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Oxidized LDL (oxLDL) has been shown to play a crucial role in the onset and development of cardiovascular disorders. The study of oxLDL, as an initiator of inflammatory cascades, led to the discovery of a variety of oxidized phospholipids (oxPLs) responsible for pro-inflammatory actions. Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) is frequently used by the scientific community as a representative oxPL mixture to study the biological effects of oxidized lipids, due to the high abundance of PAPC in human tissues and the biological activities of oxidized arachidonic acids derivatives. Most studies focusing on oxPAPC effects rely on in-house prepared mixtures of oxidized species obtained by exposing PAPC to air oxidation. Here, we described a multi-laboratory evaluation of the compounds in oxPAPC by LC-MS/MS, focusing on the identification and relative quantification of the lipid peroxidation products (LPPs) formed. PAPC was air-oxidized in four laboratories using the same protocol for 0, 48, and 72 h. It was possible to identify 55 different LPPs with unique elemental composition and characterize different structural isomeric species within these. The study showed good intra-sample reproducibility and similar qualitative patterns of oxidation, as the most abundant LPPs were essentially the same between the four laboratories. However, there were substantial differences in the extent of oxidation, i.e. the amount of LPPs relative to unmodified PAPC, at specific time points. This shows the importance of characterizing air-oxidized PAPC preparations before using them for testing biological effects of oxidized lipids, and may explain some variability of effects reported in the literature., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities., (Copyright © 2012 Elsevier B.V. All rights reserved.)

An international collaborative study was carried out for the establishment of replacement batches for the European Pharmacopoeia (Ph. Eur.) Somatropin Chemical Reference Substance (CRS) batch 2. The study was organised within the framework of the Biological Standardisation Programme (BSP) of the Council of Europe and the European Commission. Seventeen laboratories from Europe, North America, South America and Australia took part in the collaborative study. The study aimed at calibrating the somatropin content of 2 candidate preparations and demonstrating their suitability to serve as a reference substance in the tests for identification, for related proteins, for dimers and related substances of higher molecular mass (HMM), for charged variants distribution and for the assay of somatropin, as prescribed by the current Ph. Eur. monographs 0950 Somatropin bulk solution, 0951 Somatropin and 0952 Somatropin for injection. Based on the results summarised herein the Ph. Eur. Commission adopted in January 2012 candidate preparation b (cCRS-b, Sample D) as somatropin CRS batch 3 with an assigned content of 3.86 mg of somatropin monomer per vial, and candidate preparation a (cCRS-a, Sample C) as somatropin CRS batch 4 with an assigned content of 2.59 mg of somatropin monomer per vial.