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SEMI C3.35-11 01 © SEMI 1988 , 2001 5 required. This can be obt ained by preparing a standard of w a ter balance n itrogen and mixing it with dr y hydrog e n chl oride using a dynamic gas blender with mass flow controlle…

SEMI C3.35-1101 © SEMI 1988, 2001 4

4.6 Methane and Acetylene — This procedure is for the

determination of methane and acetylene in hydrogen

chloride. Samples from gas phase are analyzed by a gas

chromatograph with a flame ionization detector. A

backflush is used to keep the main component from the

detector. (See Figure 2.)

4.6.1 Detection Limit — 0.1 ppm for each impurity.

4.6.2 Instrument Parameters

4.6.2.1 Column:

Alumina-GC, 60-80 mesh, Chromopack, 1.5 m (5 ft) by

2 mm ID (1/8 in OD) ss;

Alumina-GC, 60-80 mesh, Chromopack, 2 m (6.7 ft) by

2 mm ID (1/8 in OD) ss;

or equivalent.

4.6.2.2 Detector Sensitivity: 0.012 coulombs/gram.

4.6.2.3 Carrier Flows (1 and 2): 30 mL/min helium.

4.6.2.4 Set the following rates as specified by the

instrument manufacturer.

Support Gases:

Hydrogen Flow: 30 mL/min.

Air Flow: 450 mL/min.

4.6.2.5 Temperatures:

Detector 200°C

Column Oven 100°C

4.6.2.6 Sample Volume: 0.5 mL.

4.6.2.7 Sample Flow: 200 mL/min.

4.6.3 Calibration Standard — 5 to 10 ppm each

methane and acetylene in nitrogen.

4.6.4 Operating Procedure

4.6.4.1 Install switching valve and columns.

4.6.4.2 Adjust carrier gas flows:

Switching valve in injection position

• Set a flow rate of 30 mL/min, with the regulator T1

measured at the FID outlet.

Switching valve in backflush position

• Set a flow rate of 30 mL/min, with the regulator T2

measured at the FID outlet.

• Set a flow rate of 30 mL/min, with the metering

valve, measured at the pre-column outlet.

A last adjustment between the injection and backflush

position may be carried out by the FID signal. For this,

the baseline is recorded in the injection and backflush

position. With the regulator T2, the flow rate is changed

so far as there is no offset in the baseline while

switching.

4.6.4.3 Adjust hydrogen and air flows and ignite the

burner, following the instrument manufacturer's

instructions. Allow the system to stabilize for at least 30

minutes.

4.6.4.4 Determine backflush time — Inject calibration

standard and leave the switching valve in inject position

until all components have been eluted. Determine

retention times for methane and acetylene. Choose

backflush time so that the acetylene peak is completely

registered.

4.6.4.5 Inject the calibration standard. Backflush at the

time determined in Section 4.6.4.4. Record the

retention times and peak areas.

4.6.4.6 Inject the sample to be tested in the same

manner as the calibration standard. Backflush at the

time determined in Section 4.6.4.4. Record the

retention times and peak areas.

4.6.4.7 Repeat Section 4.6.4.5.

4.6.4.8 Compare the average peak areas of the

calibration standard with those of the hydrogen chloride

sample being tested. Calculate the concentration of each

impurity, using the formula below. The results may not

exceed the specifications in Section 3 of this standard.

Sample Peak Area

Standard Peak Area

Concentration

of Standard

Concentration

of Sample

4.7 Water — This procedure is for the determination of

trace moisture (water) in hydrogen chloride gas using a

continuous flowing, cooled-surface condensation point

hygrometer.

4.7.1 Detection Limit — 1.0 ppm.

4.7.2 Flow Requirements

4.7.2.1 Set the sample flow rate and pressure in

accordance with the instrument manufacturer’s

instructions.

4.7.3 Calibration Standards

4.7.3.1 A calibration thermometer designed to indicate

temperatures in the –89°C (–121°F) range is required.

NOTE 4: The National Institute of Standards and Technology

(NIST) provides calibration services for the thermometers

used in condensation point hygrometers.

4.7.3.2 A calibration curve representing water added to

dried hydrogen chloride vs. condensation point is

SEMI C3.35-1101 © SEMI 1988, 20015

required. This can be obtained by preparing a standard

of water balance nitrogen and mixing it with dry

hydrogen chloride using a dynamic gas blender with

mass flow controllers or calibrated flowmeters. The

hydrogen chloride gas can be dried by passing it over

activated molecular sieve (5A) or magnesium

perchlorate.

NOTE 5: This method is not applicable if other constituents

in the gas will condense before the moisture condensation,

e.g., carbon dioxide or oil.

4.7.4 Operating Procedure

4.7.4.1 Obtain a continuous flow of sample gas from

the source using a clean stainless steel sampling line

which has been purged dry after exposure to ambient

moisture.

NOTE 6: The sampling system and hygrometer must be

designed to operate under the sample pressure, or the sample

pressure must be reduced to accommodate the pressure

restrictions of the analytical hygrometer using a regulator with

a diaphragm of stainless steel or other suitable material.

4.7.4.2 After prepurging with a dry gas, allow the

sample gas to flow through the sampling system and the

condensation point hygrometer for one-quarter hour to

two hours to allow the entire system to reach

equilibrium with regards to moisture content.

4.7.4.3 After equilibrium has been reached, cool the

mirror to determine the actual condensation point of the

sample.

4.7.4.4 Continue to verify the condensation point for at

least 30 minutes after a stable reading has been

confirmed.

4.7.4.5 Correct the condensation point reading from the

measured pressure to 1 atm of pressure. The result may

not exceed the specification in Section 2 of this

standard.

Figure 1

Metals Analysis Sampling Apparatus Vapor Phase Hydrolysis

Figure 2

Column Configuration for the Analysis of Methane, Acetylene

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