Speaker
Description
Small molecule identification is a core challenge in various areas of (bio)analytical science, including metabolomics and drug development. We present several examples demonstrating the direct applicability of infrared (IR) ion spectroscopy in the fields of drug metabolism and metabolomics. We present developments that combine separation by high performance liquid chromatography with IR spectroscopy of mass-selected ions. This approach provides information on functional groups in an unknown and has the potential for reference compound free identification in combination with theoretically predicted IR spectra.
In a first example, we focus on the differentiation of N-acetylmannosamine, a recently discovered biomarker for NANS-deficiency, a new inborn error of metabolism in sialic acid metabolism, from other possible enantiomeric N-acetylhexosamines found at the same m/z. This differentiation is not possible using standard operating HPLC-MS/MS protocols in most bioanalytical laboratories, as the enantiomers cannot be separated using reversed-phase chromatography and have identical MS/MS fragmentation spectra. Here, we demonstrate the use of IR ion spectroscopy to cleanly distinguish three N-acetylhexosamines directly from urine and cerebrospinal fluid (CSF) without any sample preparation (aside from dilution) or chromatographic separation.
In a second example, we use high-performance liquid chromatography in combination with IR ion spectroscopy for the identification of positional isomers of hydroxy-atorvastatins, the primary metabolites of the drug atorvastatin (lipitor).
Human diseases often have the potential to be detected by the identification of a single molecular species present in a patient body fluid. The majority of metabolomics laboratories rely on mass spectrometry to identify the presence of abnormal levels of specific small molecules in common body fluids that correlate with diseases, drug treatments, and environmental factors. However, the field is faced with a rapidly increasing number of known metabolic diseases for which these standard laboratory analytical techniques often fail to provide a definitive identification. In a final example, we have used IR ion spectroscopy to partially identify a previously detected but yet unidentified biomarker of the metabolic disease known as antiquitin deficiency. This peak “X” is thought to be associated with symptoms of intellectual disability that persist despite current treatments.
