To satisfy daily nutritional requirements or RDA, I require to express my values in grams. However, I conducted an analysis of macro (%) and micro (ppm) nutrients in fresh leaves. Although the values obtained from the analysis are in these units, is it possible to determine RDA by simply using a conversion calculator to mg/100g or grams? Or there are specific conversion factors that I would need to adopt. Furthermore, how do I adopt conversion factors for fresh values to effective uptake of nutrients from cooked vegetables? Please note that cooking and analyzing was not objective, however, I still need to determine the feasibility of consuming the vegetable and provide RDA without assuming that nutritional uptake is not affected by cooking.
You can do the calculations from % and ppm to "mg/100 g" or "g/100 g" as appropriate, this will give you the value to estimate the minimum intake required for each nutrient.
As you surmised, there is likely to be an efficiency factor to absorption of these nutrients, as sometimes there are variables that are unaccounted for in a simple mass balance estimation. Haem vs non-haem iron is one of the examples that comes to mind. Anti-nutritional components such as phytic acid are used to store phosphorus for example, but inhibit absorption in the gut. Exposure to oxygen and light over time will break down carotenoids in yellow vegetables, so freshness is possibly also something to account for.
I guess you can work out the minimum mass of food to satisfy requirements assuming 100% absorption, then find the best estimates (or worst case scenarios) of efficiency for each nutrient and multiply those. As long as you can provide a well justified argument for each calculation (with references to back you up), you should be fine. A few quick calculations will show if you are in the right range (e.g. eating 10 kilograms of any food to satisfy a daily requirement would be too much for most people).
You can also use a reference publication like McCance and Widdowson and if it is not possible to access their calculation methods then you can at least work backwards from their estimations of raw and cooked food nutrient content.
You will always have to put in a disclaimer due to variations from soil quality that food is grown in, type of cooking method, length of time since being harvested, how it was stored since then and how long it was cooked for as well as whether nutrients being referred to are water soluble or not (if the medium they are cooked in was water). I hope that is not too obvious an answer for you.
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