Author



J.S. Esteve Romerob

Latest:

Photodegradation and Photstability Studies of Bendroflumethiazide in Pharmaceutical Formulations and Urine Samples by Micellar Liquid Chromatography

A simple HPLC procedure is described for the determination of bendroflumethiazide (BMFT) in pharmaceutical formulations and urine samples. No interferences from common additives or other drugs frequently administered with BMFT or from endogenous compounds in urine samples were found. The lack of an organic solvent in the mobile phase reduces the risk of environmental contamination and human toxicity.


Jerome Bailey

Latest:

New Sample Fractionation Strategies for Proteomic Analyses by LC–MS

Mass spectrometry has long been a preferred tool for protein identification and biomarker discovery, but preparation of biological samples remains a challenge. Hindrances include the wide range of protein concentrations, sample complexity, and loss or alteration of important proteins due to sample handling. This article describes recent developments in sample fractionation technologies that are overcoming these challenges in interesting ways and are enabling in-depth proteomic studies that were not possible in the past.


Sonja Sturm

Latest:

HPLC–SPE–NMR — A Novel Hyphenation Technique

High performance liquid chromatography–solid phase extraction–nuclear magnetic resonance (HPLC–SPE–NMR) is a novel hyphenation technology that concentrates single chromatographic peaks to elution volumes matching those of NMR flow probes. The SPE unit facilitates the solvent exchange from the mobile phase of the optimized HPLC assay to a deuterated NMR solvent. The well-defined NMR solvent conditions make spectra comparisons feasible, which means databases and spectra catalogues can be used to swiftly identify analytes. The ability to accumulate analytes on the SPE cartridges by multiple trapping reduces the need to perform residual solvent suppression experiments and allows heteronuclear NMR experiments to be performed overnight. Structure elucidation of natural products directly from crude extract HPLC samples has become the key application of this technique.


John D. Lennon III

Latest:

Identifying Packaging-Related Drug Product Impurities

This month's instalment of "MS in Practice" provides a slightly different view of how practitioners employ the skills of interpretation that have been the focus in recent columns.


Paul Wynne

Latest:

The Use of Subtle Differences in Selectivity to Improve Separation of Structurally Diverse Analytes

The separation of structurally diverse analytes is often complicated by chance coelutions with other analytes or with matrix related compounds. Often the column is blamed, but while such coelutions make analysis difficult they do not necessarily indicate a faulty column, poor chromatography or method design.


Mélanie Lagarrigue

Latest:

CE–MS-MS for the Identification of Chemical Warfare Agent Degradation Products

With the threat of terrorism growing, the development of analytical techniques for the detection and identification of chemical warfare agent defradation products has increased. Capillary electrophoresis (CE) presents interesting features for this application.


Mihoko Yamaguchi

Latest:

Quantitation-Enhanced Data-Dependent (QED) Scanning of Drinking Water Samples Using EQuan for Pesticide Analysis

This application note describes an LC–MS–MS method for on-line sample preparation and concentration of drinking water samples prior to analysis using a triple quadrupole with full scan Q3 confirmation.


Diane M. Wagrowski-Diehl

Latest:

Hydrophilic Interaction Chromatography Using Silica Columns for the Retention of Polar Analytes and Enhanced ESI-MS Sensitivity

The use of a silica column for HILIC is examined, including mechanistic studies of analyte retention on silica in aqueous-organic mobile phases.


Monika Moeder

Latest:

Membrane-Assisted Liquid–Liquid Extraction Trace Analysis of Pharmaceutical Compounds in Aquatic Environments

The concept of membrane-controlled processes is widespread in nature. Nearly all biological mechanisms concerning mass transport and exchange are regulated by membrane barriers and a variety of technical and biotechnological applications have been devised based on this mechanism. Membrane applications in analytical chemistry are geared towards the enrichment of target substances from an aqueous solution or the separation of compounds from a complex matrix. This article describes membrane-assisted extraction processes to separate traces of polar pharmaceutical substances the so called emerging micropollutants from aqueous samples. Basic prospects and examples of membrane-supported extractions are presented.


Christine A. Miller

Latest:

Protein Identification in Complex Mixtures: A Comparison of Accurate-Mass Q-TOF and Ion-Trap LC–MS

Because it is extremely rapid, biomarker discovery and identification using liquid chromatography–mass spectrometry (LC-MS), including both ion-trap and triple-quadrupole LC–MS, is well established. Fractionation of complex samples before LC–MS-MS analysis might be necessary to identify the proteins, greatly increasing the number of analyses required. In this case, there is ongoing debate regarding knowing whether the protein is identified correctly, knowing how much prior fractionation is needed to reduce complexity to the point where low-abundance proteins can be detected reliably, and balancing specificity with sensitivity.


Scott Anderson

Latest:

Enantiomeric Separation of Privileged Scaffold Derivatives in Early Drug Discovery Using Chiral SFC

Successful therapeutic intervention often requires chiral medicines because of the intrinsic chirality of protein drug targets, which consist of L-amino acids. Potency, efficacy, and safety can be highly dependent on the precise stereochemical geometry of the molecules. Determining the biological profile of individual enantiomers in the early stages of drug discovery is important for successful optimization towards clinical candidates. Here we demonstrate the benefits of supercritical fluid chromatography (SFC) with three chiral stationary phases exemplified by high frequency resolution of 41 out of 50 chiral derivatives of eight commonly used drug discovery scaffolds including 1,3-thiazoles, 1,3-benzothiazoles, pyranoquinolones, indoles, and leucolines.


Gabriella Török

Latest:

Multimodal HPLC Screening of Polysaccharide-based Chiral Stationary Phases

High-performance liquid chromatography (HPLC) is a powerful tool for the enantioselective separation of chiral drugs. However, the selection of an appropriate chiral stationary phase (CSP) and suitable operating conditions is a bottleneck in method development and a time- and resource-consuming task. Multimodal screening of a small number of CSPs with broad enantiorecognition abilities has been recognized as the best strategy to achieve rapid and reliable separations of chiral compounds. This paper describes the generic screening strategy developed at Johnson & Johnson Pharmaceutical Research and Development (J&J PRD) to successfully develop enantioselective HPLC methods for chiral molecules of pharmaceutical interest.


Chuck Hollenbeck

Latest:

Laboratory Gas Safety

You have purchased a new gas chromatograph. Your company's safety office has completed a review of your lab's supplies. Before setting up your gas chromatograph, you read the instructions and familiarize yourself with the instrument. You might even give some thought to the exposure risks for the various substances in your samples. Yet, what about the less visible risks inherent in the gas delivery system that makes this a gas chromatograph?


Eric Phillips

Latest:

Analysis of Pesticides in Citrus Oil Using PTV Backflush with GC–MS-MS Triple Quadrupole for High Sample Throughput

International regulations on maximum residue levels (MRLs) of pesticides in food cover hundreds of individual contaminants at the 10 ppb or below range. The analysis of citrus oil for pesticide contamination holds specific challenges.


Aurélie Lolia

Latest:

Accelerated Buffer System for Amino Acid Analysis

The continual increase in sample numbers in busy labs means that it is often difficult for quality control or contract analysis labs to maintain short turnaround times, particularly when instruments are already running at full capacity. To address the need for faster analysis while retaining the quality of separation offered by dedicated amino acid analysers, an improved formulation of sodium citrate based buffers has been developed by Biochrom.


Dr Maria Eugenia Mongé

Latest:

Molecular Interaction Sensors: A New Type of Detector for Separation Methods

Potentiometry is a new detection method for liquid chromatography (LC) and capillary electrophoresis (CE). The principle behind this method is familiar to chromatographers because the signals depend on the partitioning tendency of analytes over the sensor coating and the eluent. This partitioning provokes a change in the surface potential and the detection of these changes can be classified as "potentiometric". A conversion algorithm is needed to convert the generated signals to concentration-related tracings (chromatograms).


Manuel Font-Rubert

Latest:

Screening Acid-Base Constants by Capillary Electrophoresis

The acid-base constants of the most frequently used antianginals (diltiazem, nadolol, propranolol and verapamil) were determined using capillary zone electrophoresis (CZE). This method is based on measuring the electrophoretic mobility of the solute as a function of pH. The buffer employed was composed of borate-phosphate buffered across the pH range of 3.0–11.2. The acid-base constants were determined by performing linear and non-linear regression on the data obtained. The results were compared with those reported in literature and with those obtained by a spectrophotometric method. After comparison of the values, no significant differences were observed between the three acid-base constants.


Kirsten Hobby

Latest:

An Expanding Role: The Use of Ultrahigh Performance LC–TOF-MS, GC–TOF-MS, Accurate Mass, and Isotope Modeling for Screening Complex Mixtures

Ultrahigh performance liquid chromatography (LC)–time-of-flight mass spectrometry –(TOF-MS) and gas chromatography (GC)–TOF-MS are powerful approaches for screening target compounds and identifying or characterizing nontarget compounds in complex mixtures. The combination of accurate mass data and newly developed software enables truly generic screening methods with TOF-MS, and the confident detection, identification, and confirmation of small molecules in a range of application areas.


Dr Marcus Brewster

Latest:

Molecular Interaction Sensors: A New Type of Detector for Separation Methods

Potentiometry is a new detection method for liquid chromatography (LC) and capillary electrophoresis (CE). The principle behind this method is familiar to chromatographers because the signals depend on the partitioning tendency of analytes over the sensor coating and the eluent. This partitioning provokes a change in the surface potential and the detection of these changes can be classified as "potentiometric". A conversion algorithm is needed to convert the generated signals to concentration-related tracings (chromatograms).


Katsuhiro Kanda

Latest:

A New Tool for Mass Analysis of Unknown Molecules: High-Resolution Multistep Tandem MS with Wide Dynamic Range Quantitative Analysis

Mass spectrometers are effective for identifying and quantifying unknown molecules, such as disease-related proteins and small molecules in pharmaceutical research and medical diagnosis. In addition, mass spectrometry (MS) can be particularly powerful when analyzing molecules with complex structures, such as posttranslationally modified proteins. Among various MS approaches, high-resolution multistep tandem MS (MS-MS) is an emerging methodology for accurate identification of complex molecules. In this article, we describe a new approach for mass analysis with enhanced quantitative capability combined with high-resolution multistep MS-MS, where the dynamic range of quantitation covers four orders of magnitude.


Joseph Everaert

Latest:

Molecular Interaction Sensors: A New Type of Detector for Separation Methods

Potentiometry is a new detection method for liquid chromatography (LC) and capillary electrophoresis (CE). The principle behind this method is familiar to chromatographers because the signals depend on the partitioning tendency of analytes over the sensor coating and the eluent. This partitioning provokes a change in the surface potential and the detection of these changes can be classified as "potentiometric". A conversion algorithm is needed to convert the generated signals to concentration-related tracings (chromatograms).


Anna Kilmek-Turek

Latest:

Retention and Selectivity of Aromatic Hydrocarbons with Polar Groups in Ternary Reversed-Phase–HPLC Systems with Tetrahydrofuran as Modifier

The variation in selectivity of aromatic hydrocarbons with bisubstituted polar groups is investigated in systems consisting of C18 stationary phase and ternary eluents. The solutions of the ternary eluents were obtained by mixing binary solvents (organic modifier + water) of similar eluent strength. Acetonitrile, methanol and tetrahydrofuran were the organic modifiers applied. The influence of the organic solvent type and its concentration in the ternary mobile phase on retention and selectivity of the solutes is discussed. An approach previously presented by our group was adapted to explain the selectivity changes.


Anne Varenne

Latest:

CE–MS-MS for the Identification of Chemical Warfare Agent Degradation Products

With the threat of terrorism growing, the development of analytical techniques for the detection and identification of chemical warfare agent defradation products has increased. Capillary electrophoresis (CE) presents interesting features for this application.


Thomas Meaker

Latest:

The Application of GC–MS to the Analysis of Pesticides on Foodstuffs

Pesticide contamination of foodstuffs has become a worldwide concern, prompting various levels of regulation and monitoring. Traditionally, pesticides are quantified with gas chromatography (GC) combined with selective detectors (ECD, FID, etc.). Selective GC detectors are great tools to quantify one or two classes at a time. However, screening for a number of different classes of pesticides requires multiple runs utilizing various GC configurations to achieve sufficient chromatographic resolution for unambiguous quantification. Gas chromatography–mass spectrometry (GC–MS) provides positive confirmation of various pesticides in a single analytical run because its superior selectivity allows interference-free quantification even with peak coelution. GC–MS has become a preferred technique for pesticide analysis because of its single-run capability.


Trisca Robarge

Latest:

Using Automated Cold-On-Column Injection for the Analysis of Explosive Residues by Negative Chemical Ionization GC-MS

Negative chemical ionization GC-MS, used in conjunction with automated cold-on-column injection, provides efficient and sensitive quantification of explosive residues for environmental and forensic applications.


Dr Karl Peeters

Latest:

Molecular Interaction Sensors: A New Type of Detector for Separation Methods

Potentiometry is a new detection method for liquid chromatography (LC) and capillary electrophoresis (CE). The principle behind this method is familiar to chromatographers because the signals depend on the partitioning tendency of analytes over the sensor coating and the eluent. This partitioning provokes a change in the surface potential and the detection of these changes can be classified as "potentiometric". A conversion algorithm is needed to convert the generated signals to concentration-related tracings (chromatograms).


Luigi Nardi

Latest:

The Possibilities and Limitations of Capillary Extraction (CEx): The Case Study of Polycyclic Aromatic Hydrocarbons (PAHs) in Clean-Water Samples

Capillary extraction (CEx) is used to study the solventless in-tube extraction of naphthalene, acenaphthene, phenanthrene, fluoranthene, chrysene, benzo(a)pyrene and coronene in aqueous samples prepared by analyte spiking into clean waters or, as an alternative, by using the generator–column method of sample preparation. Analysis of laden extractors is conveniently performed by high-resolution gas chromatography (GC), with a flame-ionization detector (FID). Extraction set-ups and main extraction variables are investigated from a practical point of view. For 2- to 4-ring polycyclic aromatic hydrocarbons (PAHs), equilibrium times are within a few minutes, analytical sensitivity is in the parts-per-billion (ppb) range and reproducibility is better than 10% relative standard deviation (RSD) (n = 6). Coronene behaviour is unique and presumably determined by extreme hydrophobicity and thus very negligible aqueous solubility: in-tube extraction of coronene seems possible only if starting from..


Kenneth Neubauer

Latest:

A Comparison of ICP-OES and ICP-MS for the Determination of Metals in Food

The determination of inorganic elements in food substances is critical for assessing nutritional composition and identifying food contamination sources. The inorganic elements of interest can be divided into two classes: nutritional and toxic. It is important to determine the levels of both sets of elements accurately to assess both the nutritional and the harmful impacts of food substances. Nutritional elements such as Mg, P, and Fe are present at high levels (milligrams per kilogram), while toxic elements such as Pb, Hg, and Cd should be present only at trace levels (nanograms or micrograms per kilogram).


Klara Valko

Latest:

Biomimetic Chromatography to Accelerate Drug Discovery: Part II

Biomimetic HPLC retention data can be used to measure how a compound will bind to proteins and phospholipids in vivo.