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The amount of X-rays needed to detect trace amounts of lead with a handheld device are probably more dangerous than the lead itself if such an device is used on a daily basis. There is a reason why your dentist goes to stand behind a wall when you she takes an X-ray of your teeth. If you would have a sample with 10% lead, the amount of X-ray used during for taking an X-ray of your teeth might be enough to measure its concentration within a few 1% accuracy, but if you are talking about 1ppm (and that is far above the 15ppb that is considered safe) you need a lot more X-ray to get a good enough reading.

Measuring exact contents with XRF is difficult if you do not have homogeneous samples due to all kinds of complicated effects where the XRF from one element interacts with the XRF of another element. To get within 1% accuracy you often need a controlled (vacum) environment and callibrate your instrument with a set of standards at regular interfalls. At least that is how it was 20 years ago when I developed software for a company that produced high-end industrial XRF measurement devices.

It's viable to get something like it on your supply chain. It's even viable to X-ray inspect fish at random in fisher's markets if you move your machine between them.

But yeah, a hand-held machine isn't viable.

I was thinking XRF used low-energy X-rays with very little penetrating power, but actually they're 20–60 kV. So I guess you're right.

What if rather than everyone needing their own, there was just a certification standard (like organic) which says the food has been scanned and confirmed to contain less than X lead/mercury/whatever?

Side note, is this what archaeologists use, to figure out the composition of a coin, etc.?

Certifications are the current situation for first world countries but it takes time to get them adopted everywhere. And if you have lead paint or pipes in your house, or if you have bought some Chinese plates with beautiful colors, who will tell you that some pigments may leak into your food.

There is the question of trust of the measurement where they will just sell you an approval stamp for 100$.

There is also the problem that some actors have incentives to cheat, like feeding insects to your salmon, and feeding the insects from literal garbage that may get contaminated by electronic components in the dumpster. Or maybe the specific salmon just ate a ball of mercury but was not selected for testing.

A generic tool, that can analyze your immediate environment without having anyone else involved is empowering and can catch a wide variety of problems that you can track further if necessary; feels like a freebie offered by Science. Although it will still need some years of work to make it as sensitive as they show it in Science-Fiction.

Humans have not evolved alongside everything we extracted from the ground since the industrial revolution. It's like a new pair of eyes that would help you avoid a bad apple or smelly fish.

If we could also get a cheap and easy to use Raman spectrometer to complete the XRF analyser it would also be a great addition.

(I don't know what archaeologists use but they definitely can use a XRF analyser to find the composition of coins)

In many parts of the world, certificates are just fancy looking paperwork that you pay for.

Did the water quality certification miss something in Flint? Certification means trust. Someone breaking that trust can have life long implcations for large groups of people. Giviing the individual power is better.

It probably passed at the treatment plant where it is easy to test. It would have failed at everyone's home though, where testing needs to be done house by house. (or maybe a statistical sample of houses)

Are they really that sensitive to be able to detect trace amounts of heavy metals distributed in let's say a relatively large piece of meat (larger than the detection area of the device, so the amount of metal it "sees" is even more decreased)?

well icp (inductively coupled plasma) is the gold standard (expensive but highly sensitive and used for heavy metals like lead in stuff).

xrf can spot higher concrntrations, but one can concentrate beforehand and then use xrf. while xrf fixed cost is 30k usd its cost is a dropjn the bucket compared to icp and solid state keeps on going.

forgive my typos commenting via phone

This doesn't sound like a solution at all.

It went from "pointing a gun at an item" to "concentrating a sample".

I've done analytical chemistry before and sampling accurately is not a trivial thing.

It probably isn't important whether the lead content is 10 ppm or 20 ppm in most cases, since neither is acceptable, so the standard of sampling involved here is far less demanding than the standard of sampling needed for analytical chemistry. You just need to avoid contaminating your sample with lead from some other source.

I would like to add a video on XRF from Applied Science, as the device is not very well known (at least in .cz, I have learned about it only recently).

https://www.youtube.com/watch?v=KdfHVcU8U7U

The dream future is both utopian and dystopian. Technology is advanced enough that such things are in hand of common man but society is so dysfunctional that basic things like clean water and food aren't ensured.

Ive been hoping to find others interested in this vein of xrf for community lead detection would be more thab happy to connect.

> These are gun-like devices that you point to a material, it shines x-ray on it and analyze the rays that comes back, which allows it to determine the elemental composition and percentages of the material for free in a few seconds. Like magic.

Hasn't that been around, in handheld form since the 60s? I think they're called tricorders.

> a 30K$ portable device, but that's because it's a low volume production.

Is this inherently true? Do the raw materials and parts the final factory buys to make the machine really cost <$100 (or so) and the cost is all in the up-front investment in the machinery to make it?

Yeah I doubt it. Applied Science on Youtube did a teardown of one and they've got crazy oil-filled high voltage electronics. It would take an insane amount of engineering to bring them down to an affordable price. Not just economies of scale.

You mean those same high voltage electronics that every CRT TV from the 90's has? The same TV's that give off so many xrays they have to shield them with leaded glass?

They were pretty affordable then, and I expect that now they can be made even more cheaply if there is demand for them.

CRT TVs are commonly only about 10 kV, while XRF needs 20–60 kV. Larger TVs were up in that range but were not handheld.

I agree that you can generate 60 kV pretty easily, though. You can do it in a smaller volume if you fill the electronics with oil, but it's not essential.

Probably a little cake of dicalcium phosphate is going to be cheaper than an XRF gun for the foreseeable future.

Aren't those are using radioactive source (which for obvious reasons you don't want to let proliferate…)

It's a x-ray tube and a x-ray sensor + analysis. It's bad radiations (like in luggage detector or dentist machine) but when you turn-off the device they stop, whereas radioactive don't stop.