JP2019049501A - Drug detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent erroneous detection of a drug having a similar ECL profile or a drug having a low concentration in a sample in drug detection using electrochemical luminescence (ECL), and a drug detection system capable of selective screening. Offer. SOLUTION: For example, as a system for detecting methanefetamine by ECL measurement using potential sweep, a potential applied to an electrode is superposed on a DC potential to be swept and an AC potential of a continuous sine wave is superimposed on a periodic sine wave. It is assumed to include a means for sweeping while modulating a potential in a wave and a means for simultaneously capturing and detecting an emission signal synchronized with the modulated potential. [Selection diagram] FIG. 5

Description

  The present invention relates to a drug detection system, and more particularly, to a drug detection system that uses electrochemiluminescence to detect a drug to be detected separately from other substances.

  The abuse of illegal drugs, which are highly dependent and harmful to human health, has become a serious issue worldwide, and in particular, amphetamines are potent central nervous system stimulants that induce insomnia and anorexia. It is recognized as a stimulant and is subject to enforcement. And, since most stimulants distributed in the country are methamphetamine (hereinafter referred to as "MA") as the main component, MA contained in biological samples such as urine, blood, saliva and amphetamine which is its metabolite are accurately identified. Detection is a key issue in enforcement.

  For detection of MA, many methods have been conventionally proposed, and representative ones are instruments such as gas chromatography combined with mass spectrometry, liquid chromatography, capillary electrophoresis chromatography, fluorometric analysis, etc. There is a detection method using an analyzer. Although these are detection means with high selectivity and sensitivity, they are time-consuming and costly in pretreatment and analysis, and because they require a large amount of measuring equipment, they are applied to on-site analysis of illegal drug extraction. Can not.

  On the other hand, as a method of MA identification in the field such as detection, an immunoassay (immunity analysis method) using a kit for detecting a drug for urine abuse such as Triage (registered trademark right holder: Allia San Diego Inc.) However, these test kits have the problem of being relatively expensive. In addition, as a method for detecting MA at a lower cost, a method utilizing a color change due to a chemical reaction with Marquis's reagent / Simon's reagent is used, but there is a disadvantage that the selectivity is relatively low. Therefore, development of a different detection principle for detecting MA more accurately has been desired.

Therefore, electrochemiluminescence (hereinafter referred to as “ECL”) is being studied as a drug detection method in biological samples that is expected to be applied in the field and high selectivity.
ECL is a phenomenon in which a luminescent chemical species generated by an electrode reaction becomes an excited state by a subsequent chemical reaction and emits light (Non-Patent Documents 1 and 2), and the following features can be obtained by using this as a drug detection means Is supposed to be obtained. (Nonpatent literature 2-4).
The background signal from the light source is reduced by eliminating the need for an excitation light source such as fluorescence spectroscopy.
Since light emission is triggered by an electrode reaction, the light emission location and light emission time can be easily controlled compared to chemiluminescence.
-The small size of the device enables on-site analysis at various sites.
-Analysis can be performed by devising the configuration of the detector even for semi-transparent biological samples such as urine and blood.

  Under the circumstances, the present inventors have proposed a method for detecting a drug by ECL using a potential sweep method in which the ECL intensity is measured while sweeping the electrode potential linearly. And, in this document, it is a drug whose structure (see FIG. 2) is similar to that of MA and which makes it difficult to identify MA by showing false positive with the above-mentioned simon reagent, which is a β 2 receptor stimulant The potential for distinction from methoxyphenamine (hereinafter referred to as "MP") (see Fig. 3), which is classified into and properly formulated as a bronchodilator, is shown. (Non-cited reference 5)

Electrogenerated Chemiluminescence; Dekker: New York, US, 2004. Miao, W. Chemical Reviews 2008, 108, 2506-2553. Jin, J .; Muroga, M .; Takahashi, F .; Nakamura, T. Bioelectrochemistry 2010, 79, 147-151. Takahashi, F .; Jin, J. Analytical and Bioanalytical Chemistry 2009, 393, 1669-1675. Fumiki, T .; Saki, N .; Hirosuke, T .; Jiye, J .; Teruo, H. In 54th Annual meeting of the International Association of Forensic Toxicologists: Brisbane, Australia, 2016, p249

  As mentioned above, drug detection by ECL measurement can be adapted for on-site drug detection by being able to screen drugs in biological samples with high selectivity depending on the detection drug and by being able to be contained in a relatively small system It shows the possibility.

  Further, according to the non-cited reference 5, ECL measurement is performed using a potential sweep method, using Ru (bpy) 32+ (tris (2, 2-bipyridine) ruthenium (II)), which is a general ECL probe, as a light emitting species. Thus, MA in the biological sample has a single emission peak observed at a specific voltage (1.2 V), while the above-mentioned MP has a peak at the same voltage as MA (1.2 V) and Two peaks were found to be observed at high voltage (1.45 V), and the difference in this ECL profile shows the possibility of selectively screening MA by ECL measurement. There is. However, at the same time, with this method, it is difficult to clearly distinguish the difference in ECL profiles between MA and MP due to the low absolute ELC intensity, especially when the concentration of MA in biological samples is at a low level. It has also been shown that it is difficult to distinguish, and in the case of detection of a target drug, there is an adverse effect on detection of a target drug if the biological sample contains a detection interfering substance with similar properties such as MP in MA detection. There was a problem left.

  Therefore, the present invention reduces drug background noise and amplifies the observed ECL signal to increase the ECL intensity during drug detection using ECL, thereby enabling drug screening that can selectively screen drugs. The task was to provide a system.

  In addition, even if there is a drug with a similar ECL profile due to structural similarity, etc., or a drug whose concentration in the sample is low and difficult to detect, false detection is prevented by changing the measured ECL profile. It was an object of the present invention to provide a drug detection system capable of identifying a target detection drug.

  The drug detection system according to the present invention comprises means for applying a continuous sine wave as a sweep potential to an electrode in contact with the sample, a luminescence signal obtained from the sample to which the sweep potential is applied, and an AC cycle of the sweep potential. Means for simultaneously obtaining the light emission signal and the obtained alternating current cycle, and means for extracting an alternating current component of the light emission signal, the alternating current component, and a predetermined drug pattern And means for comparing and detecting the drug.

  The sweep potential periodically modulated as a continuous sine wave used in the drug detection system according to the present invention is generated, for example, by superimposing the continuous sine wave alternating current potential on the sweeping direct current potential when performing potential sweep on the electrode Is possible. As a method of generating a sweep potential which is periodically modulated as a continuous sine wave, a method can be exemplified in which a potentiostat that outputs a DC potential and a function generator that outputs an AC potential are connected in series. Moreover, you may comprise by the electrochemical analyzer which the said potentiostat and the function of the said function generator were integrated.

  As a method of extracting the AC component of the luminescence signal used in the drug detection system according to the present invention, for example, using a lock-in amplifier, the AC component is taken as the AC frequency of the sweep potential acquired simultaneously with the luminescence signal. It is possible to illustrate the method of extracting At this time, if the noise component is removed by a low pass filter built in the lock-in amplifier, it is possible to improve the detection accuracy, which is preferable.

  In the drug detection system according to the present invention, as the drug to be detected, methamphetamine or a metabolite thereof can be exemplified. In this case, as a sample used for detection, a sample selected from urine, saliva, blood can be exemplified. It is.

(Action)
The emission intensity of ECL is suggested to be related to the rate at which the chemical reaction involved in the emission occurs, and the sweep rate (the rate at which the potential applied to the electrode changes) and the ECL intensity change depending on the target species. Do. Then, by superimposing the AC potential on the DC potential of the present means, a fast AC potential change occurs during the potential sweep, so that the apparent sweep speed can be temporarily increased. That is, the ECL reaction can not follow the potential change of the AC wave due to the difference in the rate at which the chemical reaction causing the luminescence is caused by the detection drug, and the change of the ECL profile is observed. it can.

  A function generated by a function generator can be connected in series with a potentiostat, or a desired superimposed signal of direct current and alternating current can be output by an electrochemical analyzer having the function.

By removing noise by the low-pass filter of the lock-in amplifier and synchronizing and simultaneously capturing the superimposed AC cycle and the measurement data of the ECL signal, the lock-in amplifier automatically generates one cycle of the AC cycle from the synchronization signal. The difference between the maximum value and the minimum value is calculated, and the difference between the maximum value and the minimum value of one cycle is integrated by the lock-in amplifier for several cycles, or time, and moving averaged and output as an analog signal it can.
Alternatively, it can be realized by connecting an electrochemical analyzer having the function to a personal computer to construct an arithmetic program.

  Since the signal corresponding to the AC component of the observed ECL can be extracted and detected by signal processing by calculation on a lock-in amplifier or a personal computer, the noise component in the ECL response according to this measurement method can be dramatically reduced. .

  In the drug detection system according to the present invention, when the drug to be detected is MA, the frequency of the continuous sine wave is preferably in the range of 5 to 200 Hz, preferably 75 to 150 Hz, and further preferably 100 Hz. desirable. If the frequency is set too low, the ECL of the MP is observed relatively strongly at the voltage at which the ECL intensity of the MA to be detected peaks, and discrimination may become difficult, and conversely, the frequency is If it is too high, the ECL intensity of both MA and MP tends to gradually decrease at a voltage at which the ECL intensity of MA and MP peaks, which may cause a problem in detection.

  In the drug detection system according to the present invention, when the drug to be detected is MA, the amplitude of the continuous sine wave is preferably in the range of 10 to 200 mV, preferably 20 to 100 mV, and further preferably 50 mV. desirable. In the analysis according to the present invention, in the amplitude range of 10 mV to 200 mV, the ECL intensity of MA tends to become strong according to the amplitude level, and when the amplitude is too small, the ECL intensity decreases and analysis becomes difficult. Become. On the other hand, if the amplitude is set too large, the width of the potential of the ECL to be measured becomes large, and this overlaps with the peak of ECL of MP, which may make discrimination difficult.

  According to the means and operation of the present invention, the background noise is reduced during drug detection by ECL, so that the luminescence signal to be measured can be amplified, and as a result, the relative strength of ECL intensity is increased. Can selectively screen the detection drug.

In addition, even if the drug has a similar ECL profile due to structural similarity, such as MA and MP, etc., and the drug whose concentration is low in the sample is also an alternating current cycle that overlaps during the potential sweep By setting the frequency etc. appropriately, the ECL profile can be changed, and as a result, identification can be made possible.
In this way, a clear identification is made possible, and a drug detection system using ECL that can screen a specific drug in one measurement without using a device such as a chromatograph or the like for detecting the target drug. Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an apparatus system for ECL measurement according to an embodiment of the present invention. The chart which shows the result of the ECL measurement which used the conventional potential sweep. Chemical reaction formula showing luminescence scheme of MA. Chemical reaction formula showing emission scheme of MP. 5 is a chart showing the result of ECL measurement using potential sweep in the form of the present invention. The graph which shows the correlation of the frequency of alternating current and ECL intensity which are superimposed by the form. The graph which shows the correlation of the amplitude of alternating current and ECL intensity which are superimposed by the said form. Graph showing the correlation between MA concentration and ECL intensity of the form.

  As an embodiment of a drug detection system using ECL according to the present invention, detection tests using the above-described MA and MP as examples will be described in detail.

Prior to describing the present embodiment, the potential sweep ECL of the conventional MA and MP will be described. FIG. 2 shows the measurement results by the conventional potential sweep ECL, and the upper graph shows the result of ECL luminescence (vertical axis) with respect to the sweep voltage (horizontal axis) versus the potential profile 21 of the sweep to the electrode and the middle graph is MA. The lower part shows the same graph 23 in MP. The measurement conditions are the same as in the measurement of the system according to the embodiment of the present invention described later, and 10 μM of MA (in the middle (a) of FIG. 2) or MP (in the lower (b) of FIG. 2) is present. A detection solution containing Ru (bpy) 32 + which is a light emitting species of 100 μM is used in a phosphate buffer solution (PBS; pH 9.0), DC potential sweep 20 mV / s; AC frequency 100 Hz; AC amplitude 50 mV; PMT voltage Measured as 500V.
Further, FIG. 3 and FIG. 4 show the chemical reaction in the case of ECL of Ru (bpy) 32+ which is a light emitting species with MA and MP, and FIG. 3 is a reaction formula of MA and FIG.

  The potential profile 21 of the conventional potential sweep (upper part of FIG. 2) rises continuously with time in the sweep by direct current only. The result of the ECL measurement is that, in the ECL measurement of MA, about 600 a. u. A single peak of was observed. On the other hand, MP's ECL measurement shows two 500a. u. Some peaks were observed, both 50a. u. Some background noise 24 has been observed.

  In the ECL measurement results, ECL emission was observed from 1.05 V, and a peak was observed at 1.2 V, which approximately matches the oxidation potential from Ru (bpy) 32+ to Ru (bpy) 33+. This is considered to be due to the fact that MA and MP have similar secondary amine skeletons and have relatively stable intermediate radicals which are electron-generated from amines by deprotonation. (Refer to reaction formulas (1) and (5) in Fig. 3 and Fig. 4)

  And, the light emitting species * Ru (bpy) 32 + is formed by the electron exchange reaction of the electrochemically generated Ru (bpy) 33 + (see the reaction formula (2)) and the intermediate radical of the above MA and MP. (See Reaction Formulas (3) and (6)), and light emission is observed when * Ru (bpy) 32+ returns to Ru (bpy) 32+. (Refer to reaction formula (4))

  On the other hand, in MP, a second peak is observed at 1.45V. This is because the benzyl cation radical is generated by electrochemical oxidation at a relatively high potential and is stabilized by the electron contribution effect of the methoxy group to the benzene ring. This allows intermediate radicals from the electrochemical oxidation of MP to last longer than MA. (Refer to reaction formula (7) (8))

  From the above results, it is shown that potential sweep ECL measurement by the difference of the peak at 1.45 V can distinguish MA and MP, but especially when the MP concentration in the sample solution is low, etc. It was not possible to completely separate from the ECL signal, and sensitive measurements derived from the 1.45 V ECL behavior were difficult.

Next, a test of potential sweep ECL measurement by superimposing AC of MA and MP by the system of the present embodiment will be described.
The sample of biological origin used for this measurement uses the urine of healthy human who added the standard solution of MA, and Ru (bpy) 32 + generally used for ECL measurement is used for the probe used as a luminescent species. The

FIG. 1 is a schematic view of a test apparatus for ECL measurement by the system of the present embodiment.
In this test device, a function generator 11 for superimposing an alternating current signal and a potentiostat 12 for outputting direct current are connected in series, and while the potential sweep is performed, a minute sine wave of the alternating current signal is superimposed on direct current to modulate The applied potential is applied to the electrodes in the ECL cell 13. The voltage supply to the electrode may be any system as long as the potential modulation as described above can be performed during the potential sweep such as an electrochemical analyzer in which the functions of the function generator 11 and the potentiostat 12 are integrated. You may use.

  In addition, the measurement of ECL is carried out in a micro electrolytic glass cell in a dark box 14, and a common three-electrode system using a glassy carbon working electrode, a silver / silver chloride reference electrode, and a platinum counter electrode is used as an electrode. The ECL, which is weak light emission from the electrode surface, was detected by a photomultiplier tube 15 equipped with a signal amplifier unit installed facing away from the working electrode by 1.0 mm.

  Further, the lock-in amplifier 16 is connected to the function generator 11 and the photomultiplier tube 15 to synchronize the sine wave of the superimposed periodic alternating voltage applied to the electrodes and the light emission signal of the observed ECL simultaneously. I got it. Then, the light emission signal observed is amplified by the preamplifier 17 and the lock-in amplifier 16 and is input to the A / D converter 18 together with the current signal from the potentiostat 12 observed at the same time, and is digitized and output to the computer 19 And The lock-in amplifier 16 also functions as a low pass filter for removing background noise.

The detection solution in this test was adjusted as follows.
5.0 mL of urine to which MA hydrochloride (manufactured by Dainippon Sumitomo Pharma Co., Ltd.) was added was aliquoted into a test tube, and 0.5 mL of 0.1 moldm-3 aqueous solution of sodium hydroxide was added to make it alkaline.

  To this solution was added 1.0 mL of ethyl acetate and stirred on a shaker for 10 minutes. Thereafter, centrifugation and separation were performed for 10 minutes using a 2000 × g centrifuge, and urine in the urine sample was extracted in ethyl acetate by phase separation of urine and ethyl acetate.

  After extraction, 0.10 mL of ethyl acetate was separated, and the pH was adjusted with phosphate buffer solution (PBS) 0.50 mL of 1.0 mmol dm 3 of Ru (bpy) 32+ aqueous solution, methanol 0.30 mL , Were added to prepare a mixed solvent.

  FIG. 5 shows measurement results of potential sweep ECL in which the alternating current according to the present embodiment is potential-modulated by superimposing alternating current, and the upper graph shows the voltage profile 51 sweeping to the electrode, the middle graph shows ECL emission against the sweep voltage of MA, lower graph 52 Shows a similar graph 53 in MP. The measurement conditions were 100 μM of Ru in a phosphate buffer solution (PBS; pH 9.0) in which 10 μM of MA (in FIG. 5 middle (a)) and MP (in FIG. 5 lower (b)) were present. A detection solution containing (bpy) 32+ was used, and was measured at a DC potential sweep rate of 20 mV / s; AC frequency 100 Hz; AC amplitude 50 mV; PMT voltage 500 V.

  In the potential profile 51 (the upper part of the figure) of this example, a minute alternating current is superimposed on a direct current, and rises with a periodic sine wave. As a result of ECL measurement, in ECL measurement of MA, only one peak of about 4500 a.u. is observed at 1.15 V, which is a voltage lower than the conventional one. In MP, the conventionally observed 1.2 V peak is almost extinguished and becomes a weak peak, and a strong peak of about 3000 a.u. is observed at 1.45 V. As a whole, the relative background noise 54 is reduced, and the fluctuation width is also small.

  Thus, among the ECL profiles of MP having two peaks in the conventional ECL measurement, the peak at 1.2 V overlapping with MA is eliminated and the absolute intensity is large (in this example, about MA 600 a.u. to about 4500 a.u.) and can clearly distinguish between ECL profiles of MA and MP. This allows MA to be detected without false positives with a single ECL measurement, without the need for other analysis.

  Here, the difference in ECL profile between MA and MP generated by ECL measurement in this embodiment is described. By synchronously capturing the ECL signal captured by the lock-in amplifier and the AC signal output from the function generator, it is possible to detect only the ECL response generated by the application of the AC potential. Also, since other noise components are removed by the low pass filter in the lock-in amplifier, a high sensitivity target component can be achieved. In addition, the signal processing by the lock-in amplifier can perform equivalent processing and analysis even by calculation by a personal computer.

The nearly disappearance of the 1.2 V peak in the ECL profile of MP is attributed to the chemical reaction rates of MA and MP with Ru (bpy) 32+.
FIG. 6 shows the correlation of ECL intensities of MA and MP due to the difference in frequency of alternating current to be modulated, and shows a graph of (A) 1.15 V and (B) 1.45 V. As the conditions for this measurement, a detection solution containing 100 μM of Ru (bpy) 32 + in a phosphate buffer solution (PBS; pH 9.0) containing 100 μM of MA (a) or MP (b), respectively, is used. DC potential sweep rate 20 mV / s; measured at AC amplitude 50 mV.

  The dependence of the ECL intensity on the overlapping frequency at 1.15 V and 1.45 V is that at 1.15 V, a strongly stable ECL signal is observed in MA between 5 Hz and 200 Hz and then gradually declines. On the other hand, the ELC intensity of MP decreases rapidly with increasing modulation frequency, and is only slightly observed at 100 Hz. This is because the dependence of the ECL intensity on the modulation frequency is related to the chemical reaction rate, and the reaction rate of the reaction formula (3) is relatively fast as described above. It is considered that ECL signals can be detected. On the other hand, in the case of MP, since the reaction rate of the reaction formula (6) is slow, the ECL reaction can not catch up with the rapid change in alternating current potential, and the change in ECL signal due to application of alternating current potential can not be observed visually It is believed that no light emission occurs.

  In contrast, 1.45 V ECL was observed only with MP. The ECL intensity is observed relatively stably at a modulation frequency of 5 Hz to 100 Hz. This is due to the fast reaction rate of the reaction formula (8).

  The results show that selective detection of MA and MP can be achieved by modulated ECL measurements. Also, it shows that 100 Hz is appropriate as the frequency of alternating current to be modulated. Here, as the modulation frequency decreases from 100 Hz, ECL of MP is observed at 1.15 Hz, while as it increases, the ECL intensity gradually decreases at 1.15 V, and at 1.45 V It was also shown that the ECL strength of

  FIG. 7 shows the correlation of ECL intensity due to differences in the amplitude of alternating ac for MA, the large graph is a chart of ECL intensities during potential sweep due to differences in amplitude (10 mV (71), 20 mV (72), 50 mV (73), 100 mV (74), a small graph (75) is a graph showing the correlation between the amplitude and the ECL intensity at 1.15 V. The conditions for this measurement are respectively detection solutions containing 100 μM of Ru (bpy) 32 + in a phosphate buffer solution (PBS; pH 9.0) in which 100 μM of MA is present, and the DC potential sweep rate is 20 mV / s; AC frequency was manually measured at 100 Hz.

  ECL intensity increases dramatically with increasing AC amplitude to 100 mV as shown in the graph, and gradually increases above 100 mV. In addition, when the AC amplitude is increased, the peak width of the potential-ECL curve is broadened. For example, when setting to 100 mV (74), an ECL signal is observed from 0.9 V to about 1.45 V. Therefore, if the AC amplitude is set too large, there is a concern that it will be difficult to distinguish between MA and MP. In addition, 50 mV was selected as an appropriate amplitude for MA detection because the absolute intensity of ECL is low if the setting is too small.

  FIG. 8 is a graph showing the correlation of ECL intensity to MA concentration, and the large graph is a chart of ECL intensity by modulated potential sweep due to difference in concentration (0 nm (81), 100 nm (82), 500 nm (83), 1000 nm (84), at 2500 nm (85), a small graph is a graph 86 showing the correlation between MA concentration and ECL intensity. The conditions for this measurement were measured at a DC potential sweep rate of 20 mV / s, AC amplitude of 50 mV, and a frequency of 100 Hz. Moreover, what added MA to the urine of normal persons was used as a sample.

  The ECL intensity of the 1.15 V peak showed a good correlation showing a linear relationship proportional to the MA concentration at 0.10 μM to 2.5 μM. In this test result, r2 = 0.998. Also, the detection limit of MA was 0.050 μM (7.5 ng / ml) in 5 ml of urine sample.

  The above embodiment is an example, and in addition to MA, ECL by modulated potential sweep of the present invention enables selective detection of various substances.

11. Function generator 12. Potentiostat 13. ECL cell 14. Dark box 15. Photomultiplier tube 16. Lock-in amplifier 17. Preamp 18. A / D converter 19. computer

Claims (16)

A means for applying a continuous sine wave as a sweeping potential to the electrode in contact with the sample;
A means for simultaneously acquiring a luminescence signal obtained from the sample to which the sweep potential is applied and an alternating current cycle of the sweep potential;
Means for performing arithmetic processing using the acquired light emission signal and the alternating current cycle to extract an alternating current component of the light emission signal;
Means for querying the alternating current component with a predetermined drug pattern and detecting the drug;
A drug detection system comprising:   The drug detection system according to claim 1, wherein the sample is a sample selected from urine, saliva and blood.   The drug detection system according to claim 1 or 2, wherein the drug is methamphetamine.   The drug detection system according to any one of claims 1 to 3, further comprising: means for removing a noise component from the luminescence signal.   The drug detection system according to any one of claims 1 to 4, wherein the frequency of the continuous sine wave is in the range of 5 to 200 Hz.   The drug detection system according to any one of claims 1 to 5, wherein the frequency of the continuous sine wave is in the range of 75 to 150 Hz.   The drug detection system according to any one of claims 1 to 4, wherein the amplitude of the continuous sine wave is in the range of 10 to 200 mV.   The drug detection system according to any one of claims 1-5, wherein the amplitude of the continuous sine wave is in the range of 20 to 100 mV. Applying as a continuous sinusoidal sweep potential to the electrode in contact with the sample;
Simultaneously acquiring a luminescence signal obtained from the sample to which the sweep potential is applied and an alternating current cycle of the sweep potential;
Operation processing using the acquired light emission signal and the alternating current cycle to extract an alternating current component of the light emission signal;
Querying the alternating current component with a predetermined drug pattern to detect the drug;
A drug detection method comprising:   10. The drug detection method according to claim 9, wherein the sample is a sample selected from urine, saliva and blood.   11. The drug detection method according to claim 9, wherein the drug is methamphetamine.   The drug detection method according to any one of claims 9-11, further comprising: means for removing a noise component from the luminescence signal.   The drug detection method according to any one of claims 9 to 12, wherein the frequency of the continuous sine wave is in the range of 5 to 200 Hz.   The drug detection method according to any one of claims 9 to 13, wherein the frequency of the continuous sine wave is in the range of 75 to 150 Hz.   The drug detection method according to any one of claims 9 to 12, wherein the amplitude of the continuous sine wave is in the range of 10 to 200 mV.   The drug detection method according to any one of claims 9 to 13, wherein the amplitude of the continuous sine wave is in the range of 20 to 100 mV.