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This article explores the progress that atmospheric pressure photoionization (APPI) has made in its relatively short history for LC–MS analysis. Specifically, the authors examine the combination of APPI and electrospray ionization (ESI).

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This article provides an overview of the most recent advances in the field of chiral and achiral separations in SFC. This involves research focused on the most critical parameters in SFC separations, but also on practical issues such as the serial coupling of columns.

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Ramipril impurities D and E are well-known degradation products of ramipril in the finished dosage form. A significant amount of an additional impurity was detected in ramipril tablets by an isocratic reversed-phase high performance liquid chromatography (HPLC) method on a short column. The structure of this impurity was proposed based on liquid chromatography–mass spectrometry (LC–MS) data using an electron spray ionization source. Structural elucidation using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy was facilitated by a newly developed preparative isolation method. This impurity was characterized as (2R,3aR,6aR)-1-[(R)-2-[[(R)-1-(ethoxycarbonyl)-3-phenylpropyl]amino]propanoyl]octahydrocyclopenta[b]pyrrole-2-carboxylic acid (impurity L). Its identification, synthesis and characterization are discussed.

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PEGylation, the process by which polyethylene glycol (PEG) chains are attached to protein and peptide drugs is a common practice in the development of biopharmaceuticals to prolong serum half-life and improve pharmacokinetics of a drug. There is increasing demand for chromatographic methods to separate the modified isoforms from the native protein. This application note describes the use of size exclusion and ion exchange chromatography for the characterization of PEGylated lysozyme.

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A new APCI/APLI source enables a high resolution TOF-MS to be coupled on LC and GC, thus increasing flexibility and performance of TOF-MS in combination with GC.

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CCC is an excellent alternative to avoid the problems associated with solid-phase adsorbents, which include irreversible adsorption of sample and the need to replace expensive columns. As a result, CCC is gaining popularity as a purification tool.

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With the forthcoming USP monograph <1058>, many laboratories are in the process of reexamining their high performance liquid chromatography (HPLC) instrumentation qualification practices. This article demystifies the qualification procedures and proposes a well designed, easy and simple set of experiments upon which to establish internal standard operating procedures (SOPs) for the complete qualification of HPLC instruments. A key concept is the development of a consistent test system, comprised of premade test solutions, a prequalified HPLC column, standardized protocols, and validated software that can be prepared in-house or purchased commercially as a kit. This system can be applied to any HPLC system worldwide, to produce comparable test results under uniform conditions. The test system is designed to be rapid, with a comprehensive performance qualification being completed in about 2 h for isocratic, and 3 h for quaternary gradient systems.

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Ramipril impurities D and E are well-known degradation products of ramipril in the finished dosage form. A significant amount of an additional impurity was detected in ramipril tablets by an isocratic reversed-phase high performance liquid chromatography (HPLC) method on a short column. The structure of this impurity was proposed based on liquid chromatography–mass spectrometry (LC–MS) data using an electron spray ionization source. Structural elucidation using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy was facilitated by a newly developed preparative isolation method. This impurity was characterized as (2R,3aR,6aR)-1-[(R)-2-[[(R)-1-(ethoxycarbonyl)-3-phenylpropyl]amino]propanoyl]octahydrocyclopenta[b]pyrrole-2-carboxylic acid (impurity L). Its identification, synthesis and characterization are discussed.

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Dionex Application note

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A synopsis of our work detailing the use of chemometric response surface methodology (RSM) in two capillary electrophoresis (CE) studies is described.

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Additional studies were undertaken to better understand the chromatographic behavior of PEGylated proteins in an effort to improve purification and characterization techniques of such proteins. Proteins were PEGylated using larger (20 KDa and 40 KDa) PEGylation reagents that are commonly used in pharmaceutical drug development. Generated PEGylated proteins were separated from unmodified proteins using different reversed phase medias (Jupiter® C4 and Jupiter® C18). In these studies it was found that the Jupiter C18 media provided the best separation of PEGylated proteins from their unmodified counterparts. Such results further clarify good method starting points for developing analytical and preparative separations of PEGylated proteins.

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The United States Geological Survey (USGS) has found pharmaceuticals and personal-care products (PPCPs) containing known or suspected endocrine-disruptors in U.S. rivers. As such, it is important to use adequate techniques to help identify these compounds and possible metabolites.

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Ramipril impurities D and E are well-known degradation products of ramipril in the finished dosage form. A significant amount of an additional impurity was detected in ramipril tablets by an isocratic reversed-phase high performance liquid chromatography (HPLC) method on a short column. The structure of this impurity was proposed based on liquid chromatography–mass spectrometry (LC–MS) data using an electron spray ionization source. Structural elucidation using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy was facilitated by a newly developed preparative isolation method. This impurity was characterized as (2R,3aR,6aR)-1-[(R)-2-[[(R)-1-(ethoxycarbonyl)-3-phenylpropyl]amino]propanoyl]octahydrocyclopenta[b]pyrrole-2-carboxylic acid (impurity L). Its identification, synthesis and characterization are discussed.

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Although not currently used in U.S. or European aquaculture, malachite green (MG) is still an effective and inexpensive fungicide that is used in other countries, particularly in Asia. During metabolism, MG reduces to leucomalachite green (LMG) (Figure 1), which has been shown to accumulate in fatty fish tissues. Trace levels of MG and LMG residues continue to be found in fish products. In a 2005 report, MG was found in 18 out of 27 live eel or eel products imported from China to Hong Kong local market and food outlets, resulting in a government recall and destruction of all remaining products (1).

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Protein and peptide analysis via tandem mass spectrometry (MS-MS) has resulted in a wealth of information regarding protein identification, structure, and abundance levels over the past 10 years. Techniques such as neutral loss scanning and collision-induced dissociation (CID) have been especially helpful in facilitating the identification of a multitude of previously unknown sites of protein phosphorylation. However, many of the techniques used to obtain this information are labor intensive and work inconsistently. To address this problem, much effort has been put forth to find alternative methods of fragmenting peptides and proteins that are less difficult and applicable to a wide gamut of peptide classes. Examples of recently developed dissociation techniques include infrared multiphoton dissociation (IRMPD) and electron transfer dissociation (ETD). The implementation of these new techniques has widened the spectrum of peptides amenable to tandem mass spectral analysis.

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Over the past several years, charged aerosol detection (CAD) has become a widely used technology in the pharmaceutical laboratory. From formulation to stability and even quality control, many analysts are turning to this technology due to its advantages of sensitivity, ease of use, dynamic range, and applicability to a wide range of analyses in the drug development process. In this article, we will examine the operation and use of CAD in a regulated environment, briefly address method development and validation specifics, and highlight a few examples illustrating some of its advantages when used in the pharmaceutical laboratory.

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The authors set out to perform a separation of seven water-soluble vitamins without the use of ion-pair reagents.

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The usefulness of liquid chromatography–mass spectrometry–mass spectrometry (LC–MS-MS) methods for the unambiguous identification and quantification of pesticides in complex matrix samples is well known. Triple-quadrupole systems have proven to be useful for this task because of their high specificity in MS-MS mode and their low detection limits. However, working in MS-MS mode makes any MS system blind to other compounds of interest.

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H-SRM provides excellent selectivity for accurate identification and quantification of pesticides in matrix, demonstrating high productivity for effective control at international maximum residue levels (MRLs).

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The nanoLC LIT-TOF approach combines multiple capabilities that improve the ability to characterize complex protein mixtures significantly.

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The CUSTODION™ SPME Syringes are a series of novel solid phase micro extraction syringes that incorporate Supelco Analytical's® (Bellefonte, Pennsylvania) SPME fiber technology. The SPME syringes are fabricated with injection-molded components and the device resembles a ball-point pen. The Supelco Analytical® SPME fiber assembly is housed inside the syringe.

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Escalating costs and increasing demands for helium, coupled with diminishing helium supply, have given rise to the investigation and use of hydrogen as an alternate choice of carrier gas for use in gas chromatography (GC) applications. This application note illustrates that the use of hydrogen as a carrier gas as an alternative to helium in refinery gas applications is not only possible, but also results in improved performance and higher sample throughput.

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Automated solid-phase extraction (SPE) has been used extensively with liquid chromatography–tandem mass spectrometry (LC–MS-MS) to facilitate high-throughput analysis in the pharmaceutical, diagnostic, and forensic toxicology areas. In this work, we demonstrate the use of a systemized approach to SPE method development and LC–MS-MS analysis. This approach provides dramatic savings in analysis time and takes advantage of new innovations in high performance liquid chromatography (HPLC) columns to provide the cleanest extracts for LC–MS injection.

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The nanoLC LIT-TOF approach combines multiple capabilities that improve the ability to characterize complex protein mixtures significantly.

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Surfactants present a real challenge to the analytical chemist as they are a very complex class of chemical compounds.

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Dilute formic acid solutions in methanol were found to decline in acid content with time, the extent of the decline depending upon the initial amount of water present in these solutions. The effect of the formic acid concentration change upon the separation of peptides using high performance liquid chromatography (HPLC) is examined briefly.

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Soft ionization MS using GC–APCI-MS and GC–SMB-MS offers complementary identification power for the characterization of natural products, as illustrated by the identification of alkanes, sterols, long chain alcohols, and derivatized polar compounds in tobacco leaf extracts described here.

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PEGylation, the process by which polyethylene glycol (PEG) chains are attached to protein and peptide drugs is a common practice in the development of biopharmaceuticals to prolong serum half-life and improve pharmacokinetics of a drug. There is increasing demand for chromatographic methods to separate the modified isoforms from the native protein. This application note describes the use of size exclusion and ion exchange chromatography for the characterization of PEGylated lysozyme.