Sample preparation method and apparatus

A method of preparing a microbiological sample including a carrier liquid and a nucleic acid analyte, the method comprising the steps of:

• depositing the sample into a reaction vessel,
• holding at a surface of the sample a body of solid oil or wax with embedded paramagnetic or magnetic beads having a coating for attracting a PNA probe,
• heating the reaction vessel at a lower end of the reaction vessel to a level sufficient to lyse the sample,
• heating the wax or oil body so that the solid oil or wax becomes molten and the beads are free to mix in the sample, and
• applying a magnetic field to attract the beads to a support after incubation when the wax or oil body is molten.

A microbiological sample preparation apparatus for preparing a nucleic acid sample for analysis with target enrichment, the apparatus comprising:

• a reaction vessel,
• a heater to heat the reaction vessel at a lower end of the reaction vessel to a level sufficient to lyse a sample with an analyte and a chelating agent in the reaction vessel, to provide a crude lysate available for binding,
• a PNA probe at a concentration sufficient for binding and capture of discernible levels of a target nucleic acid,
• a support holding a body of solid oil or wax with embedded paramagnetic or magnetic beads having a coating to which the PNA probe attach, said beads being in a solid plug of oil or wax,
• wherein the probe is immobilised on a surface of the support and/or the oil or wax body and/or the reaction vessel internal surface,
• a magnetic device for applying a magnetic field to attract the beads to the support after incubation when the wax or oil body is molten, in which the magnetic device magnetically removes the beads with the attached PNA probe and bound target nucleic acid to draw them through a fluid-fluid interface of said molten wax or oil, and
• the apparatus is configured
• so that said heating heats said wax or oil in the reaction vessel due to applied heat for lysing so that the wax or oil becomes molten and the beads are free to mix in the sample while the molten wax or oil remains on the sample surface due to floating, said mixing in the sample providing intact bead-PNA probe-target nucleic acid complexes drawing the complexes magnetically through said fluid-fluid interface of said molten wax or oil;
• and
• to move said complexes through said molten wax or oil and into an analytical vessel, or
• to solidify said wax or oil with the bound bead-PNA probes-target nucleic acid complexes separated from the lysate and sealed within the solidified wax or oil
• wherein the sample is heated with the chelating agent to provide a low ionic/high pH solution.