Applied Science - 2023-07-06
I show a "DIY" chemical color-based method to determine the amount of lead in water, and then use the method to measure the amount of lead extracted from various types of lead crystal glassware. Skip to 27:05 to see the detailed results Code, analysis, raw data, more references: https://github.com/benkrasnow/LeadCrystal Supercon 2022 talk: https://www.youtube.com/watch?v=26olExLUX-0 Average daily lead consumption: 50ug in early 1980s, about 2/3 of this came from food and water https://openlibrary.org/works/OL18340799W/Food_contamination_from_environmental_sources?edition=unset0000unse_z0t6 The FDA established a maximum daily intake for Pb called the Interim Reference Level (IRL). The IRL for children and adults is 3 μg/day and 12.5 μg/day, respectively. In 2022, FDA tightened its Interim Reference Levels (IRLs) for lead to 2.2 µg/day for children and 8.8 µg/day for females of childbearing age—a drop of 27% from the original IRLs it established in 2018. (2011) The estimated average daily dietary exposure of the French population to lead was 18 μg for adults aged 15 years or more https://apps.who.int/food-additives-contaminants-jecfa-database/Home/Chemical/3511 ChatGPT on cloudy lead acetate solutions https://chat.openai.com/share/b24593ea-e467-4c41-ac79-55a4c0546a63 Support the production of future videos on Patreon: https://www.patreon.com/AppliedScience
Dude is really putting master's thesis amount of work into a single YT video.
Ah finally we see the "I asked chatgpt and it was right" project. I saw you post about it on twitter a while ago and wondered if it would ever show up in a video. Very interesting concept and now I understand how the heavy metal tests I've used in the past work! Very cool
I would really like to see this repeated for bright green fluorescent uranium glass.
By my estimation chatgpt gets it right most of the time. Seeing the chatgpt got it wrong videos are self selecting.
@@WeBeGood06 chatgpt regularly gets huge amounts of information wrong and bullshits about knowing things it doesn't know CONSTANTLY. It's completely untrustworthy and little more than a toy for amusement that can occasionally provide a useful insight about something. Ask it about detailed topics you are already an expert on, then ask it for citations in the literature to support its claims. It will simply fabricate everything from whole cloth. See the hilariously stupid Mata V. Avianca case from a month ago.
The number of people treating it like a search engine is astounding. It's a text pattern generator; it hallucinates, it lies, it confabulates.
@AppliedScience, what version of ChatGPT, was this 3.5 or 4?
@@WeBeGood06It has categories it does great in, and others it fails in. It does best with thoroughly documentated topics that have objective and numerical truth, which makes the source data very consistent. It's efficacy drops a lot when you give it softer science
Would have been cool to see if scrubbing the crystal freed up additional lead, to simulate regular dishwashing. Great content as always.
the dishwasher might make it safer because the rinse aid leaves behind a plastic coating- that is the haze that ruins glasses in the dishwasher after a time
People still use dishwashers? Is this 1995?
@@LanceBeckman your comment makes no sense: dishwashers have only gotten increasinly energy efficient and better at cleaning difficult to clean stuff. It's like saying "Glasses? People still use glasses? What is this, the 1400s?"
@@LanceBeckman : What do you use? Hands? Is this the ancient era? Can you get your hand washing water to an equal heat?
Yeah, I was thinking the same thing. Was wondering how long term use would change it too.
A joy to hear a video so well narrated.
You must be new here...
All Ben videos are perfectly narrated.
@combcomclrlsr The extraction and narration remind me of @JamesHoffman 's coffee videos.
Absolutely!
I love this channel. He thinks about just about every atom of what's going on.
Everything is fascinating! Studied physics which included also some chamical analysis.
Applied Science is easily in the top 3 technical channels on youtube. He goes to such lengths and documents everything so well. He understands the topics so well he can explain them to about anyone. Chemistry, engineering, electronics… every video is a masterpiece lol
top 3? what are the other two then? in my world it's literally the best technical channel out there.
@@Alexander_Sannikov Nighthawkinlight is really,really good too, would be my top 3 choice
@@Alexander_SannikovTech ingredients, Nile Red, Alpha Phoenix, Breaking taps, Practical Engineering, Nile Red, Electroboom... the list is long.
As a grey-haired Chemist, I especially enjoyed seeing him use + explain the UV/VIS spectrometer that fits in the palm of your hand (the LR1). Amazingly powerful UV/VIS capability for only a fraction of the cost $$$ compared to “professional” lab equipment used at US EPA and FDA laboratories like Perkin-Elmer and Agilent. Now I know what I want for my birthday present, an LR1 👍
@@Dinnye01while i've been subscribed to all of your listed channels and while tech ingredients does occasionally get sort of close, in my opinion this channel is just miles ahead of every other one. In terms of the host's expertise level, video subjects and the sheer amount of unique stuff they have published.
You might want to check tartaric acid/tartrate as an extraction solution. Tartaric acid is famous for being found in high doses in wine while also forming extremely stable, soluble complexes with lead, being able to dissolve even lead sulfate. So real wine could extract way more lead than just dilute acetic acid...
That's a great point, there should be no acetic acid in wine unless it has turned. The root Latin words in "vinegar" are Vin = Wine and Eger = sour . Tartaric, malic, citric, and succinic are the primary acids found in wine, this is also why total acidity is more valuable than pH for testing wines acidity. Also as mentioned at the end of the video many other solvents may be drunk from these glasses which may pull out more or less lead.
Or phosphoric acid, being that kids and other non-alcoholics are going to be drinking soda out of these leaded goblets at the china-and-crystal fancy occasions.
I'm curious, I would think that the solvent would not matter much. My rationale is the lead extraction is inhibited by the diffusion through the glass, not the thermodynamics of dissolving.
@@Kycilak My bet is it depends on if the glass has been pre-extracted or not. If it has, likely no difference. If it hasn't then that first drink is going to have way more lead.
Doesn't the wine making also produce the tartaric acid or at least the cream of tartar?
Regarding the plastic carboy: many plastics have organo-metallic additives or surface contaminates which are manufacturing additives. For example, mould release agents, and many other modifier agents. Often these are left on the surface of the plastic product in relatively large amounts, or can leach out slowly over time. We had a huge problem with tin (Sn) additives leaching out of plastics in one project I worked on.
I agree, when following recipes, nothing beats the mass per mass specification. So better use mg per kg of water, not per liter 😊
26:30 : If you made standards for copper, nickel, and other metals, I think you could use a multivariate least squares approach to find the concentration of all trace metals in your sample simultaneously, which would both tell you if there's other stuff in there and give you more accurate estimates of lead that wouldn't be confounded by other metals.
This.
This assumes that the result is a linear mixture of the standards, which may not be the case. Maybe the literature has something to say, but in the absence of that, you'd have to make some samples which were known mixtures of metals to validate the method.
@@bob2859good point
@@bob2859 The data at 22:14 shows that the absorbance for lead is quite linear until you reach saturation. It should definitely be linear in the limit of low concentration.
The idea with the dithizone is to always have an excess of unreacted dithizone, so that the reactions are never starved for it and all of the metal reacts. When all of the metal reacts, the absorbance of the reacted dithizone is directly proportional to the concentration of the metal. So long as each different metal has a different absorbance spectrum when reacted with dithizone, yes, it's possible to measure the concentrations independently in the combined solution. Absorbance spectra add linearly at each wavelength and the contributing spectral curve shapes are known, so you only need a linear transformation to separate them and get the concentration of each metal.
In the hospital lab they used a multi-stage deionizer and then all the water was distributed via tin pipes. I asked why not glass and was told the deionized water would leach all sorts of impurities out of the glass.
This depends on the glass aswell, normal sodium glass tends to leach more impurities than borosilikat glass
Why not pure Sapphire? I have a Graphics tablet where the entire surface is a huge sapphire panel. It's probably the only scratch resistant thing I have.
@@AmstradExin Most likely a shaping constraint, as all synthetic sapphire applications I am aware of can be made and cut from flat sheets (screens, camera lenses etc)
@@timkurz6086 Borosilicate glass is less likely to leach impurities, but plastic containers or even soda-lime glass are specifically preferrable for boron analysis because it does not leach boron.
@@fatiheneskuru4332 seems logical to me 😂 however i have to admit ive never done boron analysis to this day nor have i heard someone doing that to encounter such a problem!
Lead crystal fluoresces a ghostly blue under UVB. An LED UV flashlight is great for uranium glass but won't cause lead crystal to glow. Love your videos!
Have you tested this yourself? what wavelengths?
I regularly see the ice blue glow of certain pieces of glass with a UVA flashlight at 365nm but I don't know for sure if it's lead, or cerium, or something else.
My family is from Hungary and my grandfather was a glass man. When they immigrated to Cleveland he continued to cut crystal. If you live in a house in Cleveland that has a chandelier it is possible that he either cut all the crystal or cut a replacement piece. He was a true artist.
as a analystical chemist i'm so happy u actually addressed the PPM PPB notation. i hate it especially when they use ppm as mg/l. its so inaccurate because of denisty and all
Even he was like .5% acetic acid. It's just natural to think that way.
It seems fine for comparisons, like 300ppb lead vs 200 ppb lead, but it’s definitely not good for specifications, because it’s vague. By volume? By mass? Certain units?
This doesn’t matter as much when there’s another reference point, but is extremely important for other purposes
Excellent video! It would be interesting to run the glass through dishwasher let's say 50times, leave it for a month and then repeat the experiments - to see A) if the dishwasher leached all the mobile lead out of the surface or B) made it worse by making the glass bit more porous(etched by the alkaline dishwasher powder) so there is more surface for the lead to come out in the next drink
In the same spirit, hand wash it with the abrasive part of a kitchen sponge and hot water
Although NileRed videos are fun, but this is how I’d like a research presentation. To go through all the aspects, mistakes and triumphs, math science and engineering, tip’s tricks and techniques, and so on. Thanks again Ben, and awesome video as always 👍
I've found myself liking Nile Red's videos less and less over recent years. IMO he's clearly appealing to a more casual viewer, and the content feels a little "dumbed down" compared to his older stuff
@@JustinDriver-m1i Yup going for a bigger audience
Nilered is just a kid making memes and throwing tantrums.
@@quarteratom lol tantrums? When did he do that?
@@iteerrex8166 https://youtu.be/tGqVMbAQhBs?t=4m6s
For example.
As someone who does water lead testing as part of my job - this is really great!
The dithizone is a great choice for YouTube because it gives a color as a function of metal content!
With your electronics chops, I'd have thought maybe you'd have designed and built a electrochemical potentiostat to perform anodic stripping voltammetry - which is also usually sensitive down to the 10 is microgram/L range. In that method dissolved lead(II) is reduced to lead metal at an electrode and then "stripped" from the electrode by applying an oxidizing potential to the electrode. Usually a mercury-lead amalgam is used to create the deposit, but bismuth also works and is non-toxic. Other metals such as copper and zinc strip off at different potentials and therefore the method can be used with other metals present and also to quantify those metals. The only downside is that you have to use the method of standard additions to each sample to make your determinations - so it is tedious (perhaps more tedious than the liquid-liquid extraction).
ben, you are a true hero in my eyes and you push me to be the man i aspire to be. the fact that your projects have such depth and involve so much scientific rigor, methodology and forethought, while at the same time being done in your garage with homemade setups, really makes me wonder about the boundaries of DIY. i do not know how you find the time, money and motivation to do these very advanced projects, but it makes me hopeful that i will get to a point in life that i can do the same. please keep being curious and making these awesome videos, because, while this community is not as big as i would like it to be, i am sure you motivate many people like me. i wish you the best of luck!
I just discovered your channel, and this one video convinced me that you are a real gift to humanity. It inspired me to know that there are people like you in the world. Thank you for your generosity in doing this experiment, and sharing it for free with the rest of the world!
Another great video. You don't let yourself get sidetracked, calmly choose a topic that appeals to you, and then kneel down fully into it. Above all, I like the versatility of the topics; well, it's all applied science.
I am a retired analytical chemist. Well done! The ultimate in metals work is an inductively coupled plasma mass spectrometer (ICP/MS). Detection limits drop from your levels by a factor of 1000 or more. Typically low limit metals work is done in a metal-free, clean room. There is no exposed metal. All labware is polyprop or PTFE (aka Teflon). Reagents are certified for metals work, or prepared in-house. One comment about your pipettes. Air displacement pipettes like you use are prone to error. Positive displacement pipettes are much better. Also, I bet if you put some high pH extractant in your lead crystal, the lead levels would go back up. Almost forgot. I knew the answer to the cloudy lead solution problem as soon as I saw it. Dissolved CO2 is a real problem in a lot of wet chemical methods.
"I bet if you put some high pH extractant in your lead crystal, the lead levels would go back up."
What do you think would happen to make the lead levels go back up?
Very interesting video. I was just researching this week about lead content in brass which could be found in espresso machines and garden hose fittings.
All machined brass. They call it "free turning" 12 percent is pretty common.
@@napalmholocaust9093while I don't know exactly what alloy you're referring to, in my experience (as a machinist) the most common free machining brass is ASTM C360, which has an allowable lead content of 3-4%. There are also other "eco brass" alloys available that have near zero lead content, specifically for use in high volume production of plumbing parts and fittings that will come into contact with drinking water.
I agree. I try not to purposefully expose myself to excess lead knowing that I'm probably exposed to it anyway through daily activities. A good goal in life is to keep lead in your bones as low as possible. 😁
From what I understand, the real danger of lead glass is it's use as a decanter for alcohol, especially if you leave liquor sitting in it for years.
From Wikipedia: In a study performed at North Carolina State University, the amount of lead migration was measured for port wine stored in lead crystal decanters.[20] After two days, lead levels were 89 µg/L (micrograms per liter). After four months, lead levels were between 2,000 and 5,000 µg/L. White wine doubled its lead content within an hour of storage and tripled it within four hours. Some brandy stored in lead crystal for over five years had lead levels around 20,000 µg/L.[21]
thank you.
The stuff you do is absolutely brilliant. Giving some figures to these kinds of toxic substances is extremely interesting.
An interesting question is how usage patterns affect things. If it's your "special crystal" that you pull it a few times per year, you have maximum recharge from migration, but minimum exposure events. If, instead, you use it every day, then you'll be extracting frequently but getting less exposure each time. If the migration is slow enough, then both might be similar in total exposure because the rate of migration matters the most.
Alternatively, if the migration is somewhat faster, then the layer of glass which is extracted from might "fill up" for the occasional user so the everyday user gets more exposure, but maybe not excessively more.
Finally, if the migration rate is pretty fast, then every extraction leads to roughly the same exposure level so the daily use might be getting a hundred times the exposure of the occasional user.
Ben's results suggest that, for his extraction method at least, his glassware isn't in the fast recharge regime. It suggests that it could be in the slow (migration limited) or medium (daily is worse than occasional, but maybe not immensely worse) regime.
Wow, that's a nice idea that you can pretty much make these glasses safe by pre-extracting most of the lead at the surface layers, awesome!
This is great advice for anyone who uses a lead crystal decanter. Or it's an excuse to drink the contents straight away 😁
The issue is that he used an acidic extraction liquid. The problem is that moast soaps especially for dishwashers are basic. Basic solutios tend to attac glass much more. So every time you put this stuff in the dishwasher you remove a small amount of glass wich could free more lead. So using citric acid is not very realistic I think. Still like always it is a super cool video.
@@electricalychalanged4911 You wouldn't want to put lead crystal into the dishwasher anyway. Even a small amount of surface clouding will ruin the visual effect it is used for...
@@electricalychalanged4911 I thought that he said "acetic", like vinegar.
Would you or somebody confirm whether or not vinegar would work, and whether or not it would damage the glass?
@@eugenetswong Vinegar is a week acid pH 4,7. Glass or SiO2 does not react at this pH. But many if not most metal oxides do, forming mostly soluble salts. That goes for lead oxides too. in the concrete case the accessible lead oxide on the surface of the Glass would be dissolved by Vinegar (and most beverages es they tend to be acidic) over time. But after putting anything basic in there pH 8 or higher (like many soaps or cleaning agents, but also some herbal tees and vegetable juices) a very thin layer of glass can be removed which would expose more lead oxide. My argument is that removing the Lead by long exposition to week acids will not make the lead glass safe to use for food in most use cases I think. So can it work? Yes, if no basic stuff touches the glass afterward . Will it damamge the glass? Defiantely not.
I used to work in R&D at a breathalyzer company. If you want to talk about confusing units, look at that industry. "%bac" can be defined in a lot of ways, just like your example of ppm. Also, we used the same method of diluting a stock solution when we were studying the linearity and sensitivity of our devices. As always, great video, Ben!
Interesting. Would love to have a discussion with you about calibration! I've recently ordered some alcohol sensors (the ubiquitous MQ-3) and I'm curious how to come up with some sort of actual measurement. How do the machines take into account people with different heights and weights? Or is that not considered at all, and it just looks at exactly how much alcohol is in the breath sample. It seems odd to me because different BAC levels show completely different levels of impairment and intoxication in different people -- but at the same time, how can you design a law for e.g. DUI without having some sort of non-subjective standard? It seems like a complex thing to do well.
@@AureliusR Impairment isn't taken into account by many (all?) legal systems, I would say because it's too difficult to measure. Instead alcohol breath or blood concentration limits are set. In New Zealand they are 250 micrograms of alcohol per litre of breath, or more than 50 milligrams of alcohol per 100 millilitres of blood which give a clear pass/fail result. Regarding calibrating an MQ3 presumably you'd want to generate a range of standard alcohol / air concentrations. More difficult than liquid solutions so have fun.
A joy to hear a video so well narrated.. A joy to hear a video so well narrated..
This is the bar for scientific communication and process documentation imo. Thank you for the videos.
I don’t know of any channel like yours, especially your presentation style, and I’m so grateful you share these experiments and adventures with us.
I loved hearing your data analysis process, especially the idea about doing a best fit with the extremal spectra! I have a background in mathematics and physics, but my mom is an abalytical chemist, and hearing theae methods of analysis is always really cool!
Thank you for teaching us about lead glass!
It would be interesting to do additional calibrations for common metal ions and then see if a multi-dimensional functional fit can get good accuracy for multiple metals at once.
If they're independent it should be pretty accurate right? But what about the unreacted values I this those are linearly dependant with every metal, or are they not? (Just learning linalg so this may be way off the mark lol)
@@xhivo97 I don't know, there were thoughts as to how these things might interact, but if we can find the ratios of bound values, then we can probably do a correlation to total unbound values. It would be work to calibrate, but if it isn't linear, we should be able to train a ML model.
I was thinking something similar, but different: instead of calibrating against ultrapure water, could the full spectrum functional fit method be used against tap water as a baseline, and just measure lead increases against that baseline?
@@aaronbotsis7218 The problem with tap water is that it tends to be inconsistent.
So you would have calibrate the baseline each time you take water fron the tap.
👍 Always excited when you post a video!
7:00 "so luckily I found a pretty good solution" very nice pun
Thank you do much for making the episode about lead crystal instead of about the machinery to check ppm. The moment is started I was thinking ‘hmm what IS lead crystal’ then you read our minds and focused on it <3
There used to be significant amounts of lead additive in some types of PVC plastic, used to improve UV resistance and extrusion characteristics. I think it's mostly been eliminated, at least in the developed world. One problem with it was that if the product (such as vinyl window blinds) were exposed to sunlight the plastic would deteriorate in a thin layer which would turn to (lead-bearing) dust which could be ingested or inhaled, and the process continued with the freshly exposed plastic.
Last cordless drill I bought new came with a charger. The charger cord does have a lead warning. It is still being shipped in (ryobi). The vinyl insulated lunch totes are notorious and used mostly by children. Don't know if those are still around but I would think so. Appently the amount of lead used shot-up in the past 10 years due to re-regulation.
**Apparently 😃
Yeah, people talk about plastic (etc) as if it’s the plastic itself that’s the only problem, but often it’s the additives and there’s little control over what is being used as additives. Or maybe it’s something made of steel, that should be safe, but what if it’s steel with a significant amount of lead in it, and so on.
I'm speculating but I would love to know if polymerisation catalyst could have been the problem. I'm sure that there is some catalyst in final product, but I have no idea if it is in high enough amount and if it would even leach in solution.
@@napalmholocaust9093That was a California warning label because the solder might have contained lead. Long standing joke is "Everything in California causes cancer, especially California." Generally anything imported through California gets one of those tags slapped on them due to California law.
I've been analyzing metals in water by ICPOES and ICPMS for 13 years and I've always wondered how metals were quantified in the days before ICP was practical. This video is fascinating for me. I love all the chemistry videos you do.
Really interesting results. I wonder how much lead was being consumed when they used to add it to sweeten wine back in the day especially compared to the fairly low amount in lead crystal. Also wonder if you dug up some dirt near an old(pre 1972ish) busy highway intersection how much lead is still in the ground from the use of leaded fuel.
Fascinating as always! One of the few channels that I have notifications turned on for; always click without even reading the title because I know it will be interesting regardless of subject!
I assume your lead glassware was all new, I would be interested in testing glassware that is decades old as most of us probably have, but inversely hasn't been used in decades. Does the lead always over large enough timescales migrate to even distribution, or is 30 year old glassware with hundreds of uses but none in the last 10 years indistinguishable from non-leaded glassware.
Yes. My thoughts exactly.
Or do a test running the glass to through a dishwasher, or the suggested soak for a few days.
@@ch94086 Or maybe scratch it with a spoon to simulate stirring a drink. If glass with lead content is softer it might be easier to scratch some of it off.
@@ch94086 Nice, soak the dishwasher in lead particles.
@@ch94086coming from a country that used to use crystal like it was going out of fashion, putting it into a dishwasher makes the glass cloudy.
This is just awesome. Knowing all this panic disorder which appears every time led is mentioned - "dont look at it, it can kill you!", I would say it is worth publishing. You have nice results!
But all these battles with reviews, registrations, editors, no affiliation, I assume, probably is too much.
I don't understand every detail of the chemistry but your combination of the subject with electronics, programming, and science [observation of the facts compared to a hypothesis] plus general intuition has always been education. My personal growth and career have been advanced by you and a few similar channels. Thank you so much for your time and the contributions you've made to the community.
Serious scientists all have the following tools: XRF Gun, Mass spectrometer, Electron microscope, Oscilloscope, Series of acids, pure forms of as many elements as possible, solder gun, wires, protective eyewear, gloves, lab coats, UV light, IR thermal camera, Series of high speed cameras for various wavelengths, vacuum pumps, vacuum chambers, CNC machines, glass making equipment, windowed high pressure metal pipes that fit together, table top electric kilns in programmable and regular forms, several computers, ultrasonic microphones, various freezers, solutions and solvents (include liquid nitrogen in there) and centrifuges.
Those all cost hundreds of thousands of dollars total. Most scientists aren't well off but are also interested in MRI machines, DNA decoders, super computers and just sort of not even think about owning but competing for time on orbitting telescopes. 😄
Point is to really know what's going on with most questions.
You don't often wonder, "does this have too much lead in it?" but if you did someone with the tools could answer that, like on this channel. 😊
A fun one today that's asked a lot but rarely meaningfully answered is, "is this computer secure?"
Good luck answering that without going over billions of lines of code and looking through hardware with electron microscopes. Some chips come with hardware vulnerabilities built in you can only see by decapsulating them. Software you must test with supercomputers for vulnerabilities not discovered yet. It takes a lab to answer such a simple question because there is a multi-billion dollar industry built to make them not secure.
Great channel.
Right when I was thinking that there may be a chance that the lead content in the glass layer, which was in contact with the water, can slowly recover over time due to diffusion within the material, you started to comprehensively answer exactly that question in your video. That's why I like your content so much. This video was super interesting, TYVM!
I'm really glad that I'm not the only one who hates PPM. I know technically it's well defined, but if you haven't read the spec, PPM can mean so many things. Is it PPM in molecule count? Is it PPM in volume? Is it PPM in weight? How would an average person know?
Even then, measuring things in Liters vs KGs is dangerous, too, because we're comparing volume with mass, disregarding any density arguments. Personally I'm very partial to always comparing mass to mass. Volume measurements only complicate things therer
I don't see this as being a problem with PPM itself as it is with just being unclear about what you're measuring. PPM is a perfectly fine unit for expressing ratios of numerical quantitiies (that have the same unit, obviously mg/L is not ppm in the first place), but a substance is not a numerical quantity. Using PPM for a concentration without specifying whether it's by volume/mass/mol is like asking for "50 water" without specifying a unit :P
Where ppm and ppb gets me is in metrology. Just state the uncertainty in the units measured, it's needlessly confusing. 10 ppm means less than +/- 10 μg
@@HBomb157 They mean completely different things, 10 ppm is a relative error, ±10 μg is an absolute error
@@MatthijsvanDuin both are usually specific for a full scale range so effectively the same. But you right. Still don't like it.
I am usually really loving every video you make, but this time I was a bit hesitant to watch it. I finally gave in just to see what it was about, and it was chock full of very interesting things that I didn’t know about lead.
In other words, another great and informative video and I should not be hesitant next time I am uncertain about any of the topics that you pick.
A very interesting video indeed. Thank you.
Thank you for your well explained videos.
I am always amazed at how much work you put in to make them.
Amazing content. Please keep uploading! I've followed your stuff for years and won't stop soon. thank you!
I think you could also do a ratiometric approach: divide the absorbance value at one maximum by the other, and plot that against the concentration of lead. In theory as one peak increases the other decreases and the ratio changes, thereby making your measurements independent of things like uneven excitation intensities across samples (since you're looking at the relationship between intensities at 2 wavelengths). This is how some fluorescent biosensors are characterized
You could do that, but it's better to treat the concentrations of unreacted dithizone and dithizone reacted with lead as independent. That's because, as Ben mentioned, you don't know how much residual unreacted dithizone you'll have in the end. It depends on the starting concentration and on how much of it reacts. The concentration of reacted dithizone is what you ultimately care about, and you'd like to measure that without interference from the the concentration of unreacted dithizone. A ratio won't accomplish that. But it is enough to sample the absorbance spectrum at just two wavelengths. Since you know the shapes of the unreacted and reacted absorbance spectra and they add linearly at each wavelength to create the observed absorbance spectrum of the combined solution, it's just a linear transformation to separate them.
Wow, I was having some flashbacks when I developed the first home cholesterol tester in 1986. You did a superb job, thanks for this excellent video!
@Muonium1 - 2023-07-06
Note that the overwhelming majority of polyethylene produced in industry, while energetically favorable and exothermic in chemical formation, still requires an inorganic or organometallic catalyst to initiate at lower temperatures and pressures. Typically these are Ziegler-Natta catalysts based on aluminum titanium chloride , the Phillips catalyst of a chromium oxide silica gel complex, or antimony oxide . Invariably, due to the viscous nature of molten PE during production, much catalyst remains in the final product, and will thus leach the metal catalyst into whatever liquid the resulting plastic vessel contains. This is almost certainly what the dithizone is detecting in your plastic water container. Incidentally, the catalyst for PVC, which the spigot may be made of, is mercury chloride, and a common stabilizer used in PVC is LEAD oxide .
@pattheplanter - 2023-07-06
Saved me writing a much less exhaustive comment.
@jannejohansson3383 - 2023-07-09
Oh fuc.. I hate plastics in fresh water pipes and some part's got touch with my drinking water.
Some lead isn't even worse thing in different plastic types.
@OutThere458 - 2023-07-09
@Muonium1 When PVC is marked as "food safe" is that meant to indicate that a different catalyst has been used? A quick Google finds there was a kerfuffle over the construction of Vermont sugar houses in 2021 due to a leeching issue from non-food-grade PVC pipe. Not many people drink from lead crystal glassware anymore, but plastic is everywhere [citation needed]. I'm a computer engineer with no materials knowledge, but I assume that the migration of lead to the barrier layer could be faster in materials other than glass, meaning the rinsing process Ben described may not be adequate protection.
@cajampa - 2023-07-14
Thanks for this, I have been wondering why I detect chromium from my RO produced water and i could not figure it out.
It is from all the PE filter housing and hoses.
Leaching the chromium catalyst in to the water.
It is very slight amount barely detected on water measuring strips.
And it is the only contaminant I can find in the water.
It is still WAY purer than the tap water though.
@Muonium1 - 2023-07-14
@@cajampa 👍🏻👍🏻