Peak in Blank Injection-RS

[shrikantgadekar]

Hi guys,

In the blank(diluent) injection,for RS method of a NCE molecule, am getting a peak exactly at a RT(about 24 min.) of main peak.
Diluent is ACN:Buffer=1:1,
Buffer here is CH3COONH4+dil. CH3COOH.
I have tried no. of expts to identify its origin.
viz. variations in system,column,chemicals but is not successful.
No matter what is done , this peak is somehow not affected and it appears same in all cases.(area is almost same )
Column is YMC Pack pro C-18(150*3 mm,5 µm),
UV is 230 nm
flow rate is 0.5 ml/min for the gradient elution

Time A B
0 70 30
27 10 90
35 10 90
37 70 30
45 70 30

MP(A)- BUFFER
MP(B)- ACN : MEOH+dil. CH3COOH= 600:400+2.5 ml

Any thoughts will be highly appreciated...![/quote]

[aicmen]

"variations in system,column,chemicals but is not successful. "
so,I am confused. Try to change diluent (ACN:Buffer=1:1)
to other rate (ACN:Buffer=1:2,1:3 etc) to see whether there will be any variation of blank peak, thus may be find the origin.

[zokitano]

Shrikant,

Try to search the forum for contamination of the mobile phase A (contamination of the water used in the mobile phase). You'll find several threads about diagnosting ghost peaks due to the present contamination in the HPLC water.

Hope this helps

[tom jupille]

This one comes up often enough that I've posted a brief (about 15 minutes) mini-seminar on our web site:
http://www.lcresources.com/more_resourc ... hp?f=3&t=5
You will have to register (free) and log in to access it.