Hi
I am trying to calculate LOD and sensitivity from the calibration curve I obtained using CA technique.
Can anyone tell me how to calculate LOD and sensitivity?
I'm not sure what you mean by CA or CV, but there are many things in common with determining LoD in instruments. You will also have to measure the noise of the system. LoD (limit of detection) is usually a signal with a S/N ratio (signal to noise) of 3. Limit of quantification is usually S/N of 10.
Noise is run with no sample, and also include solvent blanks. The conditions of the test need to be specified.
There is a mathematical formula to calculate your LOD and LOQ based on the 'standard deviation (SD)' of the concentration. This is similar to your CV or coefficient of variation.
you have to define conditions, number of runs made for blanks to calculate instrumental detection limit and number of standards run for method limit of detection, CV can be followed to calculate LOD and LOQ if we have other informations
Below are some very good references how to exactly calculate LOB, LOD and LOQ
Article Limit of Blank, Limit of Detection and Limit of Quantitation
The best resource is the international guideline from the CLSI
https://clsi.org/standards/products/method-evaluation/documents/ep17/
this is an international standard document and it is not free.
Shveta Malhotra
Coefficient of Variation (CV)
CV will be in terms of %. We will consider few percentage values. CV will not be a negative value
Signal to Noise ratio (S/N ratio)
S/N ratio is a measure that compares the level of the desired signal to the level of background noise.
Limit of Detection (LoD) – Two ways to find out LoD;
1. Based on visual approach
2. Based on Signal to Noise ratio approach
S/N ratio between 3:1 or 2:1 is generally accepted
S= Height of Signal
N= Height of Noise
Generally, LoD can be determined as S/N ratio >= 3
Limit of Quantitation (LoQ) – Two ways to find out LoQ;
1. Based on visual approach
2. Based on Signal to Noise ratio approach
S/N ratio between >= 10 are generally accepted
Generally, LoQ can be determined as S/N ratio >= 10
LoQ = 3.3 x LoD
- Badges
- Science topic