Checking and deriving the result are two separate operations.
To double-check, take the proportion of the ingredients and their composition. Cumulate all. Compare the results for both recipes.
You can reasonably assume that water makes everything that is not alcohol, in 98% ethyl alcohol and in vodka.
You don't need to compute the vitamin and lecithin, since they're identical in both recipes. So: how much water and ethyl alcohol ?