Analysis of a stable radical TEMPO shows very soft ionization conditions, almost eliminating in-source oxidation when chloroform solvent was used for analyte.
During a quantification exercise TEMPO showed a linear response over a 2 orders of magnitude in concentration with a deviation only at the very high flows of neutral analyte spray (>20 L min−1) at the highest concentration(940 M). Standard deviation for TEMPO quantification was lessthan 3%.