Separation and Analysis of Trace Degradants in a Pharmaceutical Formulation Using On-Line Capillary Isotachophoresis-NMR

Off-line coupling of capillary isotachophoresis separation to IRMPD spectroscopy for glycosaminoglycans analysis: Application to the chondroitin sulfate disaccharides model solutes

Glycans analysis is challenging due to their immense structural diversity. Isotachophoresis was investigated as separation method for the purification of isobaric sulfated disaccharides prior to their characterization by Mass Spectrometry (MS) and tunable IR multiple photon dissociation (IRMPD). This proof of feasibility study was applied to the separation and characterization of chondroitin sulfate (CS) disaccharides. ITP separation conditions were optimized. Separation starts using a 2.5 mM chloride ions and 10 mM glycine at pH 3.2 solution as leading electrolyte and a terminating electrolyte composed of formic acid 2.5 mM and glycine 10 mM at pH 3.5. The CS disaccharides sample were prepared in the terminating electrolyte. The length of injection was also investigated in order to create longer plateau-like bands of pure solutes. This strategy was helpful for collecting fraction at such microseparation scale. Indeed, capillary ITP affords the injection of few tens of nanoliter of sample. Fractionation of the CS disaccharides mixture in isolated ITP bands and collection of solutes were successfully done using a HPC coated fused silica capillary of 1m-length and 75 µm of internal diameter. Collected fractions in a final of volume 10 µL were analyzed by CZE, tandem MS and IRMPD spectroscopy. The purity of each fraction is higher than 90% and is well-adapted to IRMPD characterization.

Separation and determination of impurities in paracetamol, codeine and pitophenone in the presence of fenpiverinium in combined suppository dosage form

A new HPLC method for separation and determination of impurities in paracetamol, codeine phosphate hemihydrate and pitophenone hydrochloride in the presence of fenpiverinium bromide in combined suppository dosage form was developed and validated. The separation of paracetamol and its impurities 4-aminophenol, 4-nitrophenol, 4-chloracetanilid; codeine and its impurities methylcodeine, morphine, codeine dimer and 10-hydroxycodeine; pitophenone and its impurities 2-[4-[2-(1-piperidinyl)ethoxy]benzoyl] benzoic acid, 2-[4-[2-(1-piperidinyl)ethoxy]benzoyl]benzoic acid 2-(1-piperidinyl)-ethyl ester, methyl ester of 2-(4-hydroxybenzoyl) benzoic acid and fenpiverinium was achieved by using ion-pair reversed phase liquid chromatography with UV detection. Validation parameters such as the precision, accuracy, linearity, limit of detection (LOD), limit of quantification (LOQ) and robustness were verified for all the mentioned impurities of codeine phosphate hemihydrate and 4-aminophenol and 2-[4-[2-(1-piperidinyl)ethoxy]benzoyl] benzoic acid as the main degradation products of paracetamol and pitophenone hydrochloride, respectively. The described method was found to be useful for analysis of the stability samples and therefore suitable for routine purity testing of the drug product.

Determination of detoxification to Daphnia magna of four pharmaceuticals and seven surfactants by activated sludge

Pharmaceuticals are bioactive compounds generally resistant to biodegradation, which can make them problematic when they are released into nature. The use pattern for pharmaceuticals means that they are discharged into water via sewage treatment plants. Also surfactants are discharged through sewage treatment plants, primarily due to their use in detergents and shampoos and other cleaners. In this study the acute toxicity to Daphnia magna of four pharmaceuticals (ciprofloxacin, ibuprofen, paracetamol and zinc pyrithione) and seven surfactants (C8 alkyl glucoside, C6 alkyl glucoside, sodium caprylimidiopropionate, tallow-trimethyl-ammonium chloride, potassium decylphosphate, propylheptanol ethoxylate and alkylmonoethanolamide ethoxylate) was determined. Abiotic (without activated sludge bacteria) and biotic (with activated sludge bacteria) detoxification was also determined. The 24-h EC50s ranged from 2 μg L(-1) for the most toxic substance (zinc pyrithione) to 2 g L(-1) for the least toxic compound (C6 alkyl glucoside). Detoxification rates determined as the ratio between initial EC50 and EC50 after 1 week in water with activated sludge bacteria ranged from 0.4 (paracetamol) to 13 (zinc pyrithione). For most of these chemicals detoxification rate decreased after 1 week, but for one (alkylmonoethanolamide ethoxylate) it increased from about 2 to 30 times after 2 weeks. Many of these chemicals were "detoxified" also abiotically at about the same rate as biotically. Further studies are needed to determine the degradation products that were precipitated (aggregated) for some of the tested chemicals. Altogether, this study has shown that there are large differences in toxicity among chemicals entering sewage treatment plants, but also that the detoxification of them can differ. Therefore, the detoxification should receive more attention in the hazard and risk assessment of chemicals entering sewage treatment plants.

Trace analysis in complex mixtures using a high-component filtering strategy with liquid chromatography-mass spectrometry

Trace constituents are widely present in complex mixtures, and trace analysis is challenging because of the unpredictable matrix. In this work, a high-component filtering strategy was developed for improved analysis of trace constituents in complex sample by liquid chromatography-mass spectrometry (LC-MS). Using a specifically designed chromatographic apparatus, the high-abundant fractions were filtered prior to LC-MS analysis. The samples complexity was reduced and the sample-loading amount for the rest low-level fractions can be considerably increased. The application of this approach was illustrated with an analytically challenging sample, a traditional Chinese herbal medicine named Compound Danshen Sample. We observed that the loss rate for 12 analytes during the filtering procedure ranged from 6.54 to 26.11%, but showed a stable repeatability with RSD<3.79%. The proposed filtering method with quadrupole time-of-flight mass spectrometritry (Q-TOF/MS) enhanced the detection capacity, offering a comprehensive characterization of 133 compounds in Compound Danshen Samples. The quantification sensitivity was also improved in trace analysis, allowing six low compounds that cannot be quantified by the traditional methods to be tested by the filtering method. It can be predicted that the qualitative and quantitative trace analysis will be greatly improved when the loading samples is increased resulting from the filtration of high-level targets. The proposed strategy is promising to monitor trace constituents in diverse complex mixtures in the analytical field of pharmaceutics, metabonomics and environments.

Heparin characterization: challenges and solutions

Although heparin is an important and widely prescribed pharmaceutical anticoagulant, its high degree of sequence microheterogeneity and size polydispersity make molecular-level characterization challenging. Unlike nucleic acids and proteins that are biosynthesized through template-driven assembly processes, heparin and the related glycosaminoglycan heparan sulfate are actively remodeled during biosynthesis through a series of enzymatic reactions that lead to variable levels of O- and N-sulfonation and uronic acid epimers. As summarized in this review, heparin sequence information is determined through a bottom-up approach that relies on depolymerization reactions, size- and charge-based separations, and sensitive mass spectrometric and nuclear magnetic resonance experiments to determine the structural identity of component oligosaccharides. The structure-elucidation process, along with its challenges and opportunities for future analytical improvements, is reviewed and illustrated for a heparin-derived hexasaccharide.

Recent developments in instrumentation for capillary electrophoresis and microchip-capillary electrophoresis

Over the last years, there has been an explosion in the number of developments and applications of CE and microchip-CE. In part, this growth has been the direct consequence of recent developments in instrumentation associated with CE. This review, which is focused on the contributions published in the last 5 years, is intended to complement the articles presented in this special issue dedicated to instrumentation and to provide an overview of the general trends and some of the most remarkable developments published in the areas of high-voltage power supplies, detectors, auxiliary components, and compact systems. It also includes a few examples of alternative uses of and modifications to traditional CE instruments.

Development of a membrane-less dynamic field gradient focusing device for the separation of low-molecular-weight molecules

Dynamic field gradient focusing uses an electric field gradient generated by controlling the voltage profile of an electrode array to separate and concentrate charged analytes according to their individual electrophoretic mobilities. This study describes a new instrument in which the electrodes have been placed within the separation channel. The major challenge faced with this device is that when applied voltages to the electrodes are larger than the redox potential of water, electrolysis will occur, producing hydrogen ions (H+) plus oxygen gas on the anodes and hydroxide (OH(-)) plus hydrogen gas on the cathodes. The resulting gas bubbles and pH excursions can cause problems with system performance and reproducibility. An on-column, degassing system that can remove gas bubbles "on-the-fly" is described. In addition, the use of a high capacity, low-conductivity buffer to address the problem of the pH shift that occurs due to the production of H+ on the anodes is illustrated. Finally, the successful separation of three, low-molecular-weight dyes (amaranth, bromophenol blue and methyl red) is described.