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Simple & Direct Mass Spectrometry Analysis

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DPiMS: Direct Probe Ionization Mass Spectrometer

Direct Probe Ionisation Mass Spectrometry

Direct Probe Ionization Mass Spectrometer (DPiMS) uses an ionization method which successfully incorporated the high ionization efficiency of electropray ionization (ESI) and the simplicity of matrix-assisted laser desorption/ionization (MALDI). This was achieved by using an ultrafine needle to sample an extremely small volume of sample on its surface and subsequently applying high voltage to the needle to imitate an ESI probe. Hiraoka et al has explained that applied voltage allows electron transfer from the solvent and causes migration of solute and solvent towards the needle-tip by electrostatic repulsion, which eventually form a jet of nano-droplets and a Taylor cone like observed in a normal ESI process. The new ionization technique was named Probe-ESI (PESI).

Scanning Electron Microscopy Image of a PESI Probe used in DPiMS

DPiMS, with the PESI technology implemented, is characterized by the microscopic sampling volume and high sensitivity for the amount sampled. In a typical application, compounds at a low ng/mL concentration range can be readily detected by DPiMS, in which case the actual abundance of compound subjected to MS can be as small as a few attograms. For this, DPiMS can be a robust solution for the routine analysis of high-complexity matrices, such as plasma or food extract, as contamination of MS hardware can be perfectly mitigated. Moreover, direct sampling from solid samples causing minimal destruction might enable new applications such as real-time analysis of live tissues or cells.

Mechanism of Action

1. DPiMS works with 'wet' samples

Solid Samples

DPiMS Solid Sample Preparation (i)
(i) Cut approximately 2-3 mm square of sample.
DPiMS Solid Sample Preparation (ii)
(ii) Place solid samples in a biological sample plate. Snap close the plate, then add a small volume of wetting agent on top.

Liquid Samples

DPiMS Liquid Sample Preparation
Liquid samples can be crude but ionization occurs more efficiently after appropriate dilution. Spot samples directly into a disposable liquid sample plate.

Single data acquisition completes within seconds

The probe is first lowered into the sample and then raised to the top position.
As the probe raises, samples are evenly coated on the surface.
Voltage applied to the probe needle causes migration and subsequent electrospray from the tip-end. Ions generated travel towards the orifice and into the mass spectrometer.

DPiMS can be used interchangeably with LC/MS

The ionization unit of DPiMS can be detached and replaced with the heated ESI unit to enable LC/MS analysis using the same MS hardware and operating software. Switching takes only a few minutes without the need for special tools or service engineers.

Tackle Challenges in Various Applications


Polar compounds are challenging to analyze in complex food matrices

Some compounds are not amenable to chromatographic separation

Wide-ranging samples states and sample types

Trade-off between low sample volume and high-throughput

Features of DPiMS

  • Perform MS analysis directly on the sample

  • Suitable for thermally labile compounds, no direct heat applied

  • Highly resistant to MS contamination

The unique ionization mode of DPiMS offers much quicker and simpler analysis

DPiMS has the potential to fill the gap between liquid chromatography and gas chromatography techniques

DPiMS can provide a method that works provisionally for a variety of sample types and sample states

Clinical testing labs are looking at on-site microvolume analysis, this can be enabled by DPiMS's unique configuration


Download the free Application Booklet  and learn more about the DPiMS-8060

Direct Probe Ionization Mass Spectrometer - Application Booklet