optical rotation using the following formulae.Р纯液体旋光度:РFor neat liquids :Р αD20=αl∙ρ20Р溶液中物质的旋光度:c为浓度,单位g/l。РFor substances in solution: where c is the concentration of the solution in grams per litre.Р αD20=1000αl∙cР按下式计算以g/l为单位的溶解物质的浓度c,或以m/m 百分比为单位的浓度c′:РCalculate the content c in grams per litre or the content c′ in per cent m/m of a dissolved substance using the following for mulae :Р c=1000αl∙αD20 c‘=1000αl∙αD20∙ρ20Рα= 20 ± 0.5°C下,旋光度读数,单位度(°)Рl = 测定管长度,单位dm。Рρ20 = 20 °C 下溶液密度,单位g/cm3,本药典在2.2.5节中以相对密度代替密度。Рc = 溶解物质的浓度,单位g/l。Рc′= 溶解物质的浓度,单位g/l。Рα= angle of rotation in degrees read at 20 ± 0.5°C;Рl = length in decimetres of the polarimeter tube;Рρ20 = density at 20 °C in grams per cubic centimetre.РFor the purposes of the Pharmacopoeia, density isРreplaced by relative density (2.2.5).
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