ASTM D5303-20

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5303 − 19 D5303 − 20
Standard Test Method for
Trace Carbonyl Sulfide in Propylene by Gas
Chromatography
This standard is issued under the fixed designation D5303; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers the determination of traces of carbonyl sulfide (COS) in propylene. It is applicable to COS
concentrations from 0.5 mg ⁄kg to 4.0 mg ⁄kg (parts per million by mass). See Note 1.
NOTE 1—The lower limit of this test method is believed to be below 0.1 mg ⁄kg, depending on sample size and sensitivity of the instrumentation being
used. However, the cooperative testing program was conducted in the 0.5 to 4.0 range due to limitations in preparing commercial test mixtures.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. Specific hazards statements are given in Section 89.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1835 Specification for Liquefied Petroleum (LP) Gases
D3609 Practice for Calibration Techniques Using Permeation Tubes
D4468 Test Method for Total Sulfur in Gaseous Fuels by Hydrogenolysis and Rateometric Colorimetry
E355 Practice for Gas Chromatography Terms and Relationships
E840 Practice for Using Flame Photometric Detectors in Gas Chromatography
3. Terminology
3.1 Definitions:
3.1.1 Additional terminology related to the practice of gas chromatography can be found in Practice E355.
3.1.2 liquefied petroleum gas (LPG), n—hydrocarbon gases that can be stored or handled in the liquid phase through
compression or refrigeration, or both.
3.1.2.1 Discussion—
LPG’s generally consist of C and C alkanes and alkenes or mixtures thereof and containing less than 10 % by volume of higher
3 4
carbon number material. Vapor pressure does not normally exceed 2000 kPa at 40 ºC.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 propane/propene mixtures, n—mixtures primarily composed of propane and propene where one of these components is
usually in the concentration range of 30 % to 85 % by mass with the other comprising the majority of the remainder. Commercial
Propane in Specification D1835 is typically this sort of product mixture.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.D0.03 on Propylene.
Current edition approved May 1, 2019July 1, 2020. Published June 2019July 2020. Originally approved in 1992. Last previous edition approved in 20122019 as
D5303 – 92 (2012).D5303 – 19. DOI: 10.1520/D5303-19.10.1520/D5303-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5303 − 20
3.2.1.1 Discussion—
Other components may be present, usually at less than 10 % by mass.
4. Summary of Test Method
4.1 A procedure is given for removing a sample from the sample cylinder, separating COS from propylene, detecting COS,
calibrating the detector, quantitating COS content in the sample, and assaying the gas standard. General comments and
recommended techniques are given.
4.2 A relatively large volume of sample is injected into a gas chromatograph having a single packed column, operated
isothermally at 10 °C to 50 °C, that separates COS from propylene. COS is detected with a flame photometric detector.
4.3 Calibration data, based on peak areas, are obtained using a known gas standard blend of COS in the range expected for the
sample. The COS peak area in the sample is measured and the concentration of COS calculated.
4.4 The COS gas standard blend is assayed prior to use for calibration.
5. Significance and Use
5.1 In processes producing propylene, COS usually remains with the C hydrocarbons and must be removed, since it affects
product quality. COS acts as a poison to commercial polymerization catalysts, resulting in deactivation and costly process
downtime.
5.2 Accurate gas chromatographic determination of trace COS in propylene involves unique analytical problems because of the
chemical nature of COS and idiosyncracies of trace level analyses. These problems result from the reactive and absorptive nature
of COS, the low concentration levels being measured, the type of detector needed, and the interferences from the propylene sample
matrix. This test method addresses these analytical problems and ways to properly handle them to assure accurate and precise
analyses.
5.3 This test method provides a basis for agreement between two laboratories when the determination of trace COS in propylene
is important. The test method permits several calibration techniques. For best agreement between two labs, it is recommended that
they use the same calibration technique.
6. Interferences
6.1 Hydrogen sulfide (H S) or sulfur dioxide (SO ) can be present in the propylene and must be separated from COS. (See Note
2 2
2.)
NOTE 2—H S and SO are separated from COS with the Carbopack BHT 100 columns or with the Chromosil 300 column.
2 2
7. Apparatus
7.1 Gas Chromatograph—Any gas chromatograph (GC) equipped with a flame photometric detector/electrometer system
(FPD), as described in 6.27.2, may be used. A GC/FPD equipped with an output signal linearizer is also permitted.
7.2 Detector System, flame photometric detector, either single or dual burner design. Noise level must be no more than one
recorder chart division (see 6.57.5). The signal for COS must be at least twice the noise level at the 0.1 mg ⁄kg level. A discussion
−12
of this detector is presented in Practice E840. The electrometer used with the detector must have a sensitivity of 10 A full scale
on a 1 mV recorder to achieve optimum detectability at lowest levels.
NOTE 3—The sulfur detector based on the chemiluminescence principle (GC_SCD) has shown good results for COS. However, no precision is
determined for this detector in this application. The achievable lower limit for COS in Propylene is 0.04 mg ⁄kg (30 ppbMol).
7.3 Column—Any column that will effect the complete separation of COS from propylene and other compounds normally
present in propylene concentrates, and that is sufficiently inert to preclude the loss of COS, may be used. Columns that meet these
criteria, and that were used in the cooperative study for this test method, are listed in Table 1.
7.4 Sample Inlet System—Any gas sampling valve or gas tight syringe that will permit introduction of up to 5.0 mL to the
column, and that will not cause any loss of COS, is suitable.
7.5 Recorder—Any strip chart recorder with a full scale range of 1 mV, a maximum full scale balance time of 2 s, and a
minimum chart speed of 0.5 cm ⁄s, may be used.
7.6 Data Handling System—Any commercially available GC integrator or GC computer system capable of accurately
integrating the area (uVs) of the COS peak is satisfactory. Data systems that will linearize the logarithmic output of the FPD are
also satisfactory.
7.7 Sample Cylinders, 300 mL capacity or larger, fluorocarbon lined stainless steel, Type DOT 3E, 12409 kPa (1800 psi)
working pressure.
D5303 − 20
A
TABLE 1 Suitable GC Columns and Temperatures
Column Packing and Oven
B
Size, m × mm Tubing Type
Number Temperature, °C
1 0.9 × 3.78 SS Porapak R, 80/100 Mesh; 47
C
2 1.4 × 3.78 TFE Carbopack BHT 100, 40/60
D
Mesh; 25,40
D
3 1.8 × 3.78 TFE Carbopack BHT 100; 25,30
4 1.8 × 3.78 TFE Porapak Q, AW, 50/80 Mesh
2.4 × 3.78 TFE (Above in Series); 74
5 2.4 × 3.78 SS Carbopack BHT 100; 47
6 2.8 × 3.78 TFE Carbopack BHT 100, 40/60
Mesh; 50
7 3.6 × 3.78 TFE Carbopack BHT 100, 40/60
Mesh; 50
E
8 4.3 × 3.78 TFE Chromosil 300; 50
9 6.1 × 3.78 TFE Hayes Sep Q, 80/100 Mesh; 65
A
These columns have been tested cooperatively and found suitable for use with
this test method.
B
316 SS Tubing for columns or connection of sample cylinder to sampling system
can be TFE lined internally to improve on system stability. This tubing is
commercially available from chromatography vendors.
C
TFE—Homopolymer of tetrafluoroethylene.
D
Identical columns used by different labs at different temperatures.
E
Propyne (methyl acetylene) can interfere with COS using this column.
8. Reagents and Materials
8.1 Air, zero grade.
8.2 Carbonyl sulfide (COS), lecture bottle, 97.5 % min. (Warning—Toxic! See Section 89, Hazards.)
8.3 Gas Calibration Blends, 1 mg ⁄kg to 10 mg ⁄kg COS in either nitrogen, argon, propylene or a propylene/argon mixture. They
can be obtained from any commercial supplier or prepared as shown in Appendix X1 or Test Method D4468.
8.4 Gas Sampling Syringe, 0.1 mL, 1.0 mL, and 5.0 mL.
8.5 Gas Sampling Valve and Sample Loops, fluorocarbon or 316 stainless steel. See Footnote B of Table 1.
8.6 Glass Vials, 125 cm.
8.7 Hydrogen, pure grade, 99.9 %.
8.8 Isooctane (2,2,4-trimethylpentane), sulfur free, minimum purity 99 mol %. (Warning—Flammable! Health Hazard.)
8.9 Nitrogen or Helium, 99.999 % min.
8.10 TFE-fluorocarbon septa and aluminum seals for vials.
9. Hazards
9.1 Carbonyl sulfide is toxic and narcotic in high concentrations, and upon decomposition can liberate hydrogen sulfide.
Exposure to dangerous concentrations of COS is most likely when handling the pure component for preparation of standard blends
for assaying the COS calibration gas standards.
10. Sampling
10.1 Supply samples to the laboratory in high pressure cylinders coated internally with TFE-fluorocarbon, or otherwise specially
treated to reduce or eliminate loss of COS due to reaction with the cylinder walls.
10.2 The sample cylinder and contents should be at room temperature prior to sampling to the chromatograph. Test samples as
soon as possible after receipt.
NOTE 4—Cooperative studies indicate that the measured value for COS will decrease with time.
10.3 Place the sample cylinder in a vertical position and use either of the following two techniques to obtain a vaporized sample
from the container for introduction into the GC.
10.3.1 Connect the sample cylinder to the sampling valve on the chromatograph, using a minimum length of 316 ss tubing, so
that sample is withdrawn from the bottom of the cylinder. Adjust the flow rate from the sample cylinder so that complete
vaporization of the liquid occurs at the cylinder valve. A flow rate of 5 bubbles ⁄s to 10 bubbles ⁄s through a water bubbler placed
at the sample vent is sufficient (see Note 5). Turn the sampling valve to the “flush” position and flush for approximately 15 s. Shut
off the cylinder valve and allow the pressure to drop to atmospheric.
NOTE 5—If the flow rate is too fast, warming of the valve can be required to avoid freezing and to ensure complete vaporization of the sample.
D5303 − 20
10.3.2 Alternatively, obtain a sample with a gas tight syringe. A convenient way to do this is to use flexible plastic tubing to
connect the bottom of the sample cylinder to the water bubbler and then to pierce the tubing with the
...