Examination of Analysis of the Total Sulfur Content Using Nexis™ SCD-2030

Significance of the Topic

In many industrial and research laboratories, rapid and accurate determination of total sulfur content in complex matrices is critical for quality control, environmental compliance and process optimization. Traditional GC methods require full chromatographic separation of individual sulfur species, which increases analysis time and complexity. The Nexis SCD-2030 coupled with a sulfur chemiluminescence detector (SCD) offers a selective and equimolar response to sulfur atoms, enabling direct quantification of total sulfur without the need for column separation.

Objectives and Study Overview

This study aimed to evaluate the feasibility and accuracy of quantifying total sulfur in unknown samples by two approaches: conventional analysis with full GC column separation and a simplified method omitting the column separation step. By comparing results from both methods against theoretical values, the work demonstrates whether direct detection using deactivated tubing can replace traditional separations for total sulfur assays.

Methodology and Used Instrumentation

The experimental setup employed a Shimadzu Nexis GC-2030 gas chromatograph equipped with an SCD-2030 detector. Two analytical modes were configured:

• With separation: SH-Rtx-1 capillary column (30 m × 0.25 mm i.d., 0.25 µm), helium carrier, split ratio 1:30, temperature ramp from 50 °C to 200 °C.
• Without separation: deactivated fused silica tubing (15 m × 0.2 mm i.d.), helium carrier at constant pressure (10 kPa), column held at 200 °C for 10 min.

Standards for calibration were prepared by diluting thiophene in hexane to sulfur molar concentrations of 1.19 × 10^-3, 1.19 × 10^-4 and 1.19 × 10^-5 M. Unknown samples were mixtures of S-methyl thioacetate, diisopropyl sulfide and dimethyl trisulfide in hexane, yielding total sulfur concentrations of 4.33 × 10^-4 M (Sample A) and 4.33 × 10^-5 M (Sample B). Calibration curves (area vs. sulfur content) showed R² values of 0.9999 in both modes.

Main Results and Discussion

Quantification with separation involved summing individual sulfur species based on retention times and calibration factors. The simplified mode produced a single composite peak representing total sulfur. Results for both samples were as follows:

• Sample A (4.33 × 10^-4 M theoretical): 4.61 × 10^-4 M with separation, 4.74 × 10^-4 M without separation.
• Sample B (4.33 × 10^-5 M theoretical): 4.21 × 10^-5 M with separation, 4.23 × 10^-5 M without separation.

These close agreements (<10 % deviation) confirm that direct detection without chromatographic separation delivers accurate total sulfur measurements, streamlining analysis workflows.

Benefits and Practical Applications

• Significant reduction in analysis time by eliminating chromatographic separation.
• Maintains high sensitivity and selectivity for sulfur atoms through equimolar SCD response.
• Simple calibration using a single sulfur standard (thiophene) suffices for total sulfur quantification.
• Applicable across diverse sample types including petroleum products, resins and food matrices.

Future Trends and Applications

Advances in detector design and data processing may enable real-time monitoring of sulfur levels in process streams. Integration with automated sampling systems could further reduce manual intervention. Expansion of the method to other heteroatom detections (e.g., nitrogen chemiluminescence) may broaden its scope in environmental and petrochemical analysis. Miniaturized GC-SCD systems could be deployed for field screening of sulfur pollutants.

Conclusion

The Nexis SCD-2030 effectively quantifies total sulfur in complex samples without the need for chromatographic separation, providing results equivalent to traditional methods while offering faster cycle times and simplified workflows. This approach offers a robust solution for routine sulfur analysis in research, quality control and industrial laboratories.

References

1. Takemori Y. Examination of Analysis of the Total Sulfur Content Using Nexis™ SCD-2030. Application Note No. G340, Shimadzu Corporation, First Edition Nov. 2020.