Forens Sci Med Pathol (2007) 3:93–100 DOI 10.1007/s12024-007-0011-8
ORIGINAL PAPER
Treatments against hair loss may hinder cocaine and metabolites detection Alessandra Zucchella Æ Cristiana Stramesi Æ Lucia Politi Æ Luca Morini Æ Aldo Polettini
Accepted: 8 December 2006 / Published online: 9 May 2007 Humana Press Inc. 2007
Abstract Recently, some of the hair samples that we routinely analyse for drugs of abuse did not produce valid results for cocaine and metabolites. A series of very intense interfering peaks with ion fragments common to cocaine (CO), and benzoylecgonine (BE) were found to cover up the ‘‘cocaine’’ region of the chromatogram. In one of these cases the subject declared he had used a lotion containing Minoxidil in order to prevent hair loss. Starting from this observation we found that the interfering peaks belonged to four different TMS derivatives of Minoxidil. Minoxidil interference was further investigated by applying Tricoxidil, a Minoxidil solution, to the hair of CO-free volunteers and to a CO-positive hair strand dipped into Tricoxidil. Hair were analysed before and after treatment. In both cases interfering peaks were absent in the chromatograms of untreated hair and appeared in treated hair. In the CO-positive hair detection of CO, BE and internal standard was completely hindered after treatment with Minoxidil. Attempts to separate interfering peaks from CO and metabolites by modifying the temperature programme failed. None of the hair washing methods tested (methanol; dichloromethane; sodium dodecyl sulphate water solution, 1% w/v followed by
The data were presented at the Hair Testing Meeting, Vadstena, Sweden, May 2006. Conflict of interest statement: All authors declare that to the best of their knowledge and belief, they are not involved in no situation or action that might be regarded as a potential conflict of interest with the matters discussed in this manuscript. A. Zucchella C. Stramesi (&) L. Politi L. Morini A. Polettini Department of Legal Medicine & Public Health, University of Pavia, Via Forlanini 12, 27100 Pavia, Italy e-mail: [email protected]
methanol; phosphate buffer 0.1 M, pH 6 followed by methanol) succeeded in removing Minoxidil interference. However, a simple solution to partially overcome the problem was to dry up the derivatised extract, reconstitute it in methanol (in order to switch back Minoxidil derivatives to the native molecule), and re-inject it: owing to the higher polarity, underivatised Minoxidil does not interfere any more with the chromatography of CO, at the expense of the disappearance of BE and ecgonine methyl ester both producing TMS derivatives. This strategy was applied to four real cases where Minoxidil interference was recognised: in two of these cases CO was detected. The problem of Minoxidil interference on CO detection may be limited to procedures involving trimethylsilylation, which is probably the most commonly adopted derivatisation in laboratories performing hair analysis for drugs of abuse. Keywords Hair analysis Cocaine Minoxidil Interference Forensic toxicology
Introduction Cosmetic treatments such as bleaching, dyeing or perming have been studied to evaluate to what extent they may alter the results of hair analysis for drugs of abuse [1–4]. Different authors agree that a decrease in drug content is noticed when hair has been submitted to these processes. However, to the best of our knowledge, no publications deal with the effects of treatments against hair loss on hair analysis for drugs of abuse. This study started when the routine GC–MS analysis for alkaline drugs of abuse [5] of some real samples showed a series of very intense interfering peaks with ion fragments common to cocaine (CO) and metabolites. The first case
94
Forens Sci Med Pathol (2007) 3:93–100
N
N
NH2 +
N
O
-
NH2 Fig. 1 Minoxidil (C9H15N5O, 209.13 a.m.u.) structural formula
was related to the renewal of a driving licence and it was not possible to give results proving the presence or absence of CO in the hair sample. At the time we could not give a plausible explanation of this phenomenon. A further three cases occurred some months later and in one of these cases
a patient reported the use of an anti-hair loss product containing Minoxidil. Minoxidil (Fig. 1: (6-1-piperidinyl)2,4-pyrimidine diamine-3-oxide) is an antihypertensive that acts predominately by causing direct peripheral vasodilatation of the arterioles. It was introduced in the 1970s as a treatment for hypertension and showed hypertricosis as common side effect. This led to the development of topical formulations widely used for stimulating hair growth. Nowadays, Minoxidil is the active ingredient of lotions against hair loss such as Aloxidil, Minovital, Minoximen, Regaine and Tricoxidil. In this study, we first verified whether the cause of the interference was in fact the Minoxidil lotion, and second, upon finding that it was the underlying cause, we developed an alternative low-cost procedure to perform the routine analysis of CO and metabolites on Minoxidilpositive samples. Minoxidil
Abundance 3000000 2800000 2600000 2400000 2200000 2000000 1800000 1600000 1400000 1200000 1000000 800000 600000 400000 200000 0 4.50
Time-->
5.00
5.50
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
Abundance 360000
193
Minoxidil 110 164
300000
84
200000 138 67 43 150
100000
55 124
m/z-->
75
0 40
50
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70
178
98
80
90
100
207
110
120
130
140
150
160
170
180
190
200
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220
Fig. 2 Minoxidil methanol solution injected in GC–MS scan mode without derivatisation (1 ll, 10 ng/ll). Total ion chromatogram and mass spectrum of Minoxidil (RT = 7.40 min)
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Forens Sci Med Pathol (2007) 3:93–100
95
Experimental
Drug free-hair
Chemicals
Tricoxidil (1 ml) was applied every day, for 3 weeks, on the posterior vertex of the head of three volunteers, as recommended by the drug information leaflet. Hair was cut from the same area before the first application and at the end of the treatment, and analysed as described in the sample preparation paragraph. A single hair strand of a drug-free volunteer was isolated and dipped in 3 ml of Tricoxidil for 30 min before routine analysis.
Pure standards of methyl ecgonine (ME), benzoylecgonine (BE), CO and scopolamine were purchased from S.A.L.A.R.S. (Como, Italy). Minoxidil, N-Methyl, Ntrimethylsilyl trifluoroacetamide (MSTFA), sodium hydroxide and potassium dihydrogen phosphate were purchased from Sigma (Milan, Italy). Hydrochloric acid, methanol, dichloromethane, propan-2-ol and ammonium hydroxide (C. Erba, Milan, Italy) were reagent grade. Bond Elut Certify LCR cartridges (10-ml capacity, 130 mg) were obtained from Varian (Harbor City, CA, USA). Tricoxidil, a solution of Minoxidil 2% w/v for topic use, is a commercial product sold over the counter at the chemist’s.
Hair strands testing positive for cocaine and metabolites Four different hair strands, which had tested positive for CO and benzoylecgonine at various concentrations (Sample 1: CO: 2.0 ng/mg, BE: 0.71 ng/mg; Sample 2: CO: 2.8 ng/mg, BE: 0.6 ng/mg; Sample 3: CO: 0.7 ng/mg, BE: 0.2 ng/mg, Sample 4: CO: 0.6 ng/mg, BE: 0.2 ng/mg) were dipped in 3 ml of Tricoxidil for 30 min and then analysed as described.
Hair samples Hair collected from drug-free volunteers and hair strands that had previously tested positive for CO and metabolites were used.
Abundance
Minoxidil 2TMS
1.05e+07
8000000
6000000
4000000
↓
2000000
0
Time-->
Minoxidil 4TMS
Minoxidil TMS
8.0
8.2
Minoxidil 3TMS
8.4
8.6
8.8
9.0
↓
9.2
9.4
9.6
9.8
10.0
10.2
Abundance
337
1000000
Minoxidil 2TMS
900000
322 308
800000 700000 600000 500000 254
73
400000 300000
100000 m/z-->
153
99
200000 45
59
115
281
239 171
130
194
208
222 351
0 40
80
100
120
140
160
180
200
220
240
260
280
300
320
340
Fig. 3 Minoxidil injected in GC–MS scan mode after trimethylsilyl derivatisation (1 ll, 10 ng/ll). Total ion chromatogram and mass spectrum of the bis TMS derivative of Minoxidil (RT = 8.8 min)
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Forens Sci Med Pathol (2007) 3:93–100
Sample preparation
HCl at 45C in a thermostatic bath. At the end of incubation, the tubes were allowed to cool at room temperature. After adjusting the pH to about 7 using 1 M NaOH, 1 ml of 0.1 M phosphate buffer (pH 7) was added. The centrifuged (4,500 rpm, 5 min) aqueous phase was submitted to solid-phase extraction (SPE) with Bond Elut Certify cartridges. After conditioning the cartridge with 2 ml of methanol and 2 ml of phosphate buffer 0.1 M (pH 7), the aqueous phase was transferred into the cartridge reservoir using a Pasteur pipette (in order to avoid transfer of the hair residues into the column), and run through the solid phase.
In all cases whole hair was put in a 10-ml glass tube and, after the addition of 1 ml of methanol, vortex-mixed for 30 s and centrifuged (4,500 rpm, 5 min). Methanol was then removed with Pasteur pipette. After drying under nitrogen flow, hair was cut with scissors into 1–2 mm segments. Aliquots of 50 mg of hair were placed in glass tubes and the internal standard was added (corresponding to 1.5 ng/ mg of hair) and incubated overnight with 1 ml of 0.1 M Fig. 4 Total ion chromatogram (A), and selected ion monitoring of the typical ion fragments of CO (B), and BE (C) of a drugfree volunteer hair sample analysed before Tricoxidil application
Abundance
A
550000 500000 450000 400000
scopolamine
350000 300000 250000 200000 150000 100000 50000 8.00
Time-->
8.20
8.40
8.60
8.80
9.00
9.20
9.40
9.60
9.80
10.00
10.20
Abundance 75000 70000
B
65000 60000 55000 50000
CO
45000 40000 35000 30000 25000 20000 15000 10000 5000 0 8.50
Time-->
8.55
8.60
8.65
8.70
8.75
8.80
8.85
8.90
8.95
9.00
9.05
9.10
9.15
Abundance 60000
C
55000 50000 45000 40000
BE
35000 30000 25000 20000 15000 10000 5000 Time-->
123
0 9.00
9.05
9.10
9.15
9.20
9.25
9.30
9.35
9.40
9.45
9.50
9.55
9.60
9.65
9.70
9.75
Forens Sci Med Pathol (2007) 3:93–100
97
GC–MS analysis
The cartridge was then rinsed with 2 ml of bidistilled water, 3 ml of 0.1 M HCl and 5 ml of methanol, and allowed to dry for 5 min under vacuum. Two consecutive elutions were performed using a mixture of dichloromethane and propan-2-ol (8:2 v/v) containing 2% ammonium hydroxide. The extracts were combined and evaporated to dryness under a gentle nitrogen stream at 75C. A 50-ll volume of MSTFA was added to the dried extracts. The tubes were tightly closed, vortex mixed (10 s) and heated at 75C for 15 min. After cooling at room temperature, 1 ll was injected into the GC.
Fig. 5 Total ion chromatogram (A), and selected ion monitoring of the typical ion fragments of CO (B), and BE (C) of a drugfree volunteer hair sample (same as in Fig. 4) analysed after Tricoxidil application (1 ml applied every day, for 3 weeks, on the posterior vertex)
Abundance 1e+07
A Hewlett-Packard (Palo Alto, CA, USA) Model 6890 gas chromatograph equipped with a Model 5973 mass-selective detector and 7673 automatic injector was used. Injections (pulsed splitless, 1 min with a column head pressure of 172 kPa) were performed on a Hewlett-Packard Ultra 2 (5% phenyl, methylsilicone) fused-silica capillary column (12 m · 0.2 mm I.D., 0.33-lm film thickness). Helium was used as the carrier gas at a flow rate of 1 ml/ min (constant flow mode). The operative temperatures
A
9000000 8000000 7000000 6000000 5000000 4000000 3000000
BE
scopolamine
2000000
CO 1000000
Time-->
8.20
8.40
8.60
8.80
9.00
9.20
9.40
9.60
9.80 10.00 10.20 10.40 10.60 10.80
Abundance
B
450000 400000 350000 300000
CO
250000 200000 150000 100000 50000
Time-->
0 8.55
8.60
8.65
8.70
8.75
8.80
8.85
8.90
8.95
9.00
9.05
9.10
Abundance
C 400000 350000
BE
300000 250000 200000 150000 100000 50000 0
Time-->
9.00
9.05
9.10
9.15
9.20 9.25
9.30
9.35
9.40
9.45
9.50
9.55
9.60
9.65
9.70 9.75
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Forens Sci Med Pathol (2007) 3:93–100
were as follows: injector, 250C; column, maintained at 100C for 2.25 min and programmed at 40C/min to 180C, then at 10C/min to 290C, the final temperature being held for 5 min; transfer line, 280C. Analyses of hair extracts were performed both by full scan and by selected ion monitoring. The following ions were extracted as qualifier (ions underlined were used for quantification, retention times (RT) at reported conditions given in parentheses): m/z 82, 96, 240, 271 for ME TMS (about 4.7 min); m/z 82, 182, 272, 303 for CO (8.8 min); m/z 82,
240, 346, 361 for BE TMS (9.3 min); m/z 94, 138, 154, 375 for scopolamine (9.9 min).
Results and discussion A standard solution of Minoxidil (10 ng/ll in methanol) was injected in GC–MS scan mode without and with derivatisation with equal volume of MSTFA at 75C for 15 min, in the latter case after drying the methanol under a
Abundance 3200000
A
3000000 2800000 2600000 2400000 2200000 2000000 1800000 1600000
BE
1400000
CO
1200000
scopolamine
1000000 800000 600000 400000 200000
Time-->
8.00
8.20
8.40
8.60
8.80
9.00
9.20
9.40
9.60
9.80
10.00
10.20
CO Abundance 600000
Abundance 380000
B
C
300000
400000 200000
BE 200000
100000
0
Time--> 8.50 8.55 8.60 8.65 8.70 8.75 8.80 8.85 8.90 8.95 9.00 Abundance 360000
Time-->
0 9.05
9.10
9.15
9.20
9.25
9.30
9.35
9.40
9.45
9.50
9.55
D
300000
scopolamine
200000
100000
Time-->
0 9.45
9.50
9.55
9.60
9.65
9.70
9.75
9.80
9.85
9.90
Fig. 6 Total ion chromatogram (A), and selected ion monitoring of the typical ion fragments of CO (B), BE (C) and scopolamine (D) of a positive real hair sample (CO = 2.0 ng/mg; BE: 0.7 ng/mg) dipped into Tricoxidil (3 ml, 30 min)
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Forens Sci Med Pathol (2007) 3:93–100 Abundance
99 Abundance
A
260000
B
240000
CO
200000
200000
BE 100000
Time-->
100000
0 8.50 8.55
8.60
8.65
8.70
8.75
8.80
8.85
8.90
8.95
9.00 Time-->
Abundance
0 9.05
9.10
9.15
9.20
9.25
9.30
9.35
9.40
9.45
9.50
9.55
C
160000
scopolamine 100000
50000
0 9.40
Time-->
9.45
9.50
9.55
9.60
9.65
9.70
9.75
9.80
9.85
9.90
Fig. 7 Selected ion monitoring of the typical ion fragments of CO (A), BE (B) and scopolamine (C) of a real hair sample of a subject who reported the use of a lotion containing Minoxidil
stream of nitrogen (Figs. 2, 3). As reported in Fig. 3, the derivatisation process lead to the synthesis of four different TMS derivatives: mono-, bi-, tri- and tetra-TMS Minoxidil. According to the RT and the fragmentation pattern of these derivatives, it could be responsible for interfering with the chromatographic repartition of CO and metabolites. Moreover, while the analysis of the hair from drug-free volunteers before the 3-week application of Tricoxidil did not show the presence of interfering peaks (Fig. 4), the analysis after the treatment confirmed that the regular use of the preparation produced the interfering signal of Minoxidil derivatives (Fig. 5). Similar results were
CO
Abundance 130000
obtained for the samples of the three volunteers. However, in all cases, the abundance of the interfering signal was much lower than in the real cases where the determination of CO and its metabolites was hindered. Conversely, the results obtained for either drug-free or CO-positive hair dipped into Tricoxidil for 30 min (Fig. 6) were similar to those obtained for real cases (Fig. 7) and the detection of all analytes, internal standard included, was hampered. This fact lead us to suspect that, at least in some of the real cases observed, the lotion had been used at a higher than recommended dosage, probably aiming at altering the result of analysis.
Abundance 110000 100000
A
B
100000
50000
50000
Time-->
0 8.50 8.55 8.60 8.65 8.70 8.75 8.80 8.85 8.90 8.95 9.00
BE
0 Time--> 9.05 9.10 9.15 9.20 9.25 9.30 9.35 9.40 9.45 9.50 9.55
Abundance 240000
C
200000
100000
Time-->
scopolamine
0 9.40 9.45 9.50 9.55 9.60 9.65 9.70 9.75 9.80 9.85 9.90
Fig. 8 Selected ion monitoring of the typical ion fragments of CO (A), BE (B) and scopolamine (C) of a derivatized sample (same as in Fig. 7) evaporated to dryness under nitrogen flow and then reconstituted in 50 ll of methanol (1 ll injected)
100
Unfortunately, attempts to separate interfering peaks from CO and metabolites by modifying the GC temperature programme failed. Furthermore, none of the hair washing methods tested (methanol, 1 ml; dichloromethane, 1 ml; sodium dodecyl sulphate water solution, 1 ml, 1% w/ v followed by methanol, 1 ml; phosphate buffer 0.1 M pH 6, 1 ml, followed by 1 ml methanol; with each solvent the sample was vortex mixed for 30 s and centrifuged before removal) succeeded in removing Minoxidil interference. However, we found a simple, although partial, solution to overcome the problem by drying up the derivatised extract, reconstitute it in methanol in order to switch back Minoxidil derivatives to the native molecule, and re-inject it. Owing to the higher polarity, underivatised Minoxidil does not interfere with the chromatography of CO and cocaethylene (CE), as these compounds do not undergo trimethylsilylation, at the expense of the disappearance of BE and ME, both producing TMS-derivatives, though. This strategy was applied to four real cases where Minoxidil interference was recognised: in two of these cases CO was detected (Fig. 8). It must be noted, however, that the failure in detecting CO metabolites (apart from CE) does not allow to carry out a diagnosis of CO use, as it cannot be excluded that the mere presence of CO is due to external contamination. In such cases the analysis of an alternative hair sample, such as pubic or axillary, might be helpful in the interpretation of results. The problem of Minoxidil interference on CO detection may be limited to procedures involving trimethylsilylation, which is probably the most commonly adopted derivatisation in laboratories performing hair analysis for drugs of abuse.
Conclusions Minoxidil was ascertained to be responsible for interfering in hair analysis for CO and metabolites by our GC–MS method. This hindrance is expected whenever the
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Forens Sci Med Pathol (2007) 3:93–100
procedure involves TMS-derivatisation of the analytes. However, when the CO determination is found to be compromised by the presence of Minoxidil in the sample, the following strategies can be applied: – Drying up of the TMS-derivatives, reconstitution in methanol and re-injection in the GC–MS system (underivatised Minoxidil does not interfere with CO determination); – Analyses of alternative hair, as pubic or axillary (this approach might be helpful especially in combination with the previous one); – An alternative derivatisation mode might be taken into consideration.
Educational message (1) (2) (3)
It is well known that dying and bleaching of hair may obscure results from hair analysis. We have shown that hair loss treatments also may interfere with drug analysis in hair. Alternative body hair or alternative derivatisation agent can be used to overcome minoxidil interference.
References 1. Cirimele V, et al. Drug concentration in human hair after bleaching. J Anal Toxicol 1995;19:331–2. 2. Potsch L, Skopp G. On cosmetically treated hair — aspects and pitfalls of interpretation. Forensic Sci Int 1997;84:43–52. 3. Jurado C. Influence of the cosmetic treatment of hair in drug testing. Int J Legal Med 1997/1999;110:159–69. 4. Yegles M. Influence of bleaching on stability of benzodiazepine in hair. Forensic Sci Int 2000;107:87–92. 5. Montagna M, Polettini A, Stramesi C, Groppi A, Vignali C. Hair analysis for opiates, cocaine and metabolites. Evaluation of a method by interlaboratory comparison. Forensic Sci Int 2002;128:79–83.
ORIGINAL PAPER
Treatments against hair loss may hinder cocaine and metabolites detection Alessandra Zucchella Æ Cristiana Stramesi Æ Lucia Politi Æ Luca Morini Æ Aldo Polettini
Accepted: 8 December 2006 / Published online: 9 May 2007 Humana Press Inc. 2007
Abstract Recently, some of the hair samples that we routinely analyse for drugs of abuse did not produce valid results for cocaine and metabolites. A series of very intense interfering peaks with ion fragments common to cocaine (CO), and benzoylecgonine (BE) were found to cover up the ‘‘cocaine’’ region of the chromatogram. In one of these cases the subject declared he had used a lotion containing Minoxidil in order to prevent hair loss. Starting from this observation we found that the interfering peaks belonged to four different TMS derivatives of Minoxidil. Minoxidil interference was further investigated by applying Tricoxidil, a Minoxidil solution, to the hair of CO-free volunteers and to a CO-positive hair strand dipped into Tricoxidil. Hair were analysed before and after treatment. In both cases interfering peaks were absent in the chromatograms of untreated hair and appeared in treated hair. In the CO-positive hair detection of CO, BE and internal standard was completely hindered after treatment with Minoxidil. Attempts to separate interfering peaks from CO and metabolites by modifying the temperature programme failed. None of the hair washing methods tested (methanol; dichloromethane; sodium dodecyl sulphate water solution, 1% w/v followed by
The data were presented at the Hair Testing Meeting, Vadstena, Sweden, May 2006. Conflict of interest statement: All authors declare that to the best of their knowledge and belief, they are not involved in no situation or action that might be regarded as a potential conflict of interest with the matters discussed in this manuscript. A. Zucchella C. Stramesi (&) L. Politi L. Morini A. Polettini Department of Legal Medicine & Public Health, University of Pavia, Via Forlanini 12, 27100 Pavia, Italy e-mail: [email protected]
methanol; phosphate buffer 0.1 M, pH 6 followed by methanol) succeeded in removing Minoxidil interference. However, a simple solution to partially overcome the problem was to dry up the derivatised extract, reconstitute it in methanol (in order to switch back Minoxidil derivatives to the native molecule), and re-inject it: owing to the higher polarity, underivatised Minoxidil does not interfere any more with the chromatography of CO, at the expense of the disappearance of BE and ecgonine methyl ester both producing TMS derivatives. This strategy was applied to four real cases where Minoxidil interference was recognised: in two of these cases CO was detected. The problem of Minoxidil interference on CO detection may be limited to procedures involving trimethylsilylation, which is probably the most commonly adopted derivatisation in laboratories performing hair analysis for drugs of abuse. Keywords Hair analysis Cocaine Minoxidil Interference Forensic toxicology
Introduction Cosmetic treatments such as bleaching, dyeing or perming have been studied to evaluate to what extent they may alter the results of hair analysis for drugs of abuse [1–4]. Different authors agree that a decrease in drug content is noticed when hair has been submitted to these processes. However, to the best of our knowledge, no publications deal with the effects of treatments against hair loss on hair analysis for drugs of abuse. This study started when the routine GC–MS analysis for alkaline drugs of abuse [5] of some real samples showed a series of very intense interfering peaks with ion fragments common to cocaine (CO) and metabolites. The first case
94
Forens Sci Med Pathol (2007) 3:93–100
N
N
NH2 +
N
O
-
NH2 Fig. 1 Minoxidil (C9H15N5O, 209.13 a.m.u.) structural formula
was related to the renewal of a driving licence and it was not possible to give results proving the presence or absence of CO in the hair sample. At the time we could not give a plausible explanation of this phenomenon. A further three cases occurred some months later and in one of these cases
a patient reported the use of an anti-hair loss product containing Minoxidil. Minoxidil (Fig. 1: (6-1-piperidinyl)2,4-pyrimidine diamine-3-oxide) is an antihypertensive that acts predominately by causing direct peripheral vasodilatation of the arterioles. It was introduced in the 1970s as a treatment for hypertension and showed hypertricosis as common side effect. This led to the development of topical formulations widely used for stimulating hair growth. Nowadays, Minoxidil is the active ingredient of lotions against hair loss such as Aloxidil, Minovital, Minoximen, Regaine and Tricoxidil. In this study, we first verified whether the cause of the interference was in fact the Minoxidil lotion, and second, upon finding that it was the underlying cause, we developed an alternative low-cost procedure to perform the routine analysis of CO and metabolites on Minoxidilpositive samples. Minoxidil
Abundance 3000000 2800000 2600000 2400000 2200000 2000000 1800000 1600000 1400000 1200000 1000000 800000 600000 400000 200000 0 4.50
Time-->
5.00
5.50
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
Abundance 360000
193
Minoxidil 110 164
300000
84
200000 138 67 43 150
100000
55 124
m/z-->
75
0 40
50
60
70
178
98
80
90
100
207
110
120
130
140
150
160
170
180
190
200
210
220
220
Fig. 2 Minoxidil methanol solution injected in GC–MS scan mode without derivatisation (1 ll, 10 ng/ll). Total ion chromatogram and mass spectrum of Minoxidil (RT = 7.40 min)
123
Forens Sci Med Pathol (2007) 3:93–100
95
Experimental
Drug free-hair
Chemicals
Tricoxidil (1 ml) was applied every day, for 3 weeks, on the posterior vertex of the head of three volunteers, as recommended by the drug information leaflet. Hair was cut from the same area before the first application and at the end of the treatment, and analysed as described in the sample preparation paragraph. A single hair strand of a drug-free volunteer was isolated and dipped in 3 ml of Tricoxidil for 30 min before routine analysis.
Pure standards of methyl ecgonine (ME), benzoylecgonine (BE), CO and scopolamine were purchased from S.A.L.A.R.S. (Como, Italy). Minoxidil, N-Methyl, Ntrimethylsilyl trifluoroacetamide (MSTFA), sodium hydroxide and potassium dihydrogen phosphate were purchased from Sigma (Milan, Italy). Hydrochloric acid, methanol, dichloromethane, propan-2-ol and ammonium hydroxide (C. Erba, Milan, Italy) were reagent grade. Bond Elut Certify LCR cartridges (10-ml capacity, 130 mg) were obtained from Varian (Harbor City, CA, USA). Tricoxidil, a solution of Minoxidil 2% w/v for topic use, is a commercial product sold over the counter at the chemist’s.
Hair strands testing positive for cocaine and metabolites Four different hair strands, which had tested positive for CO and benzoylecgonine at various concentrations (Sample 1: CO: 2.0 ng/mg, BE: 0.71 ng/mg; Sample 2: CO: 2.8 ng/mg, BE: 0.6 ng/mg; Sample 3: CO: 0.7 ng/mg, BE: 0.2 ng/mg, Sample 4: CO: 0.6 ng/mg, BE: 0.2 ng/mg) were dipped in 3 ml of Tricoxidil for 30 min and then analysed as described.
Hair samples Hair collected from drug-free volunteers and hair strands that had previously tested positive for CO and metabolites were used.
Abundance
Minoxidil 2TMS
1.05e+07
8000000
6000000
4000000
↓
2000000
0
Time-->
Minoxidil 4TMS
Minoxidil TMS
8.0
8.2
Minoxidil 3TMS
8.4
8.6
8.8
9.0
↓
9.2
9.4
9.6
9.8
10.0
10.2
Abundance
337
1000000
Minoxidil 2TMS
900000
322 308
800000 700000 600000 500000 254
73
400000 300000
100000 m/z-->
153
99
200000 45
59
115
281
239 171
130
194
208
222 351
0 40
80
100
120
140
160
180
200
220
240
260
280
300
320
340
Fig. 3 Minoxidil injected in GC–MS scan mode after trimethylsilyl derivatisation (1 ll, 10 ng/ll). Total ion chromatogram and mass spectrum of the bis TMS derivative of Minoxidil (RT = 8.8 min)
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Forens Sci Med Pathol (2007) 3:93–100
Sample preparation
HCl at 45C in a thermostatic bath. At the end of incubation, the tubes were allowed to cool at room temperature. After adjusting the pH to about 7 using 1 M NaOH, 1 ml of 0.1 M phosphate buffer (pH 7) was added. The centrifuged (4,500 rpm, 5 min) aqueous phase was submitted to solid-phase extraction (SPE) with Bond Elut Certify cartridges. After conditioning the cartridge with 2 ml of methanol and 2 ml of phosphate buffer 0.1 M (pH 7), the aqueous phase was transferred into the cartridge reservoir using a Pasteur pipette (in order to avoid transfer of the hair residues into the column), and run through the solid phase.
In all cases whole hair was put in a 10-ml glass tube and, after the addition of 1 ml of methanol, vortex-mixed for 30 s and centrifuged (4,500 rpm, 5 min). Methanol was then removed with Pasteur pipette. After drying under nitrogen flow, hair was cut with scissors into 1–2 mm segments. Aliquots of 50 mg of hair were placed in glass tubes and the internal standard was added (corresponding to 1.5 ng/ mg of hair) and incubated overnight with 1 ml of 0.1 M Fig. 4 Total ion chromatogram (A), and selected ion monitoring of the typical ion fragments of CO (B), and BE (C) of a drugfree volunteer hair sample analysed before Tricoxidil application
Abundance
A
550000 500000 450000 400000
scopolamine
350000 300000 250000 200000 150000 100000 50000 8.00
Time-->
8.20
8.40
8.60
8.80
9.00
9.20
9.40
9.60
9.80
10.00
10.20
Abundance 75000 70000
B
65000 60000 55000 50000
CO
45000 40000 35000 30000 25000 20000 15000 10000 5000 0 8.50
Time-->
8.55
8.60
8.65
8.70
8.75
8.80
8.85
8.90
8.95
9.00
9.05
9.10
9.15
Abundance 60000
C
55000 50000 45000 40000
BE
35000 30000 25000 20000 15000 10000 5000 Time-->
123
0 9.00
9.05
9.10
9.15
9.20
9.25
9.30
9.35
9.40
9.45
9.50
9.55
9.60
9.65
9.70
9.75
Forens Sci Med Pathol (2007) 3:93–100
97
GC–MS analysis
The cartridge was then rinsed with 2 ml of bidistilled water, 3 ml of 0.1 M HCl and 5 ml of methanol, and allowed to dry for 5 min under vacuum. Two consecutive elutions were performed using a mixture of dichloromethane and propan-2-ol (8:2 v/v) containing 2% ammonium hydroxide. The extracts were combined and evaporated to dryness under a gentle nitrogen stream at 75C. A 50-ll volume of MSTFA was added to the dried extracts. The tubes were tightly closed, vortex mixed (10 s) and heated at 75C for 15 min. After cooling at room temperature, 1 ll was injected into the GC.
Fig. 5 Total ion chromatogram (A), and selected ion monitoring of the typical ion fragments of CO (B), and BE (C) of a drugfree volunteer hair sample (same as in Fig. 4) analysed after Tricoxidil application (1 ml applied every day, for 3 weeks, on the posterior vertex)
Abundance 1e+07
A Hewlett-Packard (Palo Alto, CA, USA) Model 6890 gas chromatograph equipped with a Model 5973 mass-selective detector and 7673 automatic injector was used. Injections (pulsed splitless, 1 min with a column head pressure of 172 kPa) were performed on a Hewlett-Packard Ultra 2 (5% phenyl, methylsilicone) fused-silica capillary column (12 m · 0.2 mm I.D., 0.33-lm film thickness). Helium was used as the carrier gas at a flow rate of 1 ml/ min (constant flow mode). The operative temperatures
A
9000000 8000000 7000000 6000000 5000000 4000000 3000000
BE
scopolamine
2000000
CO 1000000
Time-->
8.20
8.40
8.60
8.80
9.00
9.20
9.40
9.60
9.80 10.00 10.20 10.40 10.60 10.80
Abundance
B
450000 400000 350000 300000
CO
250000 200000 150000 100000 50000
Time-->
0 8.55
8.60
8.65
8.70
8.75
8.80
8.85
8.90
8.95
9.00
9.05
9.10
Abundance
C 400000 350000
BE
300000 250000 200000 150000 100000 50000 0
Time-->
9.00
9.05
9.10
9.15
9.20 9.25
9.30
9.35
9.40
9.45
9.50
9.55
9.60
9.65
9.70 9.75
98
Forens Sci Med Pathol (2007) 3:93–100
were as follows: injector, 250C; column, maintained at 100C for 2.25 min and programmed at 40C/min to 180C, then at 10C/min to 290C, the final temperature being held for 5 min; transfer line, 280C. Analyses of hair extracts were performed both by full scan and by selected ion monitoring. The following ions were extracted as qualifier (ions underlined were used for quantification, retention times (RT) at reported conditions given in parentheses): m/z 82, 96, 240, 271 for ME TMS (about 4.7 min); m/z 82, 182, 272, 303 for CO (8.8 min); m/z 82,
240, 346, 361 for BE TMS (9.3 min); m/z 94, 138, 154, 375 for scopolamine (9.9 min).
Results and discussion A standard solution of Minoxidil (10 ng/ll in methanol) was injected in GC–MS scan mode without and with derivatisation with equal volume of MSTFA at 75C for 15 min, in the latter case after drying the methanol under a
Abundance 3200000
A
3000000 2800000 2600000 2400000 2200000 2000000 1800000 1600000
BE
1400000
CO
1200000
scopolamine
1000000 800000 600000 400000 200000
Time-->
8.00
8.20
8.40
8.60
8.80
9.00
9.20
9.40
9.60
9.80
10.00
10.20
CO Abundance 600000
Abundance 380000
B
C
300000
400000 200000
BE 200000
100000
0
Time--> 8.50 8.55 8.60 8.65 8.70 8.75 8.80 8.85 8.90 8.95 9.00 Abundance 360000
Time-->
0 9.05
9.10
9.15
9.20
9.25
9.30
9.35
9.40
9.45
9.50
9.55
D
300000
scopolamine
200000
100000
Time-->
0 9.45
9.50
9.55
9.60
9.65
9.70
9.75
9.80
9.85
9.90
Fig. 6 Total ion chromatogram (A), and selected ion monitoring of the typical ion fragments of CO (B), BE (C) and scopolamine (D) of a positive real hair sample (CO = 2.0 ng/mg; BE: 0.7 ng/mg) dipped into Tricoxidil (3 ml, 30 min)
123
Forens Sci Med Pathol (2007) 3:93–100 Abundance
99 Abundance
A
260000
B
240000
CO
200000
200000
BE 100000
Time-->
100000
0 8.50 8.55
8.60
8.65
8.70
8.75
8.80
8.85
8.90
8.95
9.00 Time-->
Abundance
0 9.05
9.10
9.15
9.20
9.25
9.30
9.35
9.40
9.45
9.50
9.55
C
160000
scopolamine 100000
50000
0 9.40
Time-->
9.45
9.50
9.55
9.60
9.65
9.70
9.75
9.80
9.85
9.90
Fig. 7 Selected ion monitoring of the typical ion fragments of CO (A), BE (B) and scopolamine (C) of a real hair sample of a subject who reported the use of a lotion containing Minoxidil
stream of nitrogen (Figs. 2, 3). As reported in Fig. 3, the derivatisation process lead to the synthesis of four different TMS derivatives: mono-, bi-, tri- and tetra-TMS Minoxidil. According to the RT and the fragmentation pattern of these derivatives, it could be responsible for interfering with the chromatographic repartition of CO and metabolites. Moreover, while the analysis of the hair from drug-free volunteers before the 3-week application of Tricoxidil did not show the presence of interfering peaks (Fig. 4), the analysis after the treatment confirmed that the regular use of the preparation produced the interfering signal of Minoxidil derivatives (Fig. 5). Similar results were
CO
Abundance 130000
obtained for the samples of the three volunteers. However, in all cases, the abundance of the interfering signal was much lower than in the real cases where the determination of CO and its metabolites was hindered. Conversely, the results obtained for either drug-free or CO-positive hair dipped into Tricoxidil for 30 min (Fig. 6) were similar to those obtained for real cases (Fig. 7) and the detection of all analytes, internal standard included, was hampered. This fact lead us to suspect that, at least in some of the real cases observed, the lotion had been used at a higher than recommended dosage, probably aiming at altering the result of analysis.
Abundance 110000 100000
A
B
100000
50000
50000
Time-->
0 8.50 8.55 8.60 8.65 8.70 8.75 8.80 8.85 8.90 8.95 9.00
BE
0 Time--> 9.05 9.10 9.15 9.20 9.25 9.30 9.35 9.40 9.45 9.50 9.55
Abundance 240000
C
200000
100000
Time-->
scopolamine
0 9.40 9.45 9.50 9.55 9.60 9.65 9.70 9.75 9.80 9.85 9.90
Fig. 8 Selected ion monitoring of the typical ion fragments of CO (A), BE (B) and scopolamine (C) of a derivatized sample (same as in Fig. 7) evaporated to dryness under nitrogen flow and then reconstituted in 50 ll of methanol (1 ll injected)
100
Unfortunately, attempts to separate interfering peaks from CO and metabolites by modifying the GC temperature programme failed. Furthermore, none of the hair washing methods tested (methanol, 1 ml; dichloromethane, 1 ml; sodium dodecyl sulphate water solution, 1 ml, 1% w/ v followed by methanol, 1 ml; phosphate buffer 0.1 M pH 6, 1 ml, followed by 1 ml methanol; with each solvent the sample was vortex mixed for 30 s and centrifuged before removal) succeeded in removing Minoxidil interference. However, we found a simple, although partial, solution to overcome the problem by drying up the derivatised extract, reconstitute it in methanol in order to switch back Minoxidil derivatives to the native molecule, and re-inject it. Owing to the higher polarity, underivatised Minoxidil does not interfere with the chromatography of CO and cocaethylene (CE), as these compounds do not undergo trimethylsilylation, at the expense of the disappearance of BE and ME, both producing TMS-derivatives, though. This strategy was applied to four real cases where Minoxidil interference was recognised: in two of these cases CO was detected (Fig. 8). It must be noted, however, that the failure in detecting CO metabolites (apart from CE) does not allow to carry out a diagnosis of CO use, as it cannot be excluded that the mere presence of CO is due to external contamination. In such cases the analysis of an alternative hair sample, such as pubic or axillary, might be helpful in the interpretation of results. The problem of Minoxidil interference on CO detection may be limited to procedures involving trimethylsilylation, which is probably the most commonly adopted derivatisation in laboratories performing hair analysis for drugs of abuse.
Conclusions Minoxidil was ascertained to be responsible for interfering in hair analysis for CO and metabolites by our GC–MS method. This hindrance is expected whenever the
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Forens Sci Med Pathol (2007) 3:93–100
procedure involves TMS-derivatisation of the analytes. However, when the CO determination is found to be compromised by the presence of Minoxidil in the sample, the following strategies can be applied: – Drying up of the TMS-derivatives, reconstitution in methanol and re-injection in the GC–MS system (underivatised Minoxidil does not interfere with CO determination); – Analyses of alternative hair, as pubic or axillary (this approach might be helpful especially in combination with the previous one); – An alternative derivatisation mode might be taken into consideration.
Educational message (1) (2) (3)
It is well known that dying and bleaching of hair may obscure results from hair analysis. We have shown that hair loss treatments also may interfere with drug analysis in hair. Alternative body hair or alternative derivatisation agent can be used to overcome minoxidil interference.
References 1. Cirimele V, et al. Drug concentration in human hair after bleaching. J Anal Toxicol 1995;19:331–2. 2. Potsch L, Skopp G. On cosmetically treated hair — aspects and pitfalls of interpretation. Forensic Sci Int 1997;84:43–52. 3. Jurado C. Influence of the cosmetic treatment of hair in drug testing. Int J Legal Med 1997/1999;110:159–69. 4. Yegles M. Influence of bleaching on stability of benzodiazepine in hair. Forensic Sci Int 2000;107:87–92. 5. Montagna M, Polettini A, Stramesi C, Groppi A, Vignali C. Hair analysis for opiates, cocaine and metabolites. Evaluation of a method by interlaboratory comparison. Forensic Sci Int 2002;128:79–83.
