A strategy to determine the elemental composition of organic impurities in commercial preparations was established by combining high-performance liquid chromatography (HPLC)-Fourier transform ion ...cyclotron resonance mass spectrometry (FT-ICR-MS) and fraction collector with direct infusion-FT-ICR-MS (DI-FT-ICR-MS). Under HPLC-FT-ICR-MS mode, all impurities in model sample were chromatographically separated and collected by fraction collector according to their retention time. The accurate mass of each impurity and their candidate formulae under 1 ppm mass tolerance were calculated. Subsequently, theoretical isotopic fine structures (IFSs) of the candidate formulae were generated. Furthermore, the collected fractions were tested and the experimental IFSs of impurities were acquired by DI-FT-ICR-MS mode. Finally, the elemental composition of all impurities was decisively determined by comparing the experimental and theoretical IFSs. Our results demonstrate that the combined strategy is effective in separating impurities and acquiring accurate mass by HPLC-FT-ICR-MS, obtaining the appropriate samples by fraction collection technology for DI-FT-ICR-MS, and acquiring the IFSs of impurities by DI-FT-ICR-MS. It could be concluded that the strategy is an accurate and standard independent approach to determine the elemental composition of organic impurities in commercial preparations.
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•A dual mode-combined FT-ICR-MS was proposed.•The proposed mode was implemented by fraction collection technology.•A strategy to determine elemental composition of organic impurities in commercial preparations was highlighted.•The superiority of the strategy was proved.
The role of organic reagents (flocculant and flotation collectors) and impurity (lubricating oil) in zinc deposition and in product quality is described in this paper. In the presence of a flotation ...collector for zinc and a lubricating oil, characterized by polar amine and non-polar alkyl groups, respectively, by using Fourier transform infrared spectroscopy, an inhibition of the metal nucleation process was observed, which was found to be particularly significant for electrolyte contaminated with the amine-containing compound. The current efficiency (CE) dropped from 93.7% (organic-free solution) to 21.6% in the presence of 50mg·L−1 of collector for zinc, and a negative but smaller effect was observed in the presence of similar amounts of the lubricating oil (90.7%). The addition of a flocculant and a collector for impurities, which contain the polar amide and carboxyl groups in their molecules, respectively, caused minor increases in the nucleation overpotential for zinc deposition and only at relatively high concentrations (100mg·L−1). The addition of these compounds to the solution slightly increased CE. The characterization of the Zn deposits by X-ray diffraction and scanning electron microscopy revealed the formation of pores in deposits obtained from solutions containing the collector for impurities or lubricating oil, and different growth patterns were identified when the flocculant or collector for zinc was added to the solution. The observed trends have been interpreted in terms of the polar character and reactivity of the organic molecules to Zn2+ ion, and adsorption on the cathode surface.
•Amine-containing and non-polar compounds inhibited Zn nucleation.•Amine-containing compound strongly affected current efficiency.•Amide- and amine-containing compounds altered the growth pattern of Zn.•Control and optimization procedures were implemented in the industrial unit.
Key issues related to determining the limit of quantification (LOQ) in practice are considered. Requirements to the value of LOQ and its precision and accuracy are formulated. It is shown that the ...use of a calibration curve for LOQ determination may result in erroneous conclusions for impurity determination methods. Answers to a number of questions relevant to practice are given. The precision of the LOQ value should always be checked if the LOQ is determined from a calibration curve. A typical requirement for LOQ precision is RSD ≤ 5.0%. An RSD ≤ 10% is acceptable in exceptional cases of a very low LOQ concentration. For this, the validation documentation should visually confirm the acceptability of the LOQ value by a chromatogram of a solution of the determined substance with the LOQ concentration.
The undesirable influence of organic impurities in toluene feedstock has been investigated on purity of synthesized Toluene diisocyanate and density of rigid polyurethane foam. Xylene, Ethyl ...cyclopentane, and Methyl benzothiophene were considered to represent three classes of impurities, including aromatics, non-aromatics, and sulfurcompounds, respectively. Statistical design of experiment using response surface methodology was applied for the quantification of the data acquired in pilot scale using impure Toluene model. Results showed that the concentration of 2-Nitro-4-isocyanatotoluene impurity in toluene diisocyanate and density of foam increased by 470% and 42%, respectively, for the examined rate of toluene impurity. Moreover, SEM graphs revealed that cell size and number of closed-cells decreased by ~55%, producing more open cells. Ethyl cyclopentane had the most effect (74.4%) on density among the variables investigated. Subsequently, an activated carbon-based adsorptive process was implemented in laboratory batch mode at 20±1°C to achieve an appropriate level of impurity in industrial-grade toluene. The simultaneous-competitive adsorption of three classes of described impurities was carried out and the highest adsorption capacity of 7.3, 47.4, and 161.5 mg/g was achieved for aromatics, non-aromatics, and sulfur compounds, respectively. The Langmuir isotherm model exhibits satisfactory equilibrium data for non-aromatics and sulfur compounds and for aromatics the Freundlich was the best one.
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► A novel approach for degradation of organic impurities in water is proposed. ► Visible light photocatalysis of TiO
2/Fe
2O
3 for salicylic acid and 4-CP has been studied. ► ...Degradation is realized by absorption, COD and TOC analysis of samples. ► Comparison of all catalyst in terms of efficient degradation of water is studied.
The visible light photochemical and photocatalytic oxidation of salicylic acid and 4-chlorophenol in a photoelectrocatalytic degradation reactor, at room temperature, under sunlight illumination, coated with anatase TiO
2-based Fe
2O
3 and AlFe
2O
3 photocatalysts were investigated. The solar radiation can effectively be applied to accelerate the process using suitable catalyst for economically cleaning the major fresh water sources. The profile of the oxidation of salicylic acid and 4-chlorophenol was followed by monitoring the target compound degradation, the total organic carbon removal and the mineralization process by chemical oxygen demand taking place during the oxidation with simultaneous conversion. Finally, based on the proposed mechanism a kinetic analysis was conducted in order to calculate the respective rate constants.
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In 2018, combined-cycle power installations equipped with heat-recovery steam generators were commissioned at the combined heat and power plant nos. 1, 2, and 3 (CHPP-1, CHPP-2, and CHPP-3) in the ...city of Kazan. The content of organic substances in the blowdown water of clarifiers, in chemically demineralized water, in evaporating plant condensate, in heat-recovery steam generator feed water and blowdown water, and in turbine condensate was investigated. Organic substances in dry form were separated from water samples using the extraction method. The physicochemical properties and structures of the separated organic impurities were determined using an elemental analysis, infrared spectroscopy, high-efficient liquid chromatography, chromatography-mass spectrometry, and nuclear magnetic resonance methods. It was found that the content of total organic carbon (TOC) was higher than its standardized value in the heat-recovery steam generator feed water, slightly higher than the standardized value in the condensate of evaporators, and in compliance with the existing standard requirements in the turbine condensate and chemically demineralized water. Humic substances that are not removed from water during its pretreatment and enter in the heat-recovery steam generator feed water were identified as the main organic component. It is shown that ion exchange is an efficient technology for removing organic impurities from makeup water for the heat-recovery steam generator.
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