DMG acts strange any expert suggestion is welcome

[bee]

i recently order dimethylglyoxime i have a cheap source and using it more than few months. my first stock of five bottles each one hundred gram is work perfectly.
my first try is i use for palladium nitrate solution where stannous chloride test and old DMG give me good results of Pd. i pour the new DMGh2 solution into palladium nitrate and notice the strong reaction all pd is suddenly precipitate like previous experience but then into seconds all pd is dissolve again and lots of fizzing.then i use aqua regia solution same reaction the fizzing is fast reaction is fast and there is no orange pulp no precipitate. i wonder what is happening, have left 50ml old solution for tests purpose use the old DMG solution work perfectly no fizzing and precipitate orange pulp suddenly without any reaction where i think as there is 1 mole sodium hydroxide solution there should be no fizzing and ph should be low when i use DMG solution where the things are opposite the ph is increased when i use the new dmg and no precipitate beside fast fizzing and after 12 hours a white powder of something is settle down. looks like reaction of NAOH, i contact the source send them dmg with old specimen and said its not working they said they sold to many school laboratories and never get a complain. i am sure school labs are not using for precipitate Pd. but my supplier send me three bottle of DMG each hundred grams sample and said try to use and which one is perfect for my work they can supply me i wonder is this happen before with any forum member. or is there few versions of dimethylglyoxime i open the new three sample two are giving me same odor and one is odor less i am try to make three small batch today and ,ll give the results to forum member but i am happy to share my experience with DMG all DMG donot work perfectly only those who are odor less when you open the container its suddenly give you the strange odor very nasty and fast where some dmg donot give any kind of smell.
now i use the dmg which has no odor and its work perfectly i am not chemist why is this happening can any chemist explain is this possible that most dmg are fake or something.
so my personal experience is only dimethylglyoxime which has no odor is working perfectly others not.
thanks
bee

 

[Lino1406]

DMG does not need NaOH
Enough to take 1/2g + 50cc ethanol + 50cc water
After adding several drops to acidic sample, add ammoniac to a faint smell

 

[kurt]

DMG does not need NaOH
Enough to take 1/2g + 50cc ethanol + 50cc water
After adding several drops to acidic sample, add ammoniac to a faint smell

Lino1406 - the NaOH is used to dissolve the DMG & is what should be used (or at least what I recommend to be used) when preparing DMG instead of using an alchohol based (ethanol, methanol etc.) solvent

Why? --- because alchohol's added to some metal nitrate solutions can & will make explosive fulminates of some metals - silver fulminate & mercury fulminate being the 2 most common fulminates --- fulminates are "very" presure sensitive explosives with silver fulminate being the most sensitive - so sensitive it can explode under its own wieght & in water (or when wet)

In fact when making silver fulminate (intentionally) it must be done in very small batches & very controled

using DMG prepared with an alchohol based solvent as a precip reagent in a metal nitrate solution (especially silver nitrate) is a lab disaster waiting to happen

its one thing to use a drop or 2 of alchohol prepared DMG to test a few ml of solution for Pd (not a big worry) --- but it could be a real bummer to try to precip Pd from large volumes of solution - if silver is also in solution

using NaOH to dissolve your DMG is a safer bet then using alchohol's

This was discussed back in July last year in "help needed" thread title --- DMG + Methanol = explosive compounds ?

Kurt

 

[kurt]

bee - my DMG has a VERY strong smell to it & it works just fine for preciping Pd so I don't think its a question of if it has an oder or not --- why yours is not working I don't know

Kurt

 

[bee]

thanks kurt
its true that methnol ethnol not recommanded and please every one first read the cemistry books and read this awesome forum posts related to the subject then also google search give you so much information and then you should try somthing becaus chemistry donot have brain it wont warn you.so please use the NAOh
i am still searching the issue which i face and now i have send two specimens to labs and write them the all story i hope i ,ll get bak the response into this week
lets see what happend.
thanks
bee

 

[Lino1406]

1.With these enormous amounts of NaOH, it is
not sure what reacts first, NaOH or DMG
2.The white precipitate is coming from base metal
e.g. Ca, Pb, Sn and NaOH
3.It is either no DMG or No Pd situation

 

[bee]

ok receive the result.
there is no DMG
now get the fresh DMG bottle and its strange its have strong odor but its working great.
personal experience when mix Naoh with dmg the compound is very strong acts fast also you ,ll see the white precipitate but its gone when you stir the solution some time red precipitate is also shows with white which is hope fully iron but when you stir well only fluffy orange pulp is left. the small amounts of other metals left no doubt but you can re purify or something but my results with acetic acid conversion of pd(dmg) are 99%.
thanks for comments
bee

 

[kurt]

1.With these enormous amounts of NaOH, it is
not sure what reacts first, NaOH or DMG
2.The white precipitate is coming from base metal
e.g. Ca, Pb, Sn and NaOH
3.It is either no DMG or No Pd situation

Lino1406 - When you use NaOH to prepare your DMG you only use 4 grams of NaOh per 100 ml of water which will dissolve 5.8 grams of DMG --- so thats not an enormous amount of NaOH --- 43 ml of DMG prepared this way will precip 1 gram PD

In order for the NaOH from DMG prepared this way to precip anything from an acidic solution you would need to ad enough for the NaOH to change the solution from acidic to at least nutral or basic & at 4 grams NaOH/100 ml water it wont change the PH enough to precip anything

What happens when you use DMG prepared this way is that a precip will form from the NaOh when it first hits the solution - but that precip goes right back into solution because theres not enough NaOH to change the solution from acidic to basic - then the DMG (which precips Pd from an acidic solution) drops your Pd

Using DMG prepared with alchohols to precip Pd from nitrate solutions of other metals can form fulminates of "some" metals --- silver is one of those metals that will form a fulminate --- silver fulminate is a VERY presure sensitive explosive - sensitive enough that it can explode under its own weight & when wet

Kurt

 

[Lino1406]

4 g NaOH, 5.81g DMG...seems Mr Bee used 40g NaOH
(However, this was not the problem, as admitted)