The amount of powdered juice that can dissolve in 5 ml of water depends on the product itself and the solubility. In most cases, powdered drink mixes specify a ratio of powder to water, often about 1 to 2 teaspoons (roughly 5 to 10 grams) for 8 ounces (240 ml) of water.For 5 ml of water, you might want to start with a very small quantity, such as a pinch or roughly 0.5 - 1 gram, and adjust for taste and solubility. Hope this helps