A certain mainstream store near me has "100% tech grade d-limonene" for sale at an inexpensive price.

Is there any reason to suspect this would not be suitable for spice?

Last time I extracted was over a decade ago, I was living in a different country, and ordered my limonene from a supply shop that no longer exists. (Pinching myself) I was expecting more of a scavenger hunt.

If it's labelled correctly it should be fine. Sometimes orange oil terpenes get labelled as limonene and oxygenated minor components such as citral can make things get messy. Stirring - maybe while gently heating - a sample of it with solid caustic soda would inform of the presence of oxygenated terpenoids by producing a brown, tarry discoloration after some minutes.

The other thing to be wary of is any coloration in the product. Limonene should be a clear, water-white liquid. If it's orange that means it's expressed oil rather than steam-distilled and it will contain non-volatile impurities.

Awesome, thank you. That's great to know about the color - I've seen reviews for it in other places where people complained it was clear and not orange