How to calculate the replacement degree of sodium methyl cellulose in medicinal crosslinking.

How to calculate (-) the replacement degree of sodium methyl cellulose for medicinal crosslinking. Principle after the chemicalized carboxyl starch in du (700 soil 25) degrees C burn ash after getting the residue zhi sodium oxide dao, and then with acid-base titration sodium oxide content, and according to the sodium oxide content calculated replacement degree.
2. Instruments and reagents (1) high temperature furnace (0 to 0 degrees C), titration tube (50 ml), beech (300ml), 3 x glass core crucible (30 ml), filter bottle (0 ml), pumping pump.
(2) 0.lmol/L NaOH standard solution, 0.lmol/L HCl standard solution, 0. l% methyl red.
3. The operating procedure states that the sample of about 1.2g is placed in a 300 ml beost, 20 ml 0.5mol/L HCl solution is acidified, stirred thoroughly 15min to no particles, added a drop of phenolic indicator, then added 0.5mol/L NaOH solution and red, continue stirring until the sample dissolves, and then drips 3 drops of 0.5mol/L Naoh solution.
stirring side drops plus 95% ethanol solution, when the test liquid appears white precipitation, quickly add about 200 ml of 95% ethanol solution, then precipitate precipitation.
stir and heat in a water bath to make the precipitation clear and large.
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Will be precipitated into the 3 s glass core crucible, filtered, first washed with 80% ethanol several times (about ml), then washed with 95% ethanol 3 times (about 60 ml), sucked dry, moved into the oven, baked at 105 degrees C to a constant mass (about 3h), cooling weighing.
the weighed dry CMS into a dry 30 ml porcelain crucible, in a high-temperature furnace, slowly heat up to 700 degrees C, maintain 30min, remove cold to room temperature.
moisten the burning matter with a small amount of distilled water, wash it again with ml distilled water fractions, and move to a 250 ml beost, heating slowly on the electric furnace until boiling, keeping 5min.
2 to 3 drops of methyl red indicator, with 0.lmol/L HCl standard solution titration to the end.
4. Results The concentration of HCl-Titration-timed consumption of HCl standard liquid product (ml) CHCl-HCl standard solution (mol/L)m- sample mass (g) (ii) acid wash method 1. Principle methyl starch samples are fully washed with acid solution, so that they are all converted into acidic CMS (HCMS), and then added a known excess of NaOH standard solution, so that HCMS and NaOH occur a medi-right reaction, and then use the standard HCl solution back to drop the remaining NaOH, so as to measure the replacement degree of CMS.
titration is done after the addition of an excess NaOH standard solution, but instead a standard Na0H solution is used for titration.
2. Instruments and reagents (1) electromagnetic agitator, titration tube (50ml), beech (50ml).
(2) 2mol/L HCl solution (made with 70 methanol solution), 0.1mol/L NaOH standard solution, 0.1mol/L HCl standard solution, 0.1% phenolic indicator.
3. The operating procedure accurately weighs 0.5g samples, places them in a 50ml small beost, adds 2ml/L HCl solution 40ml, and stirs 3h with an electromagnetic mixer.
, and then wash the acidified sample with 80% methanol solution, to the washing liquid without chlorine ions.
dissolved with 0.lmol/L NaOH standard solution 40 ml, under microthermal conditions, so that the solution is transparent, immediately with 0.1 mol/L standard HCl solution anti-drop to phenol agent red just receded.
Or wash with methanol to chlorine-free ions, quantitatively transfer the filter cake to a dry beech, disperse with ml of water, heat 15min in a boiling water bath, cool, and titrate with 0.lmol/L NaOH standard solution until the phenolic indicator is pink.
4. How to calculate the replacement degree of m-sample mass (g) medicinal cross-linked methyl cellulose sodium in the results calculation.