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GB/T 9721-2006 (GBT 9721-2006)

Chinese Standard: 'GB/T 9721-2006'
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Standard ID GB/T 9721-2006 (GB/T9721-2006)
Description (Translated English) Chemical reagent. General rules for the molecular absorption spectrophotometry (ultraviolet and visible)
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard G60
Classification of International Standard 71.040.40; 71.040.30
Word Count Estimation 7,727
Date of Issue 2006-09-01
Date of Implementation 2007-04-01
Older Standard (superseded by this standard) GB/T 9721-1988
Quoted Standard GB/T 6682-1992; GB/T 14666; JIG 178-1996; JIG 682-1990; JIG 689-1990
Drafting Organization Beijing Institute of Chemical Reagents
Administrative Organization Chemicals Branch of the National Standardization Technical Committee chemistry
Regulation (derived from) China National Standard Approval Announcement 2006 No.11 (Total No.98)
Proposing organization China Petroleum and Chemical Industry Association
Issuing agency(ies) Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China; Standardization Administration of China
Summary This standard specifies the requirements for instrumentation and measurement methods of chemical reagents molecular absorption spectrophotometry (UV and visible). This standard applies to absorb wavelengths between 200nm ~ 850nm, chemical reagents Determination of impurities and organic chemistry reagents, indicators and effects reagents qualitative and quantitative analysis.

GB/T 9721-2006
ICS 71.040.40; 71.040.30
G 60
Replacing GB/T 9721-1988
Chemical reagent - General rules for the molecular
absorption spectrophotometry (ultraviolet and visible)
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the PRC.
Table of contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Principles of method ... 6 
5 Reagent ... 7 
6 Instruments ... 8 
7 Determination ... 8 
This standard replaces GB/T 9721-1988 “Chemical reagent - General rules for
the molecular absorption spectrophotometry (ultraviolet and visible)”. As
compared with GB/T 9721-1988, the main changes are as follows.
- ADD the references (2 of this version);
- ADD the terms and symbols (3.4, 3.16, and 3.18 of this version);
- MODIFY the relevant contents of the “Instruments” part (6.1, 6.2 and 6.3 of
1988 version; 6 of this version);
- SUPPLEMENT the specification for the technical requirements of the
“absorption pool” (7.1.4 of 1988 version; 7.1.4 of this version);
- SUPPLEMENT the application conditions as required by the “absorbance
reading range” (7.1.6 of 1988 version; 7.1.6 of this version);
- ADD the “Determination of molar absorptivity” (7.2.4 of this version) and
the “Determination of mass absorptivity” (7.2.6 of this version);
- ELIMINATE the “precision” (8 of 1988 version).
This standard was proposed by the Chinese Petroleum and Chemical Industry
This standard shall be under the jurisdiction of the National Chemical
Standardization Technical Committee - Chemical Reagent Branch (SAC/TC
63/SC 3).
The drafting organization of this standard. Beijing Chemical Reagent Research
The main drafters of this standard. Guan Ruibao, Qiang Jinglin.
This standard was first published in 1988.
Chemical reagent - General rules for the molecular
absorption spectrophotometry (ultraviolet and visible)
1 Scope
This standard specifies the instrument requirements and determination
methods of chemical reagent molecular absorption spectrophotometry
(ultraviolet and visible).
This standard applies to the determination of the impurity contents in the
chemical reagent of the absorption wavelength between 200 nm ~ 850 nm
AND the qualitative and quantitative analysis of the organic chemical reagents,
indicators, and special reagents.
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For the dated references, the subsequent
amendments (excluding corrections) 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 6682-1992 Water for laboratory use; Specifications (eqv ISO
GB/T 14666 Terms for analytical chemistry
JJG 178-1996 Visible spectrophotometer
JJG 682-1990 Dual-beam ultraviolet visible spectrophotometer
JJG 689-1990 Ultraviolet, visible, near-infrared spectrophotometer
3 Terms and definitions
The terms and definitions as defined in GB/T 14666 AND the following terms
and definitions apply to this standard.
6 Instruments
In accordance with the sample determination requirements, it shall select the
single-wavelength single-beam or single-wavelength dual-beam UV visible
spectrophotometer which complies with the requirements of JJG 178-1996,
JJG 682-1990 or JJG 689-1990.
7 Determination
7.1 Selection of determination conditions
7.1.1 Light source
SELECT the light source based on the determined wavelength; USE the
hydrogen lamp (or tritium lamp) when the determined wavelength is 200 nm ~
350 nm, AND the tungsten lamp (or iodine tungsten lamp) when the
determined wavelength is 350 nm ~ 850 nm.
7.1.2 Slit width
SELECT the appropriate slit width in accordance with the type of substance to
be determined AND the detection requirements. Under the conditions of
ensuring consistent slit width for the incident light and the transmitted light,
ADJUST the slit width. The selection of the slit width shall ensure that the
absorbance of the substance to be determined does not increase any more
when the slit width is reduced. AND the slit width used for determination is
generally 1 nm.
7.1.3 Determined wavelength
In the development of product standards, the determined wavelength is
determined in accordance with the position of the substance to be determined,
which is generally selected from the wavelength range of the maximum
absorbance. If the maximum absorption peak is sharp OR if there is
interference from other absorption peak, it may select the other wavelengths
from the absorption curve.
7.4.4 Absorption pool
In accordance with the requirements of use, it may, in accordance with the
provisions of clause 2.2 “Matching of absorption pool” in JJG 178-1996 OR the
provisions of 12 “Specification of standard substance quartz absorption pool” in
JJG 682-1990, select the absorption pool; AND it may also use the quartz
absorption pool with the GBW 13304 standard substance certificate.
also use the standard sample comparison method to conduct calculation. As
for some acid-base indicator, it may use the column chromatography to
separate the impurities to determine the absorbance of the main solution; USE
the standard control method to calculate the content.
7.2.4 Determination of molar absorptivity
CONDUCT determination in accordance with the specified conditions of the
product standards.
The value of molar absorptivity ε is expressed by L / (cm•mol), which is
calculated in accordance with the equation (2).
A - The value of the absorbance;
c - The value of the molar concentration of the substance to be dete......
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