ANALYTICAL CHEMISTRY TEST QUESTIONS AND ANSWERS
1. What are the three Calibration assurance methods?: 1.) External
Standard
2.) Standard Addition
3.) Internal Standard
2. Describe the process for using an Internal Standard.: Internal
standard is a known amount of compound, ditterent from the analyte, that is added
to an unknown sample. • Signal from analyte is compared with signal from standard to
quantify analyte.
3. Describe the process for using a Standard Addition: constant volume
(Vunk) of the unknown solution is added to each of four volumetric flasks of volume
Vflask. Then a series of increasing volumes of stock solution are added (Vstd). Finally,
each flask is made up to the mark with solvent and mixed well.
4. Describe the process for using an External Standard.: For an external
standard quanti-tation,
known data from a calibration
standard and unknown data from
the sample are combined to
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, generate a quantitative report. It is
called external standard because
the standard or known material is
separate or external to the
unknown material.
5. What are the general features of an External Calibration Curve?:
LOD/LOQ /Linear Range, Data points, Best fit, and saturation
6. Identify the various parts of an External calibration curve.:
7. How can you determine the "Goodness of Fit"/ Validation of a
Calibration Curve?: 1.) Square of the Correlation Coeflcient (R2)
2.) Absence of a response to a blank
3.) y-intercept should be close to zero
4.) Residual plots
5.) Performance of an independent calibration check sample
8. What are two ways you can improve your Correlation Coefficient?: 1.)
Increase the number of samples
2.) Improve data precision
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1. What are the three Calibration assurance methods?: 1.) External
Standard
2.) Standard Addition
3.) Internal Standard
2. Describe the process for using an Internal Standard.: Internal
standard is a known amount of compound, ditterent from the analyte, that is added
to an unknown sample. • Signal from analyte is compared with signal from standard to
quantify analyte.
3. Describe the process for using a Standard Addition: constant volume
(Vunk) of the unknown solution is added to each of four volumetric flasks of volume
Vflask. Then a series of increasing volumes of stock solution are added (Vstd). Finally,
each flask is made up to the mark with solvent and mixed well.
4. Describe the process for using an External Standard.: For an external
standard quanti-tation,
known data from a calibration
standard and unknown data from
the sample are combined to
1/
15
, generate a quantitative report. It is
called external standard because
the standard or known material is
separate or external to the
unknown material.
5. What are the general features of an External Calibration Curve?:
LOD/LOQ /Linear Range, Data points, Best fit, and saturation
6. Identify the various parts of an External calibration curve.:
7. How can you determine the "Goodness of Fit"/ Validation of a
Calibration Curve?: 1.) Square of the Correlation Coeflcient (R2)
2.) Absence of a response to a blank
3.) y-intercept should be close to zero
4.) Residual plots
5.) Performance of an independent calibration check sample
8. What are two ways you can improve your Correlation Coefficient?: 1.)
Increase the number of samples
2.) Improve data precision
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15
