[Pharma]

I use Excel too (remake of my fertiliser database)… would work way smoother were I able to program VBA…

[Pharma]

@Perry true that! I had to look up the word ‘corollary’; I thought it has something to do with corals because octyl methoxycinnamate and benzophenone-3 harm corals (as @Doreen pointed out).

Maybe you know (cause the profs I asked didn’t) why sunscreens have to be so highly lipophilic? Turning them less lipophilic, maybe even water soluble should more or less completely deprive them of their ecological and hormonal side effects. Although, development went exactly the other way round with the first UV-filter, PABA…

@ngarayeva001 Especially benzophenone-3, avobenzone, and the ones containing camphor and cinnamic acid as part of their structure are problematic and are sometimes also banned or under REACH investigation. Using ‘nano-zinc’ and other nanomaterials is playing with the unknown and has, with some applications, already proven to be a bad idea. Nanomaterials are tempting and promising, opening doors to rooms we didn’t even knew were there because they behave in unique ways, ways we don’t fully understand, let alone were able to predict. As much as the scientist in me adores such materials, I also fear the unforeseen effects they cause in nature and how the play tricks with our immune system which both can’t handle this whole new universe.

One problem with these compounds isn’t just a possible health concern per se but tissue accumulation over the years, widespread use and constant exposure, and also the huge tonnage which, because these compounds are not sufficiently degraded in water treatment plants, ends up in the oceans where it accumulates further and they kills a plethora of species or renders them sterile (e.g. fish and crocodiles).

The only two ‘healthy’ solutions we have are to do everything we can to ‘close’ the ozone hole and avoid sun exposure (stay home, stay safe, for once not because of coronavirus).

Sunlight is beautiful and is life but it’s also 80% of skin ageing and the main reason for skin cancer… there is no black and white in nature, nature takes every shape and doesn’t know ‘good’ or ‘evil’, humans have just forgotten to live with that and always want what we in Switzerland call ‘De Füüfer und s Weggli’ = engl. have the five cents and the milk roll (which back in the day cost 5 cents).

[Pharma]

The original publication regarding parabens and breast cancer was not that great a read and not very well done… but it got blown up to the size of Saturn by media picking it up from other attention snatching media… and it got all twisted up and people started panicking. The following publication was relativising things greatly but nobody cared. The usual *shrug*…

There is no reason why methyl paraben should/could be problematic. Propyl paraben might be if eaten at considerable amounts. The highly lipophilic ones on the other hand do bear the potential of endocrine disruptors much like most of the sunscreen ingredients do. Though there’s a small difference between these: sunscreens are used at hundred times higher concentrations and from what we know, they cause serious harm to aquatic life and are potentially altering development of embryos and small children. Parabens don’t.

I should still have a 20 year old book somewhere on my shelves by a researcher from university Zurich who got silenced by lawsuits and lobbying involving several of the big companies selling sun creams and the like. What she uncovered/published wasn’t really new but now backed up by science and the world shat on her because $$, no real alternative, and people want to bronze (oh, and did I mention $$?). BTW students got that book for free, nobody wanted to publish it because of fear and so she paid the first and only edition out of her own pockets. When I first met her, she was still in fighting mode but some time later she was broken (and broke) ;( .

Bottom line is: parabens are, compared to most equally efficient alternatives, harmless and very safe preservatives for topical application and even for certain foods and oral pharmaceuticals. Sunscreens (fortunately, the worst ones are now being banned) mean DEATH (probably not for you, probably for your baby, and certainly for nature).

[Pharma]

Graillotion said:

A: How to whiten a lotion without Titanium dioxide?

B: I did not understand….the concept of smaller emulsion size…

A: The stupid answer: use zinc oxide ROFLMAO!

B: The reason why an emulsion is white is due to light scattering in every direction caused by refraction. Light passing from medium X to medium Z will bend depending on the difference in refractive indices of the two media. It’s like holding a spoon in a glass of water and it will look as though it’s bent. This effect is also only possible if light doesn’t hit at a 90° angle, so you have to look at an inclined angle at your spoon/glass. If you were to fill your glass with mineral oil and put a diamond inside, the diamond will ‘disappear’ because glycerol and diamonds have similar refractory indices, light will pass straight through both and there’s no more ‘bling’ to be seen.

In case of emulsions, gazillions of tiny blobs swim in a soup, each acts as if it were a tiny shard of mirror glass and turning and bending light into different directions. This ‘blurs’ the background picture to a homogeneous white. The smaller the particle, the larger the particles, the higher the chance that light actually passes through the droplets and you can actually see the colour they have. The smaller the particle more pronounced the reflection effect becomes and the whiter your product gets. That is, until the particles are smaller than light waves and your product turns first opalescent, translucent, and finally fully transparent (example: micellar water).

Bottom line is, if you can’t remove the colour of the inner phase, you have to reduce particle size either by playing with the emulsifier (e.g. micro-/nanoemulsions) or by mechanically crushing larger particles (e.g. Ultra Turrax).

Another approach is to increase the difference between the two refractive indices.

Some indices:

Vacuum: 1

Air: 1,0003

Ethanol: 1,001

Water: 1,333

20% glucose in water: 1,364

Silicone oil: ~1,4

Vegetable oils: ~1,46-1,47

Glycerol: 1,473

Paraffin oil: 1,48

Diamond: 2,418

Titanium dioxide: 2,614

Hence, you can either reduce the amount of glycerol and other solutes in the water phase and/or add ethanol or you choose highly refractive oils.

Either way, you’ll get better refraction and an apparently whiter product.

The opposite would be to create an internal and external phase with identical indices: This turns your white emulsion into a transparent, seemingly homogeneous product. But it will look as if you just mixed the two colours of outer and inner phase like yellow and blue becoming green.

Adding ‘whitening’ ingredients or opacifiers does do something but not that much. Also playing with the amount of liquid crystal builders may help depending on emulsion type. But again, the effect is minor and plays more with the hues/brightness than actual colour.

Last thing to try is to add silica or the like to the oil phase hoping that it adsorbs and masks the colouring impurities.

[Pharma]

Check THIS out. I think the products by Ajinomoto sound really cool though I’ve never tried them.

[Pharma]

Optiphen plus should be soluble at 1%. However, the three constituents thereof are all not super well water soluble and it is therefore important to add it “drop by drop” under good stirring and only add more once the portion you just added has fully dissolved. Once it starts precipitating, you’ve lost the game.

However, Optiphen plus is quite heat tolerant, probably more than the rest of your ingredients… so, heating could be an option for other formulations.

[Pharma]

Mr_Clean said:

…
Oil and wax phase is 42%…
…ceteareth 25 at 4.5% and peg 7 glycerol cocoate at 9.5%

…water at 15% and polymers, clays…

Does that mean that polymers and clays make up 29%?

Making stable HIPE gels using PEG based emulsifiers is in principle possible (the oldest publications on HIPEs I could find were done with ceteareth-like emulsifiers) and bears the advantage that you don’t have to bother with HLB.

However, I do not know if your emulsifier combo will work but I can tell you for sure that your formulation will not work because of polymers and clay on one hand and too much water but no polyol on the other.

Another approach would be the use of lecithin for a high oil content o/w emulsion (think mayonnaise). There are different emulsifiers available which can handle large quantities of oil but don’t ask me which ones, I don’t know that by heart.

[Pharma]

There are likely several flaws in there…

Anyway, don’t forget that there are also 5% 1,3-butylene glycol in said formulation. Which brings me to the first flaw: no control without it but only your 3 preservatives/boosters. Though it is possible that there wouldn’t be much of a difference or that 2-3 times higher amounts of diols are needed if 1,3-butylene glycol isn’t used. Likely depends on the formulation (water activity!).

Try it out.

Hexanediol is approximatively twice as active as pentanediol but the latter also exists as Ecocert naturally derived product. The few trial formulations I did turned out less viscous with pentanediol but I wouldn’t interpret too much into that finding. You don’t necessarily need both and you may try out just one but at higher %. Although some stuff I’ve read implies a broader spectrum if both are mixed.

Ethylhexylglycerin is often used at 1/10 of the preservative (different blends with phenoxyethanol or chlorphenesin are commercially available) and acts as booster; meaning it lowers MIC (or lowers the amount of preservative needed) and apparently broadens the spectrum.

Me personally, I can’t/don’t want to run challenge tests because I don’t sell, so I prefer using not too much but still enough to be on the safe side. I’d at least consider to include something like GMCY or phenylpropanol to further boost the blend of 1,2-XXXdiol and ethylhexylglycerin.

[Pharma]

Unlike other oils, jojoba oil can not be turned into a fat or wax by hydrogenation since it is already fully saturated. Though liquid, jojoba oil is already a wax from a chemical point of view. This means, hydrogenated jojoba wax does not exist. It’s just a marketing term which made its way into the INCI list. It is not a chemically well defined product but a custom blend of hydrogenated oils (which are solid) and jojoba oil. The exact composition is likely a trade secret and all you might get is which type of hydrogenated oil is used and approximate ratio of it and jojoba oil.

[Pharma]

Plus, a pH shift usually indicates something unwanted going on (degradation or microbial growth). Because degradation apart from rancidity and other smelly reactions isn’t much of a concern in cosmetics (it should be but, well, it’s cosmetics and a fair amount of claim ingredients does degrade before it’s even packed), masking it seems like the logic thing to do…

[Pharma]

Here around it’s not a fragrance and I don’t think it is in the US either…

Yea, sulfite ain’t that loved on ingredient lists ;( .

[Pharma]

BTW if you were to use a dark airless dispenser, a pinch of ascorbic acid or ascorbyl palmitate should also do the trick because you worst enemy or the real problem is oxygen and sunlight (UV). A pH above 6 simply speeds up the reaction and amines are probably not present in your product.

[Pharma]

You’ll have to try it out. Thiosulfate, metabisulfite and sulfite aren’t expensive and you could try all three to see A: how much each really requires, B: which one has the lowest overall cost, and C: which, at it’s optimal concentration, does show the least effect on the product. Even if all are similar, they aren’t identical. And if you were to feel experimental, there’s not just sodium salts but also potassium and ammonium salts of all three available .

It would be advised to stay below 0.5%. We don’t know how much vanillin really degrades because it colours quite well. At 3% vanillin, 0.5% should be way more than enough. Hence, I’d start at ~0.05%.

Further things regarding stability:

Check pH: Vanillin is more stable under slightly acidic conditions.

Avoid amines such as amino acids and aqueous herbal extracts.

[Pharma]

What about naturally occurring molecules closely related to common UV filters?

- Cinnamic acid derivatives such as ferulic, sinapic, or chlorogenic acid

- Salicylic acid derivatives such as salicylate glucose ester

- Anthranilates like methyl anthranilate (probably prohibited as drug precursor)

- Flavonoids (there are MANY flavonoids in nature and most absorb UV)

- Certain anthraquinones (though most are also very red)

Though these plant constituents have one or more disadvantages such as a narrower UV spectrum, lower lipophilicity or even being hydrophilic, susceptibility to photobleaching, get assimilated (penetrate skin too easily too deeply), or are metabolically and chemically less stable…

Neither do I know whetehr they are officially approved by whatever ECO-authority nor do I know their suitability for sunscreen formulations. These compounds aren’t just natural but they are quite frequently found at considerable concentration in nature because plants use them, under others, as sunscreens.

THIS might be an interesting read.

[Pharma]

What about baseball caps, UV-proof T-shirts or simply stay out of the sun, stay home?

[Pharma]

The proposed compounds are all very similar regarding chemistry and pros and cons. Sodium metabisulfite is the most commonly used one for cosmetics and builds sodium hydrogen sulfite in solution. Sodium thiosulfate is also used as pharmaceutical drugs but its reactions may result in the formation of sulfur which could be undesirable (not dangerous, just annoying).

I’d use metabisulfite.

[Pharma]

According to Active Micro Technologies (a manufacturer of aspen tree bark extract powder), their product PhytoCide contains mostly salicylates. Salicylic acid which does occur in aspen bark is a nice preservative weren’t it for the fact that it requires a quite low pH. In other plants such as willow and meadowsweet, different salicylates are predominant and include salicin which degrades to salicyl alcohol upon metabolism or hydrolysis but both compounds aren’t antimicrobials. Methyl salicylate, another natural derivative, shows antimicrobial activity but does not occur in aspen but in wintergreen essential oil. Salicortin, tremulacin, tremuloidin and similar derivatives found in aspen and willow might show certain antimicrobial activities but are poorly investigated and may only become active upon metabolisation (leading to salicylic acid with all it’s pros and cons).

I really don’t know why PhytoCide should show any useful preservative efficacy over the claimed pH range of 3 to 9.

[Pharma]

EGF (for research and pharma purposes) is ship as lyophilisate at -20°C. Once diluted with water/culture medium, it will be active for a few days the most. If you buy a liquid with EGF and it comes at room temp, it will be toast long before it even got to the delivery service.

There are some proteins which can be kept in the fridge for a few weeks or even months but these require stabilisation through precipitation or crystallisation in speciality buffers (such as insulin, one of the rare +/- stable exception).

[Pharma]

@ngarayeva001 A buffer has to be in roughly 10 x excess or more of compound X to accurately buffer said compound X. If compound X is a defined acid or base it may be turned directly into a buffer. It’s a ‘stupid’ (no offence!) approach to add 5% glycolic acid and then try to buffer it with 5% lactic acid - sodium lactate. Glycolic acid buffers as good as lactic acid: Therefore, the way to go would be 5% glycolic acid and enough sodium hydroxide to bring the pH to the desired value. To obtain a pH of 3.8, 50 mol-% NaOH are required because that pH coincides with it’s pKa. BTW a pH at the pKa is the sweet spot for any buffer.

Calculating how much of buffer Y is required to adjust considerable amounts of substance X ain’t a cakewalk! It’s often easier to just go and add a strong acid or base to a weak base or acid, respectively, until the desired pH is reached.

A buffer is usually effective over +/- 1 unit around the pKa of the used weak acid or pKb of the used weak base. This only holds true for conditions wherein a buffer is used at 10 x excess or more. At +1-2 or -1-2 units, the buffer will only work in one direction (towards the pKa).

@Doreen CLICK and scroll down to page 14 (read the general stuff too, it’s worth the time). As you can see, citrate, malate, and succinate would be useful. Unfortunately, not many standard Good’s buffers are available for the slightly acidic range. MES is basically the only one (not my favourite for lab works or in/on humans) and is widely used in hydroponics (also not my favourite when it comes to plants). In cosmetics, you’ll find for example HEPES (I like that more) in creams which use cell culture media (a marketing ploy); HEPES should be at +/- physiologic pH if done according to good buffering practice.

My recommendation is: buffers are usually not useful in cosmetics. Simply adjusting pH is more often than not sufficient and creates a self-buffering product. If I had a gun to my head and were forced to use one for that slightly acidic range and couldn’t use above mentioned carboxylic acids, I’d go with GLDA (Dissolvine-GL). It’s usually used as chelate but buffers well at that pH range though it’s a bit problematic with electrolyte sensitive formulations if used at buffer concentrations instead of chelate concentrations.

[Pharma]

20% is a reasonably easy to use concentration and IIRC dates back to the original product which was sold that way. Sure, you can use pure one but it takes more time and work to produce (smaller) batches.

[Pharma]

It’s about as good as hypochlorite and at sufficient concentration will kill any germ. The problem is not extrapolations (being a strong oxidant, extrapolating is a safe bet), the problem is compatibility with humans. It may be enough for tap water treatment or even pools but air treatment and lungs… no bueno.

[Pharma]

PP, as mentioned, tends to hydrolyse to phosphate and PP can also be used directly as phosphorous source by certain microbes. Adding it hence introduces one of the limiting nutrients for microbial growth (one reason why lecithin is so hard to preserve).

[Pharma]

Only distilled (sometimes termed double distilled) water for injection purposes is sterile (and pyrogen free) until you open/break the bottle/vial.

Demineralised water may contain a few more trace minerals and heavy metals but addition of a chelate takes care of that.

Heat and hold or rather bring to a rolling boil removes air and CO2 dissolved in water. This may result in more stable emulsions (on a scientific ‘scale’). Alas, once you start mixing and stirring in solids, you automatically reintroduce these.

Also, many solids such as @ngarayeva001‘s Aristoflex are likely more contaminated than water. One could, if germophobia is strong enough, sterile filter water and oil phase separately through hydrophilic and lipophilic 0.2 um membranes and work under aseptic conditions… Or go and add a preservative.

[Pharma]

lewhitak said:

…if a material is said to be stable using a pH 4.0 lactate buffer BUT after you add all the additional ingredients to the system you are more at a 4.5 or what have you. Do you then have to re-adjust to a pH 4.0? …

You don’t add a lactate buffer but, in that case, just lactic acid and at the end, adjust to pH 4 with diluted sodium hydroxide or whichever base is proposed. Thereby, you create the pH 4 lactate buffer.

[Pharma]

Chlorine dioxide is only useful for serious threats such as anthrax. Furthermore, it shouldn’t be used in an inhabited room but the desired application in the form of air humidifiers or air freshener indicates it is for use in close proximity of people. It is intended to be used in empty buildings which stay that way until it has fully degraded. ClO2 is highly toxic but, alas, promoted in certain media as silver bullet against various diseases such as cancer much like MMS aka Miracle Mineral Supplement or Master Mineral Solution.

Sometimes I think to myself that we must be in the middle of a zombie apocalypse because so many people act either crazy or stupid and use social media more than their brains.