Liquid chromatography–electrospray ionization mass spectrometry for direct identification and quantification of iophenoxic acid in serum

Abstract

Liquid chromatography-electrospray ionization mass spectrometry for direct identification and quantification of iophenoxic acid in serum" (2006 AbstractA liquid chromatographic-electrospray ionization mass spectrometric technique was developed for direct quantitation of iophenoxic acid (IA) in serum. IA was spiked into canine, feline, bovine, equine, and porcine sera, extracted, and quantified using negative ion monitoring following chromatographic separation on a Luna C18(2) 3 m (100 mm × 2.1 mm) reversed-phase column. The limit of detection was 25 ng/mL and the limit of quantification was 50 ng/mL. Inter-and intra-assay accuracy (86-113% and 87-115%, respectively) and precision (1.8-7.7%) were calculated. Analysis of serum collected from feral pigs, raccoons, and opossums following ingestion of IA-marked baits confirmed the appropriateness of this method for bait acceptance studies.

Analysis by LC/ESI-MS of iophenoxic acid derivatives and evaluation as markers of oral baits to deliver pharmaceuticals to wildlife

“…Thus, the LOD and LOQ equates to 0.312 g/ml and 0.626 g/ml in serum. This LOQ was calculated according to the spike levels in serum samples giving recovery values (accuracy) between 80% and 120% and coefficients of variation (precision) <20% [15]. If we use the same criteria with our data (Table 2), the LOQ may be established at around 0.2 g/ml for Mt-IPA, and 0.1 g/ml for Et-and Pr-IPA.…”

“…1). The use of an internal standard has been recommended before [14], but it was not used in the other described methods for IPAs analyses [14,15]. We have used Bt-IPA as internal standard because of its similarity with the other IPA derivatives in terms of extraction and analysis, but also because it can be perfectly separated and identified among the other IPAs.…”

“…Moreover, the serum volume used by us (0.1 ml) was smaller than the volume used by Jones [14] (0.4 ml). The method of Wiles and Campbell [15] based on LC/MS-MS yielded LOD and LOQ values of 25 ng/ml and 50 ng/ml, respectively, in the final extract of 5 ml obtained from 0.4 ml of serum. Thus, the LOD and LOQ equates to 0.312 g/ml and 0.626 g/ml in serum.…”

“…The chromatographic method was developed following Jones [14] and Wiles and Campbell [15], with some modifications. The injection volume was 50 l. The chromatographic conditions of analysis consisted in a gradient elution of two solvents (A: 0.025% acetic acid in H 2 O; B: 0.125% acetic acid in acetonitrile).…”

“…One of these described by Jones [14] to determine Et-IPA in biological fluids was done using high performance liquid chromatography (HPLC) followed by UV detection. Later, a method for direct determination of Et-IPA was described by Wiles and Campbell [15] in which liquid chromatography (LC) was coupled to electrospray ionization-mass spectrometry (ESI-MS) in the negative ion mode.…”