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BACKGROUND Chemical phase analysis of antimony ores involves three mineral phases:valentinite, stibnite and insoluble antimonate. Solvents used for extracting various antimony mineral phases are different. In addition, coexisting ions are complex and concentration gradients vary greatly. These factors affect the accurate determination of antimony chemical phases by inductively coupled plasma-optical emission spectrometry (ICP-OES). OBJECTIVES To solve the problem during rapid and accurate measurement of chemical phases of antimony ore. METHODS The effects of hydrochloric acid, nitric acid and potassium sulfate-nitric acid-sulfuric acid on the determination of antimony by ICP-OES were studied with valentinite, stibnite and antimonate as selective separation solvents. RESULTS The same concentration of hydrochloric acid and nitric acid medium had no effect on the determination of antimony. The same standard solution series can be used to determine antimony in valentinite and stibnite. Hydrolysis of antimony can be avoided by using 15%-20% hydrochloric acid or nitric acid of. Mixed acid medium (4g/L potassium sulfate-15% nitric acid-3% sulfuric acid) had an effect on the determination of antimony. The matrix matching method can be used to solve the problem. In determining the amount of antimony in antimonate, the calibrated solution was formulated to add the same amount of mixed acid as the antimonate leaching agent. The detection limits of antimony in valentinite, stibnite and antimonate mineral phases by ICP-OES were 0.0006%, 0.0012% and 0.0021%, respectively, by choosing the 206.833nm line as the analytical line, under optimized analytical method flow and measurement parameters. The relative standard deviations (n=12) of the method were 0.16%-5.76%, and the absolute relative deviations of phase addition and total amount were 0.07%-7.38%. CONCLUSIONS The precision and accuracy of the method meet the quality control requirements of antimony ore chemical phase analysis, and provide fast and accurate measurement of antimony ore chemical phase.

Currently, a few chemical phase analysis methods possess a common application, but most of them are designed for samples in a specific ore district and thus the accuracy of analytical results and the application range of a selected analytical process are not certain. Verification of chemical phase analysis by selected analytical process and method accuracy are the primary problem in this field. The representative antimony ore type, single antimony sulfide ore was chosen as the research object for the study. The main mineral phases of antimony are determined by mineral identification. When valentinite mineral cannot be acquired, the proportion of valentinite in mixing oxide ore (mixture of valentinite and antimonate) is determined by valence analysis. Moreover, the selected separation condition among valentinite, stibnite and antimonate is determined by comparison of condition experiment and X-ray Diffraction Analysis. Results show for the sample with antimony suldide content higher than 35%, the extraction time for the antimony sulfide phase should change from 30 minutes to 40 minutes. When the leaching rate of stibnite is increased by 4%-6%, the analysis error of antimonates phase can be reduced by 45%-70%. Antimony sulfide was leached completely, and the analysis accuracy of antimonite and cervantite phases improved. This method is suitable for chemical phase analysis of different types of ores (oxidized and sulfide ores) from different regions.

Anion exchange resin has been applied to Re separation after acid digestion of Cu-Pb-Zn ores and Re was determined by Inductively Coupled Plasma-Mass Spectrometry(ICP-MS). ReO4- in solution was adsorbed by exchange resin and was then eluted from the resin by eluant. This method has a long process, which affects its stability and accuracy. Matrix elements are selected as the goal and 8 g of 732 cation exchange resin in 2% nitric acid medium for 1.5 h static adsorption is used. This method can effectively eliminate the influence of matrix elements on the ICP-MS determination of rhenium. Quartz was used as the blank and mixed with low Re samples. The acquired detection limit was 0.004μg/g, the precision(RSD) is less than 6%, and the recovery ranged from 96% to 104%. The 732 cation exchange resin under the acidic condition has the recovery of >95% for most matrix elements except tungsten and molybdenum, which reduced ionic strength and the concentration of interference elements. Rhenium can be directly determined by ICP-MS, which is simpler and faster than the anion exchange resin separation method.

The interaction between warfarin and bovine serum albumin (BSA) under pseudophysiological conditions was investigated by UV-Vis absorption spectrometry and spectrofluorimetry. The quenching mechanism of BSA by warfarin was discussed. It showed that the quenching process was a dynamic quenching, and the quenching constants were 6.05 x 10(4) L x mol(-1) at 16 degrees C and 6. 14 x 10(4) L x mol(-1) at 37 degrees C, separately. Based on the Förster theory of non-radiative energy transfer, the energy transfer efficiency and the distance of BSA to warfarin were calculated, which was 0.37 and 3.15 nm, respectively.

The spectroscopic characteristic of interaction of fluorescein sodium and gold nanoparticles with different sizes was investigated via UV-Vis and fluorescence spectrophotometry. It was shown that fluorescein sodium adsorbed respectively onto the different sized gold nanoparticle surface suffers different extent of quenching of their fluorescence. The quenching efficiency is different for different sized gold nanoparticles. It was found that smaller gold nanoparticles are more efficient quenchers due to their larger surface areas. The quenching mechanism was discussed. It was a dynamic quenching.