[Kass1]

Hi,

I did a lab experiment to determine the caffeine content in soft drink and coffee usin UV/Vis.

It would like to use the graph to determine the caffeine in soft drink in ppm, mg of caffeine per 100,l. caffeine in coffee in mg/100ml, caffeine mg.kg of powder.


I am abosultely stumped with how to answer this, do I use the y=mx+c equation? would someone please point me in the write direction?

Thanks

[wildfyr]

Yep, use the equation. You can plug X into the equation excel generated to get Y.

However, uv vis doesn't measure emission. What does measure?

[Kass1]

Thanks but am not doing this with excel.
Which are my values that is needed?

[wildfyr]

I'm confused. There are screen shots of excel graphs, and the raw data in the spread sheet.

Also I continue to be confused. This does not look like uv-vis. It mentions emission and the values go up with concentration. Is it a fluorimeter?

[Arkcon]

Excel has given you a formula, that relates x and y.  You labeled, your two axes, x and y, with your terms -- emission (sic? ETA: as wildfyr: noticed too) and concentration.  Now, you have to use what you've done, to get the answer you want.

Consider: Pretend you did a reading of a 10 ppm standard, and got a result of .5 AU.  If you did an unknown, and got 0.5, you'd know the answer.

Pretend you did two points 5 and 10 ppm, and got .5 and 1.0 AU, and got an unknown of 0.75.  You'd also know the answer, since its exactly in the middle, you'd take an average.

If you do enough of these, in your career, you might actually get something like that.  Its fun.

You have a more complicated formula, but the algebra is actually pretty easy.