temp_RR
Harmless
Posts: 3
Registered: 31-3-2019
Member Is Offline
|
|
Testing for lead or it's oxides - best method?
I want to try an experiment with heating 60/40 lead solder and drawing the fumes through a paper and or cloth filter (vacuum) and then test the filter
to see if there is any lead. I also want to try heating lead in a small cast iron pan with a torch and do the same thing. I want to see how much,
if any lead comes off an at what temperatures it does or doesn't come off as a vapor. I know the BP of lead is near 3200F but I keep having people
telling me it's vaporizing while I solder... They don't seem to understand rosin core solder.
So, does anyone know of a substance, possibly a solution, that I could use to wipe on the filter and reveal Pb or PbO/PbO2/Pb3O4?
|
|
|
Sulaiman
International Hazard
Posts: 3695
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
Here in EU we do not use lead or rosin in solder for manufacturing
- their negative effects on the environment and health being pretty much accepted.
Where I worked as a repair engineer we used non-rosin cored Pb:Sn or lead-free solder depending upon what we were repairing,
in either case we had extraction/filtering available
https://uk.farnell.com/weller/t0053660699n/fume-extraction-u...
more for the flux fumes than lead,
so you may want to investigate the rosin flux fumes before the lead.
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
Loptr
International Hazard
Posts: 1348
Registered: 20-5-2014
Location: USA
Member Is Offline
Mood: Grateful
|
|
Rhodizonate or sulfide are most common ions used in kits to react with lead that might be present. You can find lead testing kits online.
"Question everything generally thought to be obvious." - Dieter Rams
|
|
|
SaccharinSlayer751
Harmless
Posts: 6
Registered: 28-3-2019
Member Is Offline
Mood: Newfound respect for TATP
|
|
If you really want to make a lead testing solution at home and are willing to put a bit of work in to do so, there is a quite easy method to do so
with sulfides involving nothing but a trip to the hardware store and a propane torch or outdoor stove. I would recommend making a solution of sodium
sulfide that you can add to anything that you suspect might contain soluble lead. If it does, a very dark black insoluble precipitate of lead sulfide
will form which should be easy to see even in small amounts. I'd be more than happy to post a detailed how to, but only if you are able to get your
hands on some elemental sulfur (garden dust), steel wool, and sodium hydroxide (drain cleaner) and are willing and cautious enough to work with H2S.
It's pretty serious stuff, 1ppt will kill and you can't smell it after 100ppm, but as long as you are working outside and do everything correctly,
there should be minimal risk.
[Edited on 4-3-2019 by SaccharinSlayer751]
|
|
|
temp_RR
Harmless
Posts: 3
Registered: 31-3-2019
Member Is Offline
|
|
Quote: Originally posted by Loptr  | | Rhodizonate or sulfide are most common ions used in kits to react with lead that might be present. You can find lead testing kits online.
|
Thanks! That looks perfect for testing lead and it looks like a great prospect for a synth because it's really potassium rhodizonate looks to be
relatively expensive buy and should be a fun synth to do.
When you said "or sulfide" what did you mean?
|
|
|
woelen
Super Administrator
Posts: 8012
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
Any soluble sulfide will do the job. Most common is sodium sulfide. You can get that on eBay, but most chemical sellers also sell this chemical, also
to private individuals. It is used for hobby purposes, such as toning black and white photographic images.
Be careful with Na2S. It is quite toxic and if you add acid to it you get H2S. H2S is toxic and has an awful smell. It is not as toxic as
SaccharinSlayer751 suggests though. At 1 ppt (part per trillion) you won't even smell it. At 1 ppm it has a horrible smell, but otherwise it does no
harm, not even when exposure is for several hours. At 10 ppm it irritates the eyes and slowly does damage to them. At 100 ppm it kills your sense of
smell in just a few minutes (which receovers, when you are in fresh air again). At exposure to 200 ppm for several minutes it can cause edema and may
lead to death. A concentration of 100 ppm is quite high already. That's 100 ml of gas in each cubic meter of air. If you are outside you will have a
hard time producing that kind of concentrations.
|
|
|
unionised
International Hazard
Posts: 5126
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
At 1 ppt (part per thousand), it will kill you.
|
|
|
RedDwarf
Hazard to Others
Posts: 166
Registered: 16-2-2019
Location: UK (North West)
Member Is Offline
Mood: Variable
|
|
Which just demonstrates the danger of using TLAs and assuming you mean the same thing as your reader will think 
|
|
|
SaccharinSlayer751
Harmless
Posts: 6
Registered: 28-3-2019
Member Is Offline
Mood: Newfound respect for TATP
|
|
| Quote: Originally posted by RedDwarf | | Which just demonstrates the danger of using TLAs and assuming you mean the same thing as your reader will think |
My bad, even wikipedia warns that "One part per thousand should generally be spelled out in full and not as 'ppt'"
[Edited on 4-4-2019 by SaccharinSlayer751]
[Edited on 4-4-2019 by SaccharinSlayer751]
|
|
|
SaccharinSlayer751
Harmless
Posts: 6
Registered: 28-3-2019
Member Is Offline
Mood: Newfound respect for TATP
|
|
| Quote: Originally posted by RedDwarf | | Which just demonstrates the danger of using TLAs and assuming you mean the same thing as your reader will think |
My bad, even wikipedia warns that "One part per thousand should generally be spelled out in full and not as 'ppt'"
|
|
|
maldi-tof
Harmless
Posts: 39
Registered: 3-4-2019
Member Is Offline
|
|
Hi,
As commented before, lead can be tested via sulfides.
Where I work, we test lead with freshly prepared H2S. It is made warming ferrous sulfide with HCl, and collecting the gas generated (H2S) in water.
For the determination, it is better to buffer the solution to pH 4.
It is not a sensitive method for lead. Arsenic, copper, molybdenum, cadmium and silver will turn yellow too.
If you Google: heavy metals 231 USP, you'll read different validated methods to test lead.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
