•
4
•
2005vol. 2
Figure1
AnRtx®-440 column resolves lidocaine/caffeine, and
other cocaineadulterants, tobaseline.
Figure2
Analyze cocaineadulterants in6.5minutes, usingan
Rtx®-440 column inaGC/MSanalysis.
Illicitcocaine iscommonly“cut”withadulterantsor
diluents to increase theamountofproductavailable
for sale. Because the composition of an illicit
cocainemixture canbe specific toonedealer, iden-
tification of adulterants and diluents in seized
cocaine iscritical indetermining thepossibleroutes
of distribution and sales.
EitherGCorHPLC canbeused to identify cocaine
adulterants such as sugars, anesthetics, analgesics,
and stimulants.GC is themost common analytical
techniqueused foranalyzingall cocaineadulterants
except sugars. Although sugars can be derivatized
for analysis by GC, they are more easily detected
usingHPLC.
GC
Cocainemixturecomponentscanbedetectedusing
flame ionization detection (FID, Figure 1), nitro-
gen-phosphorus detection (NPD), or mass spec-
trometry (MS). Although FID or NPD provide
good sensitivity for the adulterants, GC/MS is the
mostwidelyaccepteddetectionmethod.MS is very
sensitive, provides positive identifications basedon
mass spectra, andMSdataareacceptedas confirm-
ing evidence in courts of law.
Among the column types we evaluated, only
Rtx®440columns resolved lidocaineandcaffeine to
baseline (Figure 1). To evaluate the columns, we
preparedmock samples of illicit cocaine by adding
equal concentrationsof avarietyof adulterantsand
diluents to cocaine hydrochloride.We used stimu-
lants, including caffeine, local anesthetics, such as
lidocaine, and over-the-counter analgesics, such as
phenacetin, and followed a simple “dilute and
shoot” sample preparation scheme to dissolve the
samples for analysis.
Wedeveloped aGC/MSmethod that enabledus to
identify each adulterant or diluent, focusing on
maximizing resolution while minimizing total
analysis time in order to increase sample through-
put. In the optimized GC/MSmethod (Figure 2),
total analysis time was 6.5 minutes. Unlike in the
GC/FID analysis (Figure 1), caffeine and lidocaine
were not resolved to baseline, but were resolved by
approximately 40% (Figure 2), due toMS vacuum
effects on sample flow through the column.
Caffeine and lidocaine have very different mass
spectra,however,andextracted ionanalysisensured
IdentifyandQuantifyAdulterants inSeizedCocaine
UsingGC/MS (Rtx®-440Column) andHPLC/RI (Pinnacle II™AminoColumn)
By Kristi Sellers, Clinical/Forensic Innovations Chemist, and RickMorehead, R&DGC ColumnGroup Leader
• LowbleedRtx®-440 column improves resolutionand inertness for adulterantsbyGC/MS.
• GC/MSprovidespositive identification for all adulterants except sugars; data canbeusedas evidence.
• HPLC is thepreferred chromatographicmethod for identifying sugars as adulterants.
GC_PH00769
Rtx
®
-440 30m, 0.25mm ID, 0.50µm (cat.# 12938)
Sample:
100µg/mL each compound inmethanol
Inj.:
1.0µL split (split ratio 1:10), laminar cup splitter
inlet liner (cat.# 20801)
Inj. temp.:
250°C
Carrier gas:
helium, constant flow
Flow rate:
1mL/min.
Oven temp.:
150°C to 275°C@ 25°C/min.,
to 300°C@ 15°C/min.
(hold 5.0min.)
Det.:
FID@ 300°C
1. benzocaine
2. phenacetin
3. prilocaine
4. lidocaine
5. caffeine
6. procaine
7. cocaine
8. tetracaine
GC_PH00770
Column:
Rtx
®
-440 30m, 0.25mm ID, 0.50µm (cat.# 12938)
Sample:
100µg/mL each compound inmethanol
Inj.:
1.0µL split (split ratio 1:10), laminar cup splitter inlet liner (cat.# 20801)
Inj. temp.:
250°C
Carrier gas:
helium, constant flow
Flow rate:
1mL/min.
Oven temp.:
150°C to 275°C@ 25°C/min., to 300°C@ 15°C/min. (hold 5.0min.)
Det.:
MS
Transfer line temp.: 180°C
Scan range:
35-550amu
Ionization:
EI
Mode:
scan
1. benzocaine
2. phenacetin
3. prilocaine
4. lidocaine
5. caffeine
6. procaine
7. cocaine
8. tetracaine
