ISO 6326-4:1994
(Main)Natural gas — Determination of sulfur compounds — Part 4: Gas chromatographic method using a flame photometric detector for the determination of hydrogen sulfide, carbonyl sulfide and sulfur-containing odorants
Natural gas — Determination of sulfur compounds — Part 4: Gas chromatographic method using a flame photometric detector for the determination of hydrogen sulfide, carbonyl sulfide and sulfur-containing odorants
The method specified uses a single temperature-programmed column, and a sulfur-selective flame photometric detector. It is applicable to the determination of hydrogen sulfide, carbonyl sulfide, C1 - C4 thiols and sulfides and tetrahydrothiophene, generally in the range 0,5 µmol/mol to 50 µmol/mol. It is also applicable to the quantitative determination of sulfur compounds other than hydrogen sulfide, when hydrogen sulfide is present at concentrations up to 5000 µmol/mol.
Gaz naturel — Détermination des composés soufrés — Partie 4: Détermination du sulfure d'hydrogène, du sulfure de carbonyle et des composés soufrés malodorants par chromatographie en phase gazeuse avec détecteur à photométrie de flamme
General Information
Relations
Standards Content (Sample)
IS0 6326=4:1994(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(I EC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 6326-4 was prepared by Technical Committee
lSO/TC 193, Natural gas, Sub-Committee SC 1, Analysis of natural gas.
IS0 6326 consists of the following parts, under the general title Natural
- Determination of sulfur compounds:
gas
- Part I: General introduction
- Part 2: Gas chromatographic method using an electrochemical de-
tector for the determination of odoriferous sulphur compounds
- Part 3: Determination of hydrogen sulfide, mercaptan sulfur and
carbonyl sulfide sulfur by potentiometry
- Part 4: Gas chromatographic method using a flame photometric de-
tector for the determination of hydrogen sulfide, carbonyl sulfide and
sulfur-containing odoran ts
- Part 5: Lingener combustion method
0 IS0 1994
All rights reserved. No part of this publication may be reproduced or utilized in any form or
by any means, electronic or mechanical, including photocopying and microfilm, without per-
mission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 1 ----------------------
Introduction
The standardization of several methods for the determination of sulfur
compounds in natural gas is necessary in view of the diversity of these
compounds [hydrogen sulfide, carbonyl sulfide, thiols (mercaptans), tetra-
hydrothiophene (THT), etc.] and the purposes of the determinations (re-
quired accuracy, measurement at the drilling head or in the transmission
pipes, etc.).
In order to enable the user to choose the method most appropriate to his
needs and to perform the measurements under the best conditions,
IS0 6326 has been prepared in several parts.
IS0 6326-l gives a rapid comparison of standardized methods and there-
fore provides information for the choice of the method.
The other parts of IS0 6326, including this part, describe in detail the
various standardized methods.
The determination of total sulfur is specified in IS0 4260:1987, Petroleum
Determination of sulfur content - Wickbold
products and hydrocarbons -
combustion method.
. . .
Ill
---------------------- Page: 2 ----------------------
This page intentionally left blank
---------------------- Page: 3 ----------------------
IS0 6326-4: 1994(E)
INTERNATIONAL STANDARD
Natural gas - Determination of sulfur compounds -
Part 4:
Gas chromatographic method using a flame photometric
detector for the determination of hydrogen sulfide,
carbonyl sulfide and sulfur-containing odorants
IS0 6143:1981, Gas analysis - Determination of
1 Scope
composition of calibration gas mixtures - Compari-
son methods.
This part of IS0 6326 specifies a precise and accurate
method for the analysis of sulfur compounds in natu-
ral gas.
3 Principle
This method is applicable to the determination of hy-
drogen sulfide, carbonyl sulfide, Cl-C4 thiols and sul-
The components are separated using a temperature-
fides and tetrahydrothiophene (THT), generally in the
programmed oven and a column of
range 0,5 ~mol/mol to 50 ~mol/mol. It is also appli-
styrene/divinylbenzene porous polymer beads and
cable to the quantitative determination of sulfur com-
measured with a sulfur-selective flame photometric
pounds other than hydrogen sulfide, when hydrogen
detector. Potentially interfering hydrobarbons are also
sulfide is present at concentrations up to
separated from the sulfur compounds. Some sulfur
5 000 ~mol/mol.
compounds are not completely resolved from others.
Identification can be aided by selective scrubbing of
The method uses a single temperature-programmed
the sample to remove different types of sulfur com-
column, and a sulfur-selective flame photometric de-
pound (see 7.4.2).
tector (FPD).
4 Materials
4.1 Gases
2 Normative reference
4.1.1 Carrier gas, nitrogen, helium or argon, [purity
The following standard contains provisions which,
> 99,9 % (I&Z)], free from oxygen and moisture.
through reference in this text, constitute provisions
of this part of IS0 6326. At the time of publication, the
edition indicated was valid. All standards are subject
4.1.2 Auxiliary gases, hydrogen and oxygf ?n or air,
to revision, and parties to agreements based on this
[purity > 99,9 % (m/m)].
part of IS0 6326 are encouraged to investigate the
possibility of applying the most recent edition of the
and sul-
standard indicated below. Members of IEC and IS0 4.2 Reference materials, individual thiols
lene, hy-
maintain registers of currently valid International fides in the range Cl to C4, tetrahydrothiopt
Standards. drogen sulfide and carbonyl sulfide.
---------------------- Page: 4 ----------------------
IS0 6326-4: 1994(E)
The tube shall have the following dimensions:
5 Apparatus
- length: 1,2 m;
5.1 Gas chromatograph, capable of temperature
- diameter: 2 mm internal or external, depending on
programming and fitted with an FPD.
the chromatograph;
NOTE 1 The FPD is insensitive to hydrocarbons, and
- radius: suitable for the chromatograph.
therefore may not register the presence of a hydrocarbon
which co-elutes with and, consequently, may quench the
response of a sulfur compound. The conditions quoted in
5.3.2 Packing
this method should avoid such interference for the majority
of natural gas compositions. If required, the column effluent
can be split between the FPD and a parallel flame ionization styrene/divinylbenzene porous
5.3.2.1 Material:
detector (FID). The FID will clearly show potential hydro-
polymer beads, of particle size 150 pm to 180 km (80
carbon interference.
to 100 ASTM mesh).
Before use, the packing shall be washed with acetone
51.1 Column oven, with a temperature range of
to remove soluble impurities.
50 “C to 250 “C, capable of being maintained at within
& 0,5 “C at any temperature in the range during an NOTE 2 This is conveniently carried out by placing a
suitable quantity of packing into a sintered filter funnel con-
analysis.
nected to a vacuum source.
The packing shall be washed with 2 or 3 aliquots of
5.1.2 Temperature control. The oven shall be pro-
acetone, and then dried by continuing to draw air
vided with a linear programmer suitable for providing
through it.
a rate of temperature change of 10 “C/min over the
specified range.
After packing, overnight treatment, at approximately
230 “C with carefully dried carrier gas flowing, is
necessary for good separation.
5.1.3 Flow controller, to supply a suitable carrier
gas flowrate.
5.3.2.2 Method of packing: any method which re-
sults in uniform packing may be used.
5.1.4 Pressure controllers and restrictors, to sup-
NOTE 3 The following method is suitable. Close the col-
ply suitable auxiliary gas flowrates.
umn outlet with a sintered disc or glass wool plug. Connect
a reservoir containing rather more packing than is required
to fill this column, to the inlet, and apply a pressure of
5.2 Injection device, comprising either
400 kPa of nitrogen to the reservoir. The flow of packing
into the column may be assisted by vibration. When the
column is full, allow the pressure to decrease normally be-
- a gas-tight syringe, of capacity 5 ml, constructed
fore disconnecting the reservoir. Porous polymer beads of-
of glass and polytetrafluoroethylene (PTFE), or
ten collect static changes, which makes their handling
difficult. This effect can be reduced by chilling the batch in
- a bypass injector, capable of injecting samples
a closed container in a refrigerator for several hours before
from 0,5 ml to 5 ml.
use.
A valve constructed entirely of PTFE is suitable under
all circumstances. Certain valves constructed of
5.3.2.3 Efficiency: when operated under the rec-
stainless steel and PTFE have also been found to be
ommended conditions, the separations shall be simi-
suitable. Before use, any such valve shall be tested
lar to, or better than, those shown in figures 1 and 2.
for
possible adsorptive effects on sample com-
ponents.
5.3.2.4 Adsorptive behaviour
NOTE 4 Loss of sulfur compounds by adsorption onto
surfaces can occur anywhere in the system, not only in the
5.3 Column: a single column sha I be used.
column. Hydrogen sulfide and thiols of low relative mol-
ecular mass are most likely to be lost in this way, and
therefore the effect can be evaluated by successive in-
5.3.1 Tube, constructed of glass, perfluoro(ethylene-
jections of a stable gas mixture containing hydrogen sulfide
propylene) (FEP), or any material which has been
or methanethiol at an appropriate concentration. A gradual
shown not to absorb sulfur compounds and which is
increase in peak size with successive injections indicates
suitable for the temperature range given in 7.1 .l .l .
adsorptive losses. In many cases, such losses can be re-
The form of the tube is suitable for the chromatograph
duced by injection of commercially available silanizing re-
(5.1).
agents, such as dimethyldichlorosilane (DMCS).
---------------------- Page: 5 ----------------------
5.4 Flame photometric detector, operating in the independently heated, set it to 100 “C + 10 “C. If
sulfur mode.
there is a separately heated inlet zone, set it tu
100 “C * 10 “C.
If used with an amplifier, the time constant shall be
not greater than 0,l s.
7.1.1 Oven and column
5.5 Potentiometric recorder, with a sensitivity and
7.1.1.1 Temperature programme
impedance suitable for the detector or amplifier and
a response time not greater than 0,5 s.
Set t
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.