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Dear Group,
I have set up a LCMSMS assay for sertraline hydrochloride. I am using
MRM in ES + mode. MPA is 0.1 % formic acid and MP B is acetonitrile. I
am unable to get LOQ below 10 ng/ml because of high carry over. My
auto sampler is CTC PAL..
I have tried following to reduce carry over:
1.Used wash solvent 1 as 1 % triethylamine in methanol.
2. Used wash solvent 2 as mixture of Methanol, acetonitrile, hexane
and acetone. and give total 5 wash cycles.
3. Inject 5 blanks after high concnetration injection.
4. Opened injection valve and cleaned thoroghly.
5. Sonicated syrunge and refixed.
6. Changed gaurd column..
7. Systematically removed all components starting from autosampler.
Looks like sertraline sticks in all parts of HPLC system..
Does any one has a majic solution to wash away the drug completely?
Thanks for help.
Vinayak
SPECIFIC SOLUTIONS ARE APPRECIATED .
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The following message was posted to: PharmPK
The TEA will compete or displace/ try TFA. This will ion pair and may
help remove from sinks.
--
Ed O'Connor, Ph.D.
Laboratory Director
Matrix BioAnalytical Laboratories
25 Science Park at Yale
New Haven, CT 06511
Web: www.matrixbioanalytical.com
Email: eoconnor.-at-.matrixbioanalytical.com
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Dear Vinayak,
1) You can try with buffer ammonium acetate pH 3.5 and
acetonitrile(40:60) mobile phase.
2) Needle wash 340:330:330(Water:meoh:acetonitrile).
3) You can increase recovery to achieve your LOQ by adding some basic
buffer in the plasma.
4) How is the baseline? If not try to get it near to zero.
Reduction of carry over, increase in recovery and reducing baseline
may lead to achieve 10 ng/mL LOQ.
Hope the above exercise will solve your problem.
thanks,
with regards,
rashmi
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The following message was posted to: PharmPK
Dear Vinayak,
We've got a CTC Pal as injector and I use for many drugs:
Wash solvent 2: EtOH/Water (80/20) (3 times)
Wash solvent 1: Water/MeOH/ACN(50/25/25) + 0.1% HCOOH (3 times)
I also use a 100uL syringe to inject my samples (injection volume
10uL, it
works well) and specify a rinse volume for syringe of 50 uL.
For injection valve, 3 times with both wash solvent.
For HPLC conditions, I think that you run a gradient, if not, it's
sometimes
(always) better for low LOQ, and rinse the chromatographic system with
100%
PMB.
Have you got a diverted valve?
What is your flow rate, do you split the mobile phase?
What is your mass spec ?
Fabrice Guillet
XENOBLIS
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