ABSTRACT A gas chromatography‐mass spectrometry method was developed and validated for the quantitative determination of 26 polycyclic aromatic hydrocarbons (PAHs) in textile, polymer, and rubber consumer articles. PAHs were extracted by ultrasound‐assisted extraction (UAE) with n ‐hexane (60 min, 60°C) and cleaned up on silica gel. Separation was achieved on a DB‐5MS column (30 m × 0.25 mm × 0.25 µm) with electron ionization (70 eV) and selected ion monitoring. The method was linear from 0.04 to 5.0 mg L − 1 (). Intra‐day and inter‐day relative standard deviations were 4.92%–5.66% and 9.00%–11.50%, respectively. Recoveries were 88.5%–95.1%. Limits of detection and quantification were 0.001 and 0.01 mg L − 1 , respectively. The method was applied to real consumer articles. Compared with previously reported UAE methods, this study provides a validated application for the simultaneous analysis of selected PAHs in complex consumer‐article matrices.
ABSTRACT This study presents a comprehensive equivalency evaluation of a gas‐assisted dynamic accelerated solvent extraction (GA‐dASE) workflow, as an alternative to some of the steps described within Method 1633A for the extraction and analysis of per‐ and polyfluorinated alkyl substances in soils and sediments. The GA‐dASE workflow automates the extraction step, otherwise labor‐intensive in Method 1633A. Except for the extraction step, both workflows employ identical solvents, cleanup chemistry, and liquid chromatography–tandem mass spectrometry procedures for 40 per‐ and poly‐fluorinated alkyl substances (PFAS). Comparative analysis across Ottawa sand, soils contaminated with PFAS, and standard reference materials demonstrated strong agreement between the two methods. Native and spike recoveries for most target analytes fell within ±30% of each other, and isotope‐dilution internal standard recoveries generally met Method 1633A acceptance criteria. Notable discrepancies were observed for three compounds when extract pH was not adjusted in the range of 6–7 prior to extract cleanup; however, recoveries met the state‐of‐the‐art workflow performance criteria either when pH was adjusted or by using more appropriate labeled reference compounds. Sediment analysis demonstrated that GA‐dASE recoveries closely matched certified reference material values, with perfluorooctanesulfonic acid concentrations agreeing within 97%. Overall, the GA‐dASE workflow provided a streamlined, automated extraction alternative that maintains analytical accuracy and precision while improving productivity and reducing manual labor.
ABSTRACT Nitrosamine drug substance‐related impurities have attracted increased regulatory attention because their occurrence at trace concentrations may affect pharmaceutical quality. Dabigatran Etexilate Mesylate contains nitrogen‐containing functional groups that may be susceptible to nitrosation under certain conditions, resulting in the formation of N‐nitroso‐dabigatran etexilate. Therefore, a sensitive liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) procedure was developed and validated for determination of N‐nitroso‐dabigatran etexilate in Dabigatran Etexilate Mesylate drug substance. Chromatographic separation was achieved on a Shim‐pack Scepter C18 column (150 × 4.6 mm, 3.0 µm) using gradient elution with 20 mM ammonium formate buffer (pH ∼5.0) and acetonitrile: water (90:10, v/v) as mobile phases. Quantitative analysis was performed in positive electrospray ionization mode using multiple reaction monitoring with the transition m/z 658.10 → 365.10. The method was evaluated for specificity, linearity, precision (including intermediate precision), accuracy, and sensitivity. A linear response was obtained across the studied concentration range with a correlation coefficient ( r 2 ) of 0.9979. The limit of detection and limit of quantification were established at 0.0173 and 0.0525 ppm, respectively. Accuracy studies demonstrated satisfactory recovery across the evaluated concentration levels, while precision results confirmed reproducible analytical performance. The developed LC‐MS/MS method provides a sensitive approach for the determination of N‐nitroso‐dabigatran etexilate in Dabigatran Etexilate Mesylate drug substance.
ABSTRACT As semiconductor manufacturing advances, ultra‐high‐purity hydrogen quality has become important for process reproducibility, equipment reliability, and contamination control. The emerging introduction of liquefied hydrogen alongside conventional gaseous hydrogen requires analytical criteria that account for feedstock‐dependent behavior after purification. An operating semiconductor hydrogen supply system was used as a field platform to compare argon, nitrogen, carbon monoxide, carbon dioxide, methane, and non‐methane hydrocarbons after getter and cryogenic purification using multi‐channel gas chromatography with plasma emission detection. Raw liquefied hydrogen showed lower impurity levels and narrower variability than raw gaseous hydrogen in the investigated deliveries, whereas gaseous hydrogen showed greater variation, particularly for argon, nitrogen, and methane. At the final supply line, most target impurities in liquefied‐hydrogen‐derived product were below the method detection limits, whereas residual signals in gaseous‐hydrogen‐derived product reflected both feedstock characteristics and purification pathway. The main contribution is a process‐resolved interpretation framework linking raw‐feed measurements, individual purifier outlets, and final endpoint signals. These results indicate that interpretation criteria derived from gaseous‐hydrogen operation may require verification before application to liquefied‐hydrogen‐based systems, especially when vaporization history and purification pathway differ.
ABSTRACT Iguratimod (IGU) is a novel cytokine inhibitor clinically approved for the treatment of rheumatoid arthritis. The structural features of the drug reveal several potential labile sites, including the sulphonamide group, formamide moiety and aryl–aryl ether linkage, all of which are susceptible to hydrolytic cleavage. The current study is undertaken with the objectives of developing a stability‐indicating high‐performance liquid chromatography (HPLC) assay for simultaneous quantification of IGU and its degradation products (DPs), characterisation and cytotoxicity assessment of the DPs. The present study investigates the forced degradation behaviour of IGU under various stress conditions. The DPs were separated and characterised by high‐resolution mass spectrometry and nuclear magnetic resonance spectroscopy. A possible degradation mechanism was proposed. A selective stability‐indicating HPLC assay was developed for the quantification of the drug and its DPs. In vitro cytotoxicity of the DP was assessed using the MTT cell viability and DNA ladder assays, whilst DNA damage markers were monitored by western blotting. The drug was susceptible to degradation under acidic and basic conditions, yielding two DPs. The acid DP exhibited a distinct capacity to compromise genomic stability. These results suggest that the conversion of IGU to its DP under acidic conditions confers significant DNA‐damaging properties. Given that the acid degradant is also a major metabolite of IGU, a thorough toxicological evaluation is warranted. Owing to the facile formation of the acid DP, the developed method can be applied to monitor IGU and its degradation during processing with acidic excipients and dissolution testing samples in an acidic medium. The method can also be modified to monitor IGU and acid degradants from plasma samples.
