USP / EP formula to calculate S/N ratio

[Peter Apps]

You are not serious - are you?

Ya M serious. Coz m new to this. I've performed AMV for one of our product. As I am doing right the first time, m confuse which value should be considered for H and h.

Pls. help me.

Thanks.

Somewhere in the data software there will be a function that will give you a number for signal:noise - run that. And please don't use text message abbreviations when you post on here.

Peter

[mk_3249]

You are not serious - are you?

Ya M serious. Coz m new to this. I've performed AMV for one of our product. As I am doing right the first time, m confuse which value should be considered for H and h.

Pls. help me.

Thanks.

Somewhere in the data software there will be a function that will give you a number for signal:noise - run that. And please don't use text message abbreviations when you post on here.

Peter

Thanks Peter

[mk_3249]

h is from the bottom of the noise to the top of the noise (i.e. define a region that you consider to be background, draw a line that just touches the bottoms of the noise spikes, and another that just touches the tops, and measure the distance between them). H is the height of the peak, theoretically measured from the middle of the base-line to the middle of the noise at the top of the peak, but as danko has pointed out, because of software constraints, it's usually measured somewhere else. Frankly it doesn't matter, because S/N is just not a good way to determine LOD/LOQ. It's better used as an ongoing measure of performance, in which case it doesn't matter how you define it, provided you always calculate it the same way.

Thank You Very much

[Hollow]

there was once an article about the LOD and it's concept behind, the overlapping of two distribution curves and the allowed uncertainty.

Therefore, the whole bandwith of the baseline could be seen as 6 sigma and from there the necessary peak height for a certain (user defined) uncertainty could be estimated.

The Limit of detection
By: Ricard Boqué, Yvan Vander Heyden
LCGC Europe,
Feb 1, 2009
Volume 22, Issue 2

Link:
http://www.chromatographyonline.com/lcg ... ail/581574