Jacob Bell
New Member
Ann Warner
I report how some adulterants affect results for drugs of
abuse in urine as measured by Roche AlA, Syva EMIT d.a.u.,
and Abbott TDx FPIA (fluorescence polarization immunoassay)
for the following drugs: amphetamines, barbiturates,
benzodiazepines, cannabinoids, cocaine, opiates, and phencyclidine
(PCP). Sodium chloride interfered negatively with
all of these drugs when assayed by EMIT and caused a slight
decrease in measured benzodiazepine concentration by FPIA.
Drug concentrations were also decreased by added H202
(EMIT: benzodiazepine), Joy#{1d7e4t}ergent (EMIT: cannabinoid,
benzodiazepines, PCP), NaHCO3 (EMIT: opiate; FPIA: PCP),
or NaHCIO4 (EMIT, AlA, FpIA: amphetamines, opiates, PCP;
EMIT, FPIA: cannabinoid; EMIT: benzodiazepines). False-positive
results were caused by H202 (FPIA: benzodiazepines)
and Joy (AlA, FPIA: benzodiazepine, cannabinoid; FRIA: barbiturate,
amphetamine). Sodium bicarbonate causes a suspiciously
high pH in the urine, NaHCIO4 an apparently low pH
(using pH paper).
A major issue in programs for testing urine for drugs of
abuse is the development of a collection process that will
ensure the integrity of the specimen. In no other type of
laboratory testing does the person being tested have both
the opportunity and the incentive to alter the collected
specimen. Because of the opposition to witnessed collection,
other approaches are needed to eliminate specimen switching
or adulteration.
Procedures for identifying or eliminating specimen tampering
at the collection site include requiring removal of all
outer bulky garments and purses, or use of an examining
gown; coloring of the water in the toilet; and collecting the
specimen directly into a cup containing a temperaturesensitive
material, after which the collection-site person
pours the specimen into the transport container.
Use of a collection device such as the Franidin Collector
(Franklin Diagnostics, Inc., 60 Franklin St., Morristown, NJ
07960) not only can assist in identifying specimens that may
not be the subject's urine (urine kept in a plastic bag taped
to the body will not achieve the normal temperature range
of 96.4-100.4 #{17b6}uFt),also makes it difficult for the subject to
add liquid adulterants, because it takes 1-2 mm for the
temperature to equilibrate. Further, the size of the container,
approximately 85 mL, precludes adding solid adulterants
and easily getting them into solution. At the time the
collection person pours the urine into the transport container,
adulteranta such as isopropanol or sodium hypochiorite
can be detected by smell, even if they have not already
interfered with the temperature reading. Use of solid adulterants
may be detected by the presence of residues in the
container. Pre-analytical checks of pH and relative density
will identify samples adulterated with sodium chloride,
sodium hypochlorite, and sodium bicarbonate.
However, given the desperation and cunning of many
drug users and the potential for improper collection and lack
of adulteration testing, I examined the effect of several
common chemicals on immunoassay methods in case they
escaped detection in pre-analytical examinations. Some of
these chemicals have been recommended for use as potential
adulterants (1).
Materials and Methods
Drug-free normal human urine collected at different
times but from a single individual was used for all testing.
To separate portions of the urine I added a single drug to
give a concentration that would yield a positive result at or
near the cutoff value for the assay, after diluting the sample
with the adulterant. Table 1 lists the drugs studied, their
approximate final concentrations, and the assay methods
used. I added 1 volume of liquid adulternts to 4 volumes of
drug-containing urine, using an automatic dilutor (Micromedic
Systems, Horsham, PA).
Cannabinoid specimens, so diluted, gave results that
indicated that the drug was being absorbed by the plastic
tubing as the drug-containing urine passed through the
dilutor. Some additional testing of an unadulterated specimen
containing the same cannabinoid metabolite, divided
into different types of storage containers, including glass
and several types of plastic, verified that drug concentrations
were decreased after contact with some of the plastics
used, but not with glass, and that ethanol could partly
reverse the process. Thus, for this study, all the dilutions
were done with glass pipets.
Liquid adulterants used were ethanol (950 milL), isopropanol,
ethylene glycol, sodium hypochlorite (52.5 mL/L, as Clorox#{174h})y,drogen peroxide (30 mL/L), and Joys detergent
(10-fold predilution). Solid adulterants used were sodium
chloride (250 g/L final concentration) and sodium bicarbonate
(200 g/L final concentration). Drug-free urine, 1 mL, was
added to samples adulterated with sodium chloride and
sodium bicarbonate, to equalize the drug concentrations in
all samples to be tested. An unadulterated sample was
prepared containing the same concentration of drug as the
adulterated samples. Results for all samples were then
compared with those for the unadulterated specimen.
The sodium hypochiorite caused vigorous fizzing the first
few minutes after addition; and sodium bicarbonate, at the
concentration tested, gave a saturated solution, with some
residue present. Otherwise, none of the adulterants caused
any changes in the appearance or turbidity of the urine.
I tested each set of specimens by RIA (Roche Diagnostics,
Nutley, NJ), the EMIT d.a.u. enzyme iinmunoassay (Syva
Co., Palo Alto, CA) in an Hitachi 705 (BMD, Indianapolis,
IN), and fluorescence polarization immunoassay (s'rsA) in
the TDx (Abbott Laboratories, N. Chicago, IL). I evaluated
the results of these assays to determine if the adulterated
specimens produced changes in counts per mm, absorbance,
or net polarization, respectively, when compared with unadulterated
specimens containing the same concentration of
drug. A second set of adulterated specimens, containing
either no drug or a drug other than the one being assayed,
was evaluated along with the samples containing the drug
of interest. Samples were tested in duplicate in the RIA and
singly in the EMIT and rn assays.
Results
Drug concentrations that fell within the linear portion of
the assay curves were used sothat the effects caused by the
adulterants could more readily be observed, because I was
mainly interested in relative results for adulterated specimens
as compared with unadulterated specimens containing
the same concentration of drug.
The results are summarized in Tables 2, 3, and 4. I
anticipated that solvents such as ethanol, isopropanol, and
ethylene glycol might affect viscosity and thus the accurate
pipetting of samples, but I observed no effects with these
solvents except in the case of the cannabinoid-containing
specimens, and this may have had more to do with an effect
on solubility or adherence of the drug to the containers used.
For unknown reasons, this effect was not observed with the
EMIT assay.
The effect of NaCl in the EMIT assays has been previously
reported (2-4). I also noted that the absorbance changes in
drug-free samples containing NaC1 were decreased compared with normal drug-free urine, adding evidence that the
effect of NaCI is on the EMIT assay reagents. Sodium chloride
did not affect RIA, and only a slight effect was noted with
one of the FPIA assays.
I expected that pH extremes would have a negative effect,
and strongly basic specimens (NaHCO& actually yielded
increased values for some of the RIA assays, with the same
effect for drug-free specimens, indicating that pH per se is
affecting assay reagents. Sodium bicarbonate depressed
apparent concentrations for one EMIT and one FPIA assay.
Handsoap reportedly is an effective adulterant for the
EMIT benzodiazepine, barbiturate, and cannabinoid assays
(4). Using the liquid detergent, Joy, I found these same three
assays were affected; however, barbiturates demonstrated
increased rather than decreased concentrations. The effect
of Joy on the EMIT assays was found in both drug-free and
drug-containing specimens. The most interesting effect of
Joy, however, is that it causesfalse-positive results for three
of the spIA and one of the RIA assays, along with increased
concentrations for drug-containing specimens for these
same assays.
The effect of NaHC1O4 on all three iinmunoassays for
several of the drugs, coupled with the fact that drug-free
specimens were not affected, suggests that NaHC1O4, a
strong oxidizing agent, may react with the drugs or antibody
and interfere with the antibody reaction. Harder to
explain are the effects on the n'i benzodiazepine and RIA
barbiturate assays, and the fact that the EMIT and FPIA
cannabinoid assays give decreased concentrations but the
RIA doesnot. The finding of benzodiazepine (by FPIA) in the
drug-free specimen is coupled with a slight decrease in
concentration of the drug-containing sample. These may be
off-setting effects, with actual drug reacting with Na}IClO4
to give a decreased value coupled to a positive effect on the
assay as a whole. The increased apparent concentrations observed for the barbiturate and cannabinoid RIA may be
due to pH, because these assays also gave increased results
in the presence of (basic) NaHCO3.
Hydrogen peroxide, on the other hand, is acidic, and may
be exerting a pH effect upon the rn benzodiazepine assay,
because increased apparent concentrations were observed in
both drug-containing and drug-free specimens. The diluentwell
solution was bright yellow in the presence of peroxide.
The RIA and FPIA for cannabinoids gave enhanced results
for the drug-containing specimens with no effect observed in
the drug-free samples.
Although the cannabinoid assay seems particularly sensitive
to adulterants, with at least one type of immunoassay
affected by every one of the adulterants tested, overall only
four of the 15 effects observed resulted in decreased concentrations,
and therefore successful adulteration with these
chemicals to achieve a negative result will be difficult. The
RIA was affected by six of the eight adulterants, all of the
effects being in a positive direction. The only false-positive
results was the Joy (RIA, rI'IA). If a specimen containing Joy
is confirmed by use of the Toxi-Lab TLC system (Marion
Scientific, St. Louis, MO), the extraction will be very messy
even when the three-extraction clean-up procedure is used.
A weak but definite positive, compared with the unadulterated
specimen, was observed for a drug-containing specimen.
Evidently adulteration is a two-edged sword, with the
possibility of producing a false negative outweighed, in
many cases, by the specter of false positives.
DIscussion
At least some of the advice being given to drug users on
how to adulterate urine samples successfully will not be
totally effective if immunoassay is used for screening-with
some notable exceptions.
The most effective of the adulterants I tested is sodium
chloride, which will be a concern only for laboratories that
use the EMIT technology. This and other studies indicate
that the minimum amount of sodium chloride that must be
added to produce a negative result varies with different
assays, but it is substantial. The effective amounts used in
this study would be difficult to store (e.g., under fingernails)
and require time and stirring for solution to be complete.
Others have reported that amounts from 50 to 75 gIL are
effective in producing false negatives, depending upon the
assay and drug concentration used (3-5). I found that 50 g/L
was insufficient to affect the EMIT cannabinoid assay. Sufficient
sodium chloride to produce falsely negative results will
result in a residue (which can be noted by the collection-site
person), a high relative-density reading, and a delta absorbance
value less than the negative calibrator.
Other adulterants that might be problematic include
NaHC1O4, which should be readily recognized by its smell
(even one adulterated sample in a group is easily detected)
and its reaction with pH paper. Although NaHC1O4 is basic
and a urine treated with it will give a pH reading of -'-10
with a pH meter, if pH paper is used, a bright-red (but
rapidly fading) color indicative of an acid pH of --1 is
produced.
Other false negatives of concern are those caused by
dilute Joy and NaHCO3. Sodium bicarbonate in the concentration
tested will not go completely into solution and will
result in a pH of 8-9, which should be considered abnormal
by the laboratory and should result in a request for a fresh
sample. Joy did not cause any changes in appearance, pH, or
relative density, but can be detected by vigorously shaking a
small amount of the urine. More copious, longer-lasting
bubbles are formed compared with normal urine, and when
held to the light they refract it to give the typical rainbow
appearance of soap bubbles.
A major drawback, for the subject, to the use of Joy or
NaHCO3 is the fact that these compounds also cause falsepositive
results in several assays, hardly the result desired
by the subject adding adulterants to ensure a negative result.
Of the two assays currently of most interest, cocaine and
cannabinoids, the cocaine assay was found to be a robust
one, with only NaC1 producing a decreased result with the
EMIT assay. The cannabinoid assay appears to be very
sensitive to adulterants, yielding both decreased and increased
results, depending upon the adulterant and immunoassay
method used; however, most of these effects were in
the positive rather than the negative direction.
These results indicate that specimen adulteration is complicated
for the subject by the fact that some adulterants
shown to cause falsely lowered results can be readily
detected by either trained collection-site personnel or by
simple laboratory procedures such as temperature, pH,
relative density, residue checks, and shake and sniff tests. In
addition, the undesired result of an enhanced or false
positive, produced by a number of potential adulterants,
makes their use less attractive as a mechanism for producing
a false-negative result. The laboratory needs to assess,
based upon the methods used for screening, what preanalytical
tests for detection of adulterants are necessary.
This study was designed to serve as a starting point in
making such decisions.
I gratefully acknowledge the gift of reagents by Roche Diagnostic
Systems, and thank Dainien Brandeis, George Wadih, Tom Mertens,
and Lori Hindenlang for their technical assistance.
References
1. Hoffman A. Steal this urine test. New York: Viking Penguin
Books, 1987;240-2.
2. Andersen 0, Eriksen PB. Specific conductivity of urine and
sensitivity of enzyme immunoassay methods of analysis for drugsof
abuse.Cliii Chem 1977:23;751-3.
3. Kim HJ, Cerceo E. Interference byNaCI with the EMIT method of
analysis for drugs of abuse. Clin Chem 197622;1935-6.
4. Mikkelsen SL, Ash KO. Adulterants causing false negatives in
illicit drug testing. Clin Chem 1988:342333-6.
5. Warner A. Opiates: use, abuseand current methods of detection
and measurement. In-service training and continuing education.
Washington, DC: Am Assoc Clin Chem, Inc., 1988.
Source: Interference of common household chemicals in immunoassay methods for drugs of abuse
I report how some adulterants affect results for drugs of
abuse in urine as measured by Roche AlA, Syva EMIT d.a.u.,
and Abbott TDx FPIA (fluorescence polarization immunoassay)
for the following drugs: amphetamines, barbiturates,
benzodiazepines, cannabinoids, cocaine, opiates, and phencyclidine
(PCP). Sodium chloride interfered negatively with
all of these drugs when assayed by EMIT and caused a slight
decrease in measured benzodiazepine concentration by FPIA.
Drug concentrations were also decreased by added H202
(EMIT: benzodiazepine), Joy#{1d7e4t}ergent (EMIT: cannabinoid,
benzodiazepines, PCP), NaHCO3 (EMIT: opiate; FPIA: PCP),
or NaHCIO4 (EMIT, AlA, FpIA: amphetamines, opiates, PCP;
EMIT, FPIA: cannabinoid; EMIT: benzodiazepines). False-positive
results were caused by H202 (FPIA: benzodiazepines)
and Joy (AlA, FPIA: benzodiazepine, cannabinoid; FRIA: barbiturate,
amphetamine). Sodium bicarbonate causes a suspiciously
high pH in the urine, NaHCIO4 an apparently low pH
(using pH paper).
A major issue in programs for testing urine for drugs of
abuse is the development of a collection process that will
ensure the integrity of the specimen. In no other type of
laboratory testing does the person being tested have both
the opportunity and the incentive to alter the collected
specimen. Because of the opposition to witnessed collection,
other approaches are needed to eliminate specimen switching
or adulteration.
Procedures for identifying or eliminating specimen tampering
at the collection site include requiring removal of all
outer bulky garments and purses, or use of an examining
gown; coloring of the water in the toilet; and collecting the
specimen directly into a cup containing a temperaturesensitive
material, after which the collection-site person
pours the specimen into the transport container.
Use of a collection device such as the Franidin Collector
(Franklin Diagnostics, Inc., 60 Franklin St., Morristown, NJ
07960) not only can assist in identifying specimens that may
not be the subject's urine (urine kept in a plastic bag taped
to the body will not achieve the normal temperature range
of 96.4-100.4 #{17b6}uFt),also makes it difficult for the subject to
add liquid adulterants, because it takes 1-2 mm for the
temperature to equilibrate. Further, the size of the container,
approximately 85 mL, precludes adding solid adulterants
and easily getting them into solution. At the time the
collection person pours the urine into the transport container,
adulteranta such as isopropanol or sodium hypochiorite
can be detected by smell, even if they have not already
interfered with the temperature reading. Use of solid adulterants
may be detected by the presence of residues in the
container. Pre-analytical checks of pH and relative density
will identify samples adulterated with sodium chloride,
sodium hypochlorite, and sodium bicarbonate.
However, given the desperation and cunning of many
drug users and the potential for improper collection and lack
of adulteration testing, I examined the effect of several
common chemicals on immunoassay methods in case they
escaped detection in pre-analytical examinations. Some of
these chemicals have been recommended for use as potential
adulterants (1).
Materials and Methods
Drug-free normal human urine collected at different
times but from a single individual was used for all testing.
To separate portions of the urine I added a single drug to
give a concentration that would yield a positive result at or
near the cutoff value for the assay, after diluting the sample
with the adulterant. Table 1 lists the drugs studied, their
approximate final concentrations, and the assay methods
used. I added 1 volume of liquid adulternts to 4 volumes of
drug-containing urine, using an automatic dilutor (Micromedic
Systems, Horsham, PA).
Cannabinoid specimens, so diluted, gave results that
indicated that the drug was being absorbed by the plastic
tubing as the drug-containing urine passed through the
dilutor. Some additional testing of an unadulterated specimen
containing the same cannabinoid metabolite, divided
into different types of storage containers, including glass
and several types of plastic, verified that drug concentrations
were decreased after contact with some of the plastics
used, but not with glass, and that ethanol could partly
reverse the process. Thus, for this study, all the dilutions
were done with glass pipets.
Liquid adulterants used were ethanol (950 milL), isopropanol,
ethylene glycol, sodium hypochlorite (52.5 mL/L, as Clorox#{174h})y,drogen peroxide (30 mL/L), and Joys detergent
(10-fold predilution). Solid adulterants used were sodium
chloride (250 g/L final concentration) and sodium bicarbonate
(200 g/L final concentration). Drug-free urine, 1 mL, was
added to samples adulterated with sodium chloride and
sodium bicarbonate, to equalize the drug concentrations in
all samples to be tested. An unadulterated sample was
prepared containing the same concentration of drug as the
adulterated samples. Results for all samples were then
compared with those for the unadulterated specimen.
The sodium hypochiorite caused vigorous fizzing the first
few minutes after addition; and sodium bicarbonate, at the
concentration tested, gave a saturated solution, with some
residue present. Otherwise, none of the adulterants caused
any changes in the appearance or turbidity of the urine.
I tested each set of specimens by RIA (Roche Diagnostics,
Nutley, NJ), the EMIT d.a.u. enzyme iinmunoassay (Syva
Co., Palo Alto, CA) in an Hitachi 705 (BMD, Indianapolis,
IN), and fluorescence polarization immunoassay (s'rsA) in
the TDx (Abbott Laboratories, N. Chicago, IL). I evaluated
the results of these assays to determine if the adulterated
specimens produced changes in counts per mm, absorbance,
or net polarization, respectively, when compared with unadulterated
specimens containing the same concentration of
drug. A second set of adulterated specimens, containing
either no drug or a drug other than the one being assayed,
was evaluated along with the samples containing the drug
of interest. Samples were tested in duplicate in the RIA and
singly in the EMIT and rn assays.
Results
Drug concentrations that fell within the linear portion of
the assay curves were used sothat the effects caused by the
adulterants could more readily be observed, because I was
mainly interested in relative results for adulterated specimens
as compared with unadulterated specimens containing
the same concentration of drug.
The results are summarized in Tables 2, 3, and 4. I
anticipated that solvents such as ethanol, isopropanol, and
ethylene glycol might affect viscosity and thus the accurate
pipetting of samples, but I observed no effects with these
solvents except in the case of the cannabinoid-containing
specimens, and this may have had more to do with an effect
on solubility or adherence of the drug to the containers used.
For unknown reasons, this effect was not observed with the
EMIT assay.
The effect of NaCl in the EMIT assays has been previously
reported (2-4). I also noted that the absorbance changes in
drug-free samples containing NaC1 were decreased compared with normal drug-free urine, adding evidence that the
effect of NaCI is on the EMIT assay reagents. Sodium chloride
did not affect RIA, and only a slight effect was noted with
one of the FPIA assays.
I expected that pH extremes would have a negative effect,
and strongly basic specimens (NaHCO& actually yielded
increased values for some of the RIA assays, with the same
effect for drug-free specimens, indicating that pH per se is
affecting assay reagents. Sodium bicarbonate depressed
apparent concentrations for one EMIT and one FPIA assay.
Handsoap reportedly is an effective adulterant for the
EMIT benzodiazepine, barbiturate, and cannabinoid assays
(4). Using the liquid detergent, Joy, I found these same three
assays were affected; however, barbiturates demonstrated
increased rather than decreased concentrations. The effect
of Joy on the EMIT assays was found in both drug-free and
drug-containing specimens. The most interesting effect of
Joy, however, is that it causesfalse-positive results for three
of the spIA and one of the RIA assays, along with increased
concentrations for drug-containing specimens for these
same assays.
The effect of NaHC1O4 on all three iinmunoassays for
several of the drugs, coupled with the fact that drug-free
specimens were not affected, suggests that NaHC1O4, a
strong oxidizing agent, may react with the drugs or antibody
and interfere with the antibody reaction. Harder to
explain are the effects on the n'i benzodiazepine and RIA
barbiturate assays, and the fact that the EMIT and FPIA
cannabinoid assays give decreased concentrations but the
RIA doesnot. The finding of benzodiazepine (by FPIA) in the
drug-free specimen is coupled with a slight decrease in
concentration of the drug-containing sample. These may be
off-setting effects, with actual drug reacting with Na}IClO4
to give a decreased value coupled to a positive effect on the
assay as a whole. The increased apparent concentrations observed for the barbiturate and cannabinoid RIA may be
due to pH, because these assays also gave increased results
in the presence of (basic) NaHCO3.
Hydrogen peroxide, on the other hand, is acidic, and may
be exerting a pH effect upon the rn benzodiazepine assay,
because increased apparent concentrations were observed in
both drug-containing and drug-free specimens. The diluentwell
solution was bright yellow in the presence of peroxide.
The RIA and FPIA for cannabinoids gave enhanced results
for the drug-containing specimens with no effect observed in
the drug-free samples.
Although the cannabinoid assay seems particularly sensitive
to adulterants, with at least one type of immunoassay
affected by every one of the adulterants tested, overall only
four of the 15 effects observed resulted in decreased concentrations,
and therefore successful adulteration with these
chemicals to achieve a negative result will be difficult. The
RIA was affected by six of the eight adulterants, all of the
effects being in a positive direction. The only false-positive
results was the Joy (RIA, rI'IA). If a specimen containing Joy
is confirmed by use of the Toxi-Lab TLC system (Marion
Scientific, St. Louis, MO), the extraction will be very messy
even when the three-extraction clean-up procedure is used.
A weak but definite positive, compared with the unadulterated
specimen, was observed for a drug-containing specimen.
Evidently adulteration is a two-edged sword, with the
possibility of producing a false negative outweighed, in
many cases, by the specter of false positives.
DIscussion
At least some of the advice being given to drug users on
how to adulterate urine samples successfully will not be
totally effective if immunoassay is used for screening-with
some notable exceptions.
The most effective of the adulterants I tested is sodium
chloride, which will be a concern only for laboratories that
use the EMIT technology. This and other studies indicate
that the minimum amount of sodium chloride that must be
added to produce a negative result varies with different
assays, but it is substantial. The effective amounts used in
this study would be difficult to store (e.g., under fingernails)
and require time and stirring for solution to be complete.
Others have reported that amounts from 50 to 75 gIL are
effective in producing false negatives, depending upon the
assay and drug concentration used (3-5). I found that 50 g/L
was insufficient to affect the EMIT cannabinoid assay. Sufficient
sodium chloride to produce falsely negative results will
result in a residue (which can be noted by the collection-site
person), a high relative-density reading, and a delta absorbance
value less than the negative calibrator.
Other adulterants that might be problematic include
NaHC1O4, which should be readily recognized by its smell
(even one adulterated sample in a group is easily detected)
and its reaction with pH paper. Although NaHC1O4 is basic
and a urine treated with it will give a pH reading of -'-10
with a pH meter, if pH paper is used, a bright-red (but
rapidly fading) color indicative of an acid pH of --1 is
produced.
Other false negatives of concern are those caused by
dilute Joy and NaHCO3. Sodium bicarbonate in the concentration
tested will not go completely into solution and will
result in a pH of 8-9, which should be considered abnormal
by the laboratory and should result in a request for a fresh
sample. Joy did not cause any changes in appearance, pH, or
relative density, but can be detected by vigorously shaking a
small amount of the urine. More copious, longer-lasting
bubbles are formed compared with normal urine, and when
held to the light they refract it to give the typical rainbow
appearance of soap bubbles.
A major drawback, for the subject, to the use of Joy or
NaHCO3 is the fact that these compounds also cause falsepositive
results in several assays, hardly the result desired
by the subject adding adulterants to ensure a negative result.
Of the two assays currently of most interest, cocaine and
cannabinoids, the cocaine assay was found to be a robust
one, with only NaC1 producing a decreased result with the
EMIT assay. The cannabinoid assay appears to be very
sensitive to adulterants, yielding both decreased and increased
results, depending upon the adulterant and immunoassay
method used; however, most of these effects were in
the positive rather than the negative direction.
These results indicate that specimen adulteration is complicated
for the subject by the fact that some adulterants
shown to cause falsely lowered results can be readily
detected by either trained collection-site personnel or by
simple laboratory procedures such as temperature, pH,
relative density, residue checks, and shake and sniff tests. In
addition, the undesired result of an enhanced or false
positive, produced by a number of potential adulterants,
makes their use less attractive as a mechanism for producing
a false-negative result. The laboratory needs to assess,
based upon the methods used for screening, what preanalytical
tests for detection of adulterants are necessary.
This study was designed to serve as a starting point in
making such decisions.
I gratefully acknowledge the gift of reagents by Roche Diagnostic
Systems, and thank Dainien Brandeis, George Wadih, Tom Mertens,
and Lori Hindenlang for their technical assistance.
References
1. Hoffman A. Steal this urine test. New York: Viking Penguin
Books, 1987;240-2.
2. Andersen 0, Eriksen PB. Specific conductivity of urine and
sensitivity of enzyme immunoassay methods of analysis for drugsof
abuse.Cliii Chem 1977:23;751-3.
3. Kim HJ, Cerceo E. Interference byNaCI with the EMIT method of
analysis for drugs of abuse. Clin Chem 197622;1935-6.
4. Mikkelsen SL, Ash KO. Adulterants causing false negatives in
illicit drug testing. Clin Chem 1988:342333-6.
5. Warner A. Opiates: use, abuseand current methods of detection
and measurement. In-service training and continuing education.
Washington, DC: Am Assoc Clin Chem, Inc., 1988.
Source: Interference of common household chemicals in immunoassay methods for drugs of abuse
