Tonic Cordial?

[juniperlover]

As my handle suggests, I really - really - enjoy gin. It should then follow that as a ginthusiest I also enjoy a quality tonic. Now, I've made a few different batches of tonic syrup based on recipes that I've stumbled across online (all of which have been delightfully enjoyable), and my seeking has led me to the so called 'quinine cordial'. Produced by Hendricks around 2011, the quinine cordial, unlike many tonic syrups, contains alcohol. So my query is this: has anyone on the forum ever dabbled in tonics? And, if so, what's your recipe? My current favorite is taken from Jeffrey Morgenthaler and it consists of:

4 cups water
1 cup lemongrass (I generally use dried)
¼ cup powdered cinchona bark
zest and juice of 1 orange
zest and juice of 1 lemon
zest and juice of 1 lime
1 tsp whole allspice berries
¼ cup citric acid
¼ tsp Kosher salt

I'm contemplating developing this more into a cordial style by using equal parts water and a low proof neutral. Thoughts?