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retention time deviation

Hi,
I have problem with retention time deviation.The instrument I am using is HPLC LTQ-orbitrab.
my samples are deviating upto 0.5 min(rt deviation file attached)
for this I have set a parameter bw=30sec(allowable RT correction) .so is this RT deviation of samples is acceptable or to reduce do I need to change parameter for RT correction?,if so what value shall I give.
other parameters that I have set are as follows:
1.negative ionisation
2.centwave method
3.ppm:20 (maximal tolerated m/z deviation in consecutive scans, in ppm (parts per million)
4.min peak width:10
5.max peak width:80
6.s/n threshold:5
7.integration method:1
prefilter peaks:3
9.peak intensity:2500
10.noise filter:2500
11.rt correction method:obiwrap
12.profstep:1
13.bw=30
14.mzwid:0.015
15.minfrac:0.5
16.max:100
17.minsample:3
18.isotopes and adducts
19.5ppm
20.for identification 5 ppm and for adducts M-H
please let me know the set parameters are correct or do i need to change any of them.
thank you .

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Re: retention time deviation

Reply #1 –
If obiwarp is able to correct the retention time deviations (compare TICs before and after retention time correction, the retcor curve below looks OK)
then you don't need to increase bw.

Re: retention time deviation

Reply #2 –
Thank you ralf,
I have another question for you.In xcms online maximum peak width that we can set is up to 90seconds but some compounds peak will be broader and will be detected more than 2 minuites.In such case if we give 90 seconds, will it divide the peak in to two?

Re: retention time deviation

Reply #3 –
No, it will not split up the peaks.
The peak width range is not a hard threshold it is merely used to generate the wavelets that are used for peak detection. Even if your peaks are slightly narrower or wider than the peak width range it will still detect them.