APH Method Explained | Animated GC/MS Tutorial & Hydrocarbon Calculations
MassDEP APH is the most confusing analytical method I have ever worked with—and the only one I've encountered that requires calculating calibration standards differently from actual client samples.
I created a 14-minute animated tutorial explaining the Massachusetts DEP Air-Phase Petroleum Hydrocarbons (APH) Method.
Although APH is based on EPA TO-15, its quantitation procedures are significantly different.
The video covers:
🔬 Canister preparation, sampling and preconcentration
🔬 GC/MS analysis and calibration
🔬 Establishing retention-time windows for three hydrocarbon ranges
🔬 C5–C8 and C9–C12 aliphatics: total ion chromatogram (TIC) integration
🔬 C9–C10 aromatics: extracted ions m/z 120 and 134
🔬 Subtracting internal standards, BFB and individual target analytes from the appropriate hydrocarbon ranges
Here is what makes this method particularly confusing:
Calibration standards use the designated calibration compounds and their combined responses to establish hydrocarbon range response factors.
Actual client samples require additional calculations. Internal-standard and BFB peak areas must be removed from the appropriate chromatographic ranges before quantitation. Then, individual target analyte concentrations and the aromatic fraction must be subtracted where applicable.
In other words, establishing the calibration and calculating the final sample concentrations involve different steps.
I created this animation because I believe watching these calculations is much easier than trying to understand them from pages of written instructions.
For analysts who have worked with APH: Do you find this method as confusing as I do?
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