Dear all:Back to the Top
I am developing a LC/MS/MS assay for the determination of intracellular
concentration of nucleotide drugs, such as AZT-triphosphate, and
carbovir-triphosphate. I have an API3+ and a TSQ7000 in my lab. My
questions are: 1. Will the triphosphorylated drug contaminate the API
3+ vacuum system? 2. Is TSQ7000 sensitive enough for this application?
I will really appreciate any feedbacks from the group. Thanks.
Luke
Dear Luke,Back to the Top
API3 TSQ 7000 are quite sensitive instruments. You should not have
difficulty in sensitivity.
We have done quite bit of analysis on nucleotides. Any Triphosphate
molecule
or any other drug molecule for that matter will contaminate the mass
spec
when you inject very high concentrations say more than few ug/ml. But
major
problem is sample matrix and salt. If you don't clean up sample either
online or offline, instrument will loose sensitivity.
Dear Luke,Back to the Top
I separated and quantitated intracellular AZT_TP on HIV patients by
API2000 and it gave good sensitivity about 2 yrs ago. LOQ was less than
1 ng/ml.
When you do it on MRM mode it gives selectivity and sensitivity. Also
I precleaned the samples off line with SPE.
hope this helps
Lourdes
Dear group:Back to the Top
Thanks for all your suggestions. I am still bothered by the possiblilty
of
chemical contamination to the quadrupoles of the API 3 plus system. I
wonder if any people who worked on the intracellular nucleotide assays
have
observed any chemical contamination problems to the quadrupoles of the
API
3000 or 4000 system.
When I worked on API 3000 three years ago (when I was with a middle
pharma), I observed a severe chemical contamination to the quadruples.
It
took Sciex service engineers a great deal of efforts to decontaminate
it.
They took the Q1, and Q3 rails out and cleaned the quadrupoles
thoroughly
with KOH, and HCL.
I will start to develop a method for intracellular nucleotides
determination on an API 3 system. (I do not have API 3000 system now) I
know that the nucleotides and their fragmentation ions (with phosphate
groups covalently bonded) are typically not volatile, so these compounds
will stay on the surface of the quadrupoles, and cause chemical
contaminations. This may not present a serious problem for API 3000, or
4000s, becuse most of the ions passing into the vacuum chamber will be
pumped out by the turbo molecular pumps. However, it could cause serious
problems for the API3, since everything will be condensed onto the cryo
shells during the operation, and only be pumped out during the recycle
process of the cryo pump. This potential problem worries me greatly.
I want to know if anybody has observed similar contamination issue while
working on the analysis of intracellular nucleotide drugs on any
LC/MS/MS
system, and I really apprecite that if you share with me your experience
and thoughts. Thanks a lot in advance.
Luke
Dear group:Back to the Top
Thanks for all your suggestions. I am still bothered by the possiblilty of
chemical contamination to the quadrupoles of the API 3 plus system. I
wonder if any people who worked on the intracellular nucleotide assays have
observed any chemical contamination problems to the quadrupoles of the API
3000 or 4000 system.
When I worked on API 3000 three years ago (when I was with a middle
pharma), I observed a severe chemical contamination to the quadruples. It
took Sciex service engineers a great deal of efforts to decontaminate it.
They took the Q1, and Q3 rails out and cleaned the quadrupoles thoroughly
with KOH, and HCL.
I will start to develop a method for intracellular nucleotides
determination on an API 3 system. (I do not have API 3000 system now) I
know that the nucleotides and their fragmentation ions (with phosphate
groups covalently bonded) are typically not volatile, so these compounds
will stay on the surface of the quadrupoles, and cause chemical
contaminations. This may not present a serious problem for API 3000, or
4000s, becuse most of the ions passing into the vacuum chamber will be
pumped out by the turbo molecular pumps. However, it could cause serious
problems for the API3, since everything will be condensed onto the cryo
shells during the operation, and only be pumped out during the recycle
process of the cryo pump. This potential problem worries me greatly.
I want to know if anybody has observed similar contamination issue while
working on the analysis of intracellular nucleotide drugs on any LC/MS/MS
system, and I really apprecite that if you share with me your experience
and thoughts. Thanks a lot in advance.
Luke
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)