically 0.3–1200 pmol). The lower limit of detection was 0.3 pmol for all InsPs, excluding InsP₂ (0.15 pmol) and InsP₆ (3 pmol). The method accuracy of all analytes ranged between 87 and 111% with the inter- and intra-day precision of 0.9–15 and 2.2–11%, respectively. This method was successfully applied to quantitate InsPs in different types of crop seeds, organs, and a maize inbred germplasm collection composed of hundreds of inbred lines, showing its potential for promoting the nutrition and genetic research of InsPs.     

A Novel Derivatization Method Coupled with GC–MS for the Simultaneous Determination of Chloropropanols

A sensitive and rapid derivatization method for the simultaneous determination of chloropropanols [1,3-dichloropropan-2-ol (1,3-DCP), 2,3-dichloropropan-1-ol (2,3-DCP) and 3-chloropropane-1,2-diol (3-MCPD)] has been developed. The three chloropropanols were silylated with 1-trimethylsilylimidazole and then determined by GC–MS. n-Undecane was used as the internal standard. The limits of detection (LOD) were 0.20, 0.10, 0.14 μg kg^?1 for 1,3-DCP, 2,3-DCP and 3-MCPD, respectively. The three compounds behaved >0.999 of linearity and satisfactory precision with the relative standard deviation (RSD) <10%. The excellent validation data suggested that this method was more effective than heptafluorobutyrylimidazole derivatization, and 1-trimethylsilylimidazole was considered as a promising silylating reagent to be widely applied to measurements of chloropropanols in real samples.     

Simultaneous Analysis of Carbamate and Organophosphorus Pesticides in Water by Single-Drop Microextraction Coupled with GC–MS

Single-drop microextraction (SDME) has been coupled with gas chromatography–mass spectrometry to enable rapid and simple simultaneous analysis of carbamate and organophosphorus pesticides (OPP). The significant conditions affecting SDME performance (microextraction solvent, extraction time, solvent volume, sample pH, stirring speed, and ionic strength) were studied and optimized. Extraction was achieved by suspending a 1.5-μL drop of toluene from the tip of a microsyringe directly immersed in 5-mL aqueous donor solution at pH 5 stirred at 800 rpm. The dynamic linear range and detection limits of the method were evaluated by analysis of water samples spiked with carbamate pesticides and OPP. Under selected ion-storage mode, very low detection limits (0.02–0.50 ng mL^?1) and good linearity (0.5–200 ng mL^?1) were achieved. When SDME was applied to analysis of pesticides in natural water samples good recoveries (89.4–102.1%) were obtained. Inter-day and intra-day RSD of most results were below 5.4 and 6.1%, respectively. The method proved to be a rapid and simple tool for extraction and analysis of these pesticides in water samples.     

Application of Gas Chromatography‐Tandem Mass Spectrometry (GC‐MS‐MS) with Pulsed Splitless Injection for the Determination of Multiclass Pesticides in Vegetables

Abstract

GC‐MS‐MS was used to analyze vegetables for 14 pesticide residues. In the same run, the optimal ionization mode (electron ionization or chemical ionization) for each pesticide was selected. The method includes a simple extraction procedure with acetone and dichloromethane. A solid‐phase extraction tube was used for cleanup. The 1 µL of the final solution was injected into the instrument by pulsed splitless injection mode that can improve the sensitivity. The average recoveries were ranged from 78% to 102%. The relative standard deviation was lower than 18.4%. The calculated limits of detection were equal or lower than 0.02 mg/kg.     

Determination of Poricoic Acid A in Rat Plasma after Oral and Intravenous Administration by LC–MS–MS and Its Application to a Pharmacokinetic Study

A sensitive and specific liquid chromatography–tandem mass spectrometry (LC–MS–MS) method was developed and validated for the quantification of poricoic acid A (PAA) in rat plasma. The plasma samples were precipitated by protein precipitation with methanol. Glycyrrhetic acid was used as the IS. Chromatography was performed on a Dionex C₁₈ 120 Å (4.6 × 250 mm, 5 μm) column with the mobile phase composed of acetonitrile–water (90:10, v/v) at a flow rate of 0.8 mL min^?1. A tandem mass spectrometer equipped with an ESI source was used as the detector and was operated in the negative ion mode. Quantification was performed using multiple reaction monitoring (MRM) of the transitions m/z 497.4 → 423.3 and m/z 469.2 → 425.1 for PAA and IS, respectively. The calibration curves were linear over the range of 5–5,000 ng mL^?1 (r ² = 0.9966) and the lower limit of quantification (LLOQ) was 5 ng mL^?1. In this range, RSDs were <10% for intra-assay and inter-assay precisions. The accuracy expressed by deviation (DEV) was <6%, and the extraction recoveries of QC samples were >78%. The validated method was successfully used to study the pharmacokinetics of PAA in rats after intravenous administration at a dose of 1.0, 2.5 and 5.0 mg kg^?1 and oral administration at a dose of 25, 50 and 100 mg kg^?1, respectively. The relative bioavailability of PAA in rats following oral administration was achieved.     

Quantitative and Qualitative Analysis of CKD-501, Lobeglitazone, in Human Plasma and Urine Using LC–MS/MS and Its Application to a Pharmacokinetic Study

A simple, rapid and sensitive LC–MS/MS method in positive ion mode was developed and validated to determine CKD-501, lobeglitazone, in human plasma and urine using glipizide as an internal standard (IS). Lobeglitazone is a novel thiazolidinedione (TZDs)-based peroxisome proliferator-activated receptor (PPAR) agonist, used for the management of type-2 diabetes. After mixing the IS, dissolved in acetonitrile, with a plasma or urine sample containing lobeglitazone, 10?μL of supernatant was injected into the LC–MS/MS system. Quantification was performed in the multiple reaction monitoring (MRM) mode using transition of 481.5?→?152.2 (m/z) for lobeglitazone and 446.1?→?321.2 (m/z) for the IS. The method showed good linearity over concentration ranges of 0.5–1,000?ng?mL^?1 for plasma and 0.2–250?ng?mL^?1 for urine (r ²?≥?0.9996). The mean percent extraction recovery of lobeglitazone was 90.8?% for plasma and 87.3?% for urine, while the recoveries of the IS were greater than 86.4?% for both. The intra-day and inter-day precision of plasma ranged from 1.1 to 3.7 and 2.5 to 3.3?% (RSD), respectively, and the intra- and inter-day precision of urine ranged from 1.5 to 2.7 and 3.2 to 3.5?%, respectively. This method is simple, sensitive, and applicable for the pharmacokinetic study of lobeglitazone in human plasma. Most of the urine concentrations of lobeglitazone were below the LLOQ because the lobeglitazone is extensively metabolized.     

GC–MS Combined with Chemometrics for Analysis of the Components of the Essential Oils of Sweet Potato Leaves

Essential oils from the leaves of two cultivars of sweet potato have been investigated by gas chromatography–mass spectrometry with the help of two chemometric resolution methods, heuristic evolving latent projections and selective ion analysis, and use of temperature-programmed retention indices. The overall volume integration technique was used for quantitative analysis. Eighty-four and forty-five components, accounting for 89.39 and 98.08% of the oils, were tentatively identified in the two cultivars. Thirty-four components were identical in both cultivars. Major constituents of Shuiguo were germacrene D (21.83%), germacrene B (15.17%), caryophyllene (12.44%), and n-hexadecanoic acid (11.24%). Caryophyllene (28.73%), γ-muurolene (13.07%), and β-caryophyllene epoxide (9.04%) were the major components of Xiangshu-17. These results indicate the method is suitable for analysis of the two-dimensional data obtained from essential oils.