ABSTRACT
Introduction Mass spectrometry (MS) is one of the most powerful analytical techniques, particularly for pharmaceutical analysis, where good selectivity and high sensitivity are often needed. In the pharmaceutical industry measurements of drugs and their metabolites in plasma are essential for drug discovery and development. e more accurate and rapid these measurements, the more quickly a drug can progress towards regulatory approval. Time-of-ight mass spectrometer (TOF-MS) delivers high sensitivity, resolution, and exact mass measurements .A variety of ion source and software options makes MS a versatile choice for a range of analytical challenges.1-5
Bupivacaine (Bup),amemberofthepipecoloxylidide group (Fig. 1), is the most commonly used local anesthetic. Commercial Bup is the optically inactive racemic (RS) mixture of R-and S-Bup. Several recent studies have demonstrated that systemic exposure to excessive quantities of Bup result in cardio toxicity due to its high a nity for, and dwell time at, voltage-gated sodium channels. A promising alternative to Bup is ropivacaine. Ropivacaine (Rop) is a structural derivative of Bup that diers only by the replacement of the butyl group on the piperidine nitrogen atom of Bup with a propyl group (Fig. 1). e minor structural modi-cation leads to a reduced hydrophobicity and the decreased ability to diuse
into the heart and brain. As a result, Rop has lower systemic toxicity than Bup. In addition, Rop is manufactured as a pure S-enantiomer, further lowering the cardiotoxic potential. Both drugs act by blocking the conduction of impulses in target nerve structures, primarily located within the subarachinoid space.6-8 Several methods using GC with9,10 or without MS,11 high performance liquid chromatography (HPLC) with UV,12-14 mass spectrometery (MS)15-17 or amperometric detection,18 and capillary electrophoresis19 have been developed to analyze the drugs and their impurities in pharmaceutical formulations and/or biological uids.
