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SEMI C3.32-03 01 © SEMI 1987 , 2001 2 4.1.4.4 Determ i ne the time at which e t ha ne el utes from t he f ir st colum n a nd absorbs onto the s econd column so one can vent the chlorine. Inject the calibration ethane sta…
SEMI C3.32-0301 © SEMI 1987, 20011
SEMI C3.32-0301
SPECIFICATION FOR CHLORINE (Cl
2
), 99.996% QUALITY
This specification was technically approved by the Global Gases Committee and is the direct responsibility of
the North American Gases Committee. Current edition approved by the North American Regional Standards
Committee on October 17, 2000. Initially available at www.semi.org January 2001; to be published March
2001. Originally published in 1987; previously published in 1995.
1 Description
1.1 Gaseous chlorine is greenish-yellow and about 2.5
times as heavy as air. Chlorine has a disagreeable and
suffocating odor.
2 Specifications
QUALITY: 99.996%
Impurities
Maximum Acceptable Level
(ppm) (See NOTE 1.)
Carbon dioxide (CO
2
)10
Carbon monoxide (CO) 1
Hydrocarbons (C
1
– C
2
)1
Nitrogen (N
2
)20
Oxygen (O
2
)4
Water (H
2
O) (v/v) (See NOTE 2.)
TOTAL LISTED IMPURITIES
(excluding chromium, iron,
nickel, and sodium)
36
Maximum Acceptable Level
(ppm) (See NOTE 1.)
Chromium (Cr) 0.2 by wt. Liquid Phase
Iron (Fe) 0.2 by wt. Liquid Phase
Nickel 0.2 by wt. Liquid Phase
Sodium 1 by wt. Liquid Phase
NOTE 1: An analysis of significant figures has not been considered.
The number of significant figures will be based on analytical
accuracy and on the precision of the provided procedure.
NOTE 2: It is not known whether H
2
O remains as H
2
O in Cl
2
or
reacts to other species. For this reason, interpretation of H
2
O
measurement data is questionable. Test and acceptance criteria shall
be determined between user and supplier. Possible methods include:
a) determination of HCl by Fourier transform infrared spectrometry
(FTIR), mass spectrometry, or gas chromatography; b) measurement
of water by electrolysis in a P
2
O
5
cell (reported in terms of H
2
O
equivalents); c) determination of water by FTIR.
3 Physical Constants (for in formation only)
Metric Units US Units
Molecular weight 70.9 70.9
Boiling point at 1 atm -34.05°C -29.3°F
Density gas at 20°C (68°F)
and 1 atm
2.980 kg/m
3
0.1860 lb/ft
3
Specific gravity 2.473 2.473
Density liquid at -118°C
(-180.8°F)
1574.8 kg/m
3
98.26 lb/ft
3
4 Analytical Procedures
4.1 Carbon Monoxide, Carbon Dioxide, and
Hydrocarbons (CH
4
, C
2
H
2
, C
2
H
4
, C
2
H
6
) — This
procedure is for the determination of carbon monoxide,
carbon dioxide, and C
1
–C
2
hydrocarbons in chlorine.
The sample shall be vapor phase and analyzed using a
gas chromatograph with a flame ionization detector/
methanizer combination. (See Figure 1 and Notes 1, 2,
and 3.)
4.1.1 Detection Limit — 0.1 ppm (mol/mol).
4.1.2 Instrument Parameters
4.1.2.1 Injection Valve — 10 port corrosion-resistant.
4.1.2.2 Sample Volume — 2 mL.
4.1.2.3 Columns:
Column 1: Porapak P, 3.1 m (10 ft) by 3.2 mm (1/8 in) OD
ss or equivalent.
Column 2: Porapak P, 3.1 m by 3.2 mm OD ss or
equivalent.
4.1.2.4 Carrier Flow — 20 mL/min nitrogen.
4.1.2.5 Column Temperature — 40°C.
4.1.2.6 Air and Hydrogen Pressure and Flow — As
specified by the instrument manufacturer.
4.1.3 Calibration Standard — 1–5 ppm (mol/mol)
each component in nitrogen.
4.1.4 Operating Procedure
4.1.4.1 Place the 10 port valve in the sample load
position.
4.1.4.2 Turn on the methanizer heater and establish
hydrogen flow. Allow unit to heat to operating
temperature (as specified by the manufacturer).
4.1.4.3 Establish air flow and ignite burner following
the instrument manufacturer’s instructions. Allow the
system to stabilize for 15 minutes.
SEMI C3.32-0301 © SEMI 1987, 2001 2
4.1.4.4 Determine the time at which ethane elutes
from the first column and absorbs onto the second
column so one can vent the chlorine. Inject the
calibration ethane standard and record the retention
time of ethane obtained without returning the valve to
the load position. Multiply this time by 0.6. The result
will be the time during the analysis at which the
injection valve should be returned to the load position,
backflushing the chlorine to vent.
Repeat the injection of the ethane calibration standard,
including the backflush, to ensure that enough time has
passed to allow elution of ethane onto the second
column.
4.1.4.5 Inject the remaining standards using the
backflush technique. Record the retention times and
peak areas.
4.1.4.6 Analyze the chlorine sample to be tested in the
same manner as in 4.1.4.5. Repeat the sample injection
until peak areas of the impurity of interest agree within
5%.
4.1.4.7 Analyze each of the calibration standards again
as in 4.1.4.5.
4.1.4.8 Compare the average peak areas of the
calibration standards to those of the chlorine sample
being tested. Calculate the concentration of each
impurity, using the formula below. The results may not
exceed the specifications in Section 2 of this standard.
Sample Peak Are
a
Standard Peak Are
a
×
Concentratio
n
of Standard
=
Concentratio
n
of Sample
4.2 Oxygen and Nitrogen — This procedure is for the
determination of oxygen and nitrogen in chlorine. The
sample shall be vapor phase and analyzed using a gas
chromatograph with a thermal conductivity detector.
(See Figure 2 and Notes 1 and 2.)
4.2.1
Detection Limits — 2 ppm (v/v) oxygen, 5 ppm
(v/v) nitrogen.
4.2.2
Instrument Parameters
4.2.2.1 Injection Valve — 10 port corrosion-resistant.
4.2.2.2
Sample Volume — 2 mL.
4.2.2.3 Columns:
Column 1: Porapak Q, 1.8 m (6 ft) by 3.2 mm (1/8 in)
OD ss or equivalent.
Column 2: Molecular sieve 13×, 3.1 m (10ft) by 3.2 mm
OD ss or equivalent.
4.2.2.4 Carrier Flow — 20 mL/min he lium.
4.2.2.5
Temperature:
Column 30°C
Detector 50°C
4.2.3 Calibration Standard — 10–40 ppm (v/v) each
component in helium.
4.2.4
Operating Procedure
4.2.4.1 Place the 10 port valve in the sample load
position.
4.2.4.2 Inject the standard, wait one minute, then
return the valve to the sample load position to backflush
the principal gas to vent while allowing the oxygen and
nitrogen to pass to the analytical column. Record the
retention times and peak areas.
4.2.4.3
Inject the standard at least three times. All
peak areas for a specific impurity should agree within
5%.
4.2.4.4
Inject the chlorine sample to be tested in the
same manner as in 4.2.4.2 and 4.2.4.3. Record the
retention times and peak areas.
4.2.4.5
Repeat 4.2.4.2 and 4.2.4.3.
4.2.4.6 Compare the average peak areas of calibration
standards with that of the chlorine sample being tested.
Calculate the concentrations of oxygen and nitrogen,
using the formula below. The results may not exceed
the specifications in Section 2 of this standard.
Sample Peak Are
a
Standard Peak Are
a
×
Concentratio
n
of Standard
=
Concentratio
n
of Sample
4.3
Trace Elements — This procedure gives
instructions for the determination of trace elements in
liquid phase chlorine using inductively coupled plasma
mass spectrometry (ICP-MS). (See Note 4.)
4.3.1
Detection Limit — (See Note 4.)
4.3.2 Instrument Parameters — (See Note 4.)
4.3.3 Calibration Standards — (See Note 4.) All
instrument calibration standards should be prepared
from NIST-traceable reference standards.
4.3.4
Sample Collection Apparatus — (See Notes 5
and 6 and Figures 3 and 4.)
4.3.4.1 Cylinder Connector — Stainless steel, or other
suitable material, dependent on the cylinder valve used.
4.3.4.2
Fluorocarbon Tubing — 6.4 mm (1/4") and 3.2
mm (1/8") outer diameters required, lengths dependent
on construction of apparatus.
SEMI C3.32-0301 © SEMI 1987, 20013
4.3.4.3 Fluorocarbon Needle Valve — Two 6.4 mm
(1/4") needle valves (designated as V1 and V2). (See
Figure 3.)
4.3.4.4
Fluorocarbon Ball Valve — One 6.4 mm
(1/4") ball valve and one 3.2 mm (1/8") ball valve
(designated as V3 and V4, respectively). (See Figure
3.)
4.3.4.5
Fluorocarbon T-Joint — One 6.4 mm (1/4") T-
joint.
4.3.4.6 Fluorocarbon Cylinder Union — One 6.4 mm
(1/4") to 15.9 mm (5/8") iron pipe size female pipe
thread adapter to attach to the stainless steel cylinder
connector.
4.3.4.7
Fluorocarbon Reducer — One 6.4 mm (1/4")
to 3.2 mm (1/8") reducing union.
4.3.4.8 Flask Connector — One Plasmatech #16F424
flask connector, or similar, attached to a cap for the 100
mL sampling flask.
4.3.4.9
Sampling Flasks — 100 mL polypropylene
volumetric flask.
4.3.4.10 Nitrogen Source — A source of high-purity
nitrogen to purge the sampling system prior to and after
sampling and for evaporation.
4.3.4.11
Scrubber Source — A caustic scrubber source
to neutralize chlorine from the sampling process. The
scrubber is connected to an eductor tube, with the
vacuum created by an N
2
source regulated at 20 psi.
4.3.5 Operating Procedure
4.3.5.1 Assemble the system according to Figures 3
and 4, ensuring that the connections are leak tight.
4.3.5.2
Wrap Teflon tape around the threads of a 100
mL volumetric flask to ensure a good seal. Connect the
100 mL polypropylene flask to the flask connector as
shown in Figure 3. All 100 mL volumetric flasks used
for sample collection should be prepared in a similar
manner.
4.3.5.3
Clean the exterior of the cylinder CGA by
rinsing it with (in succession) 10% HNO
3
/DI H
2
O,
isopropanol/DI H
2
O, and DI H
2
O. The CGA must be
free of residue. The CGA is then cleaned and dried with
a cotton swab. Dry the exterior of the CGA with the
high-purity N
2
. Repeat the process for the nut and
gland. The cylinder CGA must be completely dry prior
to connecting the nut and gland.
4.3.5.4
Invert the cylinder with a cylinder inverter and
connect the cylinder CGA to the nut and gland.
4.3.5.5
Purge the system by opening V1 and V2 and
allowing high purity N
2
to flow through the system at
5–10 psig for a minimum of three minutes. The ball
valves (V3 and V4) remain in the open position.
4.3.5.6
Close V1 and V2. To condition the sampling
system, open the cylinder valve, then slowly open V2 to
allow Cl
2
to flow into the sample flask. After collecting
70–100 mL of Cl
2
, close the cylinder valve and open
V1 to purge the system.
4.3.5.7 Discard the initial Cl
2
sample by passing it
through to the scrubber, remove the flask and replace it
with a labeled sample flask. Continue to purge the
system for at least two minutes. Close V1 and V2. Open
the cylinder valve, then slowly open V2.
4.3.5.8
Allow 100 g of sample to be introduced into
the sample flask. Once this is completed, close V2, then
close the cylinder valve. Open V1 and V2 to allow for
purging of the Cl
2
in the sample flask with high purity
N
2
flowing through the system at 5 psig. This will
purge the Cl
2
at a rate of 7–10 gms per minute.
4.3.5.9 When the sample has been flushed, replace the
sample flask with another flask. Loosely cap the sample
flask to allow for any residual Cl
2
to evaporate. If
additional samples from the same cylinder are desired,
repeat Steps 4.3.5.5 through 4.3.4.9.
4.3.5.10
Close V1 and disconnect the cylinder valve
connector from the cylinder valve. Return the cylinder
to the upright position. Rinse the cylinder CGA and nut,
gland with DI H
2
O, and dry with N
2
. Remove the
cylinder from the cylinder inverter.
4.3.5.11
Repeat Steps 4.3.5.3 to 4.3.5.10 for additional
cylinders.
4.3.5.12
After obtaining all samples of interest, hand
dry the connector and place it into an oven to prevent
corrosion and build-up of condensation. Clean the
tubing and valve system with a 10% HNO
3
/DI H
2
O
solution and store in a 25% HNO
3
/DI H
2
O solution.
4.3.5.13 Fill each sample flask with a solution of 5%
ultrapure HNO
3
/DI H
2
O spiked with 25 ppb of an
internal standard (such as indium) up to the graduation
mark. Allow the samples to digest in the solution in the
flasks for a minimum of one hour. (See Note 7.)
4.4
Water — This procedure is for the determination
of moisture in gas phase chlorine using a continuous
flow electrolysis of water in a phosphorous pentoxide
(P
2
O
5
) cell. (See Notes 2 and 8.)
4.4.1 Detection Limit — 1 ppm (vol/vol).
4.4.2 Flow Rate — Set the sample flow rate and
pressure in accordance with the instrument
manufacturer's instructions.