Identification of Volatile Compounds and Selection of Discriminant Markers for Elephant Dung Coffee Using Static Headspace Gas Chromatography-Mass Spectrometry and Chemometrics.

Elephant dung coffee (Black Ivory Coffee) is a unique Thai coffee produced from Arabica coffee cherries consumed by Asian elephants and collected from their feces. In this work, elephant dung coffee and controls were analyzed using static headspace gas chromatography hyphenated with mass spectrometry (SHS GC-MS), and chemometric approaches were applied for multivariate analysis and the selection of marker compounds that are characteristic of the coffee. Seventy-eight volatile compounds belonging to 13 chemical classes were tentatively identified, including six alcohols, five aldehydes, one carboxylic acid, three esters, 17 furans, one furanone, 13 ketones, two oxazoles, four phenolic compounds, 14 pyrazines, one pyridine, eight pyrroles and three sulfur-containing compounds.

The role of previously unmeasured organic acids in the pathogenesis of severe malaria.

Introduction: Severe falciparum malaria is commonly complicated by metabolic acidosis. Together with lactic acid (LA), other previously unmeasured acids have been implicated in the pathogenesis of falciparum malaria.

Methods: In this prospective study, we characterised organic acids in adults with severe falciparum malaria in India and Bangladesh.

Characteristic fingerprint based on gingerol derivative analysis for discrimination of ginger (Zingiber officinale) according to geographical origin using HPLC-DAD combined with chemometrics.

Chromatographic fingerprints of gingers from five different ginger-producing countries (China, India, Malaysia, Thailand and Vietnam) were newly established to discriminate the origin of ginger. The pungent bioactive principles of ginger, gingerols and six other gingerol-related compounds were determined and identified. Their variations in HPLC profiles create the characteristic pattern of each origin by employing similarity analysis, hierarchical cluster analysis (HCA), principal component analysis (PCA) and linear discriminant analysis (LDA).

Evaluation of a modified QuEChERS method for analysis of mycotoxins in rice.

A simple and efficient QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparation method was modified to provide good analytical results for 14 mycotoxins in rice. The method involved mixing sample with acidified aqueous acetonitrile, followed by salt-out liquid partitioning using MgSO4, NaCl, and citrate buffer salts. The extract was cleaned-up by dispersive solid-phase extraction with MgSO4, PSA, C18, and alumina-neutral.

Liquid chromatographic-mass spectrometric method for simultaneous determination of small organic acids potentially contributing to acidosis in severe malaria.

Acidosis is an important cause of mortality in severe falciparum malaria. Lactic acid is a major contributor to metabolic acidosis, but accounts for only one-quarter of the strong anion gap. Other unidentified organic acids have an independent strong prognostic significance for a fatal outcome.

Low-temperature cleanup with solid-phase extraction for the determination of polycyclic aromatic hydrocarbons in edible oils by reversed phase liquid chromatography with fluorescence detection.

Low-temperature cleanup, which is a simple and cost-efficient sample preparation technique that allows the convenient treatment of multiple samples simultaneously, was developed in conjunction with solid-phase extraction (SPE) cleanup for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in refined and used edible oil samples by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Samples are extracted with a small amount of organic solvent and most of lipids in the extract were removed by low-temperature cleanup. SPE cartridge was used to further cleanup prior to HPLC-FLD analysis.

Separation selectivity patterns of fully charged achiral compounds in capillary electrophoresis with a neutral cyclodextrin.

Based on the separation selectivity equation, related to the dimensionless parameters for fully charged achiral analytes using a neutral CD, the separation selectivity can be classified into seven patterns. With respect to CZE without CD, the presence of CD in the buffer may improve, or reduce, the separation selectivity with this effect being accompanied by the same or reversed electrophoretic mobility order for charged analytes. This can depend on the separation selectivity of the two analytes in free solution, the binding selectivity, the separation selectivity of analyte-CD complexes and the ratio of electrophoretic mobility of the analytes in free, and complexed forms.

Fast, low-pressure gas chromatography triple quadrupole tandem mass spectrometry for analysis of 150 pesticide residues in fruits and vegetables.

We developed and evaluated a new method of low-pressure gas chromatography-tandem mass spectrometry (LP-GC/MS-MS) using a triple quadrupole instrument for fast analysis of 150 relevant pesticides in four representative fruits and vegetables. This LP-GC (vacuum outlet) approach entails coupling a 10 m, 0.53 mm i.

Qualitative aspects in the analysis of pesticide residues in fruits and vegetables using fast, low-pressure gas chromatography-time-of-flight mass spectrometry.

Quantitative method validation is a well-established process to demonstrate trueness and precision of the results with a given method. However, an assessment of qualitative results is also an important need to estimate selectivity and devise criteria for chemical identification when using the method, particularly for mass spectrometric analysis. For multianalyte analysis, automatic instrument software is commonly used to make initial qualitative identifications of the target analytes by comparison of their mass spectra against a database library.

Efficient hydrophilic interaction liquid chromatography-tandem mass spectrometry for the multiclass analysis of veterinary drugs in chicken muscle.

A simple and sensitive method has been developed for multiresidue analysis of 24 important veterinary drugs (including 3 aminoglycosides, 3 β-lactams, 2 lincosamides, 4 macrolides, 4 quinolones, 4 sulfonamides, 3 tetracyclines, and amprolium) in chicken muscle. The method involved a simple extraction using (1:1, v/v) of 2% trichloroacetic acid in water-acetonitrile, followed by removing fat with hexane, dilution of sample extract, and filtration prior to liquid chromatography-tandem mass spectrometric (LC-MS/MS) analysis. Hydrophilic interaction liquid chromatography (HILIC) proved to be very effective for separation of a wide range of polar and hydrophilic compounds (providing high sensitivity and good peak shape) compared to reversed phase and ion-pair separation.

High throughput analysis of 150 pesticides in fruits and vegetables using QuEChERS and low-pressure gas chromatography-time-of-flight mass spectrometry.

A higher monitoring rate is highly desirable in the labs, but this goal is typically limited by sample throughput. In this study, we sought to assess the real-world applicability of fast, low-pressure GC-time-of-flight MS (LP-GC/TOFMS) for the identification and quantification of 150 pesticides in tomato, strawberry, potato, orange, and lettuce samples. Buffered and unbuffered versions of QuEChERS (which stands for "quick, easy, cheap, effective, rugged, and safe") using dispersive solid-phase extraction (d-SPE) and disposable pipette extraction (DPX) for clean-up were compared for sample preparation.

Comparison of QuEChERS sample preparation methods for the analysis of pesticide residues in fruits and vegetables.

This article describes the comparison of different versions of an easy, rapid and low-cost sample preparation approach for the determination of pesticide residues in fruits and vegetables by concurrent use of gas and liquid chromatography (GC and LC) coupled to mass spectrometry (MS) for detection. The sample preparation approach is known as QuEChERS, which stands for "quick, easy, cheap, effective, rugged and safe". The three compared versions were based on the original unbuffered method, which was first published in 2003, and two interlaboratory validated versions: AOAC Official Method 2007.

Extension of the QuEChERS method for pesticide residues in cereals to flaxseeds, peanuts, and doughs.

A simple method was evaluated for the determination of pesticide residues in flaxseeds, doughs, and peanuts using gas chromatography-time-of-flight mass spectrometry (GC-TOF) for analysis. A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, which was previously optimized for cereal grain samples, was evaluated in these fatty matrices. This extraction method involves first mixing the sample with 1:1 water/acetonitrile for an hour to swell the matrix and permit the salt-out liquid-liquid partitioning step using anhydrous MgSO(4) and NaCl.

Selectivity comparisons of monolithic silica capillary columns modified with poly(octadecyl methacrylate) and octadecyl moieties for halogenated compounds in reversed-phase liquid chromatography.

Stationary phase selectivities for halogenated compounds in reversed-phase HPLC were compared using C18 monolithic silica capillary columns modified with poly(octadecyl methacrylate) (ODM) and octadecyl moieties (ODS). The preferential retention of halogenated benzenes on ODM was observed in methanol/water and acetonitrile/water mobile phases. In selectivity comparison of selected analytes on ODM and ODS, greater selectivities for halogenated compounds were obtained with respect to alkylbenzenes on an ODM column, while similar selectivities were observed with a homologous series of alkylbenzenes on ODM and ODS columns.

Rapid determination of phenoxy acid residues in rice by modified QuEChERS extraction and liquid chromatography-tandem mass spectrometry.

A new method for the analysis of phenoxy acid herbicide residues in rice, based on the use of liquid extraction/partition and dispersive solid phase extraction (dispersive-SPE) followed by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS), is reported. 5% (v/v) formic acid in acetonitrile as the extraction solvent and inclusion of citrate buffer helped partitioning of all the analytes into the acetonitrile phase. The extract was then cleaned up by dispersive-SPE using C18 and alumina neutral as selective sorbents.

Micro-scale membrane extraction of glyphosate and aminomethylphosphonic acid in water followed by high-performance liquid chromatography and post-column derivatization with fluorescence detector.

A carrier-mediated supported liquid membrane micro-extraction using single hollow fiber membrane suitable for the determination of the herbicide glyphosate and its main metabolite aminomethylphosphonic acid in water is reported. A solution of 0.20 M Aliquat-336, a cationic carrier, in di-n-hexyl ether was selected as the supported liquid.

Comparison of resolution in microemulsion EKC and MEKC employing suppressed electroosmosis: application to bisphenol-A-diglycidyl ether and its derivatives.

The resolution (R(s)) of hydrophobic analytes in microemulsion EKC (MEEKC) and MEKC with suppressed electroosmosis was investigated using bisphenol-A-diglycidyl ether and its derivatives (BADGEs) as test analytes. Separation scales were compared using our equation for the resolution, R(s)= (square rootN/4)(alpha-1)/(1+K(2)),where k is the retention factor, alpha the selectivity (alpha = k(2)/k(1) for k(2) > or = k(1)>0), and N the average efficiency. At given concentrations of SDS and organic cosolvent in the buffer, in comparison with MEKC, MEEKC was found to provide better resolution of BADGEs, mainly due to the significantly smaller k in MEEKC, but not the greater alpha in MEEKC, while a comparable range of N.

Solid-phase extraction for multiresidue determination of sulfonamides, tetracyclines, and pyrimethamine in Bovine's milk.

This paper describes a systematic approach to the development of a solid-phase extraction method for simultaneous extraction of 10 antibiotic residues in bovine milk, belonging to groups of sulfonamides, tetracyclines, and pyrimethamine. The sample preparation steps include acidic deproteinization of milk proteins followed by sample enrichment and cleanup using a polymer-based Oasis HLB solid-phase extraction cartridge. The analyses were carried out by using a method based on liquid chromatography-electrospray ionisation-mass spectrometry with positive ion mode.

Retention factor and retention index of homologous series compounds in microemulsion electrokinetic chromatography employing suppressed electroosmosis.

The retention factor (k) and retention index (I) of homologous series compounds such as alkylbenzenes (BZ), alkylaryl ketones, alkylbenzoates, and alkylparabens in microemulsion electrokinetic chromatography (MEEKC) with suppressed electroosmosis were investigated in a wide range of SDS concentrations ([SDS]), temperatures, and concentrations of organic cosolvents (phi). Using BZ as standards, the retention indices of other homologous series compounds were determined and they were found to be independent of [SDS] and temperature, while are dependent on the types and concentrations of organic cosolvents. The retention factor linearly increases with increasing [SDS], while linearly decreases with increasing temperature.

Validation of a liquid chromatography-mass spectrometry multi-residue method for the simultaneous determination of sulfonamides, tetracyclines, and pyrimethamine in milk.

A multiresidue method suitable for confirmation and determination of six sulfonamides (SAs), three tetracyclines (TCs), and pyrimethamine (PYR) in cow milk was validated. Milk samples were extracted using copolymer Oasis HLB solid-phase extraction (SPE) and analyzed by liquid chromatography-electrospray mass spectrometry with positive ion mode. Estimated method detection limits (MDL) and method quantitation limits (MQL) ranged from 0.

Simultaneous determination of bisphenol-A-diglycidyl ether, bisphenol-F-diglycidyl ether, and their derivatives in oil-in-water and aqueous-based canned foods by high-performance liquid chromatography with fluorescence detection.

A gradient reversed-phase liquid chromatography with fluorescence detection method for simultaneous identification and quantification of bisphenol-A-diglycidyl ether (BADGE), bisphenol-F-diglycidyl ether (BFDGE), and their 10 derivatives in food matrixes was developed and validated for the analysis of oil-in-water- and aqueous-based foodstuffs. The method linearity range 0.016-10 ppm which are hundred-fold below and tenfold above the EU restriction at 1 ppm (mg/kg).