Dear Dilara,

You can only measure the signal of a blank solution as many times as you method means. After, just find the standard deviation of that value. As a first approximation, 3RSD will be you LoD in intensity units. The next step is building a calibration curve up. By means of which, you will be able to transform intensity into concentration. This is the simplest way. Have a nice day!

Dear Dilara,

The estimation is made according to official ICH guidelines using the S/N ratio of 3 for LOD and 10 for LOQ

here explained simply how to calculate them

https://arts-sciences.und.edu/academics/chemistry/kubatova-research-group/_files/docs/determination_of_lods_new.pdf

wish you all the best,

Sami

LOD and LOQ values can be calculated based on the following equations: LOD = (3 × )/ , LOQ = (10 × )/ , where is the standard deviation of the intercept and is the standard deviation of slope. The LOD and LOQ determined for both the sample and standard using the CE-UV method were close to 0.2 and 0.8, respectively.

Please look up to the previously added question/answers:

www.researchgate.net/post/What-is-the-exact-way-of-calculation-of-limit-of-detection-LOD-and-limit-of-quantification-LOQ-on-method-validation-studies

May be it will help.

hello

2 solutions ..

first .. you have to integrate un blank at migration time ( 30 samples for exemple)

Average Areas , Standard deviation . LOD ( Average of area Blank) + 3 x SD , LOQ same but 10* SD

Seconde

Dilute a Calibrant 1/2 1/4 1/8 1/10 ...etc .. pass dilution ( 30 x each).. do a CV % .. when it more than 20 % .. it's the LOQ

Good Luck

Why do you want to use LOD and LOQ solely based on s/n ratio?

I agree with the second solution of Bianchi for the LOQ. Look at the goal of your analysis and find out what imprecision you need in the lowest range of interest. For example CV 20% . Then construct a plot of imprecion against concentration and read (or interpolate) the concentration were the CV is 20%