Hydrogen sulfide (H2S), carbonyl
sulfide (COS), and methyl mercaptan
(CH3SH) are common
components in light hydrocarbon
streams. They have corrosive and toxic properties
that can damage pipes and equipment.
The emission of undesired odors caused by
volatile sulfur compounds in intermediates
and final products can have serious economic
and environmental impact. In addition, the
presence of sulfur can affect the performance
of industrial processes, resulting in chemical
reactions, loss of catalyst activity (catalyst
poisoning), and ultimately lower yield.
These sulfur components must be quantified
at low-ppb levels.1,2 They can be
measured with sulfur-specific detection
devices such as a pulsed flame photometric detector (PFPD), but large sample volumes
are needed to reach the desired
low-ppb detection limits. This creates
matrix overload and quenching
effects (decreased signal/sensitivity
due to background interferences) on
most sulfur-specific detectors, limiting
the detector’s sensitivity and linearity
and raising quantification limits.
The Agilent J&W Select Low Sulfur
porous layer open tubular (PLOT) column
capillary (Agilent, Middelburg,
The Netherlands) with novel stationary
phase was developed for the analysis
of sulfur species such as H2S, COS,
and CH3SH in light hydrocarbon C3
matrices. The column has high loadability
properties and unique selectivity,
giving baseline resolution for sulfur
components and matrix components.
The following was used—GC-PFPD column:
Agilent J&W Select Low Sulfur,
60 m × 0.32 mm (p/n CP8575); oven:
65 °C isotherm; carrier gas: helium with
a constant flow of 2.0 mL/min; injector:
200 °C, split 1:20; detector: PFPD, 200
°C; sample: propylene matrix containing
~500 ppb H2S, COS, and CH3SH;
injection volume: 1 mL; injection: gas
Results and discussion
The stationary phase shows good selectivity
between H2S, COS, and low mercaptans
in various C3 hydrocarbon matrices.
Therefore, coelution of the sulfur components
and the matrix, which causes
quenching, is avoided.
The system was equipped with a gas sampling
valve.The gas sampling valve event
table is shown in Table 1; the detector settings
are shown in Table 2.
Figure 1 - Chromatogram of sulfur compounds H2S, COS,
and CH3SH in a propylene matrix using the Agilent J&W Select
Low Sulfur column with GC-PFPD.
The chromatogram of sulfur compounds
H2S, COS, and CH3SH in a propylene
matrix is illustrated in Figure 1. Methyl mercaptan
shows peak broadening from column
overloading due to the large amount
of propylene. The propylene matrix elutes
between COS and methyl mercaptan.
The Agilent J&W Select Low Sulfur column
used in a GC with a sulfur-specific
detector, such as a PFPD, can detect H2S,
COS, and CH3SH at trace levels in a
propylene matrix as a result of effective
separation of the sulfur compounds and
the matrix. Separating the matrix from
the sulfur components eliminates the
quenching effects caused by the matrix,
and gives a better response for the sulfur
compounds. The column provides a good
response for reactive sulfur compounds,
such as H2S, which makes detections
of 20 ppb possible. Although this is
a PLOT column, no spikes will be
observed because the column does not
shed particles. It can therefore be used
safely in combination with valves.
- Wardencki, W. Review: Problems with
the determination of environmental
sulphur compounds by gas chromatography.
J. Chromatogr. A 1998, 793,
- Firor, R.L.; Quimby, B.D. Comparison
of sulfur selective detectors for low-level
analysis in gaseous streams. Agilent
Technologies publ. 5988-2426EN.
Ms. Jacobse is Research Engineer GC, Agilent
Technologies, Herculesweg 8 4338 PL, Middelburg,
The Netherlands; tel.: +31 118 671570;
fax: +31 118 671569; e-mail: helena.jacobse@