Quantification From Mhe Measurements - Thermo Scientific TriPlus RSH User Manual

1
Getting Familiar with Your TriPlus RSH
MHE Station

Quantification from MHE Measurements

Example of Quantitative Determination: Acetone and 2-Propanol in Granulate Samples
56 TriPlus RSH User Guide
The raw data from analytical samples deriving from MHE measurements must be treated
differently from those deriving from a classic, static headspace experiment.
In general, software packages for chromatographic data handling are not designed to cope in
an automated manner with MHE raw data.
Raw data can be extracted from a chromatogram resulting from a single GC run into an Excel
spreadsheet.
A sample Excel spreadsheet with a template is provided for quantification using the MHE
technique.
An example with explanations is given in the section
Determination: Acetone and 2-Propanol in Granulate Samples"
The determination of residual solvents, such as acetone and 2-propanol in granulates as used
in the production of pharmaceutical products, is most often performed by headspace analysis.
Often the analysis is performed as a standard, single extraction determination with
quantitation based on direct comparison to the response from gas standards.
The drawback of this procedure is that it neglects any sample with matrix interaction.
This can lead to the analyte not residing entirely in the gas phase (the headspace) in its
distribution between the condensed phase and the headspace. In this case the analyte amount
will be underestimated. In other words, the determined amount of analyte will be lower than
the true value.
In contrast, a true measure of the total content of the analyte can be obtained by applying
multiple headspace extraction (MHE).
The following simple example briefly describes the practical steps involved in such an
MHE-determination
The current example describes the procedure to determine the residual content of acetone and
2-propanol in samples of polyvinyl pyrrolidone-bound 5-amino salicylic acid (5-ASA)
granulate. For simplicity, only the determination of the acetone content is discussed.
The determination of the 2-propanol content is performed using a similar procedure.
A three-level calibration curve (double determination at each level) is used for the
quantitation – thus a total of six calibration samples are run. In this particular example, the
calibration curve is used for determining the acetone content in one sample – in practice the
number of samples will obviously be larger.
"Example of Quantitative
on page 56.
Thermo Scientific