蔗糖和薄荷醇的旋光度和比旋光度

旋光是物质的性质，当线性偏振光穿过这些物质时，使偏振平面旋转。这是特别发生在左右圆偏振光的折射率不同的光学活性物质上的性质。将光朝着光源顺时针方向旋转的光学旋转被定义为右旋（+）和相反的左旋（-）。偏振平面的旋转角称为旋光度，偏振仪是测量光旋光度的仪器。Application Note P-0002 Optical rotation measurement of sucrose and l-menthol Introduction Optical rotation is the property of substances， rotating the plane of polarization when linearly-polarized light passes through such substances. This is the property which occurs specifically to optical active substances in which the refractive indices of r ight and l eft circularly-polarized l ight are di f ferent. Optical rotation that rotate light in a clockwise direction as viewed towards the light source is defined as dextrorotation (+) and the opposite， levorotation (-). The angle of rotated plane of polarization i s called as optical rotation and polarimeter i s the instrument to measure such optical rotation. Optical rotation is proportional to cell pathlength and is related to sample concentration， measurement wavelength and temperature. The specific optical rotation [o]t is calculated from the following formula using temperature t (℃)， wavelength x (nm)， cell pathlength 1 (dm)， sample concentration c (g/100 ml) and measured optical rotation a. JP， USP and EP suggest to measure optical rotation using D-line of Na lamp. Polarimeter is used for several purposes such as purity certification of sugar， veri f ication of pharmaceuticals and optical purity determination of optical active substances obtained from asymmetric synthesis in organic chemistry field. Keywords： Optical rotation measurement， sucrose， menthol， ORD Optical rotation measurement of sucrose 5 g/100ml of sucrose (Wako Pure Chemical Industries， Ltd.， JIS special grade)V Was P prepared and measured using P-2000 with 100mm cell， Na lamp D-line under 20℃. Figure 1 shows the printout view of measurement result. The average of optical rotation in 5 times measurement Was+3.32644deg. and i ts specific optical rotation calculated Was +66.5280 which is in good agreement with t he specific optical rotation of 5g/100ml sucrose solution described in JIS K0063 1)，+66.500. 5%Sucrose_20℃.p1d [Data Information [Comment]Creation Date 2012/06/11 8：56 Sample name 5% Sucrose Comment [Measurement Information1 UserInstrument Name P-2000 Division Model Name P-2000 Company JASCOSerial No. A071661232 Light Source NaMonitor wavelength589 nm D.I.T. 5 sec No. of cycle 5Cycle interval O secTemp. Monitor HolderTemp. Corr. FactorNone Aperture(S)8.0nmAADperture(L) 2.0nm Mode Optical RotationFactor1 NO. Sample No. Mode Calc. Data Meas. Data PMT Voltage[V] Temperature(C) 1 1 1-1 Specitic O.R. +66.5348 +3.3267 243 19.99 2 2 1-2 Specific O.R. +66.5388 +3.3269 243 19.99 3 3 1-3 Specific O.R. +66.5368 +3.3268 243 19.99 4 4 1-4 Specific O.R. +66.5428 +3.3271 243 19.99 5 5 1-5 SpecitIc O.R. +66.5388 +3.3269 243 19.99 6 6 AVg. +66.5384 7 7 S.D 0.0030 8 8 C.V 0.0045 Figure 1 Printout view of optica l rotation measurement of 5g/100ml sucrose solution. JAS.CO Application Note P-0002 Optical rotation measurement of 1-menthol l-menthol (Wako Pure Chemical Industries， Ltd.) was prepared under the condition suggested in JP (2.5g ethanol (95)， 25ml， 100mm) and its optical rotation was measured. I ts specific optical rotation was calculated to be [o]20p=-50.01 which is well within the JP criteria：-45.0~-51.0. Generally， optical rotation is increased in shorter wavelength region. For optical rotation measurement，Na lamp D-line is usually appl i ed， while when the optical rotation of the sample is very small using D-line，by i rradiating shorter wavelength l ight， optical rotation can be measured i n easier way. In this application data， optical rotation measured using P-2000 with both Na lamp D-line and Hg lamp emission line wavelength (546， 436，405，365 nm) and ORD spectrum (showing wavelength dispersion of optical rotation) measured using J-820 +ORDM-401 were compared. As shown in Figure 2， both measured values by P-2000 and ORDM-401 are very consistent. Like this， by employing shorter wavelength light for samples with small optical rotation， the measurement can be implemented easily. 250 300 350 400 450 500 550 600 650 700 Wavelength (nm) Figure 2 Optical rotation of 1-menthol and comparison with ORD spectrum ： P-2000 measured value ：ORD spectrum Reference (1) Optical rotation of sucrose solution described i n JIS K0063 is referred to Handbook of Chemistry and Physics， 42nd Edition (1960-1961)， P1784， The Chemical Rubber Co.，Ohio， U.S.A..