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GB/T 35925-2018 PDF in English

GB/T 35925-2018 (GB/T35925-2018, GBT 35925-2018, GBT35925-2018)
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GB/T 35925-2018: PDF in English (GBT 35925-2018)

GB/T 35925-2018
ICS 71.040.40
G 09
Determination of Impurity Fluorine Ion in Water
Soluble Chemicals – Ion Chromatography Method
Issued by. General Administration of Quality Supervision, Inspection and
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Principle ... 4
4 Reagents and Materials ... 5
5 Apparatus ... 5
6 Analytical Procedures ... 5
7 Result Calculation ... 7
8 Precision ... 7
Appendix A (Informative) Reference Chromatographic Conditions ... 8
Appendix B (Informative) Relevant Chromatograms of Determination of
Impurity Fluoride ion in Water-Soluble Chemicals ... 9
Determination of Impurity Fluorine Ion in Water
Soluble Chemicals – Ion Chromatography Method
1 Scope
This Standard specifies the ion chromatographic method for the determination of
impurity fluoride ion (F-) content in the water-soluble chemicals.
This Standard is applicable to the determination of fluoride ion content in water-soluble
chemicals with fluoride ion content ≤400mg/kg.
In this Standard, the quantitative limit of organic chemicals is 0.02mg/kg; while the
quantitative limit of inorganic chemicals is 4.0mg/kg.
This Standard is not applicable to the insoluble chemicals and the chemicals with main
component containing fluorine.
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) are applicable to this document.
GB/T 6682 Water for Laboratory Use – Specifications
3 Principle
After treatment, the sample forms an aqueous solution; enters into the ion exchange
chromatographic column with ion exchange resin as a stationary phase; the ion
exchange resin is distributed by fixed charged group and free coordination ion; when
eluted with a suitable eluent, the active exchange group on the ion exchange resin
undergoes the ion exchange with ions in the test solution and ions in the eluent. As the
eluent continues to flow, the anion in the test solution and the exchange group continue
to occur exchanging – eluting – re-exchanging – re-eluting; depending on the different
retention characteristics of the test anion on the chromatography column, the
separation is realized; finally, the test anion is carried by the eluent to the detector and
form a chromatographic peak. The group ion is qualitative by the retention time of each
scale; perform ultrasound for 10min; stand for 60min; filter the supernatant by the filter
membrane for testing.
Organic chemicals. pipette 50mL of specimen into 100mL beaker; add 150µL of
sodium hydroxide (4.2) to alkalinize; then evaporate to near dryness in water bath;
dilute the slag with pure water; make constant volume into 10mL volumetric flask;
perform ultrasound for 10min; stand for 60min; filter the supernatant by the filter
membrane for testing.
Alkali chemicals. accurately take 1.0g~3.0g (accurate to 0.001g) of specimen into
50mL beaker; dissolve into water; then transfer to 100mL volumetric flask; dilute to the
scale; perform the ultrasound for 10min; stand for 60min; take the supernatant to pass
the hydrogen-type cation exchange cartridge; collect the filtrate to filter by the filtered
membrane for testing.
6.2 Ion chromatographic conditions
a) Mobile phase. select according to the separation column, so that meet the
requirements of separation in 5.5; meanwhile the main component can be eluted
without disturbing the subsequent separation. For example, 20mmol/L sodium
hydroxide solution (4.1).
b) Flowrate. 1.0mL/min.
c) Column temperature. 30°C.
d) Sample injection volume. 25µL.
e) Detector. conductivity detector.
6.3 Standard working curve
Preparation of standard working solution. take 10mL of fluoride ion standard stock
solution (4.3) into a 100mL volumetric flask; dilute with water to the scale; then prepare
the 10µg/mL fluoride ion standard solution. Separately take 0.4mL, 0.8mL, 1.0mL,
2.0mL, 4.0mL, 5.0mL, 20.0mL, 50.0mL of fluoride ion standard solution into 100mL
volumetric flasks; dilute with water to the scale; then prepare the standard working
solution with fluoride ion concentration of 0.04µg/mL, 0.08µg/mL, 0.1µg/mL, 0.2µg/mL,
0.4µg/mL, 0.5µg/mL, 2.0µg/mL, 5.0µg/mL; such solution shall be prepared for current
Take the above standard working solutions from the low to high concentrations into the
ion chromatograph; draw a standard curve with ion concentration as abscissa and
peak area as the ordinate.
6.4 Sample determination
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.