sensitivity

[gokul]

Hi

to improve the sensitivity of an analyte does we need to preconcentrate the analyte or change the composition of buffer or mobile phase?? i was confused by the material i have or i didn't understnad the problem properly can anybody help me about this question

any help is very much appreciated..

thanks in advance

[saioa]

Well, not sure what you meant but depending on your detection method the answer might be different, e.g. in UV depending on the wavelength you choose the sensitivity can change. In LC-MS many parameters can affect your sensitivity
If you preconcentrate your sample then you are decreasing the limit of detection of the whole methodology but it does not neccesarily mean you improve the sensitivity of your instrument.

[Mark Tracy]

Sensitivity is just the slope of a plot of signal (y) versus amount (x). Often, when speaking informally, one will use sensitivity as a measure of detection limit, but this is not the recommended use for the word. So...

Preconcentration is a means of lowering the overall detection limit of your method; think of it as the inverse of dilution. It does not make your detector response bigger for a given mass of analyte injected into the column. It does increase the detector response for a given amount of specimen.

You can change the detector response by changing the chromatography. Making the peak elute earlier by changing gradient, buffer, column length, etc. will make it narrower and higher, so if you are using peak height, your sensitivity increases. Anything that compresses the same mass of analyte into a smaller volume of mobile phase will increase the sensitivity of detection.

[gokul]

Hi Tracy and Saioa

thank you very much and it really helped to clear my confusion.. I appreciate your prompt replies

thank you once again