Special Issues-05-01-2017

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Analysis of Organic Compounds in Water Using Unique Concentration–Injection Techniques for Portable GC–MS

May 1st 2017
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A simple method for extraction and concentration of trace organic compounds found in water for gas chromatography-mass spectrometry (GC-MS) analysis was developed. The method used 25 and 45 mL glass vials with a 5-10 µm thick polymer coatings for extraction of analytes from 20 and 40 mL water samples, respectively. Analytes were subsequently transferred from the polymer coating into an organic solvent, which was reduced in volume to 200-400 µL for analysis. A 10-20 µL sample from the vial was transferred to a tiny coiled stainless steel wire filament using a micro-syringe, or by dipping the coil into the sample. After air evaporation of the solvent, the coil was inserted into the heated injection port of a portable GC-MS system where the analytes were desorbed. Injection using the coiled wire filament eliminated sample discrimination of high boiling point compounds, and minimized system contamination caused by sample matrix residues. The GC-MS contained a new resistively heated column bundle that allowed elution of low-volatility compounds in less than 4 min. Analyses of organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyl congeners, pyrethroid insecticides, phthalate esters, and n-alkanes in water and wastewater samples were accomplished for low ppb concentrations in less than 10 min total analysis time.


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Testing the Limits of Ion Mobility Mass Spectrometry to Compare a Nonbiological Complex Drug Product and Purported Generics—A Case Study with Copaxone

May 1st 2017
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Ion mobility mass spectrometry (IMMS) is a two-dimensional technique that allows separation of ionized molecules based on molecular size, shape, and mass‑to‑charge ratio (m/z). It has rapidly become a valuable application for analyzing isomeric compounds in a complex matrix (e.g., proteomic and lipidomic samples) or complex mixtures of structurally related and isobaric analytes (e.g., oil samples or polymer blends). IMMS was investigated as a possible technique to compare purported generic products with Copaxone®, a drug for treating relapsing‑remitting multiple sclerosis, which contains a very complex mixture of synthetic peptides. The analysis was performed on 15 randomly chosen batches of Copaxone® and 5 batches of purported generics that are marketed drugs in their country of origin. All samples were compared to a reference batch of Copaxone® (P53961) using Waters HDMS Compare software. The analysis produced heat maps that highlighted significant intensity differences in peptides at various m/z and drift times. A quantitative assessment of these heat maps was also performed by summing all the pixel values to produce a total pixel value (TPV). While the average TPV for the Copaxone® batches was 510811, the TPVs of the purported generics were 8-13 fold higher (2301682 to 4276572).