Automating Dilute and Shoot

Martin Perkins

25th October 2013

The idea behind Dilute and Shoot is to take advantage of sensitivity improvements to reduce the need for sample handling by eliminating the need for sample clean-up.

If you are running samples by dilute and shoot on a routine basis, this still leaves you with plenty of work to do and a strong case for automation.

If you are working with dirty, high matrix samples, insoluble and involatile materials can give real headaches due to excessive instrument down-time. On the other hand, sample clean-up is time consuming, error-prone and usually results in lower recoveries for your analytes.

The Dilute and Shoot approach is attractive. You simply dilute the sample with a suitable solvent, (this reduces the concentration of problem matrix material in the vial), inject the same volume as before and use the greater sensitivity and selectivity of a modern mass-spec to compensate for the dilution of your analytes.

The theory is sound enough and in the real World, the approach works in a fair number of cases. It is wrong, however, to think that dilute and shoot is free of all sample preparation. You still have to add internal standards to every sample and, of course, you still have to dilute every sample.

If you are running full batches of samples; spiking and diluting by hand will still occupy someone full-time and be prone to the usual human errors.

There can be other complications. Carrying out preparations by hand, batch-wise; although the first sample in the batch can be run immediately, the last sample in the batch could well be analysed 16 hours after it was prepared. This leads to significant variations across the batch in some cases. Just-in-time sample preparation (where every sample is treated exactly the same) is just about impossible to achieve manually.

There is a powerful argument to be made for automating sample dilution, spiking and injection is something that the GERSTEL MultiPurpose Sampler (MPS) can easily be set-up to do.

What is more, the cost of employing an MPS to do these simple, tedious, but vital tasks, in a just-in-time fashion, is much lower than the cost of employing an expensive human (who can be better used on more cerebral tasks).

We would be happy to work through this calculation with you.

The automation capabilities of the MPS extend far beyond adding standards and solvents, so for any samples that need more in the way of clean-up (solid phase clean-up, filtration etc). The MPS will be able to help with these too.

For more information, please call on 01223 279 210 or email