ARGON

New specifications prepared at the 53rd JECFA (1999) and published in FNP 52 Add 7 (1999).

SYNONYMS

INS No. 938

DEFINITION

Chemical names

Argon

C.A.S. number

7440-37-1

Chemical formula

Ar

Formula weight

40.0

Assay

Not less than 99.0% by volume

DESCRIPTION

Colourless and odourless gas

FUNCTIONAL USES

Packaging gas

CHARACTERISTICS

IDENTIFICATION

Flame test

The flame of a burning splinter of wood is extinguished when inserted into an upright test tube filled with argon

PURITY

Water

Passes test
See description under TESTS

Oxygen, nitrogen, hydrogen

Not more than 1.0% in combination
See description under TESTS

Odour

Carefully open the container valve to produce a moderate flow of gas. Do not direct the gas stream toward the face, but deflect portion of the stream toward the nose: no appreciable odour is discernible

TESTS

PURITY TESTS

Water

Pass 24,000 ml of the gas sample through a suitable water-absorption tube no less than 100 mm in length, which previously has been flushed with about 500 ml of the sample and weighed. Regulate the flow so that about 60 min will be required to for passage of the gas. The gain in weight of the absorption tube does not exceed 1.0 mg.

Oxygen, nitrogen, hydrogen

Determine by Gas chromatography using the following conditions:

Column:

- material: stainless steel

- length: 6 m

- internal diameter: 6 mm

- packing material: appropriate molecular sieves, e.g. 5A

Carrier:

- gas: Helium (not less than 99.99 % (v/v))

- flow: 30 ml/min

Detector: thermal conductivity detector

Injector: loop injector

Column temperature: 50�

Detector temperature: 130�

Reference gas (a): reference gases hydrogen, oxygen, nitrogen

Gas to be examined (b)

Procedure: Individually inject reference gases (a). Adjust the injected volumes and operating conditions so that the analyzer will be capable of separating and detecting the named components with a sensitivity of 0.1 �l/l or 10% of the specified maximum amount of the component, whichever is greater. Appropriate impurity concentrating techniques may be used to attain the sensitivity. The analyzer is to be calibrated at appropriate intervals by the use of individual calibration gas standards.

Inject the gas to be examined (b). In the chromatogram obtained with the gas to be examined, the total areas of the hydrogen, oxygen and nitrogen should not exceed 1.0% of the total volume of the gas to be examined.

METHOD OF ASSAY

After determination of the total content of water, hydrogen, oxygen and nitrogen the balance consists of argon

	New specifications prepared at the 53rd JECFA (1999) and published in FNP 52 Add 7 (1999).
SYNONYMS	INS No. 938
DEFINITION
Chemical names	Argon
C.A.S. number	7440-37-1
Chemical formula	Ar
Formula weight	40.0
Assay	Not less than 99.0% by volume
DESCRIPTION	Colourless and odourless gas
FUNCTIONAL USES	Packaging gas
CHARACTERISTICS
IDENTIFICATION
Flame test	The flame of a burning splinter of wood is extinguished when inserted into an upright test tube filled with argon
PURITY
Water	Passes test See description under TESTS
Oxygen, nitrogen, hydrogen	Not more than 1.0% in combination See description under TESTS
Odour	Carefully open the container valve to produce a moderate flow of gas. Do not direct the gas stream toward the face, but deflect portion of the stream toward the nose: no appreciable odour is discernible
TESTS
PURITY TESTS
Water	Pass 24,000 ml of the gas sample through a suitable water-absorption tube no less than 100 mm in length, which previously has been flushed with about 500 ml of the sample and weighed. Regulate the flow so that about 60 min will be required to for passage of the gas. The gain in weight of the absorption tube does not exceed 1.0 mg.
Oxygen, nitrogen, hydrogen	Determine by Gas chromatography using the following conditions: Column: - material: stainless steel - length: 6 m - internal diameter: 6 mm - packing material: appropriate molecular sieves, e.g. 5A Carrier: - gas: Helium (not less than 99.99 % (v/v)) - flow: 30 ml/min Detector: thermal conductivity detector Injector: loop injector Column temperature: 50� Detector temperature: 130� Reference gas (a): reference gases hydrogen, oxygen, nitrogen Gas to be examined (b) Procedure: Individually inject reference gases (a). Adjust the injected volumes and operating conditions so that the analyzer will be capable of separating and detecting the named components with a sensitivity of 0.1 �l/l or 10% of the specified maximum amount of the component, whichever is greater. Appropriate impurity concentrating techniques may be used to attain the sensitivity. The analyzer is to be calibrated at appropriate intervals by the use of individual calibration gas standards. Inject the gas to be examined (b). In the chromatogram obtained with the gas to be examined, the total areas of the hydrogen, oxygen and nitrogen should not exceed 1.0% of the total volume of the gas to be examined.
METHOD OF ASSAY	After determination of the total content of water, hydrogen, oxygen and nitrogen the balance consists of argon