Accurate mass liquid chromatography/mass spectrometry on orthogonal acceleration time-of-flight mass analyzers using switching between separate sample and reference sprays. 1. Proof of concept

This paper describes the use of two separate electrosprays for introducing sample and reference for accurate mass liquid chromatography/mass spectrome try (LC/MS) on an orthogonal acceleration time-of-flight mass analyzer. Thi s is carried out using an adaptation of the multiplexed electrospray ion so urce in which only two of the sprays are utilized. Results are shown for th e positive ion detection of trace-level components in complex matrixes and good mass accuracies are obtained, even for very low level components. An e xample of accurate mass measurements obtained using negative ion LC/MS is a lso shown. To obtain additional structural information, an example of cone voltage fragmentation is included and shows that good mass accuracy can be obtained for both precursor and fragment ions.