N, N-diethylhydroxylamine, morpholine, and cyclohexylamine analysis in steam turbine water by gas chromatography with chemiluminescence detection.

We have developed a fast, reliable, and cost-effective analytical method for determining N,N-diethylhydroxylamine, morpholine, and cyclohexylamine in aqueous matrices. These compounds are essential oxygen scavengers used in several industrial applications including boiler water treatment to prevent corrosion in steam turbines. By leveraging gas chromatography coupled with nitrogen chemiluminescence detection, our technique offers exceptional sensitivity, selectivity, and ease of use. A 30 m × 0.32 mm i.d. × 3 µm column, composed of 5% phenyl and 95% dimethylpolysiloxane, specifically optimized for nitrogen-containing compounds, was used for separating the analytes. A co-solvent approach with 1:1 ratio of 2-propanol and water was used to enhance chromatographic peak symmetry in highly polar matrix likes water. Nitrogen chemiluminescence detection advantageously yields a compound-independent response for nitrogen, enabling the quantification of analytes with any organic nitrogen chemicals detectable by gas chromatography, with an accuracy of ±5%. This method streamlines the workflow and reduces operational costs. Method performance metrics include a detection limit of 0.1 ppm (w/w) N, a relative standard deviation (RSD) of <3% at 100 ppm (w/w), and an analysis time of under 11 min while maintaining a high degree of selectivity. Validated with real-world samples from steam turbine condensate and commercial car wash water, this method demonstrates robust performance and reproducibility. The rapid turnaround, minimal maintenance, and low cost of ownership make this technique an optimal solution for routine monitoring in industrial settings. This research work represents a significant advancement in boiler water analysis, combining analytical rigour with practical efficiency to support asset integrity and operational reliability.