Detection limits of electron and electron capture negative ionization-mass spectrometry for aldehydes derivatized with o-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride

Abstract

In contrast to common expectations, the differences in limits of detection (LODs) between electron capture negative ionization (ECNI) and electron ionization (EI) mass spectrometry (MS) were found to be insignificant for a wide range of aldehydes derivatized with o- (2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride. Comparison of the two ionization methods based on LOD confidence intervals revealed that a traditional presentation of the LOD or limit of quantitation (LOQ) as a single value may over/underestimate the significance of obtained results. LODs were between 20 and 150 pg injected for the majority of tested derivatized carbonyls using both ionization methods. ECNI-MS improved LODs by ϳ10-to 20-fold only for two derivatized aldehydes, 4-hydroxybenzaldehyde and 5-(hydroxymethyl)furfural. Selectivity of ECNI did not appear to be beneficial when analyzing a wood smoke particulate matter (WS-PM) extract, possibly because the majority of interferences were removed during sample preparation (i.e., liquid-liquid extraction). The impact of four different data acquisition modes of transmission quadrupole (TQ)-MS on LODs and their precisions was also investigated. As expected, LODs in the selected ion monitoring (SIM) were ϳtwo to four times lower than those obtained using total ion current (TIC) mode. More importantly, TQ-MS in the selected ion-total ion (SITI) mode (i.e., acquiring SIM and TIC data in a single analysis) provided signal-to-noise ratios and precisions, which were comparable to SIM alone. (J Am Soc Mass Spectrom 2010, 21, 592-602)

Limits of detection for the determination of mono- and dicarboxylic acids using gas and liquid chromatographic methods coupled with mass spectrometry

“…As expected, further improvements in detection limits were achieved by the use of either selected ion monitoring or recently introduced parallel scanning in TIC and SIM (i.e., SITI). Similarly as observed in previous method development, SITI scan provided comparable data to those obtained by SIM [42]. The SITI mode thus showed an advantage of high sensitivity while maintaining the benefit of providing the TIC mass spectra, thus allowing for the identification of unknowns.…”

Electron ionization induced fragmentation of fluorinated derivatives of bisphenols

“…In the presented work, the addition of fluorine atoms to the structure of bisphenols has probably no impact on ionization, as the charge of the molecular ions after ionization is located in the native structure of the analytes. In reports of other types of derivatization with the addition of fluorine atoms (namely aldehydes derivatized with O ‐(2,3,4,5,6‐pentafluorobenzyl)hydroxylamine hydrochloride), it was discovered that a change from EI to electron capture negative ionization has a minor impact on the obtained limits of detection 21 …”

Separation of dansylated 17β-estradiol, 17α-estradiol, and estrone on a single HPLC column for simultaneous quantitation by LC–MS/MS

“…Limits of detection (LODs) were calculated according to the International Conference on Harmonization Guidelines [31] based on the standard deviation of the y -intercepts and the slope of regression lines in the range of the LOD. LOD confidence intervals were determined according to a recent report [32]. The calculated LODs were also verified experimentally by the analysis of QC samples spiked with the analytes at their LOD levels.…”