What are the parameters to look out for when performing a TRPS measurement?

Tips on how to obtain a good TRPS meausurement

Baseline current

Monitor the change in baseline current as this indicates the state of the nanopore. The baseline current first and foremost reflects the conductivity of the electrolyte at that particular setting.If your particles have been prepared in the same electrolyte, the conductivity (or current in nA) should be similar.

We recommend that the baseline current change/varies within 10% between successive recording is acceptable. A sudden change in baseline current could mean that:

• The nanopore is partially blocked (e.g. current falls from 100nA --> 80nA), and/or
• The nanopore may have been modified (e.g. current jumps from 100nA --> 120nA).

Rate plot

Concentration value is measured by comparing the gradient of the rate plot of sample to calibration measurement. System stability is crucial for obtaining a linear plot and this can be achieved by taking extra care during sample preparation step so not to introduce any contaminants in the sample.


Calibration Recording

It's good practice to run a calibration recording after each sample recording, however provided that the samples doesn't modify the nanopore, a few samples can be recorded in succession before a calibration is recorded.

For example, ideally, a sample is measured by recording a calibration particle in between each sample e.g. Cal 1, Sample 1, C2, S2, C3, S3, C4, etc.....

Alternatively, the samples could also be measured in these configuration:

1. C1, S1, S2, C2, S3, S4, C3, etc.(Recommended)
2. C1, S1, S2, S3, .....C2. This configuration is risky as some sample may modify the nanopore and cause calibration runs to be invalid.