Gas Chromatography Question

[piff]

Gas Chromatography Question

We did a lab at Pitt on Wednesday, and the report is due tomorrow. Now in shutdown mode, I have put it off till now, figuring that it would tell me how to calculate retention times. It doesn't tell me. Does anyone here know how to calculate them? My chart speed is 2cm/min. if it helps. Thanks in advance. I'm going to take a long shower, so if you have other questions, I can answer once I come back.

 

[Raft Boy]

Wow. Weird experiment to make you calculate the retention times. All the GCs that I know of put them on there for you. Anyway, about the only thing I can figure out is to measure the distance from the start and divide by the chart rate.

-Rafty

 

[{KOW}Spazed]

Wow. Weird experiment to make you calculate the retention times. All the GCs that I know of put them on there for you. Anyway, about the only thing I can figure out is to measure the distance from the start and divide by the chart rate.

-Rafty

That is what we did on our chromatography lab on Friday. . we used plants and not gas though.


Just measure the total distance traveled and then the total distance the color traveled. Divide to get the percent and your done.

 

[Raft Boy]

Just measure the total distance traveled and then the total distance the color traveled. Divide to get the percent and your done.

Seems more like you're describing Thin Layer Chromatography and Rf values to me.

-Rafty

 

[piff]

Thanks guys, but I think enough staring at it figured it out for myself. I just measured the distance from injection point to peak. The problem with what both of you described was that my graph is simply a grid with numbers up the side in no apparent measurement and it's in black and white, out of a copy machine. Either way, thanks, now let this thread die or be deleted.

 

[{KOW}Spazed]

Eh you use the same basic princibles when doing either, I really should know the difference between the two. . .I have a test on them Tuesday.

 

[Raft Boy]

Eh you use the same basic princibles when doing either, I really should know the difference between the two. . .I have a test on them Tuesday.

Really, the only thing that those two have in common is that both separate compounds. TLC is a qualitative analysis and GC is not. TLC is mainly based on the polarity of the compounds you're studying and GC is primarily based on the volatility (i.e. boiling points) of them. There are lots more, but you get the idea.

Anyway, since this is the OTF, we don't let threads die. We hijack them! So who likes beer? :drink: :buddies:

-Rafty

 

[tintrail]

not me, my drink of choice is either bacardi gold, or smirnoff triple black. :thumbsup:

 

[AeroJonesy]

Shock! I do not like beer. What is wrong with me?

 

[Underseer]

Shock! I do not like beer. What is wrong with me?

Ah-ha! So you are a closet commie subverter! Caught ya red-handed!

 

[AeroJonesy]

Ack! My secret is exposed!

*Doesn't know whether to run or hide in shame*

*Eats a baby*

 

[tintrail]

Shock! I do not like beer. What is wrong with me?

got a quick question for ya. are you of the femlae species? this question is not motivated by this response, but just a general question.

 

[AeroJonesy]

got a quick question for ya. are you of the femlae species? this question is not motivated by this response, but just a general question.

I can be whatever you want me to be, baby. Of course, if you want me to be a female, I will have to hide certain male organs in a banana hammock.

 

[tintrail]

I can be whatever you want me to be, baby. Of course, if you want me to be a female, I will have to hide certain male organs in a banana hammock.

haha no thanks, stick to being who you are. i was just confuzzled because some time ago you made a post which made it seem like you were a girl, but then i remembered that you were majoring in something like aeronautics or something, and you being a girl didnt fit the stereotype that i have.

anyways, thanks for the confirmation.

 

[Crispyknight]

I've never understood why you have to use such archaic equipment in labs. Measuring a pen-and-paper chart to calculate retention times stopped happening in working labs more than a decade ago. GCs and HPLCs can be had for a few thousand dollars used in fine condition, but you're being forced to use equipment from the 70's? Bah.