New mass spectrometric approaches to structural analysis in mixtures

UPLC/MS for the identification of β-blockers

The beta-blockers Oxprenolol, Metoprolol, Acebutolol, Atenolol, Propranolol, Pindolol, and Alprenolol were analysed by both UPLC/MS and HPLC/MS using mobile phases containing acetonitrile, TFA and either H2O or D2O. UPLC gave superior separation performance and the quality of the mass spectra were at least as good as those from HPLC.

Identification of the 'wrong' active pharmaceutical ingredient in a counterfeit Halfan drug product using accurate mass electrospray ionisation mass spectrometry, accurate mass tandem mass spectrometry and liquid chromatography/mass spectrometry

Methodology is presented for identifying an unknown active (pharmaceutical) ingredient (AI) in a counterfeit drug product. A range of mass spectrometric techniques, i.e., accurate mass mass spectrometry, tandem mass spectrometry (MS/MS) and liquid chromatography/mass spectrometry (LC/MS), has been employed to determine the AI in a counterfeit Halfan suspension, an antimalarial drug. In particular, use of LockSpray accurate mass MS/MS allowed identification of parts of the molecule from fragments, hence limiting the number of possible elemental compositions for the nominal mass of 278 found for the AI in the counterfeit product. The analysis of the isotope pattern observed for the protonated molecule further reduced the number of possible elemental compositions. A literature search for readily commercially available compounds of molecular formula C(12)H(14)N(4)O(2)S suggested that the AI was either sulfamethazine or sulfisomidine. An LC/MS separation of those two compounds and reference MS/MS spectra obtained for sulfamethazine and sulfisomidine led to the conclusion that the AI in the counterfeit Halfan suspension is sulfamethazine, which is an antibacterial agent.

Faster compound analysis by mass spectrometry — the ToF revolution

The introduction of the orthogonal Time of Flight (ToF) analyser has enabled ToF to be applied to continuous ionisation sources. In this technique, pulses of ions are ejected orthogonally from the main ion beam. This paper describes our development of techniques utilising the advantages of orthogonal-ToF for the analysis of small molecules especially drug substances. The fast scanning ability of the ToF enables its use with fast chromatographic procedures and can also be utilised to enable parallel detection of multiple LC columns. The medium resolution giving accurate mass measurement is utilised for faster and more reliable structural determination. These techniques are being used daily in our laboratories and some examples are shown.