On-line direct liquid introduction interface for micro-liquid chromatography/mass spectrometry: application to drug analysis.

The research article is about an integrated micro-liquid chromatograph/mass spectrometer system designed for routine drug and metabolite determinations in biological fluids. The system is sensitive, stable and can be constructed using commercially available materials.

System Design and Assembly

• The research team has developed an advanced micro-liquid chromatograph/mass spectrometer (micro-LC/MS) system.
• The apparatus is designed for routine determinations of small quantities (1-10 ng) of drugs and their metabolites extracted from biological fluids.
• Notably, the micro-LC is constructed from high-performance liquid-chromatographic instrumentation using commercially available components. This approach permits greater accessibility and flexibility for labs with different budgets and resources.

Mode of Operation

• The integrated mass spectrometer operates in the chemical ionization mode. This technique is used to generate ions from molecules for subsequent mass spectrometry analysis.
• A unique feature of the system is its direct liquid introduction interface, which can be built using commercially available materials. This interface allows direct injection of the sample into the system, enhancing the speed and efficiency of analyses.

Performance and Applications

• The researchers present chromatographic and mass spectral results that prove the system’s ability to separate and determine multiple components in standard trace concentrations and in biological samples.
• An example of using this system was exemplified in equine urinary extracts, proving its applicability in veterinary drug testing.
• The performance of this micro-LC/MS system was further demonstrated by accurately analysing record-low determinations of trichlormethiazide, affirming its high sensitivity and stability.