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Dear All,
I am Subramanian from India. I am interested to know
1.why we are not adding Internal Standard in Blank sample of Human
Plasma in the analysis of BE/BA studies in HPLC?
2.Can we withdraw the Blood from the Vein and reinject after it is
sucked immediately to check whether the Blood is coming out during
the Blood collection even after injecting heparin in low volume?
3.whether High, Medium and Low control samples has to be injected
in HPLC after every 5 analysis even after injecting Linearity
standards?
I will be thankful for the answers.
Yours Truly,
Subramanian
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Dear Subramanian,
As answer to your queries,
1. Most assays request that you run a blank sample (plasma with no
analyte nor internal standard) as well as a zero sample (blank spiked
with internal standard). This enables one to ascertain whether there are
any interfering peaks at the retention time of the analyte and the
internal standard, and it also allows one to observe the internal
standard resolution, without any analyte.
2. I am not too sure what you are asking in the second question.
3. Calibration standards should be analysed for every run, but quality
control samples must also be run. The control samples are most useful
when placed intermittently throughout the run. I am not aware of any
specific guidelines (i.e. every 5 samples) but as long as you are
tracking the linearity of the assay system throughout the run (e.g.
beginning, middle and end). This is especially important when you have
many samples, as conditions may change to alter the assay system. I have
also read that QC samples should make up at least 10% of your total
number of samples (excluding calibration standards).
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