Development of Sequential Injection Analysis for Determination of 1–(3–Dimethylaminopropyl)–3–Ethylcarbodiimide Hydrochloride (EDC・HCl) Based on Condensation Reaction between Malonic Acid and Ethylenediamine

A sequential injection analysis (SIA) using a specific condensation reaction between malonic acid and ethylenediamine with 1–(3–dimethylaminopropyl)–3–ethylcarbodiimide hydrochloride (EDC・HCl) in aqueous media was developed for EDC・HCl determination. EDC・HCl can act as a dehydration or condensation reagent for the formation of amide (peptide). The proposed system, whose operation was fully automated by a lab–made computer–controlled program, consisted of a syringe pump, a selection valve, a spectrophotometer and a computer. The product in the condensation reaction accelerated at 60C could be detected at 262 nm. The calibration graph of EDC・HCl showed a good linearity: the regression equation and correlation coefficient (r) were y = 1.5 × 10 x – 3 × 10 (y, absorbance; x, M concentration of EDC・HCl) and r = 0.998, respectively. The limit of detection (LOD) was 2.0 × 10 M and the sample throughput was 17 samples per hour. The automated SIA for EDC・HCl determination has improve the reaction efficiency and the sensitivity by coupling with forward and backward mixing in the reaction coil.