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### Topic: need help calculating concentration from a calibration curve  (Read 14596 times)

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#### sule21

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##### need help calculating concentration from a calibration curve
« on: February 17, 2007, 06:13:32 AM »
okay...so i have to determine the concentration of riboflavin from a fluorescent spectrophotometric methods....and so far i've got the Wavelength (544.29 nm), i've got the signal run values (too many numbers to plug in), and i've concentrations; and now i've got to make my calibration curve

now....when i make my calibration curve for fluorescent signal intensity vs. concentration, how do i figure out concentration???

most importantly, what does the slope of the calibration curve for this graph give me???

*delete me*!!

#### enahs

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##### Re: need help calculating concentration from a calibration curve
« Reply #1 on: February 17, 2007, 12:41:09 PM »
Your calibration curve should be a straight line. You should also make your program give you a linear equation to that line. Put

Then, when you measure your unknown, you know the absorbance, and you can either plug that into the equation of the line and get concentration, or read it from the graph by looking at the absorbance, seeing where your calibration line has that value and reading the concentration at that point (however, the equation method is much more accurate).

The slope should be ?*b.
This is the only variables you have in your beers-lambert law. Sure it could be b+? or b/? b?. Etc etc. But this is basic algebra to figure it out.

http://www.chm.davidson.edu/ronutt/che115/Spectro/Spectro.htm

#### dfx-

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##### Re: need help calculating concentration from a calibration curve
« Reply #2 on: February 17, 2007, 06:13:46 PM »
For small concentrations, calibration should give epsilon by calculation..

Epsilon + unknown values + constant..
BSc(Hons) in Forensic and Environmental Analysis

#### generalsky

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##### Re: need help calculating concentration from a calibration curve
« Reply #3 on: February 26, 2007, 09:20:53 AM »
perhaps use the software of office is a good choice to make that straight line.

other things should be cared to determine the concentration in this method such as the value of unknow should in the range of the straight line.

perhaps my English is so poor that i can not make you understand.

any question or detail, you can ask me by E-mail: jiangcius@yahoo.com.cn