GB/T 614-2021 English PDF (GBT614-2021)

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GB/T 614-2021: Chemical reagent -- General method for the determination of refractive index
GB/T 614-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.040.30
CCS G 60
Replacing GB/T 614-2006
Chemical reagent - General method for the
determination of refractive index
(ISO 6353-1:1982, Reagents for chemical analysis –
Part 1: General test methods, NEQ)
ISSUED ON: AUGUST 20, 2021
IMPLEMENTED ON: MARCH 1, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Principles of the method ... 5
5 Apparatus ... 5
6 Test method ... 5
Chemical reagent - General method for the
determination of refractive index
1 Scope
This document specifies the general method for measuring the refractive index
of liquid organic reagents by the Abbe refractometer method or the automatic
digital display refractometer method.
This document is suitable for the determination of light-colored and transparent
liquid organic reagents with a refractive index ranging from 1.3000 to 1.7000.
The automatic digital display refractometer method in this document is also
suitable for the determination of dark, translucent and opaque liquid organic
reagents.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) is applicable to this standard.
GB/T 6682 Water for analytical laboratory use -- Specification and test
methods
JJG 625 Verification regulation of abbe refractometer
3 Terms and definitions
The following terms and definitions apply to this document.
3.1 Refractive index
Under the conditions of the sodium spectrum D line and 20 °C, the ratio of the
speed of light in the air to the speed of light in the test object; or when the light
passes through the test object from the air, the ratio of the sine of the incident
angle to the sine of the refraction angle.
6.2.2 Use the grade 2 water or working sample to calibrate the Abbe
refractometer. Under the conditions of the sodium spectrum D line and 20 °C,
the refractive index of the grade 2 water is n=1.3330. The refractive index of the
working sample and the calibration method of the instrument refer to the
instruction manual.
6.2.3 Before the measurement, it shall clean the surface of the prism. It may
use ethanol, ether or a mixture of ethanol and ether to clean; then use lens
paper or medical cotton to absorb-dry the solvent.
6.2.4 Use a dropper to add a few drops of the sample that is at about 20 °C to
the surface of the prism; immediately, close the prism and tighten it. The sample
shall be uniform, without bubbles and fully fill the field of view; wait for the
reading of the thermometer of the prism to return to 20.0 °C ± 0.1 °C.
6.2.5 Adjust the reflector mirror to make the field of view bright. Rotate the
reading handwheel to make the light and dark boundaries appear in the field of
view; at the same time, rotate the handwheel of the dispersive prism (Amici
Prism) to make the color at the boundary line completely disappear; then rotate
the handwheel to make the light and dark boundary line in the center of the
cross line. Observe the scale value indicated on the right side of the reading
lens's field of view; that is the measured value of the refractive index.
6.2.6 Record the refractive index value and retain it to the fourth decimal place.
6.2.7 Repeat the determination according to the above steps. The absolute
difference between the two determination results shall not be more than 0.0002.
Take the arithmetic mean value of the two determinations as the measurement
results.
6.3 Automatic digital display refractometer method
6.3.1 Operate and set up the instrument according to the requirements of the
instrument manual.
6.3.2 It may use water, ethanol, ether or a mixture of ethanol and ether to clean
the surface of the prism of the measuring cell of the instrument; then use lens
paper or medical cotton to absorb-dry the solvent.
6.3.3 Use a dropper to add a few drops of grade 2 water to the surface of the
prism of the measuring cell of the instrument. The prism needs to be submerged.
Close the measuring cover. Until the temperature reaches 20.0 °C ± 0.05 °C,
the instrument automatically detects and displays the refractive index value.
The refractive index of grade 2 water shall be .