Instrumental Analysis Exam I Review questions
with verified answers
1) Be able to discus the various calibration methods and when would it
be most appropriate to use each. Ans✓✓✓ External standard:
prepared separately from sample; assumes no matrix interference
Internal standard: used to compensate for instrumental drift, is added
in equal concs to all samples and standards; known amount of
compound, diff from the analyte, added to unknown sample; used
when detector response varies slightly from run to run; use when
recognizing significant instrumental drift
Standard additions: used to compare matrix interference, standards
prepared in sample itself
absorbacne Ans✓✓✓ ability of a molecule to absorb photon under
specified conditions
absorptivity Ans✓✓✓ ability of a molecule to absorb photons under
specific conditions
Amplitude Ans✓✓✓ measure of change in a single period
Band sepctra Ans✓✓✓ several groups of lines closely packed; aren't
resolved; only molecules
,Be able to discuss types various types of errors (random and
systematic) and how to detect and correct for them Ans✓✓✓ Random
error: can't be defined or eliminated
Systemic: can be discovered, corrected, is reproducible, and leads to
bias
i. Instrumental
ii. Personal
iii. Method
Be familiar with and be able to discuss the issues involved in selecting
an appropriate analytical method for a proposed analysis Ans✓✓✓ a.
Random error
b. Systemic error: instrumental, personal, method
c. Bias, Sensitivity, Selectivity, Detection limit
LOL, LOQ and Dynamic range
Be familiar with the various atomization techniques Ans✓✓✓ a. Flame
structure: important regions of flame include primary combustion zone,
interzonal region and secondary combustion zone
i. Flame has diff temps throughout
, b. Electrothermal atomization: samples placed in carbon tube that is
heated electrically
i. Drying --> char --> atomization
1. Sample residence is much greater compared to flame atomizer -->
high limit and sensitivity
Beers Law Ans✓✓✓ measuring conc. of absorbing species
A=abc
A= measured absorbance
a=absorptivity
b=path length
c=analyte conc.
Bias Ans✓✓✓ difference between actual and measured value,
associated with accuracy
blackbody radiation Ans✓✓✓ molecular oscillations excited in the
condensed solid by thermal energy
chemiluminescence Ans✓✓✓ emission of light during a chemical
reaction that does not produce significant quantities of heat
Cohorent radiation Ans✓✓✓ phases of two or more waves
representing radiation differ by a known constant
with verified answers
1) Be able to discus the various calibration methods and when would it
be most appropriate to use each. Ans✓✓✓ External standard:
prepared separately from sample; assumes no matrix interference
Internal standard: used to compensate for instrumental drift, is added
in equal concs to all samples and standards; known amount of
compound, diff from the analyte, added to unknown sample; used
when detector response varies slightly from run to run; use when
recognizing significant instrumental drift
Standard additions: used to compare matrix interference, standards
prepared in sample itself
absorbacne Ans✓✓✓ ability of a molecule to absorb photon under
specified conditions
absorptivity Ans✓✓✓ ability of a molecule to absorb photons under
specific conditions
Amplitude Ans✓✓✓ measure of change in a single period
Band sepctra Ans✓✓✓ several groups of lines closely packed; aren't
resolved; only molecules
,Be able to discuss types various types of errors (random and
systematic) and how to detect and correct for them Ans✓✓✓ Random
error: can't be defined or eliminated
Systemic: can be discovered, corrected, is reproducible, and leads to
bias
i. Instrumental
ii. Personal
iii. Method
Be familiar with and be able to discuss the issues involved in selecting
an appropriate analytical method for a proposed analysis Ans✓✓✓ a.
Random error
b. Systemic error: instrumental, personal, method
c. Bias, Sensitivity, Selectivity, Detection limit
LOL, LOQ and Dynamic range
Be familiar with the various atomization techniques Ans✓✓✓ a. Flame
structure: important regions of flame include primary combustion zone,
interzonal region and secondary combustion zone
i. Flame has diff temps throughout
, b. Electrothermal atomization: samples placed in carbon tube that is
heated electrically
i. Drying --> char --> atomization
1. Sample residence is much greater compared to flame atomizer -->
high limit and sensitivity
Beers Law Ans✓✓✓ measuring conc. of absorbing species
A=abc
A= measured absorbance
a=absorptivity
b=path length
c=analyte conc.
Bias Ans✓✓✓ difference between actual and measured value,
associated with accuracy
blackbody radiation Ans✓✓✓ molecular oscillations excited in the
condensed solid by thermal energy
chemiluminescence Ans✓✓✓ emission of light during a chemical
reaction that does not produce significant quantities of heat
Cohorent radiation Ans✓✓✓ phases of two or more waves
representing radiation differ by a known constant
