New low-index liquid refractive index standard: SRM 1922.
A new standard for the calibration of refractometers has been developed. Standard Reference Material (SRM) 1922 is a mineral oil with a refractive index nD = 1.46945 at 20 degrees C, which is within the range of the Brix scale (% sucrose). The change in refractive index with temperature (dn/dT) has been characterized for the range 15 degrees C to 35 degrees C to allow for calibrations within that range of temperatures. The refractive indices were measured at 5 wavelengths in the visible spectrum by using the method of minimum deviation with a +/- 2-3 x 10(-5) uncertainty at 20 degrees C. The values of nD and dnD/dT were determined by fits of a two-term Cauchy function to the values at the measured wavelengths with a +/- 6 x 10(-5) uncertainty in nD at 20 degrees C.
Verkouteren
J R
JR
Surface and Microanalysis Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Leigh
S D
SD
D002138:Calibration; D005504:Food Analysis / Q000295:instrumentation / Q000379:methods / Q000592:standards; D017408:Guidelines as Topic; D008899:Mineral Oil / Q000592:standards*; D012015:Reference Standards; D012031:Refractometry / Q000592:standards*; D013696:Temperature
C421824:SRM 1922; D008899:Mineral Oil