pgiorgos

22 hours ago, hypervalent_iodine said:

DCM is not something I would use outside of a hood unless I was putting it on a rot evap. I think you are probably okay, but if you are uncomfortable with people using it outside of a fume hood, I would speak to someone about it. If you are concerned about symptoms, you should see a doctor. 

Also, regarding your question about the silica plate - it does not give an acidic smell, but I would avoid the dust. Small bits from cutting plates aren't anything to worry about, but larger amounts of free flowing particles (for say, columns) you should be mindful of and only work with inside a hood. 

Thank you for the answer my friend. I cannot understant why some people dont care about safety. Sometimes i want to quit lab cause of the "dont care" of some people. They use substances like this in a way that its not correct and we inhale a lot of things. Sometimes i dont know exactly what they use and accidentally i smell ammonia, dcm, acetic acid sometimes. I hope that i wont have a big problem for the short period i will be there (about 8-9 months). I want to do something else but i love science so i want to stay for these months. I take measures but sometimes i cannot avoid smell small amounts of organic solvents like dcm because someone forget the hood, forget to open windows, forget to inform etc. We live in a hurry and we forget serious things sometimes. So now i think that my cough is due to dcm or i am too anxious and i think such things. I really dont know. Thank you again my friend.

9 hours ago, hypervalent_iodine said:

It has a very distinctive smell, but I wouldn’t call it acidic. I have inhaled DCM before and from memory it can sting a bit, but it isn’t lingering. I believe the main problem with it is more the long term effects from constant exposure, anyway (as well as environmental concerns). Was / is your hood working - i.e was it sucking in air? You can check by getting a bit of paper towel and seeing if it is pulled into the hood when held just under the sash. If it is, and if everything was fully contained to the hood, you shouldn’t have inhaled much or any. The culprit may be something else in the lab. Did you let the plate dry fully before developing it?

 

Side question, 50 mL for a single TLC?! Are you doing prep TLC with huge plates or something?

I used such amounts cause i had a lot of samples to spot so i wanted a big chamber. The hood is in a very good situation and it works fine. My problem is that everyone in the lab use DCM out of the hood. They want to run a TLC plate and they dont prepeare the chamber in a hood. They transfer liquids with DCM out of the hood and sometimes they evaporate out of the hood. I m not sure about the smell of DCM but i dont want to learn :P. Maybe i smell it every day but i dont know if its DCM or not. I AM GOINT TO STAY for 8 months in the lab so sometimes i think that its not a long period to get a serious damage but i am not sure. I think its not good for the others too. I really dont know 

Hello again guys

Guess what am i going to talk about. safety in the lab  :p. My question is about dicloromethane this time. I have a very specific question about this stuff. I was performing an experiment in the hood and i wanted to do  TLC with dichroromethane and methanol (98/2 % ) I used 49ml of DCM and 1 ml of Meoh and i put my tlc plate inside the chamber for TLC. The absorber was at high level inside the hood but the glass of the hood was not closed all the way down cause i could not work. My head of course was outside. I had an acidic odor for a long (like an acidic sensation on my nostrils) and a bit cough when i came back home. Is DCM so hazardous in such amount (i used 98 ml in total cause i performed 2 TLC) inside a hood to cause problems? i was thinking maybe it was from the TLC plate (silica) but i know that DCM is not so safe. I have seen people perform TLC with DCM out of the hood and handle it (transfer liquids) out of the hood and sometimes poor it on the bench. Sorry if I ask safety issues but as i have said i want to handle everything in a right way. My supervisor just told me to do it in the hood and he didnt say that i do something wrong. If it was not DCM do you thing that silica plates is very dangerous (i cut it right but sometimes maybe it has some dust from the cut)

2 minutes ago, CharonY said:

You can check the evaporation rate by weighing your bottles just after collection and before evaporation and make a rough estimate from there. Unless you store them for a prolonged time and/or are in a very badly ventilated area it is rarely an issue.

The truth is that the methanol i am goint to use next week is going to take place in a hood as my supervisir told me. Maybe the ACN in this big room and with such quantities in the flasks for some hours its not a big deal

5 minutes ago, CharonY said:

The release from the hplc should be minimal and for evaporation usually you have a trap. For micro-prep good ventilation is often enough.

No i say when i have to collect my fractions in the flasks. I have 2 flasks and i collect inside my peaks( 100% ACN) and the flasks they are uncovered while i collect the quantity and finish my experiment so i am worried about these vapors but usually every flask gets 200-300 ml and then i evaporate my solvent in a rota evaporator and as you said there is a trap. I will ask if i have to cover the flasks till its time to collect but maybe i am thinking too much

4 minutes ago, CharonY said:

Most masks only protect against particulates an you need specific  ones for organic vapors. That being said, you'd first need to figure out your exposure levels (esp considering it sounds like simple prep HPLC). The MSDS sheets should give you hints about ACN safety (I do not want to make any recommendation online as I do not know your procedures and your risk of personal exposure). 

Of course i just want to learn more and more but for the final decision i always ask my supervisor in the lab and i personally read msds which is something that i think everybody should do. The quantities are not big enough but because my conical flasks are uncovered while i collect my fractions thats why i am a bit anxious from the vapor of ACN during the experiment. 

7 minutes ago, CharonY said:

1) please read the MSDS sheets. In fact, do it for every chemical you are encountering. 2) ACN has a very characteristic smell that is not acidic in any form. 3) masks, other than full-blown chemical respirator will not protect from solvents. 4) check the material of your gloves for the chemicals you are using. 5) I have the feeling that at your place the chemical safety training is inadequate, do you have a safety officer or at least a manual somewhere?

as you said i asked if i have to wear a mask and they told me that mask doesnt do anything I think that they refer to the mask with the filtrate in front not the full blown). Do you know why a simple mask like this doesnt protect you? I read msds and i ask but some people they are so harry they dont give the caution it needs, but for me its very important to know so i search for every substance. Thank for your quick response.

Hello again guys.

I have on more question about "work safe" cause for me and i think for everyone is a very important issue in a chem lab and sometimes there is no the right education on this. My question is very specific and its about handling acetonitrile (a volatile organic solvent). I perform preparative Hplc cause i want to isolate a some fractions and my mobile phases are water and acetonitrile. The prep hplc is not in an absorber. Its placed in a big lab room. I collect my fractions in conical flasks. I wear glasses, apron and gloves as they have consulted me. I dont wear a mask and i am thinking. Is ACN very toxic to human? Sometimes i feel a strange acidic odor in my nostrils but i dont know if this is from ACN. Is it a very toxic organic solvent like DCM or i dont have to worry a lot? I hope that i will survive

11 hours ago, John Cuthber said:

It rather depends on what product you extracted.

yeah but it will get more concentrated as the moisture starts to decreace? It will be like salt and water (salt gets more concentrated when water evaporates)? I know that hcl acts in a different way when we dont have water but i am not sure. My sample its a bit yellow. at the beginning it was a white powder so maybe a color reaction with hcl took place but i dont know if i have a lot of hcl or its just the color of the reaction that left behind.

On 5/6/2018 at 9:14 PM, studiot said:

You are much more likely to obtain a (sensible) discussion if you reply to participants in your threads.

 

next time 

11 hours ago, hypervalent_iodine said:

It is very, very unlikely that you have anything form the acid work up left.

THank you my friend for the answer. You say this cause there is no moisture in the sample? HCl without water lose his effectiveness?

1N HCL not 0,1 M. sorry

Hello guys. I want to ask something relative to HCL. I perfomed a liquid liquid extraction and i used 0,1 M hydrocloric acid for my experiment and then i performed neutralisation with NaOH but the final extract was a bit acidic (that what i was expected cause i used a lot of HCL). After this i collected my acidic extract (in solvent ether ) and i evaporated in rota evaporator to take my sample in "dust". Then i put my vial in vaccuum to get rid of any moistyre. My question is: Is it possible for HCL to "survive in a vial without moisture at room temperature? It will lost as a gas or it will remain inside (a small quantity). I felt like there was an acidic odor from this vial when i tried to weight a quantity from my sample. Is it possible to have concentrated HCL inside after the evaporation of solvent or it will get lost in the air as a steam? 

Hello everyone. I want to ask something. Maybe i am too scared with no reason. I inhaled a bit of acetic acid in the lab cause someone used a rota evaporator with acetic acid as organic solvent and at a point i was too close for about 20 minutes and i had a weird smell of acetic acid but because i am not so familiar yet with this stuff i was not sure it was acetic acid. It was not so annoying but after i left the lab i felt i cannot breath properly (maybe it is because i am too anxious). I also have a feeling like i want to cough all day. Maybe i am thinking too much i dont know but i want to know if its very dangerous cause i am try to learn every possible danger in the lab, Maybe i am not suitable for this place :p.  I used to work as an analytical researcher for many years and i used to do all my stuff with pc and not so much in the lab bench but i found a job and i wanted to try something different but i feel i cannot handle stuff like this. Maybe i am not so familiar yet i dont know