Quantitative Analysis of MEA-Triazine Hydrogen Sulfide Scavengers Through Innovative Transmission FTIR Spectroscopy

Significance of the Topic

The removal and quantification of hydrogen sulfide (H2S) in oil and gas streams is critical for operational safety, corrosion prevention, and compliance with environmental regulations. Monoethanolamine-triazine (MEA-triazine) scavengers are widely used to neutralize H2S, but traditional analytical methods for determining their concentration are laborious, error-prone, and time-consuming. The development of a rapid, accurate mid-infrared (mid-IR) spectroscopic method offers practical benefits for both laboratory and field environments.

Study Objectives and Overview

This study aimed to establish a mid-IR transmission method using the Agilent Cary 630 FTIR spectrometer equipped with the DialPath module to quantify MEA-triazine in aqueous solutions. Key goals included demonstrating excellent linearity, assessing interference from common viscosity-modifying solvents (methanol and isopropyl alcohol), and evaluating method robustness and throughput.

Methodology and Instrumentation

MEA-triazine standards (15–75 wt%) were prepared in water and analyzed in quadruplicate. Interference samples at 25 wt% and 50 wt% MEA-triazine contained 10, 15, and 25 % (v/v) methanol or isopropyl alcohol. Spectra were collected with the Cary 630 FTIR spectrometer featuring ZnSe optics and the DialPath accessory (50 µm path length), using 32 scans over 4000–650 cm⁻¹ at 4 cm⁻¹ resolution. The diagnostic peak region (1284.07–1203.93 cm⁻¹) was used for quantification. Agilent MicroLab Quant software applied Beer–Lambert calibration and cross-validation.

Used Instrumentation

• Agilent Cary 630 FTIR spectrometer with ZnSe optics (G8043-64002)
• Agilent DialPath transmission module with variable path lengths (G8043-68303)
• Agilent MicroLab Quant software for calibration and validation

Main Results and Discussion

The calibration exhibited outstanding linearity (R² = 0.9993) and a standard error of 0.116 %. Cross-validation confirmed predictive accuracy. Methanol addition caused slight underestimation of MEA-triazine (up to 4.36 % at 25 % methanol), while isopropyl alcohol led to overestimation (up to 6.55 % at 25 % IPA) due to overlapping spectral features. Standard deviations remained low, demonstrating high precision.

Practical Benefits and Applications

• Rapid, accurate quantification of MEA-triazine without lengthy sample preparation
• Elimination of fragile liquid cells, leaks, and air-bubble artifacts
• Minimal sample volume (7 µL) and reduced solvent usage
• Adaptable path lengths to minimize water interference
• High throughput for routine quality control in oil and gas operations

Future Trends and Opportunities

Advances may include tailored calibration models that incorporate solvent interferences, integration with portable FTIR platforms for on-site analysis, and expansion to other amine-based scavengers or corrosive contaminants. Coupling FTIR data with chemometric algorithms can further enhance specificity and automation.

Conclusion

The Agilent Cary 630 FTIR with DialPath provides a streamlined, precise, and robust method for MEA-triazine quantification in aqueous solutions. The approach overcomes limitations of traditional techniques, offering significant time savings and improved reproducibility.

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