HPLC-based method using sample pre-column clean-up for the determination of methanethiol and ethanethiol in parenteral amino acid solutions

摘要

A method has been de.veloped for the chromato- graphic determination of methanethiol (MT) and ethanethiol (ET) as contaminants in amino acid parenteral nutrition {PN) solutions. The clean-up of the samples before chromato- graphic analysis was investigated by solid-phase extraction (SPE) on pre-columns filled with polyethylene powder (PE), aluminium oxide (A1Ox), silica (SiOx), or polyurethane foam (PUF) as adsorbents. The thiols were more efficient.1y separated from the matrices by SPE on PUF pre-columns. Simultaneous derivatization and elution withDTNB (5,5'- dithiobis(2-nitrobenzoic acid)) enabled further discrimi- nation between MT and ET by reversed-phase HPLC with spectrophotometric detection. The retention times for the derivatized MT and ET species were 12.5 and 23.0 min, respectively. Recoveries from spiked PN samples were ca1- culated to be approximately 90%, and the MT and ET con- tent of commercial PN solutions was determined using the methodology described. Detection limits of 15 and 10 #mu#g L~(-1) were calculated for MT and ET,respectively.