the recovery of illicit drugs from oral fluid sampling devices

www.elsevier.com/locate/forsciint

Forensic Science International 165 (2007) 78–84

The recovery of illicit drugs from oral fluid sampling devices

Stuart Dickson *, Alexandra Park, Susan Nolan, Sarah Kenworthy, Cheryl Nicholson,Julie Midgley, Rowena Pinfold, Scott Hampton

Institute of Environmental Science and Research Ltd., Kenepuru Science Centre, PO Box 50 348, Porirua, New Zealand

Received 25 November 2005; received in revised form 3 March 2006; accepted 4 March 2006

Available online 18 April 2006

Abstract

Testing for drugs in oral fluid is a convenient procedure for determining recent drug use. A number of issues are still to be resolved and this paper

investigates the effects of storage systems on drug stability and recovery using three different collection devices supplied by Cozart, Immunalysis

and Microgenics (third party). Drugs were analysed using a range of immunoassay systems followed by MS confirmation and quantitation.

The reproducibility of the weight of specimen collected was excellent (CV < 10%) for the three collection devices tested.

Of the three systems studied, only the Cozart product gave acceptable recovery of THC from drug-spiked oral fluid. A combination of Cozart,

Immunalysis and Diagnostix immunoassays with the Cozart collection system gave the most sensitive and discriminating screening assays for the

drugs studied, namely THC, benzodiazepines, methamphetamine and morphine.

Storage at either 5 8C or room temperature had no significant effect on drug recoveries.

# 2006 Elsevier Ireland Ltd. All rights reserved.

Keywords: Oral fluid collection devices; Drug analysis in oral fluid; Drug stability and recovery

1. Introduction

Compared to other specimens, the collection of oral fluid is

less invasive and minimises embarrassment for the donor. It is

less easily adulterated, substituted and diluted than urine.

The presence of drugs and their concentrations in oral fluid is

generally considered to provide a better measure of recent

consumption and possible impairment than similar determina-

tions in urine. For these reasons, interest in the use of oral fluid

testing for drugs in the workplace [1] and at the roadside [2] is

increasing rapidly.

There are still many scientific issues to be resolved however,

including appropriate cut-off levels, sampling protocols and

assay sensitivities. Additional considerations that have received

scant attention are the variability in the volume of sample

collected and the drug recovery from the many different

specimen collection systems on the market.

This study was intended to identify a preferred supplier(s) of

an oral fluid collection kit and immunoassay screening tests for

use in further studies. We investigated the precision of the

* Corresponding author. Tel.: +64 4 914 0749; fax: +64 4 914 0770.

E-mail address: [email protected] (S. Dickson).

0379-0738/$ – see front matter # 2006 Elsevier Ireland Ltd. All rights reserved.

doi:10.1016/j.forsciint.2006.03.004

sample size collected using the collection kits provided by three

different suppliers. We have also investigated drug recoveries

from the different kits after storage for up to 10 days. Two

storage temperatures (5 8C and RT) were studied as it was

considered that samples are unlikely to be stored cold during

transport to the laboratory. The drug concentrations investi-

gated ranged upwards from the cut-off levels for THC (4 ng/

mL), methamphetamine (50 ng/mL) and morphine (40 ng/mL)

incorporated in the draft SAMHSA Guidelines [1].

The analytes investigated in this study were considered

appropriate indicators for use of the individual drugs. Cannabis

smoking for example leads to contamination of the oral cavity

with THC [3]. THC metabolites are not present in significant

levels in oral fluid [4]. Many other drugs however, are

transferred from the plasma to oral fluid with amphetamines

being present at higher levels in the latter [5]. The

benzodiazepines tested are representative of those prescribed

in New Zealand.

2. Experimental

A single collection device and immunoassay technique was

tested from three different suppliers. A Cozart collection

system with corresponding EIA kits (Cozart, Oxfordshire, UK);

mailto:[email protected]

http://dx.doi.org/10.1016/j.forsciint.2006.03.004

S. Dickson et al. / Forensic Science International 165 (2007) 78–84 79

Table 1

MS ions or transitions monitored

Drug (IS) Ion Transition

THC (d3 THC) 316/193 (319/194)

Clonazepam (d4) 316/270 (320/274)

Diazepam (d5) 285/193 (290/198)

Oxazepam (d5) 287/241 (292/246)

Triazolam (d4) 343/315 (347/319)

Methamphetamine (d5) 160, 204 (163, 208)

Morphine (d3) 414, 577 (417, 580)

an Immunalysis collection kit system with corresponding EIA

kits (Immunalysis, Pomona, California); and a third party

collection device supplied with a Microgenics MGC240 analyser

and CEDIA1 reagents (Microgenics, Fremont, California) were

all tested simultaneously for the individual drug groups to

determine the stability of the drugs in stored samples.

In addition the Cozart collected samples were screened for

THC and benzodiazepines using the Immunalysis and

Diagnostix EIA kits, respectively, to improve the sensitivity

and reproducibility of the screening process.

The same sample preparation protocol for making the stored

spiked oral fluid samples was followed every time an analyte

was investigated. Separate screening (�2) and confirmation

(�4) samples were prepared each time. Bulk oral fluid was

centrifuged and frozen upon collection, and thawed as required

for preparing working solutions. Working solutions of spiked

oral fluid (25 mL) were prepared by adding a small volume of

an ethanolic solution of known concentration of analyte to

drug-free oral fluid. All the samples (screening and confirma-

tion) were taken from the bulk solution. For each product, one

screening sample and two confirmation samples were stored at

both 25 8C (room temperature) and at 5 � 4 8C. For the

confirmations, one sample was analysed on day 0 (i.e.

immediately after collection) and day 1, the second sample

was analysed on days 3 and 10. The same sample could not be

used on all four occasions because not enough sample is

collected by any of the devices to do so.

2.1. Sample collection

Each product has a unique collection procedure which was

followed for the duration of this study. The only deviation made

to the recommended procedures was that instead of the

collection device being put in the mouth it was placed in a

beaker containing bulk spiked oral fluid. Samples were

collected by standing the collection devices in the fluid until

collection was complete.

When using the Cozart system the collection pad was placed

in the spiked oral fluid until the blue volume adequacy indicator

strip appeared. The pad was placed in the transport tube, which

contained a buffered solution that facilitated dissolution of the

pad contents. Prior to analysis, the pad was separated from the

stem of the collection device and the separator filter was used to

isolate the oral fluid from the collection pad. The sample was

then decanted into an Eppendorf tube for storage purposes (in

accordance with the supplier’s recommendation).

The Immunalysis kit was supplied within a single sealed

ziplock package (which can be reused for transportation to the

testing laboratory) with pictorial instructions on the outside.

Samples were collected by placing the collection pad in the oral

fluid until the blue volume adequacy indicator appeared. The

collection pad was then placed in the transport tube containing a

buffered solution. For analysis, aliquots were taken directly

from the transport tube.

Sample collection for Microgenics involved placing the

collection stick in the spiked oral fluid until absorption by the

sponge appeared to be complete. The oral fluid was then filtered

through the syringe device directly into the transport tube at the

time of collection. The transport tube did not contain any

buffering solution.

Fresh calibrators were prepared on the day of analysis from

the same bulk oral fluid that was used to prepare the screening

and confirmation samples.

2.2. Screening

All screening tests consisted of a single assay.

Microgenics samples were screened using an MGC240

analyser with CEDIA1 reagents for the immunoassay. The

analyser was configured by Microgenics to analyse oral fluid.

The reagents were the same as those used for urine except that

for THC the calibrators and controls contained THC rather than

carboxy-THC. Cozart supplied enzyme immunoassay (EIA)

kits for each of the drug classes and protocols for their use.

Immunalysis also supplied their own EIA kits and procedures

for their use.

For the Microgenics system both the samples and the

calibrators were analysed neat, i.e. no diluent was involved. The

cut-off level calibrator was used to calibrate the analyser, then

re-run as a sample alongside the other calibrators.

In order to match the dilution of Cozart and Immunalysis

spiked samples (during collection), the calibrators were diluted

with buffered solution from an unused collection tube prior to

analysis.

Diagnostix EIA kits (Diagnostix, Mississauga, Canada)

were also used to screen for benzodiazepines in the Cozart

collected samples.

2.3. Confirmation and quantitation

All confirmations were performed in duplicate using

Cerilliant deuterated compounds as internal standards. All

analyte concentrations refer to the concentrations in the

undiluted oral fluid. The volumes referred to throughout

Section 2.3 are the volumes of buffered (Cozart, Immunalysis)

or undiluted (Microgenics) oral fluid. LCMSMS transitions and

GCMS ions monitored are listed in Table 1. Calibration lines

for all analytes had excellent linearity and the MS chromato-

grams were free of interferences.

2.3.1. THC

THC was quantified using a routine LCMSMS method

previously validated for blood [6] except the sample volume

S. Dickson et al. / Forensic Science International 165 (2007) 78–8480

was changed from 1 mL for blood to 0.5 mL for buffered (Cozart,

Immunalysis) or undiluted oral fluid (Microgenics). Analysis

was carried out using an Applied Biosystems API365 triple

quadrupole mass spectrometer with a TurboIonSpray source.

The HPLC system was a Shimadzu 10A-VP with a binary pump.

Chromatographic separation was achieved using a Phenom-

enex Luna1 3 mm C18(2) 50 mm � 2.0 mm i.d. column with a

Security Guard cartridge (C18 4.0 mm � 2.0 mm). Analytes

were eluted using a linear gradient of 20% solvent A/80%

solvent B to 5% solvent A/95% solvent B, where solvent A was

0.1% formic acid in deionised water and solvent B was 0.1%

formic acid in methanol. The flow rate was 0.2 mL/min.

The inter-day %CVs for Cozart, Immunalysis and Micro-

genics were 5, 11 and 13, respectively, at concentrations

equivalent to15 ng/mL THC in the undiluted oral fluid (n = 6).

The limit of detection based on a signal:noise of 3:1 was less

than 0.1 ng/mL.

2.3.2. Benzodiazepines

Benzodiazepines were quantified using 0.2 mL of oral fluid

sample (diluted or undiluted) followed by an LCMSMS

procedure. The analytes were isolated by liquid–liquid

extraction of basified samples into butyl chloride. Analysis

was completed on an Applied Biosystems API2000 triple

quadrupole mass spectrometer with a TurboIonSpray source. A

Shimadzu 10A-VP HPLC was used with a binary pump to

produce the gradient. The column was held at 40 8C by a

Shimadzu CTO-10AVP column oven and the samples were

injected with a Gilson 233XL with a 402 syringe pump.

Chromatographic separation was achieved using a Phenom-

enex Luna1 3 mm phenyl hexyl 50 mm � 2.0 mm i.d. column

with a Security Guard cartridge (phenyl propyl 4.0 mm �2.0 mm). Analytes were eluted using a linear gradient of 20%

solvent A/80% solvent B to 90% solvent A/10% solvent B,

where solvent A was acetonitrile and solvent B was 2 mM

ammonium formate. The flow rate was 0.2 mL/min.

The inter-day %CVs are listed in Table 2. The concentration

of 4 ng/mL represents the concentration of the benzodiazepine

in the undiluted oral fluid. The limit of detection based on a

signal:noise of 3:1 was less than 0.5 ng/mL.

2.3.3. Methamphetamine

Methamphetamine was quantified using a GCMS method

previously validated for urine. Basified 0.2 mL oral fluid

samples (buffered or undiluted) were extracted into butyl

chloride and derivatised using pentafluoropropionic anyhdride.

Table 2

Inter-day reproducibility of benzodiazepine analysis by LCMSMS. Coefficient

of variation (%CV), for oral fluid spiked with benzodiazepine (4 ng/mL), and

stored in transport tube at 5 8C

Supplier Benzodiazepine

Clonazepam Diazepam Oxazepam Triazolam

Cozart (n = 6) 19 7 8 8

Immunalysis (n = 6) 27 8 8 25

Microgenics (n = 6) 8 7 10 12

The derivatised samples were analysed on a Hewlett–

Packard HP6890 GC system with a Hewlett–Packard HP5973

mass-selective detector. The column for both this and the

morphine analyses was a 12 m, 0.2 mm i.d., 0.2 mm film

thickness HP 5MS.

Analysis of 6 oral fluid replicates on three separate days,

using the Cozart system, gave a CV of 4% at a concentration

equivalent to 50 ng/mL methamphetamine in the undiluted oral

fluid.


than 3 ng/mL.

2.3.4. Morphine

Morphine was quantified using a GCMS method previously

validated for blood and liver samples. Basified 0.2 mL oral fluid

samples (buffered or undiluted) were extracted by solid phase

extraction using Varian Certify cartridges. The eluate was

evaporated and the samples derivatised with pentafluoropro-

pionic anhydride. Analysis was completed on a Shimadzu

GCMS-QP2010.

Inter-day CVs for the three different collection systems were

2% (Microgenics), 4% (Cozart) and 12% (Immunalysis) at a

morphine concentration equivalent to 40 ng/mL morphine in

the undiluted oral fluid (n = 6).


than 1 ng/mL.

3. Results

3.1. Precision of sample collection

The replicate sampling weights of oral fluid for the three

collection devices are listed in Table 3.

3.2. Screening

Initial screening tests showed that the Microgenics

immunoassays gave excellent sensitivity for all analytes

provided the oral fluid had not passed through the collection

system. Likewise, Immunalysis and Cozart were excellent for

methamphetamine and morphine but poor for the other

analytes.

Subsequent storage studies demonstrated that only the

Cozart collection gave good recoveries of all analytes in the

storage conditions studied (see Section 3.3). Studies were

therefore performed to establish whether combining the Cozart

samples with alternative immunoassays would produce super-

ior screening results. We were advised by the supplier that the

Microgenics assay would not work in the presence of Cozart (or

Table 3

Variation in weight (g) of oral fluid specimen sampled with different collectors

Supplier Weight range Mean weight (n = 18) %CV

Cozart 1.091–1.453 1.203 7.68

Immunalysis 1.045–1.225 1.158 5.09

Microgenics (third party) 1.232–1.667 1.429 8.72


Table 4

Immunoassay results for oral fluid samples collected in the Cozart collection

system stored at 5 8C

EIA kit THC concentration (ng/mL)

4 10 15 25

Cozart (n = 2) 0.11 0.13 0.21 0.25

Immunalysis (n = 2) 0.40 0.57 0.61 0.73

Difference in absorbance of buffer-diluted oral fluid (blank � THC-spiked).

Table 6

Immunoassay results for oral fluid samples stored at 5 8C

Collection system Methamphetamine

(50 ng/mL)

Morphine

(40 ng/mL)

Cozart (n = 4) 0.5 1.1

Immunalysis (n = 4) 0.5 1.3

Difference in absorbance of buffer-diluted oral fluid (blank� methamphetamine-

or morphine-spiked).

Table 7

GCMS concentrations (ng/mL) of methamphetamine in oral fluid after storage

for 10 days

Supplier Concentration (storage temperature)

50 ng/mL 125 ng/mL

RT 5 8C RT 5 8C

Cozart 42, 43 46, 45 125, 127 107, 110

Immunalysis 53, 54 47, 47 138, 138 146, 143

Microgenics 48, 48 49, 49 116a 117, 122

a Insufficient sample remaining.

Immunalysis) reagents. Summaries of EIA results for THC,

benzodiazepines and methamphetamine and morphine are

listed in Tables 4–6, respectively.

3.3. Quantitative results

Quantitative results for THC, benzodiazepines and mor-

phine storage studies for the three different collection and

transport kits are presented in Figs. 1–3, respectively, and

represent the mean of duplicate analyses.

Quantitative results for methamphetamine storage study are

presented in Table 7 for each of the duplicate analyses. No

results were obtained for days 0, 1 and 3 due to instrumental

problems. The results for day 10, coupled with the consistency

of the immunoassay results over the 10-day period, demon-

strated that methamphetamine was stable in all three product

kits used. Consequently it was considered unnecessary to repeat

storage studies for days 0–3.

Table 5

Immunoassay results for oral fluid samples stored at 5 8C

Collection System (EIA Kit) Benzodiazepine (4 ng/mL)

Clonazepam

Cozart (Cozart) (n = 4) �0

Immunalysis (Immunalysis) (n = 4) �0.1

Cozart (Diagnostix) (n = 4) 0.4

Difference in absorbance of buffer-diluted oral fluid (blank � benzodiazepine-spik

Fig. 1. Stability of THC in oral fluid; collected using different collection kits and stor

Czt: Cozart, Ima: Immunalysis, Mcg: Microgenics.

4. Discussion

4.1. Precision of sample collection

The replicate sampling weights of oral fluid (Table 3) are

perhaps more uniform than expected (CV < 10%) and indicate

that this is unlikely to produce major errors in drug quantitation.

Diazepam Oxazepam Triazolam

�0.1 �0 �0.1

�0.2 �0.1 �0.1

0.7 0.4 0.5

ed).

ed at room temperature. Similar results were obtained for samples stored at 5 8C.


Fig. 2. Stability of benzodiazepines in oral fluid; collected using different collection kits and stored at room temperature. Similar results were obtained for samples

stored at 5 8C except clonazepam showed no signs of significant decomposition.

Fig. 3. Stability of morphine in oral fluid; collected using different collection kits and stored at room temperature. Similar results were obtained for samples stored at 5 8C.

For the Cozart collection the nominal 1 mL specimen is diluted

with 2 mL of buffer/surfactant solution. In the extreme case

(1.453 g) the dilution would be approximately 1.453/3.4531

instead of the nominal 1/3. This would produce a maximum

overestimate of about 25% in drug concentration. Considera-

1 The specific gravity of saliva is about 1.01 [7].

tion would need to be given to this overestimation when

reporting drug levels against a specified cut-off value.

4.2. THC

Screening for THC was compromised for the Immunalysis

and Microgenics immunoassays by drug losses in the

collection and storage systems. The Microgenics THC


immunoassay gave the best discrimination between drug-free

and freshly prepared drug-spiked oral fluids. This is partly

because the samples were undiluted by transport tube

solutions. However, the drug losses through the collection

and storage process, as determined by quantitative analysis,

rendered the composite Microgenics system unsuitable for

THC oral fluid analysis.

Both the Cozart and Immunalysis immunoassays initially

appeared adequate for detecting THC at a cut-off concentration

of 4 ng/mL despite the very significant loss of THC with the

latter collection process. Closer examination however revealed

that the discrimination between drug-free and spiked oral

fluids was poor and almost certainly likely to be unsatisfactory

for a range of oral fluids. We therefore decided to test the

Cozart collection and transport tube with the Immunalysis EIA

plates.

The combination of Cozart collection with the Immunalysis

EIA gave very good discrimination between drug-free and 4 ng/

mL spiked oral fluids. Typically the drug-free oral fluid gave an

absorbance of approximately 1.6, whereas the 4 ng/mL sample

gave a reading of approximately 1.2. When screening real

specimens it is of course expected that cross-reacting

cannabinoids will enhance the sensitivity of the screening

assay.

The LCMSMS results for THC (Fig. 1) demonstrate that this

drug was recovered quantitatively from the Cozart solution but

the Immunalysis and Microgenics supplied collection devices

rapidly lost very substantial amounts of THC (>60%). Storage

temperatures do not appear to be a significant factor. It is worth

noting that Immunalysis have modified their transport tube to

address the loss of THC and Microgenics are considering

alternative collection devices. The recoveries using the Cozart

collector are comparable to those Crouch [8] obtained from the

Intercept1 device at �20 8C. The recoveries he achieved

however declined significantly at 4 8C.

Table 8

Advantages and (disadvantages) of collection systems and immunoassays

Attribute Supplier

Cozart

Sample collection Colour indication for volume adequacy

User friendly

Filtration device

Presentation Adequate instructions. Chain of custody form

Concentration (Diluted 1:2 in transport tube) Large volume

Automation of immunoassay (No)

Analyte stability Acceptable for all four groups

Sensitivity of immunoassay Excellent for methamphetamine

and morphine.

(THC and benzodiazepines poor)

Sensitivity with alternative

immunoassays

Excellent with Immunalysis THC

and Diagnostix benzodiazepines

4.3. Benzodiazepines

Neither the Immunalysis nor Cozart EIA screens performed

well for the detection of all the benzodiazepines at the

concentrations tested. They particularly lacked sensitivity to

clonazepam or triazolam. This is consistent with the cross-

reactivity data provided in the suppliers’ information sheets.

The Microgenics immunoassay displayed the best ‘‘across

the board’’ sensitivity to all four benzodiazepines with very

clear discrimination between drug-spiked and drug-free oral

fluid samples treated in the same way.

A decision was made to repeat the EIA screening using the

Cozart collection device and transport tubes with the

Diagnostix EIA plates. This followed the decision that the

Cozart collection system was our preferred choice because of

its superior performance for THC. The combination of Cozart

collection and Diagnostix EIA kits produced superior results

(Table 5) both in the discrimination of drug-free oral fluid

samples and drug-spiked samples, and in its sensitivity to all

four benzodiazepines. This is in line with cross reactivities

listed by the manufacturers of Diagnostix plates.

The choice of immunoassay screening system is of

particular importance for benzodiazepines because of the high

sensitivity required and the very low saliva/plasma ratio of

around 0.03 for many benzodiazepines [9]. Therefore, it is

anticipated that even when using the Diagnostix kits, some of

the low-dose benzodiazepines will not be detected in oral fluid.

LCMSMS quantitation of the drug-spiked oral fluid stored in

transport tubes demonstrated that both the Cozart and

Immunalysis collection systems gave excellent recoveries for

all four benzodiazepines (Fig. 2). Data is only presented for two

of the benzodiazepines (Fig. 2).

The Microgenics collection device gave excellent recoveries

for three of the benzodiazepines over the 10-day test period.

However, the concentrations of clonazepam stored in oral fluid

Immunalysis Microgenics

Colour indication for volume adequacy (No indication)

User friendly User friendly

No sample filtration device but this is

provided separately to laboratories

Filtered at time of collection

Excellent instructions and reasonable

packaging

(no chain of custody form)

(No instructions or chain

of custody form)

(Diluted 1:3 in transport tube)

Large volume

No dilution (small volume)

(No) Yes. Potential for barcoding

Acceptable for three groups

(THC unacceptable)

Acceptable for two groups

(THC very poor and

clonazepam unacceptable)

Excellent for methamphetamine,

morphine and THC

(benzodiazepines poor)

All excellent

Not tested (Not compatible)


at room temperature declined markedly. This may reflect the

recognised instability of clonazepam due to microbiological

agents [10]. Such factors may be controlled by the additives

used in the Cozart and Immunalysis kits. In retrospect there

may be merit in also monitoring the amino metabolites of nitro

containing benzodiazepines since it has been noted that the

amino metabolite levels can be higher than those of the parent

drug [11]. In the present study, however, it was considered that

the devices which minimised decomposition of the analyte after

collection would be the most appropriate.

4.4. Methamphetamine and morphine

All three immunoassays gave excellent discrimination

between oral fluid spiked at the selected cut-off values

(50 ng/mL for methamphetamines and 40 ng/mL for morphine)

and drug-free oral fluid. However, the two EIA assays were too

sensitive and gave poor discrimination between the cut-off and

higher analyte concentrations. It is probable that improved EIA

results for these two drugs would be achieved by lowering the

cut-off concentrations and/or reducing the sample volume

added to the plate.

The GCMS quantitative results for methamphetamine

(Table 7) and morphine (Fig. 3) demonstrated that all three

collection systems gave very acceptable results with no obvious

loss of analytes at the concentrations and storage temperatures

studied.

The results of the storage studies for morphine using the

Immunalysis device (Fig. 3) may suggest an initial problem

with release of the drug. However, such a conclusion should not

be reached at this stage because the variation could be due to

analytical uncertainty, given the small number of assays

performed.

4.5. Comparison of collection and immunoassay systems

The overall findings for the products from the three suppliers

are summarised in Table 8.

5. Conclusions

Substantial drug losses during collection and storage of

samples were shown to occur in drug-spiked oral fluid with

some commercially supplied collection systems. Of the three

systems tested, the Cozart collection system was the only one

acceptable for THC. Since this product also gave essentially

quantitative recoveries for the other analytes, it has been

selected for subsequent in-depth studies.

The precision of sample volume collected by all three

collection devices was acceptable but allowed for when

establishing the uncertainty of the method. It is probable that

greater variation in sample size would be found when oral fluid

samples of varying viscosity are collected from a variety of

subjects, rather than a sole supplier.

The immunoassays provided by all three suppliers

performed well for methamphetamine and morphine. For the

preferred Cozart collection system, however, the Cozart THC

and benzodiazepine EIA kits lacked adequate sensitivity.

The Cozart collection system with Diagnostix EIA plates for

benzodiazepines and Immunalysis plates for THC proved to be

the most sensitive and discriminating combination for these two

groups of analytes.

It is strongly recommended that researchers determine

recoveries before further drug studies in oral fluid are

conducted. Until such work has been performed there can be

no confidence that measured drug concentrations reliably

reflect the actual oral fluid levels. It is incumbent on regulatory

authorities to ensure that this factor is considered before setting

cut-off values or legislative thresholds for drugs in oral fluid.

Acknowledgements

The authors wish to acknowledge the assistance provided by

Richard Berezowski, Matthew Hosking and David Talbot. We

would also like to thank Bio-Mediq (Australia), Microgenics

(Australia) and Diagnostic Bioserve (NZ), who generously

donated the collection systems, EIA plates and CEDIA1

system for Cozart, Microgenics and Diagnostix, and Immu-

nalysis, respectively.

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the recovery of illicit drugs from oral fluid sampling devices

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