Author


Justin Hutzley

Latest:

FAIMS Removes Chemical Background and Interference from the Analysis of Linoleic Acid in Cancer Cell Extracts

Assay sensitivity is the lowest concentration at which a targeted analyte can be measured and is often limited by chemical background or co-eluting interferences. FAIMS in combination with liquid chromatography (LC) and zero neutral loss tandem MS was used to remove chemical background and co-eluting interferences from the analysis of linoleic acid in cancer cell extracts. Concentration of endogenous linoleic acid was determined from back-calculation of standard calibration samples fortified with deuterium-labeled linoleic acid. No internal standard was used. LC–MS-MS analysis of the cancer cell extracts resulted in an increase in signal-to-noise ratio of 10-fold. The assay sensitivity was increased 10 times over the traditional LC–MS-MS experiment exclusively due to the new FAIMS technology.


Takashi Baba

Latest:

Electron-Capture Dissociation in a Radio-Frequency Linear Ion Trap

Here we describe a new compact device for electron-capture dissociation (ECD) analysis of large peptides and posttranslational modifications of proteins, which can be difficult to analyze via conventional dissociation techniques such as collision-induced dissociation (CID). The new compact device realizes ECD in a radio frequency (RF) linear ion trap equipped with a small permanent magnet, which is significantly different than the large and maintenance-intensive superconducting magnet required for conventional ECD in Fourier-transform ion cyclotron resonance mass spectrometers. In addition to its compactness and ease of operation, an additional merit of an RF linear ion trap ECD is that its reaction speed is fast, comparable to CID, enabling data acquisition on the liquid-chromatography (LC) time scale. We interfaced the linear-trap ECD device to a time-of-flight mass spectrometer to obtain ECD spectra of phosphorylated peptides injected into a liquid chromatograph, infused glycopeptides, and intact small..


Xiaodong Liu

Latest:

A New Weak Anion-Exchange/Reversed-Phase Mixed-Mode Stationary Phase for Simultaneous Separation of Basic, Acidic and Neutral Pharmaceuticals

Mixed mode chromatography combines aspects of ion exchange chromatography and conventional reversed-phase (RP) chromatography. The combination of both hydrophobic and ion-exchange properties allows for independent control of retention for ionizable and neutral molecules.


Zheng Yang

Latest:

The Expanding Role of LC–ICP-MS Speciation Analysis in the Life Sciences: Element- Selective Screening and Species-Independent Quantification

Emerging as a complementary analytical tool to LC-MS, LC-ICP-MS brings added value to the determination of inorganic element containing molecules of biological importance.


I. Chion

Latest:

System Suitability and Validation for Chiral Purity Assays of Drug Substances

Measurement of chiral purity is a necessary means of quality control for drug substances that exhibit chiral centers. This article describes a simple and practical approach to setting up system suitability and validation for chiral purity assays.


Peter Hancock

Latest:

Determining High-Molecular-Weight Phthalates in Sediments Using GC–APCI-TOF-MS

Gas chromatography combined with atmospheric-pressure chemical ionization (APCI) was used to analyze high-molecular-weight phthalates.


Christopher J. Messina

Latest:

Application of Novel Ethylene Bridged Hybrid Particles for Hydrophilic-Interaction Chromatography

Using HILIC with highly efficient ethylene bridged hybrid (BEH) particles results in faster methods that exhibit improved polar retention, higher sensitivity, enhanced chromatographic resolution, and significantly improved column lifetime.


Laurence Castle

Latest:

The Determination of Furan in Foods — Challenges and Solutions

The determination of the carcinogenic food processing contaminant furan by headspace sampling of foods is challenging because it can easily escape from the sample during preparation. Furan can also be easily formed as a by-product when the sample is heated in the headspace apparatus. This article describes a number of approaches to overcome these difficulties and alternative methods to quantify furan in a variety of matrices.


Dr Koen Vanhoutte

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).


Philip L. Wylie

Latest:

Direct Injection of Fish Oil for the GC–ECD Analysis of PCBs: Results Using a Deans Switch with Backflushing

A Deans switch, employing Agilent's Capillary Flow Technology, was configured on an Agilent 7890A GC equipped with dual ECD detectors. A method was developed for the analysis of fish oil for PCB contamination. The Deans switch was used to heart cut 7 indicator PCBs (IUPAC Numbers 28, 52, 101, 118, 138, 153 and 180) from the primary DB-XLB column on to a DB-200 column for further separation. Fish oil from a supplement capsule was simply diluted 1:10 in isooctane and injected directly. To prevent carryover, contamination and retention time shifts, the Deans switch was used to backflush the primary column at the end of each run.


Andrew Tipler

Latest:

A Novel Method for the High-Speed Determination of Fuel Diluents in Lubricating Oils

The performance of lubricating oil is significantly degraded by the presence of fuel contaminants such as gasoline and diesel. Recycled oil is particularly susceptible to this form of contamination. Consequently, producers and distributors of lubricating oil must go to great lengths to ensure the levels of fuel contamination are kept to a safe limit (typically 4–5%) in these products.


Daniel McMillan

Latest:

A Robust and Sensitive Method for Detecting Glyphosate and Other Polar Pesticides in Food and Water: Multiple Analytes in a Single Injection without Derivatization

A new high-throughput LC–MS/MS method meets the challenge of eliminating matrix effects for monitoring, with high specificity, polar organic pesticides such as glyphosate in food and water, while meeting targeted limits of detection.


Ricard Boqué

Latest:

The Limit of Detection

The concept of the limit of detection (LOD) has been, and still is, one of the most controversial in analytical chemistry. The multiple definitions and calculation methods proposed have contributed to this situation. Although in the last years, several international organizations, such as ISO or IUPAC, have tried to reach a consensus in their definitions and have issued guidelines for the estimation of this important parameter in chemical analysis, the subject is still a matter of scientific debate. In this article, we try to clarify the definition and provide guidelines to estimate LOD in chromatographic methods of analysis.


Walter Welz

Latest:

Quality Control of Snake Venoms for Proteomic Analysis: Comparing Applicability of CGE-on-the-chip and Planar Polyacrylamide Gel Electrophoresis

The evaluation of the state of a biological sample before starting the complex analyses is a crucial step in proteomics studies. This paper compares planar polyacrylamide gel electrophoresis (SDS-PAGE) and capillary on-the-chip SDS GE (CGE-on-the-chip) in terms of the speed of analysis, sensitivity and flexibility. Snake venoms, which are heterogeneous with high bioactivity and consist mainly of proteins with a molecular weight mass range below 100 kDa, were investigated. CGE-on-the-chip was found to be a faster and more stable technique, providing more information than classical SDS-PAGE. CGE-on-the-chip was also capable of detecting many compounds over a broad molecular weight mass range whereas the SDS-PAGE is more time-consuming and provides acceptable resolution either in the very low (below 17 kDa) or in the mid- to high-molecular mass region (16–200 kDa) depending on the gel/buffer-system selected.


Justyna Sekula

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).


Keke Klomburg

Latest:

De Novo Formula Generation with "Sub-ppm" Confidence using Compass OpenAccess and the micrOTOF

Accurate mass measurements are a key element of chemical characterization. However, the accepted mass accuracy tolerance of 3–5 ppm can still leave significant ambiguity in the proposed chemical formula. Consequently a further input from other analytical techniques such as NMR or MS/MS, along with some judgment based on the synthetic history is often required to arrive at a confident formula assignment.


Jeff Goshawk

Latest:

Qualitative and Quantitative Metabolite Identification for Verapamil in Rat Plasma by Sub-2-μm LC Coupled with Quadrupole TOF-MS

An effective metabolite identification study should ideally include both qualitative and quantitative information that for both identifying metabolites, and determining the rate of clearance and the metabolic routes of the parent drug. Liquid chromatography–mass spectrometry (LC–MS) is considered the standard analytical technique for metabolite identification studies. To date, however, qualitative and quantitative information has always been obtained from two separation platforms: quadrupole time-of-flight (QTof) MS for the exact mass full-scan qualitative study, and tandem quadrupole MS for the multiple reaction monitoring (MRM) quantitative study. With advancements to QTof instrumentation, specifically, recent improvements in sensitivity and dynamic range, it is now possible to perform both qualitative and quantitative experiments on a single QTof mass spectrometer. This article describes a workflow that allows simultaneous qualitative and quantitative metabolite identification studies to be..


Maria-Elisa Capella-Peiró

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.


Donald C. Hilton

Latest:

Automated Screening for Hazardous Components in Complex Mixtures Based on Functional Characteristics Identifiable in GCxGC–TOF-MS Data

The increased resolving power provided by comprehensive two-dimensional gas chromatography (GCxGC) extends the chromatographer's ability to rapidly detect and measure smaller components in complex mixtures beyond that which was possible previously, allowing for the identification of hazardous components in complex mixtures such as foodstuffs or emergency response samples. In target analysis, the increased numbers of peaks resulting from the sample matrix can be largely ignored during the review of data. However, when the nature of the analyte of interest is not entirely known, analysis of the samples might require screening through the entire peak table for compounds with specific chemical characteristics. For example, in the analysis of foodstuffs for pesticides (1,2), GCxGC coupled with a time-of-flight mass spectrometry (GCxGC–TOF-MS) can provide low detection limits for multiple analytes in these complex samples. Yet the question remains as to whether other toxic compounds, not included in the..


Sascha Giegold

Latest:

Practical Comparison of Different Approaches to Speed Up LC Separations

This article describes and compares a number of approaches to increase the speed of liquid chromatographic separations. On a standard LC column, a gain of a factor two in the run time (from 10 to 5 minutes) was achieved by increasing the flow-rate two-fold. On a monolithic column, a column operated at high temperature (120 ?C) and a short column, flow-rates could be increased typically five-fold, resulting in run times in the order of 2 minutes. This was accompanied by a sometimes considerable loss in separation efficiency. A combination of a very short run time and unaffected separation efficiency was realized on a UPLC system, designed for use at higher pressure. By working at approximately 800 bar, the analytes could be well separated within 30 seconds.



Paul R. Loconto

Latest:

Quantitating Toxaphene Parlar Congeners in Fish Using Large Volume Injection Isotope Dilution GC with Electron-Capture Negative Ion MS

A novel automated ultratrace gas chromatography–mass spectrometry (GC–MS) method has been developed that quantitates the eight toxaphene Parlar congeners designated in U.S. Environmental Protection Agency Method 8276. This method, combined with an efficient extraction, cleanup, and fractionation technique, makes is possible to extend instrument detection limits to the low parts-per-trillion concentration level for these toxaphene Parlar congeners.


Hella Dressler

Latest:

Improvement of GC Sensitivity for Polar and Nonpolar PAHs by Using a Deactivated Liner

This article presents the findings from an analysis conducted on sensitivity in GC on the basis of the complex group of polycyclic aromatic hydrocarbons and PAH derivatives.


Robert E. Hedges

Latest:

Single-Compound Isotopic Analysis of Organic Materials in Archaeology

The authors review chromatographic separations of archaeological biomolecules for their analysis using accelerator mass spectrometry or isotope ratio mass spectrometry.



Michael Willett

Latest:

Key LC–MS Techniques Benefit Life Sciences Researchers

State-of-the-art mass spectrometry (MS) techniques of growing importance to life sciences research now include not just liquid chromatography (LC)–MSn (n = 2–11), but also LC–matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF), LC-MALDI-TOF-TOF, electrospray ionization (ESI)-TOF, and LC-Fourier transform (FT) MS.


Dominica Kozlowska

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).


Dietmar Meyer

Latest:

Improvement of GC Sensitivity for Polar and Nonpolar PAHs by Using a Deactivated Liner

This article presents the findings from an analysis conducted on sensitivity in GC on the basis of the complex group of polycyclic aromatic hydrocarbons and PAH derivatives.


Victoria Lander

Latest:

21 CFR Part 11 and Risk Assessment: Adapting Fundamental Methodologies to a Current Rule

The current final FDA guidance document discussing the revised scope and applicability of 21 CFR Part 11 clearly adopts a risk-based approach to Part 11 compliance. This is certainly a very pragmatic approach and one that many regulated firms had adopted even before the recent release of this document. This article will discuss the particulars of a risk-based approach to Part 11 compliance. The favored risk assessment protocols such as HACCP, FMEA and FMECA will also be addressed as well as how one can apply them to 21 CFR Part 11 compliance.


Gerald Hall

Latest:

A Novel Method for the High-Speed Determination of Fuel Diluents in Lubricating Oils

The performance of lubricating oil is significantly degraded by the presence of fuel contaminants such as gasoline and diesel. Recycled oil is particularly susceptible to this form of contamination. Consequently, producers and distributors of lubricating oil must go to great lengths to ensure the levels of fuel contamination are kept to a safe limit (typically 4–5%) in these products.