# LOD and LOQ

Hello, i'm a chemistry student and i'm trying to do a method validation.

I'm trying to calculate the LOD and the LOQ of my method, but i realize there're multiple ways to do so.

In the ICH HARMONISED GUIDELIN (2022 R2) they suggest to use this statistic approach for the LOQ and le LOD:

Now may i ask you if you have any paper/book where this statistic method is demonstrated? I've done plenty of research, but no one goes deep enough to explain how to obtain the "3.3" and the "10" factors. I would like to know the whole mathematical demonstration so i can argue judge better what i am using for the validation.

Sorry for disturbing you

and thank you even if you can't answer!

Parents
• Hi Nia,

most people use the definitions from the IUPAC Goldbook:

IUPAC DEFINITIONS OF LOD, LOI AND LOQ Theoretical Definitions

Abbreviation

Description

Signal Height Peak Height Remark
LOD Limit Of Detection a + 3 σ 3 σ
LOI Limit Of Identification a + 6 σ 6 σ
LOQ Limit Of Quantification a + 10 σ 10 σ 2 × noise
LDL Lowest Detection Limit (=LOD)
σ, S Standard Deviation of noise
a Arithmetic average of the noise a

Graphical Definitions

Diagram

Minimum signal height
LOD B = 3 σ
LOI C = 6 σ
LOQ D = 10 σ

Lines show the noise band width around the average value, a, which is defined as 5 σ.

Regards,

Norbert

• Hi Nia,

most people use the definitions from the IUPAC Goldbook:

IUPAC DEFINITIONS OF LOD, LOI AND LOQ Theoretical Definitions

Abbreviation

Description

Signal Height Peak Height Remark
LOD Limit Of Detection a + 3 σ 3 σ
LOI Limit Of Identification a + 6 σ 6 σ
LOQ Limit Of Quantification a + 10 σ 10 σ 2 × noise
LDL Lowest Detection Limit (=LOD)
σ, S Standard Deviation of noise
a Arithmetic average of the noise a

Graphical Definitions

Diagram

Minimum signal height
LOD B = 3 σ
LOI C = 6 σ
LOQ D = 10 σ

Lines show the noise band width around the average value, a, which is defined as 5 σ.

Regards,

Norbert

Children
No Data