Attachment  
Argon  
Argon gas  
アルゴン  
 
 
Standards for use  
Not specified  
 
Compositional specifications  
Substance name  Argon  
Molecular weight  39.95  
Chemical name  [CAS number]  Argon [7440 -37-1] 
Definition  Argon is a substance produced using the air liquefaction separation 
method . 
Content   Argon contains not less than 99.0% (vol) of argon (Ar).  
Description   Argon is a colorless gas having no odor.  
Identification  
(1) When a burning wood chip with a flame is placed in a test tube containing 
Argon, the flame goes off . 
(2) Introduce Argon into a 1 -mL gas measuring tube for gas chromatography, and 
analyze it by gas chromatography using the operation conditions given in 
Purity (ii) below.  The retention time of the main peak corresponds to that of the 
main peak obtained when the reagent argon is analyzed in the same manner.  
Purity  Oxygen and Nitrogen   Not more than 1.0% (vol) as the total amount.  
(i) Oxygen   
Measure oxygen in Argon using a  yellow phosphor luminescent oxygen analyzer 
and determine the amount (% (vol)). If the amount of oxygen obtained exceeds the 
measurement range of the meter, exactly dilute the sample gas with oxygen -free 
nitrogen, and determine the amount . 
(ii) Nitrogen   
Introduce Argon into a 1 .0-mL gas measuring tube for gas chromatography at 
constant flow rate of 50 –150 mL/min, analyze it using the operating conditions 
below, and obtain the peak area (A T) of nitrogen. Separately, prepare a constant 
amount of a uniform gas mixture with the nitrogen concentration of about 0.5% 
(vol) by mixing a constant amount of nitrogen, measured exactly, with the carrier  
 
gas given below.  Use this as the standard gas mixture. Introduce the standard 
gas mixture into a gas measuring tube with same amount at the same flow rate, 
proceed as directed for Argon, and obtain the peak area (A S) of nitrogen in the 
gas mixture. Determine the amount (% (vol)) of nitrogen in Argon by the 
formula:  
 
Amount (% (vol)) of nitrogen (N 2)=VS×AT
AS 
 
VS: Amount (% (vol)) of nitrogen in the standard gas mixture  
 
Operating Conditions  
Detector: Thermal conductivity detector  
Column: A stainless steel  tube (about 3 mm internal diameter and about 3 m 
length)  
Column packing material: 180–250 μm zeolite for gas chromatog raphy  
Column temperature: A constant temperature of 50 –150C 
Carrier gas: Hydrogen or helium  
Flow rate: A constant rate of 20 –40 mL/min  
Injection: Loop injection using a gas measuring tube  
 
(iii) Total amount  
Determine the total amount of oxygen and nitrog en from the amount (% (vol)) of 
oxygen obtained in (i) and the amount (% (vol)) of nitrogen obtained in (ii) by the 
formula:  
 
Total amount (% (vol)) of oxygen and nitrogen (% (vol)) =VO+VN 
Vo：Amount (% (vol)) of oxygen obtained in (i)  
VN：Amount  (% (vol)) of  nitrogen obtained in (ii)  
 
Water content  Not more than 0.05% (vol)  
Measure using capacitance moisture meter and determine the amount (% (vol)) of 
the water content from the obtained value.  
Assay   Calculate the content of Argon from the total amount of ox ygen and nitrogen, 
and water content obtained in Purity (iii) by the formula:  
 
Content of argon (% (vol)) = 100 −VON−VW  
 
VON：Total amount (% (vol)) of oxygen and nitrogen  
VW: Amount (% (vol)) of water content  
 
Reagent and test solutions   Argon  Ar [K1105, Sec ond grade] [7440 -37-1] 
Measurement instruments  
For a y ellow phosphor luminescent  oxygen analyzer  and a  capacitance moisture 
meter , use unit s meeting  Japanese Industrial Standards K1105.