Butoxyethanol: A Novel and Exceptionally Strong Eluent for ICPMS Detection Eliminating the Organic Mode

Inductively coupled plasma mass spectrometry (ICPMS) is gaining increasing recognition for speciation analysis of nonmetals, but many compounds, such as those containing halogens and sulfur, are highly hydrophobic, requiring the use of the organic ICPMS mode to address compatibility with reversed-phase liquid chromatography. Herein, we introduce 2-butoxyethanol (BE) as a novel eluent with exceptional elution strength and plasma tolerability. BE allows operation under standard conditions used with 100% aqueous mobile phases, with no plasma shutdown or carbon buildup. Direct comparison with methanol when used under the organic ICPMS mode showed superior sensitivity by 3-5-fold despite the employment of highly optimized and mild organic mode conditions. BE concentrations ≤30 v/v remarkably provided an elution strength matching that of 90-100% v/v methanol, which was demonstrated in multiple proof-of-concept applications involving the elution of highly hydrophobic analytes from a reversed-phase C18 column. These included separation of a complex mixture of polychlorinated biphenyls (PCBs) where superior resolution and unique chromatographic selectivity were found, as well as arsenolipid screening in seaweed, where highly complex profiles in various edible species were observed, revealing >100 signals at instrumental LOD down to 6 ng As L-1 (20 μL injection volume). The introduced eluent presents a significant advancement over previous work, including yet stronger elution than that achievable with 1,2 hexanediol at lower column backpressure, providing a major step forward in optimizing the practice of reversed-phase liquid chromatography to suit the changing demands of speciation analysis.