 I'm going to start a series of videos where we cover the different chemical methods of microbial control. So we've talked about the physical methods of control like heat and using the autoclave specifically and all sorts of different things. So we're going to focus on the chemical methods of control now. We're going to start with the group here called the phenolics, but we'll break them down into phenol, then what I like to call the phenolic specifically and then the bisphenols. So we will actually save triclosan for a separate video because it's a pretty big topic. So the first, so just the function of these, they are how they kill microbes is they denature proteins and they disrupt membranes. So obviously all living things need proteins and denaturation is when you unravel the three dimensional shape and structure of proteins so they no longer have their function. Disrupting membranes, of course, you've got the cell members, et cetera, that can rip holes in membranes and even cause them to congeal and stuff like that. So all right, so we'll start with phenol. So just historically, hopefully, hopefully if you've watched the other videos where we talked about Joseph Lister, he started using carbolic acid, also known as phenol in the 1860s to disinfect his surgical suites and surgical wounds. This led to Listerine being produced in the late 1870s and this would have been a phenolic based mixture that also had alcohol, had tons and tons of uses in the past but is still used today as a mouthwash. So most of your phenols though have been replaced by the phenolics that we'll cover next and this is a very important point. That's because phenolics are more effective, less toxic and less irritating. So obviously that's a win, win, win. They're also more stable and they persist longer on surfaces. So for every reason, the phenolics are better than this phenol that you're seeing here. So I noticed they called them cresols but we call them phenol. All right, so here we see an example of a phenolic. This is O phenol phenol. You've heard of this one as well. So this would be, this would be in Lysol. This has been around since the late 1880s in use in Lysol and one thing I like about O phenol phenol, I've already mentioned how the phenolics are better and less toxic than phenol but another huge advantage of this O phenol phenol or what you find in Lysol is that it works in the presence of organic matter. So think organic matter, blood, you know, puke, fecal material, whatever you want to think of. If you're dealing with organic matter, Lysol is a very good way to go because these phenolics work in the presence of organic matter. That's a key point there. All right. And then the last one for this group, we have the bisphenol. This is called hexachlorophenes. So I don't spend too much time talking about hexachlorophenes because a different compound will cover later called chlorhexidine has replaced it in many ways. But hexachlorophenes is very good at killing gram-positive bacteria. Any time you hear of a chemical or anything that kills gram-positive bacteria, think skin organisms. Your staff and strep organisms that dominate the skin are gram-positive. So that's the first thing I would think of. So hexachlorophenes is used in, like you see here, physohex, is actually the brand name of hexachlorophenes, which is used for hand washing. They used to use it in nurseries, like on baby skins and stuff, but before they realized that it was probably toxic. So that's what hexachlorophenes would be used for, but I don't generally make too big of a deal out of that one. All right. So that is your phenol, the original phenol that Joseph Lister was using, the phenolics, and then the bisphenol hexachlorophenes. Like I mentioned, I'll do a separate video on triglycine. So I hope this helps. Have a wonderful day. Be blessed.