@Abdullah Cocamide MEA and MIPA have very low risk of nitrosamine formation compared to DEA. If you're worried about it's possible formation, avoid preservatives as Bronopol or Bronidox which under certain conditions can act as Nitrosating agents that convert free diethanolamines (present in DEA derivatives) into nitrosamines. Formaldehyde can also catalyze the reaction. You can use some substances in your formula to also prevent is formation such as Ascorbic acid (other organic acids are weaker at preventing nitrosamine formation). This last technique is used in bakery and it's recommended by COLIPA. So, generally speaking, you need all the "wrong" ingredients so it happens, and that's why Cocamide DEA is still approved in cosmetics, as long as there are no nitrosating agents.
@Abdullah I believe there should be no problem with that preservative system. As a side note, check for the efficacy to see if there might be lack of activity against some specific microbial organism, and that the pH is adecuate for it to function properly.
The ratio of each preservative in blends we make is the same as preservatives from reputable companies like Inolex wich is broad spectrum. This way it cost much less than if we purchase the pre blend.
@Abdullah I understand, but every formula has specific needs, and the ingredients you are listing as preservatives are actually preservative boosters rather than preservatives. Companies nowadays sell them as green or natural preservatives, but most of them lack of activity against specific strains. In very simple formulas, they might work more or less combined, but if you have extracts, proteins, starches, not only you'll need higher amounts of some of them, they might fail to protect against certain microbes (not to mention that adding them in the wrong way to an emulsion, when you have solubilizers or emulsfiers, could get them out of your water phase, which is the one you want to focus on), so again, it depends on your formulation needs.
Comments
The ratio of each preservative in blends we make is the same as preservatives from reputable companies like Inolex wich is broad spectrum. This way it cost much less than if we purchase the pre blend.