Urine drug-testing tampering approaches: Turkish probationers

Abstract

The growing numbers of individual and social problems associated with drug abuse necessitate new approaches in drug-testing systems. Equally, drug abusers may attempt to invalidate drug testing using different methods such as adulteration, dilution and substitution. This study aims to investigate tampering methods commonly used by Turkish substance-using probationers and evaluate their effects on toxicological drug-testing results. Initially, probationer urinary screening test results and laboratory substitution documents were evaluated to investigate the dilution and substitution attempt. Additionally, an experimental study was carried out by using readily available household products (bleach, vinegar, drain opener, eye drops) for adulteration. The effect of these agents was investigated for 11‐nor‐9‐carboxy-Δ9‐tetrahydrocannabinol (THC–COOH), amphetamine and 3,4-methylenedioxymethamphetamine (MDMA). It was determined that probationers preferred unbranded products (syringes, nylon bottles, etc.) for urine substitution. To detect dilution, screening test results were evaluated along with creatinine values. The variability of mean creatinine values can change the rate of the before-negative and after-positive ratio. For adulteration method, the high amounts of bleach provided false-negative results for THC–COOH and amphetamine, but spiking in any concentration of bleach affected MDMA results, causing a slight increase. Vinegar did not affect the THC–COOH and amphetamine results. However, false-negative results were observed for MDMA, with high amounts of vinegar-spiked urine samples. Drain opener was added in large quantities, and false-negative results were observed for all analytes. Visine eye drops did not have any effect on THC–COOH or amphetamine, but a high quantity of eye drops had a slight decreasing effect for MDMA.

Keywords

Urine screening adulteration probation drug abuse

Introduction

Probation allows a person to serve a sentence while still being active in their daily life for a certain period set by law.¹ In Turkey, the current probation system was launched in 2005, and the last legislative revisions were published in 2013, enabling probation orders for drug abusers.² Since then, the drug-monitoring system has been the most critical part of probation, particularly to monitor those who have been charged with drug abuse. However, the system itself is not without problems, and there are issues to resolve, such as the uncertainty of content parameters, definition of specific cut-off values, application of urine integrity tests and methods of analysis.

Urine is considered to be the most suitable and preferred specimen for drug testing for probationers, since it allows a wide detection window and provides high concentration for most drugs and/or drug metabolites. It is also a relatively uncomplicated matrix, and the absence of free serum proteins, lipids and other large molecular weight biological compounds makes the toxicological analysis simpler.^3,4 Furthermore, urine collection is non-invasive and straightforward. However, the problem of tampering still persists and is most likely to cause false-negative results. So, probationers abusing prohibited drugs may be motivated to tamper with their urine specimens. Three major urine tampering methods are as follows:⁵

Substitution is the process of replacing a drug-positive specimen with a drug-negative one during the collection of urine.⁶ Probationers mostly prefer non-urine liquids, such as water or commercially available synthetic urine that possesses the same essential characteristics of human urine (i.e. the correct pH, specific gravity and creatinine concentration).⁷

Dilution involves the deliberate consumption of excess volumes of water or other fluids to dilute the urine, or the intentional ingestion of products such as diuretics and herbal teas. This method relies on increasing the metabolism, with excretion of drugs from the body such that results are below the relevant cut-off values.⁷

Adulteration is the method of spiking agents or chemicals into the urine sample, or taking some chemicals orally to obtain false-negative results. This method is applicable to products marketed explicitly for ‘passing urine drug tests’, and with others that are conventional household products, such as bleach, vinegar or eye drops.^5,7

It is essential to be aware of tampering methods to prevent the false-negative results of substance-using probationers. Hence, this study aimed to investigate tampering methods applied by Turkish probationers and to evaluate their effects on the testing results. First, laboratory substitution documents and urinary screening test results were evaluated for dilution and substitution. Then, different household products were tested for adulteration in an experimental study.

Methods

Investigation of three different tampering practices –adulteration, substitution and dilution – were performed on probationers (N = 13,808) admitted to Ege University, Institute on Drug Abuse, Toxicology and Pharmaceutical Science, Addiction Toxicology Laboratory, between 2015 and 2017 due to drug abuse. First, laboratory documents and urinary screening test results were evaluated for dilution and substitution. Second, an experimental study was designed to examine adulteration. The ethical approval and all experimental protocols were provided by the Clinical Research Ethics Committee of Faculty of Medicine, Ege University (Decision Number 13-7/1, 19 September 2013).

Materials

For the experimental study, different household products were purchased from a local store. These products were: bleach (Domestos brand containing 5.25% sodium hypochlorite per weight, packaged by Unilever, Kocaeli, Turkey), apple vinegar (containing 4–5% acetic acid, Tariş brand, Manisa, Turkey), Visine eye drops (Flarex-Alcon containing 0.1 mg benzalkonium chloride, Istanbul, Turkey) and drain opener (Pro-5 brand containing 90 ± 2% NaOH, 10 ± 2% Na₂CO₃, Antalya, Turkey). For the urine validity test, Intect 7 adulteration test strip (Branan Medical Corp., Irvine, CA) was used. These strips are fixed with seven reagent pads, which are chemically treated with specific reagents to be used in semi-quantitative tests for creatinine, nitrite, glutaraldehyde, pH, specific gravity, bleach and pyridinium chlorochromate (PCC). Following this, two different branded dip cards were used (dipcard 1: QuickTox Drug Screen, Branan Medical Corp.; dip card 2: Euphratest, Shanghai Chemtron Biotech Co. Ltd., Shanghai, PR China) for the drug detection. Immunoassay analyses were also performed using a MGC 240 benchtop analyser from Thermo Fisher Scientific (Waltham, MA). Cannabinoid (THC), amphetamine/ecstasy, sample check (CEDIA), ecstasy and creatinine (DRI) assays were measured using the enzymatic immunoassay method with the original reagents following the test instructions (Thermo Fisher Scientific).

Methods

Urine specimen collection and drug-testing procedure

Urine specimens were collected at the Ege University, Addiction Toxicology Laboratory. Before the sampling procedure, probationers’ identification was verified, and the basic sample collection procedure was explained. Probationers were asked to remove any unnecessary outer clothing and leave other personal belongings (e.g. briefcase, purse or wallet). Then, a single-use plastic urine specimen bottle was provided to him/her.⁸ After signing the consent form, the probationers provided the urine sample under supervision.

At least 30 mL urine was obtained per participant to initiate toxicological analysis.⁹ At this point, sample-collection personnel were responsible for urine temperature control and visual examinations. Meanwhile, if the collection personnel noticed any suspicious activities or behaviours (i.e. participants who were anxious, tense, shy or unwilling to participate), an official report was documented.

Following the transfer of urine specimens to the laboratory, drug-testing analysis began with the urine integrity test. The creatinine, specific gravity and pH values were used to determine the dilution of the urine specimen. Then, screening analysis was performed using the standard immunoassay protocols for each urine specimen. All results were evaluated together, interpreted and reported.

Substitution

Urine substitution is the method of replacing the abusers’ samples with a clean urine specimen, and it is possible to apply via products that are commercially sold, particularly for this purpose (Whizzinator, Urinator, etc.).⁵ A clean substance-free urine specimen from any healthy volunteer usually passes urine integrity tests (i.e. pH, creatinine and density). However, there are two major challenges in these cases: maintaining the specimen temperature and avoiding detection. In this study, official substitution reports of 13,808 drug-using probationers were checked to investigate cases of substitution attempts.

Dilution

The criteria for urine specimens analysed as ‘dilute samples’ for drug-testing guidelines are: specific gravity 1.005–1.020, pH 4.5–8 and creatinine concentration 5.0–20.0 mg/dL.¹⁰ Drug concentrations of dilute samples were normalised to the laboratory mean urinary creatinine (CR) concentration. Creatinine normalisation was based on the following equation¹¹:

\begin{array}{l} {Concentration}_{CR normalised} \\ = {Concentration}_{specimen} × (\frac{{CR}_{reference}}{{CR}_{specimen}}) \end{array}

A total of 13,808 drug-using probationers’ drug-testing results were evaluated before and after the normalisation procedure.

Adulteration

For the adulteration analysis, a drug concentration fixed urine pool was created with using selected drug-positive (from probationers) and drug-negative (from laboratory staff) urine specimens.

The adulterated urine pool was prepared as follows:

Selection of drug-positive urine samples: Probationers’ urine samples, which were positive for cannabis (11‐nor‐9‐carboxy‐Δ9‐tetrahydrocannnabinol (THC–COOH)), amphetamine (AMP) and 3,4-methylenedioxy-methamphetamine (MDMA) were selected (n = 5). Furthermore, based on the statements of participants, samples were collected from people who do not take any medication or use any other chemical substances, along with those from people who did not have any metabolic disease or who had not consumed herbal tea within the last 72 hours prior to sample collection.

Collection of drug-negative urine samples: Drug-free urine samples were collected from the laboratory staff (n = 3) and used for urine pool drug concentration adjustment.

Preparation of drug concentration fixed urine pool: Selected drug-positive and drug-negative urine samples were mixed, and urine pool concentration was adjusted above the legal limits (cut-off values in Turkey = 50 ng/mL for cannabis and 500 ng/mL for amphetamine-type stimulants).¹²

Adulteration: A 5 mL urine sample was taken from the prepared drug concentration fixed urine pool. The compounds shown in Table 1 were chosen for adulteration due to their ease of availability or because they have been reported in previous studies.^5,13 After spiking these compounds, samples were shaken gently for a minute. The prepared urine pool as a blank sample and 13 adulterated urine samples were examined for physical characteristics, appearance and the possibility of odour, and the results were recorded by two laboratory staff. Next, urine integrity tests were performed. The pH of the urine samples was measured using a pH meter (Orion™ Star A211; Thermo Fisher Scientific). Two different trademark dip cards were used, and all urine samples were analysed by using auto immunoassay kits for cannabis, amphetamine and MDMA detection. All experiments were performed in duplicate.

Table 1.

Active ingredients and adulterated amounts of household products.

Product	Active ingredient	Adulterated amounts	Adulterated sample number
Bleach	Sodium hypochlorite	0.1% (v/v)	1
		1% (v/v)	2
		10% (v/v)	3
Vinegar	Acetic acid	1% (v/v)	4
		2% (v/v)	5
		10% (v/v)	6
		20% (v/v)	7
Drain opener	Sodium hydroxide Sodium carbonate	0.2% (w/v)	8
		2% (w/v)	9
		20% (w/v)	10
Eye drops	Benzalkonium chloride	1% (v/v)	11
		2% (v/v)	12
		30% (v/v)	13

Results

Substitution results

Analyses of sample collection reports for 2015, 2016 and 2017 showed that there are 10 cases in 2015, eight in 2016 and nine in 2017 that were observed to have applied substitution. Substitution was done mostly by using syringes, nylon bottles and plastic cologne bottles, which were carrying ‘clean’ urine samples. A ‘clean’ urine specimen was placed in a bottle in the abdominal area, and a normal urine flow was attempted with the pump under the armpit, but urine sample collection personnel detected the suspicious movements.

Dilution results

Creatinine measurements were applied to detect the ‘diluted’ urine samples, and a creatinine normalisation procedure was also performed. ‘Dilute samples’ were normalised according to the mean creatinine level 150 mg/dL (CR_reference value). The mean creatinine level was calculated for all cases that were admitted for drug testing in our laboratory between 2015 and 2017. Screening test results for cases that were negative before normalisation yet positive after are shown in Table 2. After creatinine normalisation, all ‘diluted samples’ were analysed using the gas chromatography–mass spectrometry in-house method for confirmation, and all ‘diluted samples’ were reported as positive for illegal substance use.

Table 2.

Before-negative and after-positive normalisation screening test results of probationers’ frequency.

	Before-negative normalisation (N)	After-positive normalisation (N)
Cannabis	112	106
MDMA	21	21
AMP	11	9
Opiate	6	5
Benzodiazepine	3	1
Cocaine	1	0
Synthetic cannabinoids (JWH-018, JWH-073, AM-2201)	4	4
Synthetic cannabinoids (UR-114)	1	1

Experimental adulteration results

Readily available household products were investigated as adulteration agents for cannabis, amphetamine and MDMA, which are the most commonly abused substances in Turkey.¹⁴

Physical characteristics

The prepared urine pool (as a blank sample) had a normal appearance, smell and colour. After adding different household agents, it was easy to observe the physical change. Urine samples spiked with 10% (v/v) bleach were dark yellow, with an odour of strong bleach and a frothy appearance. Samples spiked with 0.1% and 1% (v/v) bleach looked and smelled like a typical urine sample. Samples spiked with 20% (v/v) vinegar had a mild vinegar scent, but other vinegar-spiked concentrations smelled normal. All samples that had drain opener added had a cloudy visual appearance, with suspension, and were undissolved. Finally, samples spiked with 30% (v/v) eye drops also had a cloudy visual appearance, but no physical change was observed for the other concentrations.

Adulteration test strip and pH meter analysis results

Adulteration test strips and pH meter results for the prepared urine pool (as a blank sample) and experimentally adulterated 13 urine samples are given in Table 3. Adulteration test strip results were evaluated according to the product instructions/limits.

Table 3.

Adulteration test strip and pH meter analysis results.

Adulterated sample ID	Sample name	pH meter results	Adulteration test strip results
Adulterated sample ID	Sample name	pH meter results	pH	Specific gravity	Bleach	Glutaraldehyde	PCC	Creatinine	Nitrite
	Urine Pool (Blank sample)	6.23	Normal (4–10)	1.005	Normal	Normal	Normal	Normal	Normal
1	0,1% (v/v) Bleach	6.25	Normal (4–10)	1.005	Normal	Normal	Normal	Normal	Normal
2	1% (v/v) Bleach	6.35	Normal (4–10)	1.005	Normal	Normal	Normal	Normal	Normal
3	10% (v/v) Bleach	7.00	Normal (4–10)	1.003	Abnormal	Normal	Abnormal	Normal	Normal
4	1% (v/v) Vinegar	5.95	Normal (4–10)	>1.020	Normal	Normal	Normal	Normal	Normal
5	2% (v/v) Vinegar	5.50	Normal (4–10)	>1.020	Normal	Normal	Normal	Normal	Normal
6	10% (v/v) Vinegar	4.37	Abnormal (2–3)	>1.020	Normal	Normal	Normal	Normal	Normal
7	20% (v/v) Vinegar	4.00	Abnormal (2–3)	>1.020	Normal	Normal	Normal	Normal	Normal
8	0,2% (w/v) Drain opener	10.12	Normal (4–10)	1.000	Normal	Normal	Normal	Normal	Normal
9	2% (w/v) Drain opener	12.79	Normal (4–10)	1.000	Normal	Normal	Normal	Normal	Normal
10	20% (w/v) Drain opener	12.82	Normal (4–10)	1.000	Normal	Abnormal	Normal	Normal	Normal
11	1% (v/v) Eye drop	6.40	Normal (4–10)	1.005	Normal	Normal	Normal	Normal	Normal
12	2% (v/v) Eye drop	6.34	Normal (4–10)	1.005	Normal	Normal	Normal	Normal	Normal
13	30% (v/v) Eye drop	6.25	Normal (4–10)	1.005	Normal	Normal	Normal	Normal	Normal

Dip-card results

The prepared urine pool (as a blank sample) was cannabis, amphetamine and MDMA positive (above the legal limits). In dip-card tests with two different brands, amphetamine and MDMA results were negative for the prepared urine pool. Results of cannabis testing are provided in Table 4. When two different trademark dip cards were compared, a difference of 15.4% was observed.

Table 4.

Results of two different trademark dip cards used for cannabis test.

Adulterated sample number	Cannabis	Dip card1	Dip card2
	Urine pool (blank sample)	Positive	Positive
1	0.1% (v/v) bleach	Positive	Positive
2	1% (v/v) bleach	Positive	Positive
3	10% (v/v) bleach	False-negative	False-negative
4	1% (v/v) vinegar	Positive	Positive
5	2% (v/v) vinegar	False-negative	Positive
6	10% (v/v) vinegar	False-negative	False-negative
7	20% (v/v) vinegar	False-negative	False-negative
8	0.2% (w/v) drain opener	Positive	Positive
9	2% (w/v) drain opener	Error	Error
10	20% (w/v) drain opener	Error	Error
11	1% (v/v) eye drops	False-negative	Positive
12	2% (v/v) eye drops	Positive	Positive
13	30% (v/v) eye drops	Positive	Positive

Error: no control line was performed.

Immunoassay results

Immunoassay analysis results are given in Figures 1 –4 for the urine drug concentration fixed urine pool and 13 adulterated urine samples. Urine sample creatinine results were found to be within the normal range (20–300 mg/dL) for all samples.

Figure 1.

Mean and standard deviations of adulterated urine samples immunoassay analysis for cannabis.*The urine pool adjusted level.

Figure 2.

Mean and standard deviations of adulterated urine samples immunoassay analysis for amphetamine. *The urine pool adjusted level.

Figure 3.

Mean and standard deviations of adulterated urine samples immunoassay analysis for MDMA. *The urine pool adjusted level.Note: 2% and 20% (w/v) drain opener added urine samples 0 ng/ml for MDMA and points are outside the axis limits.

Figure 4.

Mean and standard deviations of adulterated urine samples immunoassay analysis for sample check. *The urine pool adjusted level.Note: 10% (v/v) bleach added urine sample urine samples 0 for sample check and points are outside the axis limits. Error means device did not analyze sample.

Discussion

Three different tampering methods – substitution, dilution and adulteration – were investigated in this study. To our knowledge, apart from systematic review articles, this is the first time that three tampering approaches have been studied in a single study.^5,6

Regarding substitution, many different products/tools can be purchased for this purpose on the Internet. We observed in our reports that unbranded products, particularly those prepared by probationers, were more frequently preferred. It was also emphasised in the studies and guidelines that it is important to follow precautions and to have up-to-date knowledge of recent trends.⁵ For instance, urine temperature is one way of detecting tampering. It should be within the required temperature range (32–38°C). Temperature strips have been produced for this purpose, with the strips fixed to the collection container as supplied, or placed on the collection container.¹⁰ As a limitation of this study, urine temperature was measured manually.

Dilution has various definitions in different sources and guidelines. Therefore, many different approaches have been developed to calculate the rate of dilution in the urine. In forensic toxicological studies, the most commonly preferred dilution method is the formula that was used in the current study. In this formula, the mean creatinine value is key to evaluating the dilution of the urine samples. Furthermore, the variability of the mean creatinine value can change the before-negative and after-positive ratio. Therefore, it is still proposed that for the urinary creatinine normalisation procedures, a proper formula should be developed by using advanced mathematical and statistical methods.

For adulteration, a urine pool was created with selected samples, and the use of easily available household products as adulteration agents was tested using experimental analysis for cannabis, amphetamine and MDMA. It was shown that a change in texture could be easily observed when different household agents were added to the sample. A visual inspection of colour and odour was also necessary to discover the tampering. It is not uncommon that many drug-testing laboratories encounter suspicious specimens with odd colours and odours. One particular limitation of physical observation is that it relies on personnel who are expected to recognise suspicious specimens. Thus, the overall process of initial detection of possible fraudulent activity is open to subjectivity, and individual differences may alter the results. Therefore, it is possible that adulterated urine specimens may not be detected, especially when adulterants are at a low level.⁷ At this point, laboratory staff’s awareness and training, as well as their experience, are fundamental.¹⁵

The adulteration test strip was able to identify abnormality successfully at low pH levels. As expected, test-strip sensitivity was lower than the pH meter. The test strip was also able to detect specific gravity alteration in samples spiked with vinegar and drain opener. Glutaraldehyde and PCC are two commercially available adulterants and parameters readily available for the test strips used in the study to detect these adulterants. These parameters’ results for urine samples were ‘abnormal’ after being spiked with 10% (v/v) bleach and with 20% (w/v) drain opener, respectively. These types of adulteration test strips have already been approved by the Substance Abuse and Mental Health Services Administration to be used in drug-testing programmes at collection sites.⁸ We conclude that declaring urine samples as evidence of drug abuse requires in-depth analysis to ensure samples are free of any tampering. Therefore, adulteration test-strip results are of paramount importance.

In all adulterated urine samples and drug concentration fixed urine pool samples, amphetamine measurement was false-negative with two different trade dip cards. The amphetamine detection level is provided by the manufacturer as 1000 ng/mL for d-amphetamine metabolite.¹⁶ When tested with dip cards, our prepared drug concentration fixed urine pool (above the legal limits: cannabis 58 ± 1.1 ng/mL, amphetamine 1261 ± 55.2 ng/mL and MDMA 511 ± 1.4 ng/mL) gave false-negative results for amphetamine. Regarding the data for true-positive and false-negative results, we observed a 15.4% difference between the results of two dip cards for cannabis detection. Unfortunately, some laboratories may give drug-testing results using only these dip-card tests without urine integrity and validation tests.

Hypochlorite, which is the active ingredient of bleach, caused a strong interference with the response of amphetamine and MDMA in cloned enzyme donor immunoassay (CEDIA).^17,18 Bleach was also found to have the most significant effect on the analyses of THC, giving the false-negative result.¹⁹ Similarly, a study by Mikkelsen et al. reported that hypochlorite was capable of producing concentration-dependent signal inhibition for amphetamine.²⁰ In our study, hypochlorite concentrations affected the THC and amphetamine results significantly. At concentrations of 0.1% and 1% (v/v), bleach added to the samples provided a true-positive result for THC, but high amounts of bleach provided false-negative results. Similarly, for amphetamine, low concentrations (0.1% and 1% v/v) of bleach-spiked samples yielded the >5000 ng/mL amphetamine results, but 10% (v/v) bleach-spiked sample provided a false-negative result. Spiking samples with bleach in any concentration affected the MDMA results, with a slight increase.

Vinegar, a dilute concentration of acetic acid, was reported to be used for the reduction of THC concentrations so that the results would be below the cut‐off level when used with samples spiked with 50% (v/v) vinegar. Oliveri et al. reported that vinegar did no interfere with amphetamine and showed a minor decrease for cannabis.¹⁹ In our study, vinegar did not affect the THC and amphetamine results, but false-negative results were observed for MDMA with 10% and 20% (v/v) vinegar-spiked urine samples.

The active ingredient in drain opener is sodium hydroxide, which is a white crystalline substance with a caustic strong base effect.⁵ Oliveri et al. reported that enzyme-linked immunosorbent assay for THC and amphetamine showed that 5% (v/v) Drano, which is a different branded commercial product for drain opening, generated a significant decrease in concentration ratio, thus yielding false-negative results.¹⁹ Wu et al. showed that minimal interference was observed with low concentrations of Drano (0.1% w/v) for amphetamine. In our study, for cannabis, amphetamine and MDMA testing, false-negative results were observed when 2% (w/v) and 20% (w/v) of the drain opener was added.

Visine eye drops are also reported to be used for masking THC metabolites. Visine strongly interferes with THC detection using CEDIA and the enzyme multiplied immunoassay technique, while no effect for amphetamine was apparent.^5,7 Oliveri et al. also reported that Visine 25% (v/v) decreased the amphetamine concentration and generated false-negative results. In contrast to these reports, in our study, Visine eye drops did not have any effect on THC and amphetamine.¹⁹ Moreover, it was observed that Visine had a slight decreasing effect only for MDMA, but only when added in high amounts (30% v/v).

The values of the prepared urine pool have changed with the addition of adulteration agents with different pH and ionic strength, and as a result, differences have occurred in the concentrations of illegal substances with the active substances. The use of CEDIA in amphetamine measurement and the DRI kit in MDMA measurement may be the cause of differences in enzymatic immunoassay measurement.

The sample check test parameter provided by the manufacturer for the auto analyser immunoassay system was followed for urine sample integrity. Matriciani et al. stated that urine samples with abused drug concentrations above cut-offs could successfully tamper with adulterants in a way that could not be detected with the CEDIA sample check assay.²¹ In this study, there were false-negative results for amphetamine and MDMA, while creatinine and sample check parameters were in the normal range (Figure 4). Only 20% (w/v) drain opener added to the urine samples gave an error in auto immunoassay and could not initiate the measurement.

Conclusion

It was observed that it is possible to tamper with urine-based drug testing using various household products and to obtain false-negative results. Consequently, we recommend that physical evaluation and integrity tests should also be performed. Forensic awareness, along with relevant experience in urine collection and of laboratory personnel, are essential to detect substitution attempts. Finally, creatinine value plays a vital role in dilution determination, and findings show that drug-monitoring guidelines are critical, especially for probationer urine drug screening.

Footnotes

Acknowledgements

The authors are grateful to the Ege University Institute on Drug Abuse, Toxicology and Pharmaceutical Science Addiction Toxicology Laboratory personnel, Research Assistant Rukiye Döğer and Firat Tip Kimya San. Tic. Ltd. Şti.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The authors received no financial support for the research, authorship and/or publication of this article.

ORCID iD

Melike Aydoğdu

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