GC and GC-MS slide.ppt

GC principles

1. Gas chromatography (GC) and
Gas chromatography mass
spectrometry (GC-MS)

2. Gas Chromatography
•Function
•Components
•Common uses
•Chromatographic resolution
•Sensitivity

3. Function
•Separation of volatile organic compounds
(VOC).
•Volatile –when heated, VOCs undergo a phase
transition into intact gas-phase species.
•Separation occurs as a result of unique
equilibria established between the solutes and
the stationary phase (the GC column).
•An inert carrier gas carries the solutes through
the column.

4. GAS CHROMATOGRAPH (GC)

5. GC Components
1.Carrier Gas
2.Injector
3.Oven
4.Column
5.Detector

6. Carrier gas
•Carrier gas for gas chromatography (GC) should
be an inert gas that does not react with the
sample component.
•Carrier gas is an inert gas used to carry
samples.
•Helium (He), nitrogen (N2), hydrogen (H2), and
argon (Ar) are often used.
•Successful GC analysis requires careful control
of carrier gas.

7. Comparison of the three gases

8. Brief comparison of Carrier Gas

9. Gas tank
Oven
Column
Injector
Syringe
Detector

10. How Does Gas Chromatography
Work?

11. Injector
•A GC syringe penetrates a septum to
inject sample into the vaporization camber
•Instant vaporization of the sample, 280 C
•Carrier gas transports the sample into the
head of the column
•Purge valve controls the fraction of sample
that enters the column

12. Sample Injection Volume
•The guidelines for sample injection
volumes are as follows. If the injection
volume is too large, the peak shape will
become deformed, or the injection port will
become dirty, leading to problems.
•Liquid samples: Approx. 1 to 2 µL
•Gas samples: Approx. 0.2 to 1 mL

13. Sample Injection Methods
Hot Injection
•Split: Most of the sample is eliminated as only a portion
is injected into the column.
•Splitless: Not split, but only for 1 to 2 minutes after
injection
•Total volume injection (Direct injection): There is no
splitting mechanism.
Cold Injection
•Cold on-column injection (OCI)
•Programmed temperature vaporization (PTV)
https://www.ssi.shimadzu.com/service-support/faq/gas-chromatography/sample-
injection/index.html

14. Split Injection Method
Notes
If the split ratio is small, the peak may inadvertently broaden at the injection port,
reducing the separation
Only a portion of the injected sample is injected into the column, so the sample
vaporized within the insert must be uniform.
→ Be sure to place silica wool within the glass insert. Depending on the sample, change
the amount and positioning of the wool, or the filler within the insert.

15. Splitless (100:90) vs. Split (100:1)
Injector
Syringe
Injector
Syringe
Purge valve
open
Purge valve
closed
GC column GC column
He
He

16. Split or splitless
•Usually operated in split mode unless sample
limited
•Chromatographic resolution depends upon the
width of the sample plug
•In splitless mode the purge valve is close for 30-
60 s, which means the sample plug is 30-60
seconds
•As we will see, refocusing to a more narrow
sample plug is possible with temperature
programming

17. Gas Chromatography Columns
•Two types of columns are used in gas
chromatography: packed columns and
capillary columns.

18. 0.32 mm ID
Liquid
Stationary
phase
Mobile phase
(Helium)
flowing at 1
mL/min
Open Tubular Capillary Column
15-60 m in length
0.1-5 mm

19. Packed columns introduction
•Short, thick columns made of glass or stainless
steel tubes, packed columns have been used
since the early stages of gas chromatography.
•Packed columns produce broad peak shapes
and have low separation performance, but can
also handle large sample volumes and are not
susceptible to contamination. They are still used
today in official analytical methods and for gas
analysis.

20. Packed columns
•Viewing a cross-section image of a packed
column reveals a tube filled with a
particulate substance called packing.
Packed columns have been used
throughout the long history of gas
chromatography, and many different
packed columns have been created for
different analytical applications.

22. Packed Column info
•Stainless steel or glass tube filled with
particulate packing material (an adsorbent
material, or a support material coated or
impregnated with a solid phase).
•Internal Diameter: 2 to 4 mm
•Length: 0.5 to 5 m (most commonly 2 m)
•Packing: Support material with 0.5 to 25 % liquid
phase (partition material) or no liquid phase
(adsorbent material)
•Liquid Phase: Multiple types available

23. Packed columns example

24. Capillary columns
•Capillary columns produce sharp peak shapes, achieve
excellent separation performance, and are suited to
high-sensitivity analysis.
•In contrast, typical capillary columns consist of a thin,
fused silica glass tube with a thin, internal liquid phase
coating. Capillary columns were developed after packed
columns, and though there are fewer types of capillary
columns, their separation performance is dramatically
superior to packed columns.

25. Capillary Column info
•A typical capillary column is a thin, fused silica
glass tube, lined with a liquid phase or
adsorbent material or having a chemical bonding
layer. Thin metal tubes are also sometimes used
as capillary columns.
•Internal Diameter: 0.1, 0.25, 0.32, 0.53 mm
•Length: 5 to 100 m (most commonly 30 m)
•Material: Fused silica glass
•Liquid Phase: Good separation but less variety
than packed columns

26. Porous Layer Open Tubular (PLOT)
column
(containsimmobilizedporous
polymer/alumina, etc.)
Wall-coated open-tubular(WCOT) or
chemical bonding column
(lined with liquid phase or a chemical
bonding layer)

27. Capillary GC columns

28. capillary vs packed column gc

31. Columns and Stationary Phases

33. fused silica open tubular
(FSOT) column
•Coated with polymer, crosslinked ;
–Polydimethyl soloxane (non-polar)
–Poly(phenylmethyldimethyl) siloxane (10%
phenyl)
–Poly(phenylmethyl) siloxane (50% phenyl)
–Polyethylene glycol (polar)
–Poly(dicyanoallyldimethyl) siloxane
–Ploy(trifluoropropyldimethyl) siloxane

34. Polar vs. nonpolar
•Separation is based on the vapor pressure
and polarity of the components.
•Within a homologous series (alkanes,
alcohol, olefins, fatty acids) retention time
increases with chain length (or molecular
weight)
•Polar columns retain polar compounds to
a greater extent than non-polar
–C18 saturated vs. C18 saturated methyl ester

35. C16:0
C18:0
C18:1
C18:2
C16:1
C16:0
C18:0
C18:1
C18:2
C16:1
RT (min)
RT (min)
Polar column
Non-polar column

36. Column Type and Effect on Separation
•Packed columns produce broad peaks and
capillary columns produce sharp peaks.
•In addition, capillary columns produce
taller peaks, which allows the detection of
lower concentrations (high detection
sensitivity). This is the advantage of
capillary columns.

38. •Sharper peaks provide better separation
but also shorter analysis times.

39. •Component separation is affected by the
following elements.

40. Classification of Capillary Column Liquid Phases
Type of Solid Phase Polarity
Separation
Characteristics
Application
Operational
Temperature
Range (Approx.)
Methyl silicone Non-polar Boiling point order
Petroleum, solvents,
high boiling point
compounds
-60 to 360 °C
Phenylmethyl
Slightly polar
|
Moderately polar
Phenyl groups retain
aromatic compounds.
Perfumes,
environmental
compounds, aromatic
compounds
-60 to 340 °C
Cyanopropyl phenol
Moderately polar
|
Strongly polar
Effective at separating
oxygen-containing
compounds, isomers,
etc.
Agricultural chemicals,
PCBs, oxygen-
containing compounds
*Better to avoid use
with FTDs (NPDs)
-20 to 280 °C
Trifluoropropyl
Moderately polar
|
Strongly polar
Specifically retains
compounds that
contain halogens.
Halogen-containing
compounds, polar
compounds, solvents
-20 to 340 °C
Polyethylene glycolStrongly polar
Strong retention of
polar compounds
Polar compounds,
solvents, perfumes,
fatty acid methyl
esters
40 to 250 °C

41. General Guide to Selecting Polarity
•Selecting columns with polar properties that are
close to the polarity of the target compounds
1.Analysis of non-polar compounds → Non-polar column
2.Analysis of polar compounds → Strongly polar column
•Selection by analytical objective
1.Large difference in boiling point between analytical target
compounds → Non-polar column
2.Isomers or other compounds with little difference in
boiling points → Strongly polar column

42. Guide to Selection of Internal Diameter,
Length, and Coating Thicknes
•Selection based on required separation
1.High-resolution separation required → Internal diameter:
Thin, Length: Long
2.Adequate separation with shorter analysis time →
Internal diameter: Thick, Length: Short, Coating
thickness: Thin
•Selection by analytical objective
1.Analysis of low boiling point compounds → Length:
Long, Coating thickness: Thick
2.Analysis of high boiling point compounds → Length:
Short, Coating thickness: Thin

43. Oven
•Programmable
•Isothermal-run at one constant
temperature
•Temperature programming -Start at low
temperature and gradually ramp to higher
temperature
–More constant peak width
–Better sensitivity for components that are
retained longer
–Much better chromatographic resolution
–Peak refocusing at head of column

44. Typical Temperature Program
Time (min)
0
60
50C
220C
160C

45. Detectors
•Flame Ionization Detectors (FID)
•Electron Capture Detectors (ECD)
•Electron impact/chemical ionization (EI/CI)
Mass spectrometry

46. Flam ionization detector (FID)
•Effluent exits column and enters an air/hydrogen
flame.
•The gas-phase solute is pyrolized to form
electrons and ions.
•All carbon species are reduced to CH
2
+
ions.
•These ions collected at an electrode held above
the flame.
•The current reaching the electrode is amplified
to give the signal.

47. FID
•Advantage ;
1.general detector for organic compounds
2.Very sensitive (10
-13
g/s), normal working range is
between 0.1 and 100000 ppm
3.linearity response factors -Linear response (10
6
to 10
7
)
4.Rugged/durable
•Disadvantage: destructive nature, and specific for
volatile hydrocarbons and many carbon containing
compounds only (cannot detect inorganic substances).

49. Electron capture detector (ECD)
•To analyse halogenated compounds and is
primarily found in the environmental,
forensic and pharmaceutical markets.
•Pesticide analysis
•Up to 1000 times more sensitive than
Flame Ionization Detectors

50. GC-ECDprinciple
•ECD operates using two electrodes with a
current passing between them.
•When a sample passes between these
two electrodes, the molecules pick up
some of the electrons, causing a reduction
in the current.
•This reduction is recorded as a positive
peak in the detection of components.

51. Sensitivity for ECD
•Advantage ;
1.Exceptional sensitivity for
halogenated compounds
2.Non destructive

52. Sensitivity for ECD
•Disadvantage ;
1.Use radioactive source, need special license for
operation.
2.Need several gases for ionization
3.Detector linear range is limited to around three
or four orders of magnitude (10
3
to 10
4
),
depending upon the electronegativity of the
analyte.
4.susceptible to oxygen and water impurities

53. Electron Capture Detector
Schematic of a typical ECD detector. Red
species are β particles; green species are
nitrogen make-up gas molecules; blue
species are analyte molecules.

54. Flame Photometric Detector (FPD)
•Allows sensitive and selective measurements of
volatile sulphur and phosphorus compounds.
•FPD is highly selective as it detects element-
specific light emitted within a hydrogen flame.
•Main Applications >
1.Analysis of phosphorus pesticides
2.Analysis of sulfur-based malodors and food odor
components
3.Analysis of organic tin in marine products

55. Principle of detection used by the
FPD
•Sulfur compounds, phosphorus compounds, and
organic tin compounds each emit light at unique
wavelengths when burned.
•By passing light through a filter, only light of
these unique wavelengths reaches a
photomultiplier tube.
•The photomultiplier tube then converts the
detected light intensity into an electrical signal.

56. Flame Photometric Detector

57. Flame Thermionic Detectors (FTD)
•Selective, high-sensitivity detector for organic
nitrogen compounds and inorganic and organic
phosphorus compounds.
•Does not react to inorganic nitrogen compounds.
•Main Applications >
1.Drug analysis
2.Analysis of nitrogen and phosphorus pesticides

58. Principle of detection used by the
FTD
•FTD detects ions by reading the change in ion current
gathered at the collector.
•When a current is passed through the platinum coil with an
alkali source attached to the coil (rubidium salt), the coil
increases in temperature, which creates plasma around the
alkali source.
•Rubidium radicals (Rb*) are generated within this plasma.
-Capable of oxidizing CN and organic phosphorus
compounds
-PO2 reacts with Rb* as shown below, creating ions.
•CN + Rb* → CN-+ Rb+
PO2 + Rb* → PO2-+ Rb+
A current flows when ions gather in the collector.

59. Schematic Diagram of FTD

60. Thermal Conductivity Detectors
(TCD)
•TCD can detect all compounds other than the carrier
gas. The TCD is mainly used to detect inorganic gas and
components that the FID is not sensitive to.
•Used for both organic and inorganic compounds
detection.
•Helium is commonly used as a carrier gas. (N2 and Ar
are used to analyze He and H2.)
•Main Applications >
1.Water, formaldehyde, formic acid, etc.
2.Analysis of compounds not detectable by the FID

61. Principle of detection used by
the TCD
•TCD detects target components by reading the change
in filament temperature caused by the difference in
thermal conductivity between the carrier gas and target
components.
•A direct voltage is applied between A and B.

62. Principle of detection used by
the TCD
A direct voltage is applied between A and B.
1.When only the carrier gas is flowing at a constant
flowrate
-Each filament maintains a constant temperature and a
constant voltage is produced between C and D.
Components are eluted from an analysis-side column.
1.A change in filament temperature occurs, which
2.Changes the resistance value, and
3.Changes the voltage between C and D

63. How does a thermal conductivity
detector TCD work?
•It functions by having two parallel tubes
both containing gas and heating coils.
•The gases are examined by comparing the
rate of loss of heat from the heating coils
into the gas.
•The coils are arranged in a bridge circuit
so that resistance changes due to unequal
cooling can be measured.

64. Schematic Diagram of the TCD

65. TCD Analysis Example
•When the Thermal Conductivity of the
Analytical Target Component is Lower
than the Carrier Gas

66. TCD Analysis Example
•Selection by Analytical Objective
•Reference ;
•https://www.shimadzu.com/an/service-support/technical-
support/analysis-
basics/fundamentals/detector2.html#6_3_2_TCD

67. Mass Spectrometric detector

68. What is Mass Spectrometry?
•mass spectrometers can be used to identify
unknown compounds via molecular weight
determination, to quantify known compounds, and
to determine structure and chemical properties of
molecules
•How does a mass spectrometer perform such a
feat? Every mass spectrometer consists of at
least these three components:
•Ionization Source
•Mass Analyzer
•Ion Detection System

69. What kind of info can mass spec
give you?
•MS provides qualitative and quantitative
information about the atomic and molecular
composition of inorganic and organic materials.
•Molecular weight, Elemental composition (low
MW with high resolution instrument), Structural
info (hard ionization or CID)
•Applications include drug detection, forensic
substance identification and environmental
analysis etc.

70. MASS SPECTROMETER (MS) IS
COMMONLY USED AS A GC DETECTOR.

71. GC-MS advantages and
disadvantages
•Advantages ; enhanced sample
identification, higher sensitivity, an
increased range of analyzable samples,
and faster results.
•Disadvantages ; not capable of directly
analyzing drugs that are nonvolatile, polar,
or thermally labile. High cost, Limited
sensitivity-detection of trace pollutants

73. How does it work?
•Gas-phase ions are separated according to
mass/charge ratio and sequentially detected
•mass spectrometer generates multiple ions
from the sample under investigation, it then
separates them according to their specific
mass-to-charge ratio (m/z), and then records
the relative abundance of each ion type.

74. Basic Principle of MS
Mass spectrometer should always perform the following
processes:
1.Produce ions from the sample in the ionization source.
2.Separate these ions according to their mass-to-charge ratio
in the mass analyzer.
3.Eventually, fragment the selected ions and analyze the
fragments in a second analyzer.
4.Detect the ions emerging from the last analyzer and
measure their abundance with the detector that converts the
ions into electrical signals.
5.Process the signals from the detector that are transmitted to
the computer and control the instrument using feedback.

75. Figure: Components of a Mass
Spectrometer
http://www.premierbiosoft.com/tech_notes/mass-
spectrometry.html#:~:text=Basic%20Principle,abundance%20of%
20each%20ion%20type.

77. Parts of a Mass Spec
•Sample introduction
•Source (ion formation)
•Mass analyzer (ion sep.) -high vac
•Detector (electron multiplier tube)

78. Sample Introduction/Sources
Volatiles
•Probe/electron impact (EI),Chemical ionization (CI)
•GC/EI,CI
Involatiles
•Direct infusion/electrospray (ESI)
•HPLC/ESI
•Matrix Assisted Laser Adsorption (MALDI)
Elemental mass spec
•Inductively coupled plasma (ICP)
•Secondary Ion Mass Spectrometry (SIMS)
–surfaces

79. EI, CI
•EI (hard ionization)
–Gas-phase molecules enter source through
heated probe or GC column
–70 eV electrons bombard molecules forming
M+* ions that fragment in unique reproducible
way to form a collection of fragment ions
–EI spectra can be matched to library stds
•CI (soft ionization)
–Higher pressure of methane leaked into the
source (mtorr)
–Reagent ions transfer proton to analyte

80. To mass
analyzer
filament
70 eV e-
anode
repeller
Acceleration
slits
GC column
EI Source
Under high vacuum

81. EI process
•M + e- M
+*
f
1 f
2 f
3
f
4
This is a remarkably reproducible process. M
will fragment in the same pattern every time
using a 70 eV electron beam

83. Ion Chromatogram of Safflower Oil

85. CI/ ion-molecule reaction
•2CH
4+ e-CH
5
+
and C
2H
5
+
•CH
5
+
+ M MH
+
+ CH
4
•The excess energy in MH
+
is the
difference in proton affinities between
methane and M, usually not enough to
give extensive fragmentation

86. EI spectrum of phenyl acetate

88. Mass Analyzers
•Low resolution
–Quadrupole
–Ion trap
•High resolution
–TOF time of flight
–Sector instruments (magnet)
•Ultra high resolution
–ICR ion cyclotron resonance

89. Resolution
•R = m/z/Dm/z
•Unit resolution for quad and trap
•TOF up to 15000
•FT-ICR over 30000
–MALDI, Resolve
13
C isotope for a protein that
weighs 30000
–Resolve charge states 29 and 30 for a protein
that weighs 30000

90. High vs low Res ESI
•Q-TOF, ICR
–complete separation of the isotope peaks of a
+3 charge state peptide
–Ion abundances are predictable
–Interferences can be recognized and
sometimes eliminated
•Ion trap, Quad
–Unit resolution

91. MVVTLIHPIAMDDGLR594.3
594.7
595.0
601.3
595.3
601.0
601.7
602.0
m/z
C
78H
135N
21O
22S
2
+3
Q-TOF
901.4
891.7
902.3
900.6
891.2
892.6
LCQ
R = 0.88
m/z
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100

92. Quadrupole Mass Ion Filter

93. Ion Trap

94. Time of Flight -TOF

95. Where:
•m
i
= mass of analyte ion
•z
i
= charge on analyte ion
•E = extraction field
•t
i
= time-of-flight of ion
•l
s
= length of the source
•l
d
= length of the field-free drift region
•e= electronic charge (1.6022x10-19 C)

96. TOF with reflectron
http://www.rmjordan.com/tt1.html

97. Mass accuracy
•Mass Error = (5 ppm)(201.1001)/10
6
=
0.0010 amu
•201.0991 to 201.1011 (only 1 possibility)
•Sector instruments, TOF mass analyzers
•How many possibilities with MA = 50 ppm?
with 100 ppm?

98. Exact Mass Determination
•Need Mass Spectrometer with a high
mass accuracy –5 ppm (sector or TOF)
•C
9H
15NO
4, FM 201.1001 (mono-isotopic)
•Mass accuracy = {(Mass Error)/FM}*10
6
•Mass Error = (5 ppm)(201.1001)/10
6
=
0.0010 amu

99. Advantages and limitations of the various
mass analyzers
Mass AnalyzerDescription Advantages Limitations
Magnetic
Sector
ScanningHigh resolution Expensive and bulky
ContinuousHigh dynamic range Slow scan speed
High reproducibility High vacuum required
High sensitivity
Difficult to couple with pulsed ionization
techniques and LC
Quadrupole
ScanningCompact and simple Limited mass range
Mass FilterRelatively cheap Low resolution
ContinuousGood selectivity (SIM) Little qualitative information
Moderate vacuum required → well suited
for coupling to LC
Time-of-Flight
Non-
scanning
High sensitivity and ion transmissionRequires pulsed introduction to MS
PulsedHigh resolution Requires fast data acquisition
Excellent mass range
Fast scan speed
Ion Trap
TrapSmall and relatively cheap Limited dynamic range
PulsedHigh sensitivity Limited ion trap volume
Good resolution Limited resolution
Compact Requires pulse introduction to MS

100. Application of Mass Spectrometry
•Analysis of Biomolecules using Mass
Spectrometry
•Analysis of Glycans
•Analysis of Lipids
•Analysis of Proteins and Peptides
•Analysis of Oligonucleotides

101. Analysis of Biomolecules using
Mass Spectrometry
•Till the1970s, the only analytical techniques which provided similar
information were electrophoretic, chromatographic or
ultracentrifugation methods. The results were not absolute as they
were based on characteristics other than the molecular weight. Thus
the only possibility of knowing the exact molecular weight of a
macromolecule remained its calculation based on its chemical
structure.
•The development of desorption ionization methods based on the
emission of pre-existing ions such as plasma desorption (PD), fast
atom bombardment (FAB) or laser desorption (LD), allowed the
application of mass spectrometry for analyzing complex
biomolecules.

102. Analysis of Glycans
•Oligosaccharides are molecules formed by the association of
several monosaccharides linked through glycosidic bonds.
•The determination of the complete structure of oligosaccharides is
more complex than that of proteins or oligonucleotides.
•It involves the determination of additional components as a
consequence of the isomeric nature of monosaccharides and their
capacity to form linear or branched oligosaccharides.
•Knowing the structure of an oligosaccharide requires not only the
determination of its monosaccharide sequence and its branching
pattern, but also the isomer position and the anomeric configuration
of each of its glycosidic bonds.

103. Analysis of Lipids
•Lipids are made up of many classes of different molecules which are
soluble in organic solvents. Lipidomics, a major part of
metabolomics, constitutes the detailed analysis and global
characterization, both spatial and temporal, of the structure and
function of lipids (the lipidome) within a living system.
•Many new strategies for mass-spectrometry-based analyses of lipids
have been developed. The most popular lipidomics methodologies
involve electrospray ionization (ESI) sources and triple quadrupole
analyzers. Using mass spectrometry, it is possible to determine the
molecular weight, elemental composition, the position of branching
and nature of substituents in the lipid structure.

104. Analysis of Proteins and Peptides
•Proteins and peptides are linear polymers made up of combinations
of the 20 amino acids linked by peptide bonds. Proteins undergo
several post translational modifications, extending the range of their
function via such modifications.
•The term Proteomics refers to the analysis of complete protein
content in a living system, including co-and post-translationally
modified proteins and alternatively spliced variants.
•Mass Spectrometry has now become a crucial technique for almost
all proteomics experiments. It allows precise determination of the
molecular mass of peptides as well as their sequences. This
information can very well be used for protein identification, de novo
sequencing, and identification of post-translational modifications.

105. Analysis of Oligonucleotides with
GC-MS
•Oligonucleotides (DNA or RNA), are linear polymers of nucleotides.
These are composed of a nitrogenous base, a ribose sugar and a
phosphate group. Oligonucleotides may undergo several natural
covalent modifications which are commonly present in tRNA and
rRNA, or unnatural ones resulting from reactions with exogenous
compounds.
•Mass spectrometry plays an important role in identifying these
modifications and determining their structure as well as their position
in the oligonucleotide. It not only allows determination of the
molecular weight of oligonucleotides, but also in a direct or indirect
manner, the determination of their sequences.

106. GC Applications
Overview

107. Energy and Chemical
•Gas chromatographs are used through the
entire hydrocarbon value chain, from exploration
to final product. They are used to determine the
quality, purity, and composition of petroleum
products, including crude oil, natural gas,
liquefied petroleum gas (LPG), and refined
products like diesel fuel, gasoline, or heating oil.
•GC also are used to help develop and test
alternative energy sources, such as biofuels and
batteries.

108. Environmental
•Labs test drinking water, wastewater, soil, and
air for the presence of pollutants that can be
harmful to human health.
•GC systems give scientists the confidence that
they can implement standard methods to meet
regulatory requirements and perform untargeted
screening to discover new contaminants of
concern.

109. Food and Beverage
•Used to test crops, additives, and processed
foods and beverages, from the measurement of
pesticide residues and persistent organic
pollutants (POPs) in raw materials to the
detection and quantitation of leached materials
in packaged foods to confirmation of accurate
nutrition labeling.

110. Forensics
•Because the field of forensics is diverse and
accurate results are paramount, scientists
require versatile and dependable gas
chromatography systems.
•GC to determine blood alcohol content (BAC),
analyze samples for performance-enhancing or
recreational drugs, or confirm the identity and
potency of seized narcotics.

111. Pharmaceutical
•Pharmaceutical manufacturers must adhere to
strict regulations concerning the amount of
residual solvent and reaction by-products that
can be present in their products. They also must
test for compounds that can leach out of
packaging and into pills or other formulations.
•Gas chromatography systems help
pharmaceutical scientists test for these
contaminants to ensure they are below
mandated levels.