Lactic-Acid日本药典

1016JP XVI Lactic Acid/Official Monographs

mL of water as the dissolution medium,the dissolution rate in30minutes of Labetalol Hydrochloride Tablets is not less than75z.

Start the test with1tablet of Labetalol Hydrochloride Tablets,withdraw not less than20mL of the medium at spe-cified minute after starting the test,and filter through a membrane filter with a pore size not exceeding0.8m m.Dis-card the first10mL of the filtrate,pipet V mL of the subse-quent filtrate,and add water to make exactly V?mL so that each mL contains about50m g of labetalol hydrochloride (C19H24N2O3.HCl)according to the labeled amount,and use this solution as the sample solution.Separately,weigh accu-rately about50mg of labetalol hydrochloride for assay,pre-viously dried at1059C for3hours,and dissolve in water to make exactly100mL.Pipet10mL of this solution,add water to make exactly100mL,and use this solution as the standard solution.Perform the test with the sample solution and standard solution as directed under Ultraviolet-visible Spectrophotometry<2.24>,and determine the absorbances, A T and A S,at302nm.

Dissolution rate(z)with respect to the labeled amount of labetalol hydrochloride(C19H24N2O3.HCl)

＝M S×A T/A S×V?/V×1/C×90

M S:Amount(mg)of labetalol hydrochloride for assay C:Labeled amount(mg)of labetalol hydrochloride (C19H24N2O3.HCl)in1tablet

Assay Weigh accurately not less than20Labetalol Hydro-chloride Tablets,and powder.Weigh accurately a portion of the powder,equivalent to about1g of labetalol hydrochlo-ride(C19H24N2O3.HCl),add100mL of0.5mol/L sulfuric acid TS and600mL of water,shake vigorously for30 minutes,add water to make exactly1000mL,and filter.Dis-card the first5mL of the filtrate,pipet5mL of the subse-quent filtrate,and add0.05mol/L sulfuric acid TS to make exactly25mL.Pipet5mL of this solution,add0.05mol/L sulfuric acid TS to make exactly25mL,and use this solution as the sample solution.Separately,weigh accurately about 40mg of labetalol hydrochloride for assay,previously dried at1059C for3hours,and dissolve in0.05mol/L sulfuric acid TS to make exactly100mL.Pipet5mL of this solution, add0.05mol/L sulfuric acid TS to make exactly50mL,and use this solution as the standard solution.Perform the test with the sample solution and standard solution as directed under Ultraviolet-visible Spectrophotometry<2.24>,and de-termine the absorbances,A T and A S,at302nm.

Amount(mg)of labetalol hydrochloride(C19H24N2O3.HCl)＝M S×A T/A S×25

M S:Amount(mg)of labetalol hydrochloride for assay Containers and storage Containers—Tight ctic Acid

乳酸

C3H6O3:90.08

(2RS)-2-Hydroxypropanoic acid

[50-21-5]

Lactic Acid is a mixture of lactic acid and lactic an-hydride.

It contains not less than85.0z and not more than 92.0z of C3H6O3.

Description Lactic Acid occurs as a clear,colorless or light yellow,viscous liquid.It is odorless or has a faint,unpleas-ant odor.

It is miscible with water,with ethanol(95)and with diethyl ether.

It is hygroscopic.

Specific gravity d2020:about1.20

Identification A solution of Lactic Acid(1in50)changes blue litmus paper to red and responds to the Qualitative Tests<1.09>for lactate.

Purity(1)Chloride<1.03>—Perform the test with1.0g of Lactic Acid.Prepare the control solution with1.0mL of 0.01mol/L hydrochloric acid VS(not more than0.036z).

(2)Sulfate<1.14>—Perform the test with2.0g of Lactic Acid.Prepare the control solution with0.40mL of0.005 mol/L sulfuric acid VS(not more than0.010z).

(3)Heavy metals<1.07>—To2.0g of Lactic Acid add10 mL of water and1drop of phenolphthalein TS,and add am-monia TS dropwise until a pale red color appears.Add2mL of dilute acetic acid and water to make50mL,and perform the test using this solution as the test solution.Prepare the control solution from2.0mL of Standard Lead Solution and 2mL of dilute acetic acid,and dilute with water to50mL (not more than10ppm).

(4)Iron<1.10>—Prepare the test solution with4.0g of Lactic Acid according to Method1,and perform the test according to Method A.Prepare the control solution with 2.0mL of Standard Iron Solution(not more than5ppm).

(5)Sugars—To1.0g of Lactic Acid add10mL of water, and neutralize with sodium hydroxide TS.Boil the mixture with10mL of Fehling's TS for5minutes:no red precipitate is produced.

(6)Citric,oxalic,phosphoric and L-tartaric acid—To 1.0g of Lactic Acid add1.0mL of water,followed by40mL of calcium hydroxide TS.Boil the mixture for2minutes:no change occurs.

(7)Glycerin or mannitol—Shake10mL of Lactic Acid with12mL of diethyl ether:no turbidity is produced.

(8)Volatile fatty acids—Warm Lactic Acid:it does not produce any acetic acid-like or butyric acid-like odor.

(9)Cyanide—Transfer1.0g of Lactic Acid to a Nessler tube,add10mL of water and1drop of phenolphthalein TS, add dropwise a solution of sodium hydroxide(1in10)by shaking until a pale red color develops,add1.5mL of a so-lution of sodium hydroxide(1in10)and water to make20 mL,and heat in a water bath for10minutes.Cool,add