Abstract:

A method for the determination of ethylenediamine tetraacetic acid（EDTA）and nitrilotriacetic acid（NTA）in detergent products was established using metal-complexing derivatization and high performance liquid chromatography. The samples were extracted with water, derivatized with Cu（NO₃） ₂, purified by MAX anion-exchange solid-phase extraction, separated on an X-Bridge C_18（4.6 mm×250 mm, 5 μm） column, and detected by HPLC with a diode array detector. The retention time and UV absorption spectra were used for qualitation and the external standard method was used for quantitation. The results show that, under optimized conditions, the calibration curves show good linearity in respective ranges for NTA and EDTA with correlation coefficients（R ²）no less than 0.999 7. The LODs and LOQs are in the ranges of 10-20 mg/kg and 25-50 mg/kg, respectively. The recoveries of EDTA and NTA at the spiked levels of 0.5-100.0 mg/L are in the range of 89.8%-107.8% with the relative standard deviations（RSDs, n=6）are 1.11%-5.71%. With good precision and high accuracy, this method is suitable for the determination of EDTA and NTA in detergent products.

Key words: detergent product, ethylenediamine tetraacetic acid, nitrilotriacetic acid, metal-complexing derivatization, high performance liquid chromatography