ADV01-05_1-298

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2005 vol. 2

Figure 1

An Rtx®-440 column resolves lidocaine/caffeine, and

other cocaine adulterants, to baseline.

Figure 2

Analyze cocaine adulterants in 6.5 minutes, using an

Rtx®-440 column in a GC/MS analysis.

Illicit cocaine is commonly“cut”with adulterants or

diluents to increase the amount of product available

for sale. Because the composition of an illicit

cocaine mixture can be specific to one dealer, iden-

tification of adulterants and diluents in seized

cocaine is critical in determining the possible routes

of distribution and sales.

Either GC or HPLC can be used to identify cocaine

adulterants such as sugars, anesthetics, analgesics,

and stimulants. GC is the most common analytical

technique used for analyzing all cocaine adulterants

except sugars. Although sugars can be derivatized

for analysis by GC, they are more easily detected

using HPLC.

Cocaine mixture components can be detected using

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

most widely accepted detection method. MS is very

sensitive, provides positive identifications based on

mass spectra, and MS data are accepted as confirm-

ing evidence in courts of law.

Among the column types we evaluated, only

Rtx®440 columns resolved lidocaine and caffeine to

baseline (Figure 1). To evaluate the columns, we

prepared mock samples of illicit cocaine by adding

equal concentrations of a variety of adulterants and

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.

We developed a GC/MS method that enabled us 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/MS method (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 to MS vacuum

effects on sample flow through the column.

Caffeine and lidocaine have very different mass

spectra, however, and extracted ion analysis ensured

Identify and Quantify Adulterants in Seized Cocaine

Using GC/MS (Rtx®-440 Column) and HPLC/RI (Pinnacle II™ Amino Column)

By Kristi Sellers, Clinical/Forensic Innovations Chemist, and Rick Morehead, R&D GC Column Group Leader

• Low bleed Rtx®-440 column improves resolution and inertness for adulterants by GC/MS.

• GC/MS provides positive identification for all adulterants except sugars; data can be used as evidence.

• HPLC is the preferred chromatographic method for identifying sugars as adulterants.

GC_PH00769

Rtx

-440 30m, 0.25mm ID, 0.50µm (cat.# 12938)

Sample:

100µg/mL each compound in methanol

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 5.0 min.)

Det.:

FID @ 300°C

1. benzocaine

2. phenacetin

3. prilocaine

4. lidocaine

5. caffeine

6. procaine

7. cocaine

8. tetracaine

GC_PH00770

Column:

Rtx