Chromatographia最新文献

The European Union RoHS Directive restricts the presence of phthalate esters, polybrominated diphenyl ethers (PBDEs), and polybrominated biphenyls (PBBs) in electrotechnical products. The international standard IEC 62321-3-3 describes a method of screening for these chemicals using gas chromatography–mass spectrometry with a pyrolyzer/thermal desorption accessory (Py/TD-GC/MS). Although the IEC 62321-3-3 method is effective at determining levels of these restricted compounds in polymers, applying this method in RoHS testing poses two issues: it requires the preparation of a relative response factor (RRF) database from expensive standard mixed solutions, and it has a long analysis time (30 min). In a previous report, we described a method based on a “ready-to-use” RRF database that eliminates preparation of the RRF database. In this report, we resolved the remaining issue by improving the analytical throughput of the IEC 62321-3-3 method. By optimizing the Py/TD and GC/MS conditions, we almost halved the analysis time to 16 min while maintaining analytical accuracy. These optimized conditions were then combined with the above-mentioned “ready-to-use” RRF database to create a new method that resolves both of the issues with the IEC 62321-3-3 method. This new method demonstrated good sensitivity with a lower limit of detection of under 30 mg/kg for each target compound. We also assessed the analytical accuracy of this new method by analyzing various standard polymer materials on two different analytical instruments. On both instruments, the mean recovery rate was within 100 ± 30% for seven phthalate esters and for combined concentrations of PBDE and PBB congeners, which demonstrated that the quantitative accuracy of the new method is sufficient for RoHS testing. The new method resolves the issues with the IEC 62321-3-3 method and offers rapid, simple, and reliable screening that can be adopted for RoHS testing.

This study presents the certification of spinach and kimchi cabbage certified reference materials (CRMs), (KRISS CRM 108-05-010 and 108-05-011), for 5-Me-THF. The fresh spinach and kimchi cabbage process involved washing, freeze-drying, pulverizing, sieving, V-mixing, and bottling in 10-g portions. The 5-Me-THF in the CRMs was then extracted and analyzed using a tri-enzyme method and isotope dilution ultra-performance liquid chromatography/tandem mass spectrometry. The method validation demonstrated that the method was both repeatable and reproducible, with the recovery ranging from 96.5 to 107.2%. The stability monitoring was performed for 7 days at room temperature, 1 month at − 20 °C, and 13 months at − 70 °C, confirming the stability of the CRMs under most conditions. The certified values were (16.93 ± 0.73) mg/kg and (11.66 ± 0.25) mg/kg for spinach and kimchi cabbage CRMs, respectively. The homogeneity of the CRMs was 1.85% and 0.91% for spinach and cabbage CRMs, respectively. Additional long-term stability assessments were performed, and this suggested that the CRMs will remain valid for at least another 48 months at − 70 °C.

Cultivated Arachis hypogaea L., is commonly known as peanut. Its seed coat, also referred to as a shell, plays a critical role in safeguarding the seeds and facilitating the transportation of diverse metabolites. In the current work, an examination of metabolite profiling was executed utilizing UPLC-ESI–MS/MS in the seed coat (SeC), seed skin (SeS), and seed pulp (SeP) of four distinct peanut varieties of different geographical locations in India. The method was also validated according to ICH guidelines. A linear detector response was observed within a concentration range of 0.019–20.0 ng/mL, R² = 0.999. The limit of detection (LOD) and quantification (LOQ) of the targeted compounds were found to be within the range of 0.075–0.426 and 0.227–1.292 ng/mL, respectively. The intra-day and inter-day precision demonstrated relative standard deviation %RSD < 2%. The results of Principal Component Analysis (PCA) have demonstrated that the differentiation between varieties of peanut is attributable to the existence of luteolin and rutin having a greater impact on the identification of varieties.

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Iodine value is an essential parameter for assessing the composition and quality of oils. A commonly used method for iodine value determination is the Wijs method. Recently, the HPLC method for assay of iodine monochloride via iodination of 2-chloroaniline with iodine monochloride has been reported. This study presents an approach for iodine value determination by HPLC via quantification of the unreacted iodine monochloride after reaction with oil samples, similar to the back titration approach in the Wijs method. Chromatographic conditions consist of gradient elution using water and acetonitrile on the C18 column with a detection wavelength of 304 nm. Oleic acid, with a known iodine value (83–103 gI/100 g), was used as a method development and validation reference compound. The method was validated as per International Conference on Harmonization guidelines and was accurate (98–102%), robust, and linear (r² = 0.999) for oleic acid ranging from 5 to 20 mg. The repeatability and intermediate precision were within 1%. The validated method was applied for the iodine value determination of 10 cold-pressed oils. Thus, an HPLC method is developed, which offers minimal sample requirements, high accuracy, less manual intervention, and precision for the iodine value determination of oils.

The study aims at developing and validating a RP-HPLC (reverse phase high-performance liquid chromatography) method for the standardization of Maytenus emarginata (Willd.) Ding Hou extract by selecting Lupeol, β-Amyrin, and Stigmasterol as marker compounds. The developed analytical method used a Phenomenex C₈ column (250 × 4.6 mm; 5 μm) and the mobile phase of acetonitrile and HPLC (high-performance liquid chromatography) grade water (85:15) in isocratic elution at the flow rate 2.0 ml/min. Further, the compounds were traced at 202 nm with the run time of 9 min. The calibration curves presented good linear regression (R² > 0.999) in the tested concentrations. The developed method represented good repeatability for the estimation of the three compounds, namely Lupeol (0.009%), β-Amyrin (0.010%), and Stigmasterol (0.011%) in the samples having the RSD (relative standard deviation) of < 2% respectively. For all analytes, percentage recovery surpassed 90%. The validated RP-HPLC Method was utilized to quantify Lupeol, β-Amyrin, and Stigmasterol from methanolic extract of aerial parts of Maytenus emarginata (Willd.) Ding Hou.

We developed a rapid and user-friendly method to detect bioactive terpenes in different Cannabis flower samples based on gas chromatography-mass spectrometry (GC–MS). We validated the method in terms of linearity, repeatability, detection and quantitation limits and recovery. We quantitatively determine the amounts of six terpenes in seven Cannabis samples.

Preservatives can be used in natural and organic cosmetics to prevent quality deterioration during distribution and use, but the ingredients permitted are limited in the Republic of Korea. A method of simultaneous analysis was developed to monitor natural and organic cosmetics distributed online for the presence of 15 illegally used preservatives. Considering the complexities of the cosmetic matrices, an optimized sample preparation method is essential. Therefore, we developed the optimal purification method by comparing three preparation methods: QuEChERS, high-speed centrifugation, and solid-phase extraction (SPE). The SPE method, which exhibited the most favorable results in matrix reduction, was employed. To establish the SPE-ultra-high-performance liquid chromatography-diode array detection method, factors such as the mobile phase and column were optimized. The optimal separation of the 15 preservatives was observed under the following conditions: mobile phase A comprising 0.1% phosphoric acid in water with 0.5 mM sodium hexanesulfonate and a C₈ column (1.7 μm, 2.1 × 150 mm) as the stationary phase. The linear correlation coefficients were > 0.9998, and the limits of detection and quantitation ranged from 0.05 to 0.67 and 0.15 to 2.02 μg mL⁻¹, respectively. Using the established analytical method, illegally used preservatives were detected in products claimed to be natural and organic cosmetics sold on the market, and these findings were subsequently verified using liquid chromatography-tandem mass spectrometry. Six out of 47 samples contained phenoxyethanol and parabens. Therefore, this method will help manage the addition of illegal preservatives to natural and organic cosmetics.

Afoxolaner, a novel insecticidal and acaricidal drug substance from the isoxazoline family, is efficacious against various parasites among companion animals. In general, afoxolaner drug substance is quite stable in formulated and unformulated forms, when stored under International Council for Harmonization (ICH) guideline storage conditions. Exhaustive stress degradation studies of afoxolaner drug substance were conducted under various stress conditions to obtain an in-depth understanding of potential degradation pathways, including formation mechanisms of potential degradations products of this compound. Stressed degradation studies were carried out in the presence of various type/class of acid, base, and oxidation agents, including thermal and light irradiation. An investigational ultra-high-performance liquid chromatography (UHPLC) method was developed for the purpose of this study. The UHPLC method provided adequate separation of afoxolaner and its major degradation products that were generated in the exhaustively stressed samples. A total of five major degradation products (DPs) were formed under acidic, basic, photolytic, and oxidative stress conditions. Various analytical techniques such as high-resolution tandem mass spectrometry (HRMS/MS–MS) and nuclear magnetic resonance (NMR) were used to identify and propose the most probable chemical structures of the key unknown degradation products in the stressed degradation samples. Adequate amounts of two DPs, namely DP-1 and DP-3, were isolated and purified by semi-preparative high-performance liquid chromatography (HPLC) methods. Subsequently, these two DPs were examined in detail using both 1D and 2D NMR spectroscopy. From the proposed chemical structures of identified degradation products, most probable degradation pathways and formation mechanism is proposed.

In this work, in order to investigate retention and selectivity mechanism on hydrophilic interaction liquid chromatography (HILIC), one of the most common hydrophilic stationary phases, polyethylene glycols (PEG) of different molecular weights (200, 400, 800 and 2000 Dalton) were covalently bonded to porous silica spheres via isocyanate silane. The PEG stationary phase was then characterized in detail by infrared spectroscopy, scanning electron microscope, nitrogen adsorption–desorption isotherms, and thermogravimetric analysis, and the PEG bonding density was determined as 2.7, 2.3, 1.4, 0.26 μmol m⁻², respectively. The HILIC retention mechanism was systematically conducted by quantitative evaluation of the effect of partitioning and adsorption, hydrogen bonding and hydrophilicity, and temperature on the retention of nucleosides and nucleobases. It was found that the retention was highly relevant on the partitioning, hydrogen bonding between solutes and PEG, and strong electrostatic interactions (attractive/repulsive) between solutes and silica. To further assess the separation performance, three kinds of polar compounds (nucleosides and nucleobases, organic acids and β-blockers) were chosen as probe compounds. Among the four PEG stationary phases, it was found that the higher PEG ligand density generally resulted into more superior separation performance to these polar compounds, that is, PEG200-bonded stationary phase with highest ligand density of 2.7 μmol m⁻² generated better resolution. Furthermore, higher ligand bonding mass would increase the retention of nucleosides, nucleobases and organic acids except β-blockers. Generally, the HILIC stationary phase with continuous and dense hydrophilic layer is beneficial to the separation of polar analytes.

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