A sensitive solvent extraction method for the determination of nonamolar concentrations of silicate in natural waters is developed. According to the traditional aqueous silicate method, silicomolybdenum blue formed by...A sensitive solvent extraction method for the determination of nonamolar concentrations of silicate in natural waters is developed. According to the traditional aqueous silicate method, silicomolybdenum blue formed by the reaction between silicate and ammoni- um molydate and reduced by metol-sulfite reagent is extracted by methyl isobutyl ketone. The absorbance can be enhanced substantially up to 10-folds. The detection limit of silicate is 8 nmol/dm^3 , which is one tenth smaller than the traditional method, with the precision of 4.0% at a silicate level of 50 nmol/dm^3 and 3.2% at a silicate level of 6 μmol/dm^3. Comparing the calibration curves in the distilled water and seawater, it can be seen that the salt effect also exists in the extraction method. However, the salt effect is a linear function of the salinity and can be corrected by simple calibration. The proposed method is successfully applied to the determination of silicate in natural waters. Natural concentrations of arsenate, arsenite and phosphate cause negligible interference.展开更多
A simple and rapid colorimetric method for the and Whatman filter paper chromatography is described. determination of some amino acids on thin layer chromatography （TLC） The studied compounds are cysteine, proline, ...A simple and rapid colorimetric method for the and Whatman filter paper chromatography is described. determination of some amino acids on thin layer chromatography （TLC） The studied compounds are cysteine, proline, methionine, tryptophan glutmine, glycine, thyrosine, threonine, leucine and lysine. The method is based on the formation of color from the reaction of stannous chloride （SnCI2） and ninhydrin reagents. The procedure has been successfully applied to the assay of the standard amino acid preparation after TLC separation, and the results of the studied compounds were clear and favorable, comparing to the official methods. However, the improved TLC is much more efficient for the detection of amino acid. The main advantage of this method is that the detection of amino acids can be preformed visually.展开更多
基金The National Science Foundation of China under contract No.40606028the Special Fund from the National Key Basic Research Program of China under contract No.2006CB400601.
文摘A sensitive solvent extraction method for the determination of nonamolar concentrations of silicate in natural waters is developed. According to the traditional aqueous silicate method, silicomolybdenum blue formed by the reaction between silicate and ammoni- um molydate and reduced by metol-sulfite reagent is extracted by methyl isobutyl ketone. The absorbance can be enhanced substantially up to 10-folds. The detection limit of silicate is 8 nmol/dm^3 , which is one tenth smaller than the traditional method, with the precision of 4.0% at a silicate level of 50 nmol/dm^3 and 3.2% at a silicate level of 6 μmol/dm^3. Comparing the calibration curves in the distilled water and seawater, it can be seen that the salt effect also exists in the extraction method. However, the salt effect is a linear function of the salinity and can be corrected by simple calibration. The proposed method is successfully applied to the determination of silicate in natural waters. Natural concentrations of arsenate, arsenite and phosphate cause negligible interference.
文摘A simple and rapid colorimetric method for the and Whatman filter paper chromatography is described. determination of some amino acids on thin layer chromatography （TLC） The studied compounds are cysteine, proline, methionine, tryptophan glutmine, glycine, thyrosine, threonine, leucine and lysine. The method is based on the formation of color from the reaction of stannous chloride （SnCI2） and ninhydrin reagents. The procedure has been successfully applied to the assay of the standard amino acid preparation after TLC separation, and the results of the studied compounds were clear and favorable, comparing to the official methods. However, the improved TLC is much more efficient for the detection of amino acid. The main advantage of this method is that the detection of amino acids can be preformed visually.
