Spike vs forify sample

[dr_Pyrex]

Quite simple question: could you explain me difference (if exist) between SPIKED SAMPLES and FORTIFIED SAMPLES? I have always consider it as synonyms. Recently I have received revision of our article when reviewer has written:
"Please differentiate in the paper between fortify and spike. They mean two different things"

[Peter Apps]

I use "spike" rather than "fortify". If I used "fortify" it would be for the addition of a target analyte to a sample, while "spike" covers the addition of anything, analytes or internal standards. "Fortify" is also widely used in the sense of foods being fortified with vitamins for example.

So you might spike a sample of a fortified foodstuff with an internal standard.

Peter

[JGK]

For me:

Spiking a sample with an amount of material X implies that the original sample does not contain material X.

Fortifying a sample with an amount of material X implies that the original sample does contain material X.

For example

Sherry and Port are "Fortified" wines. Routinely, wines contain 11-15% alcohol but Sherry and Port are "Fortified" to 20%:

[dr_Pyrex]

Thanks for the answers. Today I have received opinion of my colleague (senior researcher):

"Spiking can occur at any stage of a method e.g. to monitor for losses in
recovery at any stage of the procedure, e.g. after extract, before
clean-up, concentration or at the end.

When you spike directly into food it is called fortification e.g. milk
fortified with minerals and vitamins.

Therefore, I would say that if you use the term fortify it means that
you have definetly add at the start of the procedure.

Spiking could mean anywhere along the way. "

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I appreciate personal opinions or "feelings" but I wonder if you know any guide/article regarding this issue?

[MaryCarson]

I consider them synonyms. However, for my own work, I will call a sample to which I added analyte before extraction a fortified sample, and a sample to which I added analyte to the extract right before analysis a spiked sample. It's a useful experiment to see what kind of effect matrix has on response--especially if you are not working with matrix standard curves. I do believe in unambiguously describing what one means by spiked or fortified just because of the confusion out there.

[Kenn]

I would also consider them synonymous and that spike is simply slang for fortify. Maybe because you used both the reviewer wants to know the difference between the two. I have written countless reports and never used the word spike in any of them. You very easily can fortify QC samples with your analyte at the appropriate concentrations followed by fortifying all samples with the internal standard.