Crime Busters B

[caseyotis]

Hello all!
I'm just wondering; how on Earth do they test paper chromatography at the state level, or even at regionals? I've never done the event before and I'm going straight to the states; I don't know what to expect at all. I know how to do it, but why, and what will I have to know?

[computergeek3]

Hello all!
I'm just wondering; how on Earth do they test paper chromatography at the state level, or even at regionals? I've never done the event before and I'm going straight to the states; I don't know what to expect at all. I know how to do it, but why, and what will I have to know?

You just need to know how to do it (and not mess it up)

[stephritz929]

Hello all!
I'm just wondering; how on Earth do they test paper chromatography at the state level, or even at regionals? I've never done the event before and I'm going straight to the states; I don't know what to expect at all. I know how to do it, but why, and what will I have to know?

Well, at our regionals, (NE PA) they had a Chromatography station at the front of the room, and basically whenever you found time before the end of the period was up, in the middle of your Qual/Anal, you just went up, and there were four markers, tape, a cup, and four strips of paper. You basically made a dot on the end of each strip with each marker and then you brought it back to your desk, and taped each strip to the sides of the cup. Then with the water provided you fill up the cup to, I THINK, JUST before the dot and watch the results. MAKE SURE YOU LABEL YOUR STRIPS. We forgot to do that and didn't know which was #1, #2, etc. lol. We had to guess. It's a fairly simple process, just make sure you leave time to do it and you know HOW.

[stephritz929]

So my partner and I have been practicing with Iodine, or I2, or KI or whatever you want to call it. The point is, it was that distinctive yellowish/orange color. When we got to regionals, our bottle labeled "KI" was clear. Completely threw us off. It didn't smell, it was clear, and it didn't react with anything! Fluke, or is this some substance that actually is KI? Thanks in advance.

It should have been yellowish/orange-ish/brownish, not clear.

and if it didnt react with anything, its a pretty clear sign that it wasnt the right thing

Yeah, our coach said our proctors didn't have much right in that event. Wacky substances that didn't react with anything, fake KI, but hey everyone had the disadvantage. Just glad to know that Iodine solutions are in FACT colored. I thought I was going crazy!! Thanks

[caseyotis]

Hello all!
I'm just wondering; how on Earth do they test paper chromatography at the state level, or even at regionals? I've never done the event before and I'm going straight to the states; I don't know what to expect at all. I know how to do it, but why, and what will I have to know?

Well, at our regionals, (NE PA) they had a Chromatography station at the front of the room, and basically whenever you found time before the end of the period was up, in the middle of your Qual/Anal, you just went up, and there were four markers, tape, a cup, and four strips of paper. You basically made a dot on the end of each strip with each marker and then you brought it back to your desk, and taped each strip to the sides of the cup. Then with the water provided you fill up the cup to, I THINK, JUST before the dot and watch the results. MAKE SURE YOU LABEL YOUR STRIPS. We forgot to do that and didn't know which was #1, #2, etc. lol. We had to guess. It's a fairly simple process, just make sure you leave time to do it and you know HOW.

Okay, and what will I be doing with the information gathered? Will each marker correspond to a suspect or something like that?

[cupcakegirl]

Hello all!
I'm just wondering; how on Earth do they test paper chromatography at the state level, or even at regionals? I've never done the event before and I'm going straight to the states; I don't know what to expect at all. I know how to do it, but why, and what will I have to know?

Well, at our regionals, (NE PA) they had a Chromatography station at the front of the room, and basically whenever you found time before the end of the period was up, in the middle of your Qual/Anal, you just went up, and there were four markers, tape, a cup, and four strips of paper. You basically made a dot on the end of each strip with each marker and then you brought it back to your desk, and taped each strip to the sides of the cup. Then with the water provided you fill up the cup to, I THINK, JUST before the dot and watch the results. MAKE SURE YOU LABEL YOUR STRIPS. We forgot to do that and didn't know which was #1, #2, etc. lol. We had to guess. It's a fairly simple process, just make sure you leave time to do it and you know HOW.

Okay, and what will I be doing with the information gathered? Will each marker correspond to a suspect or something like that?

Typically, they will either give you a completed chromatogram or a strip with a dot already on it for the crime scene sample. Then, once you finish all the chromatograms for all the suspects (they usually give you a marker for each suspect), you find the suspect chromatogram that matches the crime scene one. At state, they could ask you Rf factor or something, but usually this is it. Chromatography is basically free points since it's so easy, so always make sure you do it!

[caseyotis]

Ah, it makes sense now. Thank you very much, cupcakegirl!

EDIT:
I'm trying this out at home now, and it isn't working. The ink isn't separating at all. I've been cutting up coffee filters, and I've used two different kinds, and the water is moving up the slip until the Rf, but nothing is appearing. Am I doing something wrong?

[computergeek3]

I'm trying this out at home now, and it isn't working. The ink isn't separating at all. I've been cutting up coffee filters, and I've used two different kinds, and the water is moving up the slip until the Rf, but nothing is appearing. Am I doing something wrong?

It's possible that the inks you've been using aren't soluble in water. Try using Expo Vis a Vis pens (they give fun results) and other water soluble inks.

[caseyotis]

I'm trying this out at home now, and it isn't working. The ink isn't separating at all. I've been cutting up coffee filters, and I've used two different kinds, and the water is moving up the slip until the Rf, but nothing is appearing. Am I doing something wrong?

It's possible that the inks you've been using aren't soluble in water. Try using Expo Vis a Vis pens (they give fun results) and other water soluble inks.

Hmm... I don't have those, I don't think. You might be right; I'll look up some. *derp* Thanks!

EDIT: The Vis-a-Vis pens work great! I loved the results on these. For anyone who wants to practice paper chromatography, Vis-a-Vis pens are absolutely worth it.

[rookiecoach]

Hi,
I'm a completely rookie coach (obvious from my name, isn't it?) for this event -- a parent, with no science background -- and am part of a completely rookie team. And we made it to States! I wasn't involved at the Regionals, so I'm trying to sort out how to be of best support to the two students I'm working with. Here are several questions:
1) I looked at the sample tests and gave them two already. Are there more samples than what's on the wiki, that have the complete answers? (The tests on this site: http://www.soinc.org/science_crime_busters_notes -- don't have the answers so are more difficult to recreate. They also seem much shorter than what I would expect for State level, aren't they?)
2) How much knowledge are the students expected to have about the items they are testing, and what KIND of knowledge? I can't find a clear, comprehensive list anywhere, and perhaps it doesn't exist. For example, for plastics, liquids, powders -- do they need to know multiple uses for each?
3) For the analysis, do I understand correctly that the format will depend on the proctor? And so they should practice writing a narrative AND writing bullet points? Or is there an accepted format at the state level?
I'd be grateful for any support you may offer me! Thanks in advance!
Rookie Coach