Pulsed electrochemical detection of alkanolamines separated by multimodal high-performance liquid chromatography

Simultaneous quantification of alkanolamines and their dehydrogenation products in aqueous samples using high-performance liquid chromatography with pre-column derivatization with 2,4-dinitrofluorobenzene

BACKGROUND

Diethanolamine, monoethanolamine, iminodiacetic acid, and glycine are important fine chemical intermediates, often requiring simultaneous quantitative analysis in various applications. This presents the challenge of accurately quantifying multiple substances within a single sample. The catalytic dehydrogenation of diethanolamine and monoethanolamine has garnered significant research interest, yet no analytical method has been reported for the simultaneous quantification of reactants and products in the dehydrogenation reaction mixtures of different alkanolamines.

RESULTS

A high-performance liquid chromatography (HPLC) method has been developed for the simultaneous quantification of diethanolamine (DEA), iminodiacetic acid (IDA), glycine (Gly), and monoethanolamine (MEA) in aqueous solutions using 2,4-dinitrofluorobenzene (DNFB) for pre-column derivatization. The method demonstrated excellent linearity, with correlation coefficients (R2) of 0.9999, 0.9997, and 0.9998 for IDA, DEA, and Gly, respectively. The detection limits (LODs) were 0.02, 0.08, and 0.01 mg L-1, respectively. The quantification limits (LOQs) were 0.06, 0.24, and 0.03 mg L-1, respectively. Spiked recovery rates ranged from 96.99 % to 104.32 %, with relative standard deviations (RSDs) between 0.70 % and 3.03 %. For MEA and Gly, the R2 values were 0.9970 and 0.9990, the LODs were 0.12 and 0.01 mg L-1, the LOQs were 0.36 and 0.03 mg L-1, and spiked recoveries ranged from 96.24 % to 104.82 %, with RSDs between 1.22 % and 3.68 %. Compared to other methods, this HPLC approach offers superior sensitivity, accuracy, and precision.

SIGNIFICANCE

This method provides a robust reference for the individual or simultaneous quantification of alkanolamines, glycine, and iminodiacetic acid in aqueous matrices. It offers new insights into the simultaneous analysis of alkanolamines with multiple organic acids in complex matrices. Additionally, the method can guide the optimization of catalytic dehydrogenation processes for alkanolamines, potentially extending the advantages of dehydrogenation catalysts to other reactions.

Selective detection of diethanolamine utilizing an LMR/LSPR-based optical fiber sensor

Diethanolamine (DEA) is used for amine wash to remove toxic gases such as hydrogen sulphide (H2S) while processing crude oil and in other pharmaceutical products.

Solar-Photocatalytic Degradation of Waste from CO2 Removal System Using Metal Doped TiO2 Photocatalysts: Effect of TiO2 Support

The wastewater containing the spent alkanolamines and its derivatives emerging from the natural gas industries into water has become a critical concern. In the present study, Titanium dioxides was used as photocatalysts to investigate for their efficiency for the photodegradation of Diisopropanolamine (DIPA) containing wastewater under the visible light irradiation. DIPA was used as a model alkanolamine while different commercially available TiO2 were tested for photodegradation of DIPA under the visible light source. The physico-chemical properties of the prepared photocatalysts were analyzed using different characterization techniques including X-ray diffraction (XRD), Raman spectroscopy and N2-physisorption (BET).

Effect of polar and movable (OH or NH2 groups) on the photocatalytic H2 production of alkyl-alkanolamine: a comparative study

The photocatalytic production of molecular hydrogen (H2) from aqueous solutions of alkyl-alkanolamines (triethanolamine (tri-EOA), diethanolamine (di-EOA), ethanolamine (EOA), ethylamine (EA) and ethanol over Pt-loaded commercial (Sachtleben Hombikat UV100) nanoparticle titanium dioxide photocatalysts was studied. These photocatalysts were characterized using X-ray diffraction, Brunauer-Emmett-Teller, field-emission scanning electron microscopy, atomic force microscopy and UV-vis diffuse reflectance spectroscopy techniques. Effect of pH and temperature on photocatalytic hydrogen production of alkyl-alkanolamines was investigated. It was found for all molecules under study that the amount of hydrogen produced at a constant illumination time is a function of pH and temperature. At all temperatures investigated the rate of hydrogen production at pH 9 followed the order tri-EOAethanolamine >> di-EOA ≈ EOA > ethanol > EA. From the values of the photocatalytic rate constants at various temperatures, the apparent activation energies were determined for the hydrogen production. The observed dependence of the reaction rate on solution temperature cannot be related to light-driven reaction steps, because the band-gap energy of the semiconductor is too high for thermal excitation to become significant in the temperature range investigated.

Determination of diethanolamine or N-methyldiethanolamine in high ammonium concentration matrices by capillary electrophoresis with indirect UV detection: application to the analysis of refinery process waters

Alkanolamines such as diethanolamine (DEA) and N-methyldiethanolamine (MDEA) are used in desulfurization processes in crude oil refineries. These compounds may be found in process waters following an accidental contamination. The analysis of alkanolamines in refinery process waters is very difficult due to the high ammonium concentration of the samples. This paper describes a method for the determination of DEA in high ammonium concentration refinery process waters by using capillary electrophoresis (CE) with indirect UV detection. The same method can be used for the determination of MDEA. Best results were achieved with a background electrolyte (BGE) comprising 10 mM histidine adjusted to pH 5.0 with acetic acid. The development of this electrolyte and the analytical performances are discussed. The quantification was performed by using internal standardization, by which triethanolamine (TEA) was used as internal standard. A matrix effect due to the high ammonium content has been highlighted and standard addition was therefore used. The developed method was characterized in terms of repeatability of migration times and corrected peak areas, linearity, and accuracy. Limits of detection (LODs) and quantification (LOQs) obtained were 0.2 and 0.7 ppm, respectively. The CE method was applied to the determination of DEA or MDEA in refinery process waters spiked with known amounts of analytes and it gave excellent results, since uncertainties obtained were 8 and 5%, respectively.

A simple HPLC method with pulsed EC detection for the analysis of creatine

The objective of this study was to develop a simple and sensitive LC method for the determination of creatine in aqueous solutions as well as in rat plasma using electrochemical detection. The chromatographic system consisted of a GP50 gradient pump, an ED40 pulsed electrochemical detector, and an AI-450 chromatography automation system (Dionex). The mobile phase consisted of a mixture of water, acetonitrile, 0.01 M sodium acetate, and 1.0 M sodium hydroxide (2.5:2.5:90:5, V/V/V/V) at a flow rate of 1.0 ml/min. The chromatographic separation was achieved at 45 degrees C on a column with a polyhydroxylated glucose and sulfonated stationary phase. The retention times of creatine and creatinine was 3.50 and 4.73 min, respectively, with creatine fully resolved from its major degradation product, creatinine. The standard curves were linear over the concentration range of 0-20 microg/ml. Within-day and day-to-day relative standard deviations (R.S.D.) were less than 10%. This method was used to study dissolution characteristics of various creatine salts in water.