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 Wysłany: Śro 0:06, 05 Sty 2011 Temat postu: Pig bone by EDTA method of calcium and phosphorus |
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Pig bone by EDTA method of calcium and phosphorus content of
Masking, the sample solution of iron, copper, aluminum, manganese, molybdenum, nickel and other trace metals ions can be masked adequately to eliminate the phenomenon of closure indicator; second, with 1% starch solution as diluent, to prevent calcium phosphate sedimentation pool, eliminating the adsorption phenomenon,[link widoczny dla zalogowanych], but also eliminates the back end of the phenomenon; then followed,[link widoczny dla zalogowanych], with potassium hydroxide instead of sodium hydroxide, ethylenediamine enhanced the masking capability, while avoiding the sodium ion and the fluorescence calcein affect the observed color of the titration end point; Finally, the indicator selection Received date: 2005 A O1-12 Author: Duli Cheng, male, associate professor, 41 years old, engaged in inorganic and analytical chemistry teaching and research. Volume No. 4l (Total 124) Duli Cheng et al: Determination of pig bone by EDTA of calcium and phosphorus content of 59 used calcein, this indicator compared with calcium red, with strong anti-sealing ability, obvious end point color change. 1 Experimental 1.1 Reagents 1.1.1EDTA standard solution to weigh about 9.25g disodium EDTA, water 2.5L, 4L heat transferred to the dissolved reagent bottle, with a 110oC 105oC drying to constant weight CaCO calibration reference material concentration of EDTA. In this study, a solution of EDTA standard solution for the 0.01003mol / L. 1.1.2 Reagent mixture of magnesium chloride accurately weighed 9.5g, 5.25g ammonium chloride, 7ml concentrated ammonia in the 500ml beaker, add about 150ml of distilled water to make it completely dissolved, transfer to a 250ml flask, set Yung, shake. The concentration of the reagent 0.4mol / L. 1.2.1 Test Method 1.2 Determination of calcium in the pipette draw 5ml 2.5ml sample solution in 250ml conical flask 10mll% of the starch solution, add 3m120% ethylenediamine, 3m120% of the triethanolamine, adding a small amount of 10% KOH solution to adjust the solution pH value between 6-8, then add 2ml of KOH solution, the sample showed strong alkaline solution, then add l5ml water, a small amount of calcein with EDTA titration after calibration to the solution from green to yellow fluorescent yellow so far. 1.2.2 Determination of phosphorus in the sample solution obtained 2.5ml in 50ml beaker, add l0mll% of the starch solution, add 2ml of magnesium mixed reagent, stand for 5 minutes, filter, release the filter paper 20ml beaker, dilute acid to precipitate on the filter paper is completely dissolved, transfer to 250ml conical flask,[link widoczny dla zalogowanych], adjusted with ammonia buffer solution PH 8 a l0, adding 3ml triethanol ammonium, 7m12% sodium sulfide solution, l0ml ammonia buffer solution, a small amount of black T (EBT), titration with EDTA to the solution from red to blue. 2 Results and discussion 2.1 Analysis of the results of the sample pre-treatment 2.1.1 Accurately weigh 4.0g bone meal around the crucible placed in the furnace on a careful charring to the smoke-free, release 550oC to 560oC in the high-temperature furnace burning 4hr, after burning the sample added to I: I hydrochloric acid 10.0ml,[link widoczny dla zalogowanych], and dropping a few drops of concentrated nitric acid, boiling heat slightly until the left about half the volume of sample solution, remove the cooling, into the 250ml flask, quantitative , shake well and set aside. 2.1.2 Experimental determination of the results of the improved method in accordance with parallel determination of many results for the following: pig bone calcium content of l6. o0%,[link widoczny dla zalogowanych], 9.59% phosphorus content. 2.1.3 control experiment and recall rates in Table 1 did not improve the sample analysis results to compare the bone in the EDTA method contains more trace elements, with traditional masking EDTA method is not complete, so that color is not sensitive indicator end point, combined in the preparation of sample solution, the calcium ions and phosphate ions co-precipitation, thus making a determination of the results of pseudo-low. EDTA using the improved test method to overcome these shortcomings, the bone calcium and phosphorus content of the value of stable, reliable, accurate, fast and the law to achieve a satisfactory result.
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