Refractory materials have been widely used in high-temperature industries,in which the boron content has a great influence on the performance.To control the detection quality and satisfy the requirement of production ...Refractory materials have been widely used in high-temperature industries,in which the boron content has a great influence on the performance.To control the detection quality and satisfy the requirement of production and scientific research of refractories,conditional tests involving three methods for the boron determination(alkali titrimetry,inductively coupled plasma atomic emission spectrometry(ICP-AES),and curcumin absorption spectrophotometry)were carried out in this work.The affecting factors on the determination of boron were analyzed and discussed by performing the experiment.The results show that compared with curcumin absorption spectrophotometry,alkali titrimetry and ICP-AES have the advantages of simple operation,quick analysis and high precision(relative standard deviation<5%),which are more appropriate for boron determination in refractories.展开更多
The principle of using amplification reactions of iodine was employed in this paper to estimate the thiadiazole derivatives on basis of their reactions with iodine I chloroform, removal of the excess iodine and determ...The principle of using amplification reactions of iodine was employed in this paper to estimate the thiadiazole derivatives on basis of their reactions with iodine I chloroform, removal of the excess iodine and determination of the resulting iodide, after oxidation to iodate. The overall reaction gave an amplification of the iodide that is (12) times larger for the compounds: 2-amino-5-mercapto-1,3,4-thiadiazole (I);2,5-dimercapto-1,3,4-thiadiaole (II) and 2,5-diamino-1,3,4-thiadiazole (III) and (36) times for 2,5-dihydrazino-1,3,4-thiadiazole (IV) and (6) times for 5-mercapto-2[(3[5’-nitro-2-’furyl]·methylene)amino]-1,3,4-thiadiazole (V) and 5-mercapto-2[(3[5’-nitro-2-’furyl]-prop-2-enylidene)amino]-1,3,4-thiadiazole (VI). By titration, 1-mL of standard thiosulfate solution was found equivalent to 0.108 mg of (I);0.126 mg of (II), 0.16 mg of (III), 0.041 mg of (IV), 0.40 mg of (V) and 0.435 mg of (VI). Using the spectrophotometric detection for the amplification reaction gave high absorbance values at 605 nm for the blue starch-iodine complex. Beer’s law was obeyed up to 4.0 ppm for compounds (I and II);6.0 ppm for compounds (III, IV and VI) and 5.0 ppm for compound (V). The mechanism of the reactions was proposed and the analytical parameters were evaluated for both methods. The method was applied for synthetic samples of industrial importance. The recovery was comparable while the sensitivity and detection limits were better for the spectrophotometric detection.展开更多
This study compares the results of three certified methods,namely differential scanning calorimetry(DSC),the mass balance(MB) method and coulometric titrimetry(CT),in the purity assessment of ferulic acid certified re...This study compares the results of three certified methods,namely differential scanning calorimetry(DSC),the mass balance(MB) method and coulometric titrimetry(CT),in the purity assessment of ferulic acid certified reference material(CRM).Purity and expanded uncertainty as determined by the three methods were respectively 99.81%,0.16%;99.79%,0.16%;and 99.81%,0.26%with,in all cases,a coverage factor(k) of 2(P ? 95%).The purity results are consistent indicating that the combination of DSC,the MB method and CT provides a confident assessment of the purity of suitable CRMs like ferulic acid.展开更多
文摘Refractory materials have been widely used in high-temperature industries,in which the boron content has a great influence on the performance.To control the detection quality and satisfy the requirement of production and scientific research of refractories,conditional tests involving three methods for the boron determination(alkali titrimetry,inductively coupled plasma atomic emission spectrometry(ICP-AES),and curcumin absorption spectrophotometry)were carried out in this work.The affecting factors on the determination of boron were analyzed and discussed by performing the experiment.The results show that compared with curcumin absorption spectrophotometry,alkali titrimetry and ICP-AES have the advantages of simple operation,quick analysis and high precision(relative standard deviation<5%),which are more appropriate for boron determination in refractories.
文摘The principle of using amplification reactions of iodine was employed in this paper to estimate the thiadiazole derivatives on basis of their reactions with iodine I chloroform, removal of the excess iodine and determination of the resulting iodide, after oxidation to iodate. The overall reaction gave an amplification of the iodide that is (12) times larger for the compounds: 2-amino-5-mercapto-1,3,4-thiadiazole (I);2,5-dimercapto-1,3,4-thiadiaole (II) and 2,5-diamino-1,3,4-thiadiazole (III) and (36) times for 2,5-dihydrazino-1,3,4-thiadiazole (IV) and (6) times for 5-mercapto-2[(3[5’-nitro-2-’furyl]·methylene)amino]-1,3,4-thiadiazole (V) and 5-mercapto-2[(3[5’-nitro-2-’furyl]-prop-2-enylidene)amino]-1,3,4-thiadiazole (VI). By titration, 1-mL of standard thiosulfate solution was found equivalent to 0.108 mg of (I);0.126 mg of (II), 0.16 mg of (III), 0.041 mg of (IV), 0.40 mg of (V) and 0.435 mg of (VI). Using the spectrophotometric detection for the amplification reaction gave high absorbance values at 605 nm for the blue starch-iodine complex. Beer’s law was obeyed up to 4.0 ppm for compounds (I and II);6.0 ppm for compounds (III, IV and VI) and 5.0 ppm for compound (V). The mechanism of the reactions was proposed and the analytical parameters were evaluated for both methods. The method was applied for synthetic samples of industrial importance. The recovery was comparable while the sensitivity and detection limits were better for the spectrophotometric detection.
基金financially supported by the Ministry of Science and Technology of the People's Republic of China (No.2007FY130100)Major Scientific and Technological Special Project for "Significant New Drugs Creation" of China during the 12th Five-Year Plan Period (No.2012ZX09301002-001-013)
文摘This study compares the results of three certified methods,namely differential scanning calorimetry(DSC),the mass balance(MB) method and coulometric titrimetry(CT),in the purity assessment of ferulic acid certified reference material(CRM).Purity and expanded uncertainty as determined by the three methods were respectively 99.81%,0.16%;99.79%,0.16%;and 99.81%,0.26%with,in all cases,a coverage factor(k) of 2(P ? 95%).The purity results are consistent indicating that the combination of DSC,the MB method and CT provides a confident assessment of the purity of suitable CRMs like ferulic acid.
