Instrumental Analytical Chemistry questions with
verified answers
Absorption Spectroscopy Ans✓✓✓ -Light of a wavelength
characteristic of the element being sampled radiates through the atom
vapor.
-The atoms absorb some of the light.
-The amount absorbed is measured
Analyte Atomization & Ionization for Emission Spectroscopy Ans✓✓✓ -
Atomization occurs in a chemically inert environment, which prevents
oxide formation & enhances the lifetime of the analyte.
-Unlike the arc spark, & flame, the temperature cross-section of the
plasma is relatively uniform.
-Temperature uniformity means there is no self-absorption & self-
reversal effects.
-Thus, linear calibration curves over several orders of magnitude of
concentration are usually observed.
Array Transducer (AT) Ans✓✓✓ -Dispersed radiation is focused onto
an array transducer
-Allows for the the detection of multiple resolution elements (advanced
over single channel detection)
-Offers improved resolution obtained using ratio measurements and
internal standards.
-Offers improved detection of fast transient signals.
,Atomic Emission Spectroscopy Calibration Curves Ans✓✓✓ -A plot of
output current or voltage of a transducer as a function of analyte
concentration.
-When a range of concentrations is large: log-log plots are employed.
-An internal standard is often used in emission spectroscopy.
Ex.
In experiment, a fixed amount of yttrium was incorporated in all of the
standards, & the relative intensity of the analyte line to that of the
yttrium line at 242.2nm (it served as the analytical parameter).
Atomic Mass Units (amu) or Daltons (Da) Ans✓✓✓ See Lecture Ch. 11-
12 Slide 4
Atomization for X-ray Analysis Ans✓✓✓ -Does not require atomization.
-Largely indépendant of chemical composition in a sample.
-Can obtain direct measurement of fluorescence, absorption, or
emission spectrum of sample.
Atomizing Devices/Approaches Ans✓✓✓ -Continous Atomizers:
plasma & flames -- samples introduced steadily.
-Discrete Atomizers: Electrothermal analyzer -- samples introduced in a
discontinuous manner (i.e. syringes)
, Atomizing Methods Ans✓✓✓ -Flame
-Electrothermal Vaporization (ETV)
-Inductively Coupled Argon Plasma (ICP)
-Direct Current Argon Plasma (DCP)
-Microwave-induced Argon Plasma (MIP)
-Glow-discharge plasma (GD)
-Electric Arc
-Electric Spark
Collimation Ans✓✓✓ -Have all optical elements in an instrument be
properly aligned (be on their designed optical axis).
-An Example of Collimation in action is a Echelle Polychromator
Comparison of Optical ICP with Mass ICP Ans✓✓✓ -Both torch
methods are the same
-Difference comes with
Components of a Mass Spectrometer Ans✓✓✓ -Inlet:
•Introduces a micro amount of sample into ion source to be converted
into gaseous ions.
-Ionization: Accomplished by applying thermal or electrical energy.
verified answers
Absorption Spectroscopy Ans✓✓✓ -Light of a wavelength
characteristic of the element being sampled radiates through the atom
vapor.
-The atoms absorb some of the light.
-The amount absorbed is measured
Analyte Atomization & Ionization for Emission Spectroscopy Ans✓✓✓ -
Atomization occurs in a chemically inert environment, which prevents
oxide formation & enhances the lifetime of the analyte.
-Unlike the arc spark, & flame, the temperature cross-section of the
plasma is relatively uniform.
-Temperature uniformity means there is no self-absorption & self-
reversal effects.
-Thus, linear calibration curves over several orders of magnitude of
concentration are usually observed.
Array Transducer (AT) Ans✓✓✓ -Dispersed radiation is focused onto
an array transducer
-Allows for the the detection of multiple resolution elements (advanced
over single channel detection)
-Offers improved resolution obtained using ratio measurements and
internal standards.
-Offers improved detection of fast transient signals.
,Atomic Emission Spectroscopy Calibration Curves Ans✓✓✓ -A plot of
output current or voltage of a transducer as a function of analyte
concentration.
-When a range of concentrations is large: log-log plots are employed.
-An internal standard is often used in emission spectroscopy.
Ex.
In experiment, a fixed amount of yttrium was incorporated in all of the
standards, & the relative intensity of the analyte line to that of the
yttrium line at 242.2nm (it served as the analytical parameter).
Atomic Mass Units (amu) or Daltons (Da) Ans✓✓✓ See Lecture Ch. 11-
12 Slide 4
Atomization for X-ray Analysis Ans✓✓✓ -Does not require atomization.
-Largely indépendant of chemical composition in a sample.
-Can obtain direct measurement of fluorescence, absorption, or
emission spectrum of sample.
Atomizing Devices/Approaches Ans✓✓✓ -Continous Atomizers:
plasma & flames -- samples introduced steadily.
-Discrete Atomizers: Electrothermal analyzer -- samples introduced in a
discontinuous manner (i.e. syringes)
, Atomizing Methods Ans✓✓✓ -Flame
-Electrothermal Vaporization (ETV)
-Inductively Coupled Argon Plasma (ICP)
-Direct Current Argon Plasma (DCP)
-Microwave-induced Argon Plasma (MIP)
-Glow-discharge plasma (GD)
-Electric Arc
-Electric Spark
Collimation Ans✓✓✓ -Have all optical elements in an instrument be
properly aligned (be on their designed optical axis).
-An Example of Collimation in action is a Echelle Polychromator
Comparison of Optical ICP with Mass ICP Ans✓✓✓ -Both torch
methods are the same
-Difference comes with
Components of a Mass Spectrometer Ans✓✓✓ -Inlet:
•Introduces a micro amount of sample into ion source to be converted
into gaseous ions.
-Ionization: Accomplished by applying thermal or electrical energy.
