Improving sample traceability

We’ve recently investigated the use of a heating block for the heat kill step of our pathogen testing protocol which can significantly improve sample traceability when implemented along with a bar-code scanner.

Our current method requires heating an aliquot of the sample to 85-100°C for 15-20 minutes prior to running the ELISA. Most users do this by placing the tubes in a boiling water bath. However the downside of this method is the tubes cannot be bar-code labelled as standard labels don’t withstand the boiling process.

So we’ve taken a look at the viability of using a heating block to perform the same heat kill step. We performed some analysis to evaluate how quickly the samples reach the required temperature to ensure that they receive the same treatment regardless of the method used. Here’s what we found:

A sample with a starting temperature of 180C when placed into a water bath set at 950C reached 850C after 5 minutes.

A sample starting at 180C when placed into a heating block reached 850C after 7.5 minutes. A complete block of samples (24 tubes) takes exactly the same amount of time as a single tube. This is well within the 15 to 20 mins required by the method and ensures sufficient time at the target temperature for the pathogens to be effectively heat killed. The heat block process had no adverse effect on bar code labels applied to the tubes. In addition, when taking the tubes out of the block, the tops of the tubes were cool to the touch and so can be handled safely when transferring to DS2 racks.

The DS2 instrument can be fitted with an on board bar-code reader (these can also be retrofitted onto existing DS2 instruments). When bar-code labelled tubes are loaded onto the DS2 the reader will automatically detect them, scan the codes and add to the sample ID field, which will ultimately be saved to the CSV output file. You can see the bar-code reader in action in this video.

Adopting this method is a simple way of ensuring that samples are traceable throughout the testing process.