I meant to reduce the receiving solution pH to <2.0 before adding the silicon, not to add all the acid before adding the silicon. In this example, lower purity acid is preferred to avoid dropping pH too low. The process using your posted procedure would be something the following. But this is just off the cuff, Record acid volumes at each addition to reduce mixing time for future batches:
- Purified water in the beaker
- Place the beaker on mag stirrer plate.
- Insert pH probe into water (using a pH meter calibrated to pH <2.0)
- Mix water to form a weak whirlpool
- Add silicon solution
- Slowly add acid to pH 1.2-1.4 (using graduated glass dropper, all glass syringe, or PFE pipette tip)
- Mix for a while (10 mins?)
- Slowly add carnitine HLC solution to pH 1.8-1.9 (acidifying carnitine solution beforehand may be a good route)
- Slowly add acid to pH 1.2-1.4
- Slowly add carnitine HLC solution to pH 1.8-1.9
- Slowly add acid to pH 1.2-1.4
- Slowly add carnitine HLC solution to pH 1.8-1.9
- And so on until all the carnitine HLC solution has been added and pH is < 2.0
- Mix for a while (10 mins?)
- Add glycerol in the same faction as carnitine HLC solution to ensure pH doesn’t exceed 2.0
- Mix for a while (10 mins?)
- Top up the solution with water to the target final volume
- Adjust pH to 1.5-1.75
Once I conduct my planned mixing experiments and stability testing, I’ll share my formulations and protocol.
You don’t want to use Ca EDTA because in most cases you shouldn’t chelate calcium. And besides, EDTA is phytotoxic at higher concentrations (a primary reason Fe DPTA is used instead of Fe EDTA).