Chromatography Forum

Hello i need some help how i can calculed loq and lod in lc ms ms

Thanks.

LOD is the limit of detection. The lower limit where you can say that you have a signal that stands out from the baseline noise to such a degree that you can say with a certain confidence that a peak is present.
Depending who you talk to this is usually 2 or 3 times the Signal to Noise ratio (S/N).

LOQ, Limit of Quantification, is higher. 10x S/N will usually give a high degree of method reliabilty at the low end though I have seen methods run with acceptable LOQ of 5x S/N.

Alp

This is a very good article on method validation.
http://www.ncbi.nlm.nih.gov/pubmed/16781833

Forensic Science International
Volume 165, Issues 2-3, 17 January 2007, Pages 216-224

Regards,
/Rune

see also ICH's Q2(R1):

http://www.ema.europa.eu/docs/en_GB/doc ... 002662.pdf

Although this document is greatly undermined by the mischievious inclusion of the idea of validating LOD by "visual evaluation" (i.e. "I think I can see something so it must be OK"?)