TB_Instrumental Analyses

Question 1

All proteins absorb electromagnetic radiation of wavelength around 190 nm, which corresponds
to a excitation in the protein molecule. In which region of the spectrum is this wavelength found?
a. X-ray
b. ultraviolet
c. Visible
d. Infrared

Answer 1

b. ultraviolet

Question 2

Chromatography is used to
a. Separate two or more compounds based on their polarities.
b. Separate two or more compounds based on their masses.
c. Separate two or more compounds based on how strongly they interact with other
compounds.
d) all of the above.

Answer 2

d) all of the above.

Question 3

A food scientist has a sample of a plantoil and wants to determine if the oil contains saturated or
unsaturated fatty acids. Which of the following spectroscopic techniques would be most
useful for this purpose?
a.ultraviolet spectroscopy
b.visible spectroscopy
c.infrared spectroscopy
d.mass spectroscopy

Answer 3

c.infrared spectroscopy

Question 4

The concentration at which the calibration curve departs from linearity by a specified amount.
a. Limit of Blank
b. Dynamic Range
c. Limit of Linearity
d. Limit of quantitation

Answer 4

c. Limit of Linearity

Question 5

A graphical representation of measuring signal as a function of quantity of analyte.
a. Calibration curve
b. Quality Control Chart
c. Absorbance Chart
d. None of the above

Answer 5

a. Calibration curve

Question 6

What is the path of light through a spectrophotometer?
a. meter, photodetector, filter, sample, light source
b. meter, filter sample, photodetector, light source
c. light source, filter, sample, photodetector, meter
d. light source, sample, filter, photodetector, meter

Answer 6

c. light source, filter, sample, photodetector, meter

Question 7

With a “standard” sample with a known absorbance and concentration and a measured absorbance, it is
easy to determine an unknown concentration of †the same substance by.
a. Beer’s Law
b. Beer and Lambert’s Law
c. Law of mass conservation
d. none of the above

Answer 7

a. Beer’s Law

Question 8

The highest apparent analyte concentration expected to be found when replicates of a blank sample
containing no analyte are tested..
a. Limit of Detection
b. Limit of Blank
c. Limit of Linearity
d. Limit of Quantitation

Answer 8

b. Limit of Blank

Question 9

Motion of the mobile phase through the stationary phase.
a. Elution
b. Retention time
c. Eluent
d. Elution time

Answer 9

a. Elution

Question 10

A phase which sample is dissolved in may be gas, liquid, or supercritical fluid
a. stationary phase
b. reverse phase
c. normal phase
d. mobile phase

Answer 10

d. mobile phase

Question 11

In spectrophotometric methods, the _________ isolates the specific spectrum line emitted by
the light source through spectral dispersion.
a. monochromator
b. prism
c. sample compartment
d. detector

Answer 11

a. monochromator

Question 12

In AAS method, If the sample concentration is too high to permit accurate analysis in linearity
response range, there are alternatives that may help bring the absorbance into the optimum
working range.
a. sample dilution
b. using an alternative wavelength having a lower absorptivity
c. reducing the path length by rotating the burner hand
d. All of the above

Answer 12

d. All of the above

Question 13

A technique for separating mixtures into their components in order to analyze, identify, purify, and/or
quantify the mixture or components.
a. Spectrocopy
b. Chromatography
c. Gravimetry
d. Titrimetry

Answer 13

b. Chromatography

Question 14

A “modified” stationary phase where polar solutes run fast i.e. reverse order.
a. Normal phase
b. Reverse phase
c. mobile phase
d. none of the above

Answer 14

b. Reverse phase

Question 15

A graph showing the detectors response as a function of elution time : band’s shapes, position,
resolution
a. monitor display
b. quality control chart
c. calibration curve
d. chromatogram

Answer 15

d. chromatogram

Question 16

The pH meter glass probe has two electrodes, one is a glass sensor electrode and the
other is a _______electrode.
a. reference
b. anode
c. cathode
d. none of the above

Answer 16

a. reference

Question 17

Conductivity could be determined using the distance between the electrodes and their surface area using
Ohm’s law but, for accuracy, a calibration is employed using ____of well-known conductivity.
a. acid solution
b. basic solution
c. electrolytes
d. buffer solution

Answer 17

c. electrolytes

Question 18

The electrical conductivity of water is directly related to the concentration of dissolved ionized
solids in the water or
a. Total Suspended Solids
b. Total Dissolved Solids
c. Volatile Solids
d. Total Solids

Answer 18

b. Total Dissolved Solids

Question 19

At 510 nm, the iron orthophenanthroline complex has a molar absorptivity of 1.2 x 104. What
is the concentration of iron (in ppm) in a solution which gives an absorbance of 0.002 in a 1.00-
cm path length cell?
a. 7.3 x 10-3 ppm
b.8.3 x 10-3 ppm
c. 9.3 x 10-3 ppm
d.6.3x 10-3 ppm

Answer 19

c. 9.3 x 10-3 ppm

Question 20

The light source used in the visible range to 340-1000 nm.
a.deuterium
b. nerst blower
c. tungsten
d.incandescent

Answer 20

c. tungsten

Question 21

The % T of a solution in a 2.00 cm cell is 50. Calculate the %T of this solution in a 1.0 cm cell
path length.
a. 71
b. 19
c. 27
d. 20

Answer 21

a. 71

Question 22

An air sampling canister was evacuated by the local fire dep’t and brought to the environmental lab for
analysis. It was said that the sample was taken very near the site where a rusty 55-gal drum was found by
some children. A reported unpleasant smell near the site was reported. Results of gravimetric analysis of
the gas in the canister: C – 40%, H- 6.7% , O – 53.33%. What is the liquid in the drum?
a. CH2O
b. CH3OH
c. CH3CH2O
d. none of the above

Answer 22

a. CH2O

Question 23

A student has to measure out 9.40 mL of a liquid and selects a 100 mL graduated cylinder. To
improve the accuracy of the measurement, it would be most
effective to: a. take the average of multiple measurements using the graduated cylinder.
b. measure the liquid using a 25 mL graduated cylinder instead.
c. estimate the measurement obtained from the graduated cylinder to an additional
significant figure.
d. measure the liquid using a 10 mL graduated pipette instead.

Answer 23

d. measure the liquid using a 10 mL graduated pipette instead.