Determination of 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide Hydrochloride by Flow-Injection Analysis Based on a Specific Condensation Reaction between Malonic Acid and Ethylenediamine

Abstract

A sensitive and rapid flow-injection analysis was developed for the determination of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl), which was used for the formation of amide (peptide) and esters as a dehydration or condensation reagent. The EDC·HCl could be determined by the flow-injection analysis based on a specific condensation reaction between malonic acid and ethylenediamine in aquatic media. The reaction was accelerated at 60˚C, and the absorbance of the product was detected at 262 nm. The calibration graph of EDC·HCl showed good linearity in the range from 0 to 0.1% (0 to 0.0005 M), whose regression equation was y = 1.52 ¥ 10 9 x (y, peak area; x, % concentration of EDC·HCl). The proposed method allowed high-throughput analysis; the sample throughput was 12 samples per hour. The limit of detection (LOD) and the relative standard deviation (RSD) were 2 ¥ 10 -6 M and 1.0%, respectively. This reaction is proceeded in aqueous solution and specific for EDC·HCl.