02 December 2008
By:Michael McGinley
The use of polyethylene glycols (PEG) is widespread in the pharmaceutical industry as a method to improve the pharmacokinetic qualities of protein and peptide therapeutics. However, such modifications also increase the heterogeneity of protein structures and generate difficulties in purifying such modified species away from the native protein. As PEGylation exhibits the majority of its effect on the size of protein and peptides, gel filtration chromatography is an excellent method for separating proteins by their degree of PEGylation. Efforts were undertaken to evaluate using gel filtration as a method for purifying PEGylated proteins from their unmodified precursors. Several different proteins and PEGylation chemistries were evaluated on BioSep SEC 2000 HPLC columns. Results show that retention of PEGylated species is directly related to the size of the PEG reagent used; proteins modified with larger PEG moieties generally demonstrate greater resolution from unmodified proteins than small modifications...
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02 December 2008
Studies of odd-electron CID behaviours reveal that free radical fragmentation is structure-dependent and is directly correlated with the functional groups that stabilize the newly-formed free radicals.
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02 December 2008
By:Xiaodong Liu, Christopher Pohl
The separation and quantification of drug substances and counterions are two important determinations in the pharmaceutical industry.1 Drug substances and counterions are determined by HPLC (often on reversed-phase columns) and by ion chromatography (IC), respectively. IC is the preferred method for selective and sensitive screening of both cationic and anionic pharmaceutical counterions.2 To increase the analysis throughput, it is desirable that for analysis of drug formulation both drug substance and counterions can be determined within a single run. Naproxen is a non-steroidal anti-inflammatory drug commonly used for treating moderate to severe pain, fever, inflammation and stiffness. Naproxen sodium was approved by the US Food and Drug Administration (FDA) as an over-the-counter drug. No reports were found describing one technique for the simultaneous determinations of both naproxen and the counterion (Na+ ).
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02 December 2008
By:Rui Chen
A simple and fast separation and quantification method for hydrocortisone in pharmaceutical dosage form was achieved by SFC, with good linear response. Furthermore, minimal sample work-up was required for the analysis of the crème sample. The results indicate this approach can be applied as a simple and reliable separation and quantification method in the quality control of bulk and commercial crème/ointment manufacturing processes of hydrocortisone.
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02 December 2008
By:Brian De Borba, Jeff Rohrer
Cefepime is a fourth-generation cephalosporin.1 During preparation and storage, cefepime degrades by release of the N-methylpyrrolidine (NMP) side chain and opening of the beta-lactam ring. An NMP concentration increase will directly affect the potency of the active component of the drug. Therefore, it is critical to determine the amount of NMP in cefepime. The US Pharmacopeia (USP) monograph specifies the limit of NMP to <0.3% in cefepime hydrochloride and <1% in cefepime for injection.2,3 The latter is a dry mixture of cefepime hydrochloride and L-arginine. The current USP method uses cation-exchange chromatography with non-suppressed conductivity detection to determine the limit of NMP in cefepime. There are several disadvantages to this method, such as the ~3–4 h time required per injection, a lack of retention time stability for NMP in standard and sample solutions and a lack of sensitivity. In this paper, we describe an improved method using a hydrophilic, carboxylate-functionalized..
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02 July 2008
By:Jacquelyn Cole, Rui Chen
This application note describes the typical SFC method development for separating a mixture of eight polar, basic pharmaceutical relevant compounds. Compared to RPLC, there is a dramatic improvement in retaining and separating these compounds by SFC. This application exemplifies the orthogonality of SFC to RPLC, especially for separating polar compounds.
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02 July 2008
By:Stephan Bukenmaier, Martin Vollmer, Lukas Trojer, Corinne Emotte
The pressure to save active pharmaceutical ingredients drives the industry to scale-down laboratory processes. This puts the burden on the chemist to choose the appropriate analytical platform that can handle the smallest sample quantities — a challenge that drove the development of HPLC-chip/MS systems for high-sensitivity analyses of small molecules. This article presents data from the technical evaluation of a novel ultra-high capacity HPLC-chip for the quantitative analysis of small molecules using triple quadrupole MS.
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02 July 2008
By:Lee Marotta, William Goodman
The European Pharmacopoeia (EP) method 2.4.24 is the reference method for the determination of residual solvents in pharmaceutical materials. Recently, the United States Pharmacopeia (USP) has implemented a revised chapter 467; this revision has brought the methodology of USP 467 into close alignment with EP 2.4.24. The EP and USP determination of class 1 and class 2 residual solvents is performed with static headspace (HS) sample introduction and gas chromatography (GC) with flame ionization detection (FID); class 3 has flexibility in the technique, however, it is often included in the HS analysis.
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02 March 2008
By:C.E. Blythe, L. Pereira, S. Aspey, D. Milton
Drug discovery/detection commonly focuses on analytes which are present in biological matrices. Direct injection of such samples onto LC and LC–MS systems is problematic as analytes of interest can be "lost" in the concentrated matrix peak, plus instrument and column contamination readily occurs.
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