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

Tips on how to obtain a good TRPS measurement

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 varies by no more than 10% between sample and calibration recordings. A sudden change in baseline current could mean that the size of the nanopore may have changed, for example through partial blockage or tearing.

Rate plot

Concentration is calculated by comparing the gradient of the rate plot of the sample to the gradient of the rate plot of the 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 as not to introduce any contaminants into the sample.


Calibration Recording

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

Ideally, a sample set is measured by recording a calibration in between each sample e.g. Calibration (C) 1, Sample (S) 1, C2, S2, C3, S3, C4, etc.....

Alternatively, the samples could be measured in either of these configurations:

1. C1, S1, S2, C2, S3, S4, C3, etc.(Acceptable)
2. C1, S1, S2, S3, .....C2 (Not advised) This configuration is risky as some samples may modify the nanopore and end up without a valid corresponding calibration run.