Chromatography Forum

Posted: **Mon Feb 03, 2025 7:43 pm**

Hi,

I recently started working on the LCMS, and I have wondering what is most reliable way to determine the LOD and LOQ for my analyte. Using my calibration curve (standard deviation of the intercept method) gives really high values for the LOD and LOQ. Is there any other acceptable way of doing this apart from S/N? Thank you.

Posted: **Tue Feb 04, 2025 3:16 pm**

Hi Folarin,

sure there is a different way. Have a look: https://www.agilent.com/cs/library/tech ... 7651EN.pdf

Posted: **Thu Feb 27, 2025 4:57 pm**

Hi Folarin,

sure there is a different way. Have a look: https://www.agilent.com/cs/library/tech ... 7651EN.pdf

Hi Thomas,

How do I estimate the LOQ using this method? Thank you

Posted: **Tue Mar 04, 2025 1:36 pm**

Did you read the paper?
You make some injections (7-10) of a small standard and determine the standard deviation. You can then calculate a method detection limit by multiplying the SD with a t-Value (Students t for a certain 1-alpha and n-1 degrees of freedom).
Calculation example is given in the paper.

For a more detailled explanation of the method you could check the EPA document: https://www.epa.gov/sites/default/files ... 3-2016.pdf

The MDL is equivalent to a LOD. To get a LOQ, you can either just multiply by a factor (usually 3.33) or use another statistical criterion, e.g. the lowest spiked concentration that gives an acceptable RSD (e.g. <20%).

Posted: **Thu Mar 06, 2025 5:23 pm**

Did you read the paper?
You make some injections (7-10) of a small standard and determine the standard deviation. You can then calculate a method detection limit by multiplying the SD with a t-Value (Students t for a certain 1-alpha and n-1 degrees of freedom).
Calculation example is given in the paper.

For a more detailled explanation of the method you could check the EPA document: https://www.epa.gov/sites/default/files ... 3-2016.pdf

The MDL is equivalent to a LOD. To get a LOQ, you can either just multiply by a factor (usually 3.33) or use another statistical criterion, e.g. the lowest spiked concentration that gives an acceptable RSD (e.g. <20%).

Hi Thomas,

I read it

.

It didn't really mention anything related to LOQ, and I just wanted to be sure. Thank you for your response.

Chromatography Forum

DETECTION LIMIT ON LCMS

DETECTION LIMIT ON LCMS

Re: DETECTION LIMIT ON LCMS

Re: DETECTION LIMIT ON LCMS

Re: DETECTION LIMIT ON LCMS

Re: DETECTION LIMIT ON LCMS