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Study on safe disposal of cephalosporins based on kinetic pyrolysis mechanism

Fan Jiangxue, Zhang Meng, Hou Xiaofei, Wang Fang, Bai Mengyuan, Jiao Ruoxi, Yang Zhongyu, Duan Erhong, Cheng Fengfei, Zhou Wen

Polish Journal of Chemical Technology

2023

Vol. 25, nr 4

52--60

Based on the global goals for cleaner production and sustainable development, the pyrolysis behavior of cephalosporin residues was studied by TG-MS method. The influence of full temperature window on the safe disposal of residues was analyzed based on the “3-2-2” and “1+1” of thermal analysis kinetics, and the gas by-products of thermal degradation were monitored. Results showed that the pyrolysis of distillation residues were divided into low and high-temperature zones, including six stages. Maximum error rate (8.55%) by multiple scan rate was presented based on “3-2-2” pattern and maximum total fluctuation (33.7) by single scan rate was presented based on “1+1” pattern, which implied that the comprehensive multi-level comparison method was very reliable. The E value “E” of six stages showed an increasing trend ranging 166.8 to 872.8 kJ/mol. LgA(mean) was 27.28. Most mechanism function of stage 1, 2 were Z-L-T equation (3D), stage 3, 4, 6 were Avrami-Erofeev equation (AE3, AE4, AE2/3) and stage 5 was Reaction Order (O2). In addition, various small molecular micromolecule substances were detected such as C2H4O, C2H6, NH3, CH4, CO2 under full temperature windows and a possible pyrolysis path of residues was provided.

Simultaneously measure the concentrations of busulfan and phenytoin in human plasma using an HPLC-MS/MS method: Application to the TDM for children underwent hematological stem cell transplantation

Sun Ning, Li Zhuo, Zhang Meng, He Huan, Zhao Libo, Mei Dong, Zhu Guanghua, Wang Xiaoling

Acta Chromatographica

2023

Vol. 35, no. 4

302--309

In this work, a simple and rapid high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed and validated to carry out the simultaneous measurement of busulfan (BU) and phenytoin (PHT) in the plasma of children. In this method, plasma sample could be prepared by one-step protein precipitation using 1 mL of methanol/water (1:1, v/v). After centrifugation (14,500 rpm, 5 min, 4 °C), 10 μL of the supernatant was injected into a Hypersil Gold C18 column (150 × 2.1 mm, 5 μm, Thermo Fisher Scientific) for separation by gradient elution. Quantification was carried out using multiple reactions monitoring (MRM) under positive scan mode. In the method verification, the calibration curves of BU and PHT showed satisfactory linearity (r > 0.99) at the concentration ranging from 0.02 to 20 μg mL⁻¹. The accuracy and precision were tested at four concentration levels (including the LLOQ level) with the relative error (RE) ranging from −0.80% to 11.45% and coefficient of variation (CV) between 0.93% and 7.74%. There was no pronounced matrix effect to interfere with the quantitative analysis. Compared to determine BU and PHT using two individual methods, less pre-treatment process, labor and blood sample volume are required in this proposed method. Finally, this method was successfully applied to the therapeutic drug monitoring of BU and PHT for children underwent hematological stem cell transplantation.

“Noise” in climatologically driven ocean models with different grid resolution

Tang Shengquan, von Storch Hans, Chen Xueen, Zhang Meng

Oceanologia

2019

No. 61 (3)

300--307

The internally generated variability in the climate system, which is unrelated to any external factors, can be conceptualized as “noise”. This noise is a constitutive element of high-dimensional nonlinear models of such systems. In a three-layer nested simulation, which is forced by climatological (periodic) atmospheric forcing and includes an (almost) global model, a West-Pacific model, and South China Sea (SCS) model, we demonstrate that such “noise” builds also ocean models. They generate variability by themselves without an external forcing. The “noise” generation intensifies with higher resolution, which favors macroturbulence.