Hi DBC:
I'm not t clear with your Method to Titrate Alcohol in wine...
For now, I have a couple question:
1) How to determinate Thiosulphate and Dichromate Concentration?
2) Why or For What you add KI into K2Cr2O7?
The Official AOAC Method use a back-titration with Ammonium Ferrous Sulphate on dichromate +alcohol solution...after distillation...
With this method you convert the alcohol with dichromate in acetic acid...
Also is more easy after distillation, determinate the density of the distillate of wine...then go to tables to convet this density in Alcohol %.
Regards,
Chiralic