Head Space Method Development @ G1888 HS Sampler

[vdnsrinivas]

Hi,

Please let me know how to run G1888 HS sampler during method development for parameter increment ( vial equilibration).

Thanks,
Sri

[chromatographer1]

Do you have a manual to read?

Do you have a vendor sales person available locally?

Seekest thou and ye shall find.

Rod

[vdnsrinivas]

Dear Rod,

I went through the manual, but just want to know how to apply practically.

Thanks,
Sri

[chromatographer1]

First determine you can prepare and inject multiple vials of the same sample reproducibly.

Put 100 microliters of water containing 1microgram of acetone into vials as test samples.

Inject 10 vials and see if your RSD of the area of the acetone peak is less than 3%. (2% or less is good)

If so, then begin the determination of the method parameters:

1. detection limit of amount of solvent placed in vials of different sizes
2. this will determine the vial size you require.
3. loop size (based on #1 and #2) and split ratio required for good chromatography (if sample is split)
3. sample size (dependent upon #1, 2, 3 and to be within the desired range of measurement in sample)
4. pressurization (amount required to purge loop of carrier gas completely)

Once you know these factors, then you prepare 21 vials of the same sample of drug and spiked solvent,

and You heat and inject them sequentially: 5, 8, 12, 15, 20, 40, and 60 minutes at a starting temperature.

You heat and inject them sequentially: 5, 8, 12, 15, 20, 40, and 60 minutes at a 5C higher temperature.

You heat and inject them sequentially: 5, 8, 12, 15, 20, 40, and 60 minutes at a 10C higher temperature.

If needed: heat and inject them sequentially: 5, 8, 12, 15, 20, 40, and 60 minutes at a 10C lower if desired starting temperature.

I would start by assuming you can dissolve 10mg of drug into 200 microliters of dissolution solvent and you want to measure 100 ppm to 10,000 ppm of residual solvent.

I would assume a starting temperature of 80C, followed by 85C, 90C, and 70C.

I would also expect that times greater than 15 minutes are counter productive and might not be attempted.
To see how less reproducible vials heated at 60 minutes or large sample volumes can be, do that if you are interested LATER. Don't waste your time at this point.

Once you have the sample size, the solvent range, the temperature and heating times established, then you can check reproducibility of recovery from your sample.

Is this what you were looking for?

best wishes,

Rod

[Karen01]

I assume you are talking about actually run the experiment in a single 'run'.

You have you have 2 built in options to vary either HS oven temperature or Equilibration time for method development ...

There is an advanced function call Param Incr (or some such abbreviation for "parameter increment"). It allows you to step those parameters a specific amount with each vial in the run.

The other way is that you can save 4 separate methods and 'chain' then to run consecutively. The advantage is you can do more than 1 vial at each condition... This disadvantage is that you only have 4 conditions or steps.

Of course, though less convenient, you can always do multiple runs to look at different conditions.

- Karen

[vdnsrinivas]

Thanks Rod and Karen for useful inputs.

I have question regarding the sample analysis by using parameter increment. Can I use single Head space vial for all the analysis or do I need to use a sequence of head space vial for analysis??


Thanks,
Sri

[chromatographer1]

Use a single injection from each vial, running the vials in a sequence.

best wishes,

Rod