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Achieve accurate analysis of sulfur and nitrogen with the new and simplified Agilent 8355 SCD

Jason Ashe, Agilent GC Product Manager

As a direct result of the increased use of lower grade raw materials and tighter global regulations on pollution—low level sulfur testing is becoming more ubiquitous in both up and downstream activities.

Industry experts agree that sulfur chemiluminescence detection (SCD) is the detector of choice for the accurate measurement of low level sulfur in hydrocarbon matrices. However, until now, the design and user interaction has been complicated and cumbersome. Agilent has reimagined the SCD user experience by completely redesigning the 25-year-old industry standard to deliver superior results on a simplified platform. This article examines two critical aspects of the new Agilent 8355 SCD—performance and ease of operation.

GC with SCD provides rapid identification and quantitation of sulfur species

Gas chromatography with sulfur chemiluminescence detection provides a rapid means of identifying and quantifying sulfur impurities and/or sulfur based odorants in natural gas and gaseous fuels, such as sulfur compounds found in air, methane, propane, digester gas, and refinery fuel gases.

As with any process, there can be a significant impact on throughput and profitability metrics if the process is not properly controlled. Chemiluminescence is recognized as one of the most reliable detection methods for analyzing a variety of sulfur compounds.

Agilent 8355 SCD exceeds global testing requirements

A sulfur chemiluminescence detector (SCD) is comprised of three main components: Dual Plasma Burner, Reaction Cell, and Detector. Each component needs to work without fail to demonstrate robustness, ease of use, and analytical performance.

When using a SCD to test gaseous fuels, it is imperative that the entire analyzer is capable of providing the high quality data required to optimize a process and ensure regulatory compliance.

There are many ways to measure sulfur and each technique offers its own strength. The Agilent 8355 SCD has been designed to fulfill and exceed testing requirements, specifically in the areas of:

  • Linear response (Table 1)
Analyte 9.9 ppm 5.5 ppm 1.5 ppm 0.793 ppm 0.149 ppm R2
Hydrogen sulfide 4.4 % 1.0 % 0.7 % 5.8 % 6.7 % 0.999
Carbonyl sulfide 2.3 % 0.4 % 2.4 % 6.0 % 6.5 % 0.9996
Methyl mercaptan 4.6 % 0.9 % 1.7 % 6.4 % 10 % 0.9979
Ethyl mercaptan 5.3 % 1.0 % 1.6 % 5.4 % ND 0.9982
Dimethyl sulfide 4.0 % 0.6 % 1.1 % 4.0 % 9.0 % 0.9997
Carbon disulfide 4.2 % 0.8 % 0.6 % 4.2 % 4.3 % 0.9999
2-propanethiol 5.8 % 4.3 % 4.9 % 9.4 % ND 0.9753
tert-Butyl mercaptan 5.7 % 1.3 % 3.3 % 6.6 % ND 0.9976
1-Propanethiol 9.0 % 5.5 % 4.7 % ND ND 0.9934
Thiophene 4.6 % 1.2 % 1.8 % 4.8 % 3.5 % 0.9999
n-Butyl mercaptan 4.8 % 0.9 % 1.4 % 3.5 % 4.8 % 0.9998
Diethyl sulfide 6.1 % 5.5 % ND ND ND 0.9833
Methyl ethyl sulfide 5.4 % 1.4 % 2.3 % 8.9 % ND 0.9986
2-Methyl-1-propanethiol 3.9 % 2.6 % 7.6 % 7.8 % ND 0.9979
1-Methyl-1-propanethiol 5.3 % 2.4 % 3.5 % 9.4 % ND 0.9990

Table 1. Linear response of quantitation of analytes using an Agilent 8355 SCD.

  • Limit of Detection (LOD) / Limit of Quantitation (LOQ) (Table 2)
Peak Analyte LOD (pg/sec)
1 Hydrogen sulfide 0.076
2 Carbonyl sulfide 0.18
3 Methyl mercaptan 0.45
4 Ethyl mercaptan 1.0
5 Dimethyl sulfide 0.19
6 Carbon disulfide 0.090
7 2-Propanethiol 1.4
8 tert-Butyl mercaptan 1.6
9 1-Propanethiol 6.2
10 Thiophene 0.21
11 n-butyl mercaptan 0.22
12 Diethyl sulfide ND
13 Methyl ethyl sulfide 0.39
14 2-Methyl-1-propanethiol 3.2
15 1-Methyl-1-propanethiol 2.4

Table 2. LOD/LOQ levels of various analytes commonly found in sulfur.

When system uptime is crucial to your bottom line

System uptime is critical and when a problem exists, it must be isolated and corrected as quickly as possible.

Often, problems initially blamed on the chemiluminescence detector actually originate from either poor chromatographic technique or other system failures (for example, a leak at the column inlet fitting). Only after it is determined that the problem is not associated with the inlet, the column, or the autosampler is it time to troubleshoot the detector.

In the past, if a problem was isolated to the burner, it was difficult to pinpoint the actual issue. We took note of customer feedback and made significant changes to the burner, making it more robust and easier to maintain. Two specific enhancements were:

  • More robust connections—Use of double tapered ferrules are replaced with standard column nuts and ferrules.
  • Improved hardware components—Heater assembly is redesigned to be more like a Flame Ionization Detector (FID), providing Electronic Pneumatic Control (EPC) modules to independently control hydrogen flow to the upper and lower burner and using brazed hydrogen line connections to reduce the number of potential leak points.

Figure 1. Now users can replace an inner ceramic tube in minutes, not hours.

Agilent delivers 50% reduction in parts and fittings

All aspects of Agilent 8355 SCD performance and serviceability have been scrutinized, reimagined, and then redesigned for an optimal user experience. These improvements helped Agilent achieve a 50% reduction in parts and fittings. For example, replacing an inner ceramic tube now only takes 10 minutes to perform (Figure 1). The earlier SCD design used to require up to an hour for the same procedure.

The fully reimagined and redesigned Agilent 8355 SCD

Accurately measuring sulfur and nitrogen is critical to your business and your bottom line. The chemiluminescence detector you choose for your lab needs to be ready at any given time. When maintenance is required, you need the ability to perform it easily and efficiently to ensure the instrument is returned to a ready status with minimal down time. Configurable as an integrated or standalone detector, the Agilent 8355 Sulfur Chemiluminescence Detector ensures that data being generated is actionable and defendable. The new 8355 SCD is field-tested, robust, reliable, and regarded as the industry standard.

Take a moment to further explore our product literature, including in-depth articles, to learn more.