Experiment 12: Potato Chips Flashcards
To analyze content by atomic absorption spec for potato chips:
Analyte is brought into a homogeneous solution by decomposition or by extraction of the sample.
AAS analysis is based on:
Correlation of absorbance to the concentration of the analyte element in the sample solution
Correlation between absorbance may or may not be linear because of…(4)
- Nature of the element.
- Analytical spectral line.
- Configuration of the spectrometer.
- Concentration range of the analyte element.
Spec can give a direct readout of concentration bc:
Spec is microprocessor controlled. There is a program for calibrating instrument by fitting absorbances to continuous function of concentration!
If the correlation is linear…
algorithm would only accept one calibration standard (k2 and K3 set to 0)
A slight curvature in correlation
two calibrations are used, k3 set to zero
Significant curvature in correlation
three standard samples have to be used all and so all Ks are evaluated
Major emission lines of sodium and potassium
- 6nm and 590.2 nm for sodium
766. 5 nm for potassium
589.6 vs 590.2 sodium line
- The 589.6 nm line doubles in sensitivity compared to the 590.2 nm line.
- The former is used when the samples are of lower sodium concentrations, say below 4 ppm
- The latter can be used for analyte concentration up to 8 ppm.
Dynamic ranges are low concentrations are
LINEAR
Analyses performed within the linear dynamic ranges are always…
Desirable. A single point calibration would be adequate. (multiple points for above LDR)
We will use
Single point calibration of sodium and potassium at 4ppm using analytical lines of 590.2 and 766.7 nm
Solutions being used are
Sodium chloride and potassium chloride
ACETONE IS
a stabilizer for acetylene. If acetone enters into the instrument, the readings may become irrative and the machinery/tubing of the instrument can be damaged. One must stop using the tank of acetylene with FAAS when the back- pressure goes below 75 psig.
