Signal enhancement in supercritical fluid chromatography-diode-array detection with multiple injection

Area of Science:

• Analytical Chemistry
• Chromatography

Background:

• Large-volume injections in supercritical fluid chromatography (SFC) can negatively impact analytical performance.
• Concentrating analytes at the column head is a strategy to enhance detection signals.

Purpose of the Study:

• To investigate the feasibility of using multiple small-volume injections to overcome limitations of large-volume injections in SFC.
• To evaluate the signal enhancement and precision of the multiple injection approach compared to single injections.

Main Methods:

• Supercritical fluid chromatography (SFC) was employed.
• Multiple small-volume injections were performed to accumulate analytes on the column head.
• Analyte signal-to-noise ratios were compared between single and multiple injection techniques.
• Different stationary phases (diethylamine, 2-picolylamine) and sample diluents (acetonitrile, water) were tested.
• Precision of retention time and peak area was assessed for both methods.
• The approach was validated using spiked real-world samples (honey extract, ground water).

Main Results:

• Multiple injections led to signal enhancement compared to single large-volume injections.
• Signal-to-noise enhancement varied based on analyte retention, stationary phase, and sample diluent.
• The diethylamine column with acetonitrile and the 2-picolylamine column with water showed optimal performance.
• The multiple injection method demonstrated comparable precision to single injections.
• Successful application in analyzing spiked honey and ground water samples was shown.

Conclusions:

• Multiple small-volume injections are a viable strategy to enhance signals in SFC, circumventing issues with large-volume injections.
• This approach offers improved sensitivity without compromising analytical precision.
• The method shows potential for analyzing complex matrices in environmental and food analysis.