Liquid Chromatography / Mass Spectrometry (LC/MS)
A&TS has a Hewlett Packard Series 1100 MSD Liquid Chromatography/Mass Spectrometer (LC/MS). Mass Spectrometry is an analytical technique capable of revealing both the identity and quantity of chemical materials in a sample. In this technique, molecules are ionized and then separated according to their mass/charge ratio. From this pattern, the chemical structure of the “parent” compound can be determined.
For mixtures of molecules in solution, a liquid chromatograph is interfaced with the mass spectrometer to separate the individual components prior to MS analysis. The standard modes of ionization are Atmospheric Pressure Ionization (API) and Atmospheric Pressure Chemical Ionization (APCI). The effective mass range for the LC/MS is 10 to 3000 amu, with either positive or negative ionization detection modes. The system can be used for the analysis of a wide range of sample types and, with the addition of de-convolution software, the molecular weight range is extended to enable analysis of proteins, carbohydrates, etc. The LC/MS gives the molecular weight, structural information, and the essential selectivity needed to identify compounds, to check the purity of chromatographic peaks, and to quantify trace-level samples in complex matrices.
The system has a diode array detector which, combined with the mass selective detector, allows confirmation that the compounds of interest are detected, including unexpected impurities.
We typically analyze prepared samples and/or train appropriate users to operate the equipment. We assist in experiment design and spectral interpretation. Since Liquid Chromatography is an art of itself, users must supply appropriate LC conditions (solvent systems, column, flow rates, etc.) including the proper column.
