Determination of Tobramycin in M9 Medium by LC-MS/MS: Signal Enhancement by Trichloroacetic Acid.

ABSTRACT: It is well known that ion-pairing reagents cause ion suppression in LC-MS/MS methods. Here, we report that trichloroacetic acid increases the MS signal of tobramycin. To support studies of an in vitro pharmacokinetic/pharmacodynamic simulator for bacterial biofilms, an LC-MS/MS method for determination of tobramycin in M9 media was developed. Aliquots of 25??L M9 media samples were mixed with the internal standard (IS) tobramycin-d5 (5?µg/mL, 25?µL) and 200?µL 2.5% trichloroacetic acid. The mixture (5?µL) was directly injected onto a PFP column (2.0?×?50?mm, 3?µm) eluted with water containing 20?mM ammonium formate and 0.14% trifluoroacetic acid and acetonitrile containing 0.1% trifluoroacetic acid in a gradient mode. ESI+ and MRM with ion m/z 468???324 for tobramycin and m/z 473???327 for the IS were used for quantification. The calibration curve concentration range was 50-25000?ng/mL. Matrix effect from M9 media was not significant when compared with injection solvents, but signal enhancement by trichloroacetic acid was significant (?3 fold). The method is simple, fast, and reliable. Using the method, the in vitro PK/PD model was tested with one bolus dose of tobramycin.

SUBMITTER: Huang L 

PROVIDER: S-EPMC5944200 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature