KINETIC STUDY ON THE EXTRACTION OF PALLADIUM(Ⅱ) WITH BIS(2-ETHYLHEXYL)SULFIDE

The effects of concentration, temperature, stirring rate and specific interfacial area on the extraction of Pd (Ⅱ) with bis(2--ethylhexyl) sulfide (DEHS) were studied by the use of a constant interracial area cell. The results support an interracial chemical reaction regime.

STUDY ON THE SEPARATION AND EXTRACTION MECHANISM OF RARE EARTH ELEMENTS BY MEANS OF REVERSED-PHASE PAPER CHROMATOGRAPHY

Reversed-phase paper chromatography technique is used for study on the extraction mechanism and sep- aration of rare earth elements.As the stationary phase,chromatographic paper strips are impregnated with a solution of monomyristyl phosphoric acid (MPA) in chloroform.Mineral acids are used as developers. The effect of concentration of acids and/or salts upon R_f has been investigated.According to the re- sults of R_f values for a given rare earth element in various acids,the order of extraction ability is HCl>HNO_3>H_2SO_4.A tetrad effect is clearly observed.for the R_f value of rare earth elements.The effects of other parameters on the R_f value,such as the quantities of extractant retained by the paper and the temperature are also examined.Based on the determination of the molar ratio of MPA to rare earth elements and the number of H^+ ions released in extraction reaction,a reasonable mechanism is proposed.The mutual separation of heavy rare earth elements will be better than that of the light rare earth group because of the larger separation coefficient of the former.A mixture of Ho-Er-Tm-Lu is successfully separated by the present method.

Liquid chromatography tandem mass spectrometry method for the estimation of lamotrigine in human plasma:Application to a pharmacokinetic study

A reliable,selective and sensitive liquid chromatography tandem mass spectrometry method was developed and validated for the quantification of lamotrigine in human plasma using lamotrigine13C3,d3 as an internal standard.Analyte and internal standard were extracted from human plasma by solid-phase extraction and detected in positive ion mode by tandem mass spectrometry with electrospray ionization（ESI） interface.Chromatographic separation was performed on a Chromolith s SpeedROD;RP-18e column（50-4.6 mm i.d.） using acetonitrile：570.1 mM ammonium formate solution（90：10,v/v） as the mobile phase at a flow rate of 0.500 mL/min.The calibration curves were linear over the range of 5.02-1226.47 ng/mL with the lower limit of quantitation validated at 5.02 ng/mL.The analytes were found stable in human plasma through three freeze（-20℃）-thaw（ice-cold water bath） cycles and under storage on bench-top in ice-cold water bath for at least 6.8 h,and also in the mobile phase at 10℃ for at least 57h.The method has shown good reproducibility,as the intra-and inter-day precisions were within 3.0%,while the accuracies were within 76.0% of nominal values.The validated LC-MS/MS method was applied for the evaluation of pharmacokinetic and bioequivalence parameters of lamotrigine after an oral administration of 50mg lamotrigine tablet to thirty-two healthy adult male volunteers.

SPE-UPLC-MS/MS assay for determination of letrozole in human plasma and its application to bioequivalence study in healthy postmenopausal Indian women

A rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS） method is described for determination of letrozole in human plasma.Following solid phase extraction（SPE） of letrozole and letrozole-d4 on Orochem DVB-LP cartridges,chromatography was performed on Acquity UPLC BEH C_（18）（50 mm × 2.1 mm.1.7 μm） column using methanol-0.1%formic acid in water（85：15,v/v） as the mobile phase.Detection was carried out on a triple quadrupole mass spectrometer with an electrospray source,operated under positive ionization mode.Quantitation of letrozole and letrozole-d4 was done using multiple reaction monitoring（MRM） following the transitions at m/z286.2→217.0 and m/z 290.2→221.0,respectively.The calibration plots were linear through the concentration range of 0.10-100 ng/mL（r^2 ≥ 0.9990） using 100 μL human plasma.The extraction recovery of letrozole ranged from 94.3%to 96.2%and the intra-batch and inter-batch precision was ≤ 5.2%.The method was successfully applied to a bioequivalence study of letrozole after oral administration of2.5 mg tablet formulation to 16 healthy postmenopausal Indian women.The assay reproducibility was also established through incurred sample reanalysis（ISR） of 74 subject samples.

A Study on the Dynamic Adjustment of Pressure Relief Gas Drainage Drilling in Mined-Out Areas

With the development of coal mine equipment mechanization, the wide application of “hole instead of roadway” technology greatly reduces the cost of gas control engineering, but puts forward higher requirements for the effect of gas drainage. At present, the drainage effect of coal mine inspection boreholes is mainly evaluated by the drilling field, but the flow rate and gas concentration of each borehole in the drilling field are not the same, which causes the gas drainage effect not to be correctly mastered. In the present study, the pressure relief drilling in the goaf of the working face of a typical multi-coal seam group high gas outburst mining area was taken as the research object. Through the newly developed portable drilling inspection device, the pure amount of drilling drainage was investigated, and the drilling design was dynamically adjusted. The enhancement of the goaf pressure relief gas control effect ensures the gas safety of the mining face. At the same time, this improves the gas extraction rate and reduces the emission of greenhouse gases. If the data from the borehole investigation can be transmitted in real time and analyzed in big data, the optimal extraction negative pressure can be predicted through a regression algorithm. Under the control of the negative pressure of each borehole by the actuator, the extraction system can have the function of intelligent judgment.

Reaction condition optimization and kinetic investigation of roasting zinc oxide ore using (NH_4)_2SO_4

An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using（NH_4）_2SO_4. The optimized reaction conditions are defined as an（NH_4）_2SO_4/zinc molar ratio of 1.4：1, a roasting temperature of 440°C, and a thermostatic time of 60 min. The molar ratio of（NH_4）_2SO_4/zinc is the most predominant factor and the roasting temperature is the second significant factor that governs the zinc extraction. Thermogravimetric-differential thermal analysis was used for（NH_4）_2SO_4 and zinc mixed in a molar ratio of 1.4：1 at the heating rates of 5, 10, 15, and 20 K·min-1. Two strong endothermic peaks indicate that the complex chemical reactions occur at approximately 290°C and 400°C. XRD analysis was employed to examine the transformations of mineral phases during roasting process. Kinetic parameters, including reaction apparent activation energy, reaction order, and frequency factor, were calculated by the Doyle-Ozawa and Kissinger methods. Corresponding to the two endothermic peaks, the kinetic equations were obtained.

Liquid chromatography-tandem mass spectrometry method for simultaneous determination of albendazole and albendazole sulfoxide in human plasma for bioequivalence studies

An improved high performance liquid chromatography-tandem mass spectrometry（LC-MS/MS） method has been developed for sensitive and rapid determination of albendazole（ABZ） and its active metabolite,albendazole sulfoxide（ABZSO）,in the positive ionization mode.The method utilized solid phase extraction（SPE） for sample preparation of the analytes and their deuterated internal standards（ISs） from100 μL human plasma.The chromatography was carried out on Hypurity C_（18） column using acetonitrile-2.0 mM ammonium acetate,pH 5.0（80：20,v/v） as the mobile phase.The assay exhibited a linear response over the concentration range of 0.200-50.0 ng/mL for ABZ and 3.00-600 ng/mL for ABZSO.The recoveries of the analytes and ISs ranged from 86.03%-89.66%and 89.85%-98.94%,respectively.Matrix effect,expressed as IS-normalized matrix factors,ranged from 0.985 to 1.042 for the both analytes.The method was successfully applied for two separate studies in healthy subjects using single dose of 400 mg conventional tablets and 400 mg chewable ABZ tablets,respectively.

STUDIES ON THE EXTRACTION MECHANISM OF GOLD (Ⅲ) FROM HYDROCHLORIC ACID MEDIUM BY TRIPHENYLPHOSPHINE OXIDE (TPPO)

In studies on the extraction chemistry of gold, the extractants of alcohols, ethers, ketones and amines are widely used. The neutral extractants tributylphosphate (TBP) and trioctylphosphine oxide (TPPO) have been widely applied. A few experiments on the synthesis of solid complexes of transition metal ions with TPPO have been car-

Kinetic studies on the solvent extraction of uranium(VI) from phosphoric acid solution with HDEHP using laser-induced optical fiber fluorimetry

The laser-induced optical fiber fluorimetry has been used for the first time to analyse the concentration of uranium(VI) in the kinetic studies on the extraction of uranium(VI) between 0.5 mol/L H_3PO_4 solution and HDEHP-cyclohexane system with Lewis cell. The effects of stirring speed, temper- ature and concentration of uranium(VI) and HDEHP on the rate of extraction were examined. These data show that the extraction rate of uranium(VI) in this system is controlled by the chemical reaction process at the interface. The rate equations and the rate constants of the forward and reverse ex- tractions were obtained. The mechanism of the extraction has been discussed.