Determination of iminodiacetic acid and glycine in dehydrogenation products of diethanolamine by pre-column derivatization and high performance liquid chromatography

: An analytical method was developed for the determination of iminodiacetic acid (IDA) and glycine (Gly), the dehydrogenation products of diethanolamine, by high performance liquid chromatography (HPLC) coupled with pre-column derivatization using p-toluenesulfonyl chloride (PTSC) as the derivatization reagent. IDA and Gly reacted with PTSC in the alkaline environment (pH 11) under 45℃ for 15 min. Then the derivatization products were analyzed by HPLC-MS. The separation was carried out on a high performance liquid chromatograph equipped with an ultraviolet detector. A VP-ODS column (200 mm×4.6 mm, 5 μm) was employed using 0.03 mol/L ammonium acetate (pH 5.5)-acetonitrile (87:13, v/v) as mobile phases for isocratic elution at a flow rate of 1 mL/min and detection wavelength of 235 nm. The results showed good linearities for iminodiacetic acid of 900-2100 mg/L, and for glycine of 20-100 mg/L, respectively. The linear correlation coefficients (R2) were both greater than 0.999. The limits of detection (LODs) of IDA and Gly were 0.0897 mg/L and 0.0262 mg/L and the recoveries were in the range of 98.7%-99.3% and 98.0%-99.5%, respectively. The relative standard deviations (RSDs) of IDA and Gly were in the range of 0.89%-1.23% and 0.95%-1.11% (n=3). The method has the characteristics of mild reaction conditions and high accuracy, and is well suitable for the determination of IDA and Gly in industrial production.