Відео

Thank you!

Providing my teaching on UA-cam is the only thing I do "for free." I don't send out free anything. I do not consult for free. You are, of course, welcome to copy what you see behind me for your own usage.

Glad to help!

I started with a 4x8 sheet of plywood and cut it to length. It's too narrow down on the floor to put the 4' width, but up higher (above the wheel well) it's the perfect size. As far as length goes, that's complicated, because it depends how far forward you're willing to scoot the front seats. It's a bit more than 6'. (I don't know why this video is still up on this channel; most of my travel videos are on my other channel, including this follow-up that talks about my son, who's 6'2", sleeping in the Escape.)

The video literally walks you through how to do this

⁠@@Double0piI have tried to follow the steps and I am not sure where do I make mistake, my concentrations come up negative 😭. Absorbance at 238nm- Phenobarbital 0.551, Oxycodone 0.477, Unknown 0.652 At 280nm- Phenobarbital 0.07, Oxycodone 0.05, Unknown 0.493. Both samples Phenobarbital and Oxycodone are at 5.20x10^-5 M concentration. The molar abs that I calculated ( molar abs= A/C ) are at 280nm- Phenobarbital 1346, Oxycodone 962. At 238nm- Phenobarbital 10596, Oxycodone 9173. step 1 result: 0.652-9173 Coxycodone/ 10596= Cpheno step 2) 0.493= 1346 (0.652- 9173 Coxy/ 10596) + 962 Coxy Step 3) 0.493= 0.0828- 1165 Coxy + 962 Coxy 0.4102= -203 Coxy Coxy= -0.002 Step 4) 0.652- 9173 (-0.002)/ 10596= Cpheno Cpheno= -17.694/ 10596= -0.00167 😭😭😭

My pleasure!

Hi Oscar, This subject is covered in a few analytical chem textbooks (Harvey 2nd ed. is free) but they don't cover it in the depth that I do. If you want really detailed coverage, you need to get into aqueous geochemistry books like Morel & Hering. (I think that one is now out of print, which is too bad.) Understanding the interactions between all solutes in the solution is really important in environmental chemistry (which is why I have such a strong background in this stuff), but also really helps you understand interferences when doing chemical analysis.

Glad I could help! Let me know if there's anything else you think I should make a video about.

Thanks 🙂 Let me know if there's anything else you think I should make a video about.

You're welcome! Let me know if there's anything else you think I should make a video about.

Thanks. Let me know if there's anything else you think I should make a video about.

Always glad to help!

Thanks! Just got the studio set up in the new house last weekend. I suspect the video production will be slow for the next 8 weeks or so, but can start ramping up after that.

Glad it was helpful!

Thank you! Let me know if anything else needs clarification.

My pleasure! Let me know if there's anything else you think I should make a video about.

Thanks! Let me know if anything needs clarification!

Glad I could help!

I'm working on it and hope to get it out in a month or so! Sorry for the delay!

It's just an example. You can do this for literally any set of two wavelengths. Heck, you can do it for three if you are willing to wrestle with the math.

@@Double0pi Thank you! You have (hopefully) saved my lab report. Idk if I did it right but I trust your lesson 😭😭

Thank you!

It's actually quite easy. Find the conjugate acid of the weak base, look up the Ka for the conjugate acid, and then do the calculations for that. In this case, your weak base is the equivalent of the "A-" and its conjugate acid is the "HA". Hope that makes sense.

I have never heard of anyone using Raman for that, and I'm not sure it's possible (though it's not my specialty, so I could be wrong.) Raman works based on electron density, etc., and that's not going to change much (if at all) based on isotopic differences, which are linked to extra numbers of neutrons. Everyone I know who does isotopic analysis uses mass spectroscopy. In general, a regular MS is not precise enough to tell the difference between isotopes with similar masses, so often you'll find people using a tandem MS (MS-MS).

@@Double0pi thanks. I saw a few papers that discussed RAMAN as a way to help determine if a sample of carbon is in a good enough state to get dating results and may be used for relative dating purposes as a qualitative device within a site but wasn't quite good enough for a stand alone quantitative studies.

@@qrfarchaeology9391 That makes sense. Raman is great at doing qualitative and quantitative studies of hydrocarbons--the sort of compounds that would be used, eventually, to do carbon dating. So if you have an old sample and want to know if it has enough carbon left to do carbon dating, Raman would be a great tool. Being a biogeochemist, most of the people I know who use carbon-14 use it to look at carbon uptake (e.g. primary production), and there is plenty of carbon for them to analyze--so they'll use a scintillator to detect decay. I'm not sure that it is possible to do that for considerably older samples, but I am hardly the best person to talk about detection limits for that sort of instrument. I honestly have more friends who do stable isotope work (also the only isotope work I've ever done), where mass spec is the only choice.

@@Double0pi speaking of MS, I read about ZooMS where otherwise unidentifiable animal remains were fired up and a reading could be made to determine species. With RAMAN being significantly less destructive and being good for qualitative studies, would it be a good choice to use for identifying animal remains?

Some atoms can have several possibilities for oxidation states. If you learn about redox chemistry, you discover that these reactions are all about atoms changing oxidation states.