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GB/T 14571.4-2008 English PDF (GBT14571.4-2008)

GB/T 14571.4-2008 English PDF (GBT14571.4-2008)

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GB/T 14571.4-2008: Ethylene glycol for industrial use -- Determination of ultraviolet transmittance -- Ultraviolet spectrophotometric method

This Part specifies determination method for ultraviolet transmittance of ethylene glycol for industrial use within a wavelength range of 200nm~350nm. This Part is not intended to describe all security issues related to its use. It is the responsibility of the user to take appropriate safety and health measures to ensure the compliance with relevant national regulations.
GB/T 14571.4-2008
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 71.080.60
G 16
Ethylene glycol for industrial use ?€?
Determination of ultraviolet transmittance ?€?
Ultraviolet spectrophotometric method
ISSUED ON: FEBRUARY 26, 2008
IMPLEMENTED ON: AUGUST 01, 2008
Issued by: General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Method summary ... 5
4 Reagents and materials ... 6
5 Apparatus ... 6
6 Sampling ... 7
7 Apparatus preparation ... 7
8 Sample pre-processing ... 8
9 Analysis steps ... 8
10 Calculation of results ... 9
11 Repeatability limits (with nitrogen stripping treatment) ... 10
12 Report ... 10
Annex A (informative) Contrast on Clause No. between this Part and ASTM E2193-2004 ... 11
Annex B (normative) Absorbance index of reference water and determination method for water absorbance ... 12
Ethylene glycol for industrial use ?€?
Determination of ultraviolet transmittance ?€?
Ultraviolet spectrophotometric method
1 Scope
This Part specifies determination method for ultraviolet transmittance of ethylene glycol for industrial use within a wavelength range of 200nm~350nm. This Part is not intended to describe all security issues related to its use. It is the responsibility of the user to take appropriate safety and health measures to ensure the compliance with relevant national regulations.
2 Normative references
The provisions in following documents become the provisions of this Standard through reference in this Standard. For dated references, the subsequent amendments (excluding corrigendum) or revisions do not apply to this Standard, however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable. For undated references, the latest edition of the referenced document applies. GB/T 6680-2003, General rules for sampling liquid chemical products
GB/T 6682-1992, Water for laboratory use - Specifications (neq ISO
3639:1987)
GB/T 8170-1987, Rules for rounding off of numerical values
JJG 682-1990, Verification Regulation of Double Beam UV-VIS
Spectrophotometers
3 Method summary
Place sample in a 50mm or 10mm absorption cell. Use water as reference. Determine the absorbance at 220nm, 275nm and 350nm. Calculate to obtain the ultraviolet transmittance of sample under 10mm optical path. When
necessary, it may make access to nitrogen to remove dissolved oxygen from the sample. Determine the ultraviolet transmittance once again.
5.3 Reagent bottle: capacity is at least 500mL; equipped with well-sealed grinding cap.
5.4 Volumetric flask: 25mL.
5.5 Closed glass tube.
6 Sampling
According to the provisions of GB/T 6680-2003, perform sampling at a gentle flow rate. Stop sampling when the distance between the liquid level and the bottle mouth is less than 10mm. Immediately cover to store the sample. Sample shall avoid violent oscillations. Analyze as soon as possible.
7 Apparatus preparation
7.1 UV spectrophotometer: according to the following steps, according to the method specified in JJG 682-1990, inspect the performance of the photometer. 7.1.1 Wavelength accuracy: it is recommended to use naphthalene solution (4.1); inspect the wavelength accuracy of the photometer at 220nm. Use
spectroscopic pure isooctane as reference, use 10mm absorption cell to
determine the maximum absorption wavelength of naphthalene. The measured value shall be in the range of 220.6nm ?? 0.3nm. Otherwise, it shall determine the absorbance of ethylene glycol sample at a wavelength 0.6nm less than this measured value.
It shall also use cerium oxide standard solution (4.2) or yttrium oxide calibration filter (4.3) to inspect the wavelength accuracy, in accordance with requirements of 5.1.
NOTE: The absorbance of ethylene glycol varies greatly around 220nm. Therefore, it shall ensure the wavelength accuracy of the photometer at 220nm.
7.1.2 Light transmittance accuracy: use potassium dichromate standard
solution (4.4) or standard absorbance filter (4.5) to inspect the accuracy of photometer transmittance, in accordance with requirements of 5.1.
7.1.3 Stray light: use sodium iodide or potassium iodide solution (4.6) or stray light filter (4.7) to determine the light transmittance of the photometer at 220nm (i.e. stray light), in accordance with requirements of 5.1.
7.2 Glassware: use hydrochloric acid-water-methanol solution (1:3:4, volume ratio) or chromic acid lotion to thoroughly clean the absorption cell and other glassware.
than 0.01AU.
9.3 Pour out the water from the sample cell. Use nitrogen to dry. Load the sample to be tested in the sample cell. Use water (4.9) as reference. Measure and record the absorbance of the sample at each wavelength in 9.2. Note that the direction of the absorption cell in the cell holder shall be the same as in 9.2. When performing each set of determinations (9.2 and 9.3), it shall replace the water in the reference cell.
NOTE: Care shall be taken when transferring samples to avoid air bubbles and affect test results.
9.4 Empty the absorption cell and use water to rinse. According to the
requirements of 7.2, clean the absorption cell. Fill with water for storage. 10 Calculation of results
10.1 When using 50mm absorption cell, calculate the net absorbance A?? of the sample at each wavelength at 10mm optical path according to formula (1): Where,
As - Absorbance of the sample measured at the relevant wavelength;
Ac - Absorbance correction value of the absorption cell at the relevant wavelength.
If using a 10mm absorption cell, calculate the net absorbance A?? of the sample at each wavelength under the 10mm optical path, according to formula (2). 10.2 According to formula (3), calculate the light transmittance A?? of each sample at each wavelength under 10mm optical path. Values are expressed as a percentage.
10.3 Analysis results
Take the arithmetic mean of the results of two repeated measurements to report

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