The method of capillary electrophoresis amperometric detection of amphetamines
Technical field
The invention belongs to capillary electrophoresis amperometric detection technique field, be specifically related to the method for capillary electrophoresis amperometric detection of amphetamines.
The background technology amphetamine belongs to amphetamines, and its basic structure is phenethyl amine, is a kind of organic amine excitant of synthetic.Nervous centralis and stomodaeal nervous system had cause unreal effect more by force.Because it is synthetic simple, be easy to spread, so the scholarly forecast amphetamines will replace conventional medicament such as cocaine, hemp, heroin, opium gradually and become the main drug species of 21 century.People never stop the research of this class medicine and detection method thereof, are important topics of analysis field to the sensitive fast detecting of amphetamines.
Detection major part to this type of medicine concentrates on the chromatograph-mass spectrometer coupling method at present, comprises electrochemiluminescence that fluorescence, ultraviolet, laser-induced fluorescence (LIF) and development in recent years are got up or the like in addition.Wherein laser-induced fluorescence (LIF) is the high-sensitivity detection means of generally acknowledging, but the instrument costliness is not suitable for conventional analysis, thereby has limited its popularization and use.Chromatography-mass spectroscopy can also provide simultaneously the structural information of analyte except highly sensitive, the also comparative maturity of development, be of drugs detection range important with method routine.But the instrument and equipment that chromatography-mass spectroscopy needs structure is meticulous, needs good operative technique.And comprise derive step in the detection method in the past more, make The whole analytical process become complicated.Capillary Electrophoresis only needs sample size seldom, and has strong separating power, is applicable to various ions and neutral substance, is widely used in various fields.Amperometric Detection Coupled is a kind of of electrochemical detection method, its principle be compound when electrode surface generation oxidation or reduction reaction, the electrode current of generation is proportional to analyte concentration, thus analyte obtains detecting.It is low, simple to operate that capillary electrophoresis amperometric detects coupling technique instrument cost, and the compartment analysis ability is strong.
Summary of the invention the purpose of this invention is to provide a kind of sensitivity, simply, the method for the amphetamine of capillary electrophoresis amperometric check and analysis fast.
The used apparatus of this method is: internal diameter 25 μ m not coating melt silicon capillary; The little dish working electrode of diameter 33 μ m carbon fibers; ± 30kV DC high-voltage power supply; CHI 832 type galvanochemistry potentiostats.
Agents useful for same is: NaH
2PO
4, Na
2HPO
4, H
3PO
4, NaOH, amphetamine standard items, secondary water.It is pure that agents useful for same is analysis.The solution that is prepared before using all through 0.22 μ m membrane filtration.
Analyzing and testing to amphetamine is divided into following step:
1), for the sensitivity that guarantees to detect and the reappearance of analysis result, need do following processing to kapillary and working electrode
(1), kapillary before manipulating, spend the night with 0.1mol/LNaOH solution flushing, in operating process, use secondary water between twice sample introduction successively, 0.1mol/L NaOH solution, secondary water and damping fluid flushing capillary column, flush time is respectively 2min, 2min, 2min and 2-4min.
(2), the little dish working electrode of diameter 33 μ m carbon fibers is used 10.0mmol/LK before operation
3Fe (CN)
6Solution characterizes, and when obtaining typical microelectrode serpentine shape cyclic voltammogram, thinks that working electrode is in good condition.With working electrode scan round 10-20 week in detection cell buffer solution, sweep interval is-0.1-1.20V, to remove the electrode surface pollutant, the activation working electrode in the operating process; Analysis margin urine sample and when containing the urine sample of amphetamine standard items, because the matrix complicated component also needs sonicated 0.5-1.5min except that electrode scan round is handled.
2), the preparation of buffer solution
(1), the compound method of the buffer solution of pH≤4.0 is:
Elder generation's compound concentration is the NaH of 100.0mmol/L
2PO
4Solution and concentration are the H of 1.0mol/L
3PO
4Solution is then with 100.0mmol/L NaH
2PO
4Solution is diluted to 5.0-50.0mmol/L with secondary water, uses the H of 1.0mol/L afterwards
3PO
4Solution is adjusted to pH≤4.0;
(2), the compound method of the buffer solution of 4.0≤pH≤9.5 is:
Elder generation's compound concentration is the NaH of 100.0mmol/L
2PO
4With concentration be the Na of 100.0mmol/L
2HPO
4, will be made into concentration with the dilution of secondary water again with the two mixing of concentration is 5.0-50.0mmol/L, the buffer solution of 4.0≤pH≤9.5;
(3), the compound method of the buffer solution of pH 〉=9.5 is:
Elder generation's compound concentration is the Na of 100.0mmol/L
2HPO
4With concentration be the NaOH solution of 1.0mol/L, then with the Na of 100.0mmol/L
2HPO
4Be diluted to 5.0-50.0mmol/L with secondary water, the NaOH solution with 1.0mol/L is adjusted to pH 〉=9.5 afterwards.
3), the preparation of amphetamine standard solution and cyclic voltammetry experiment thereof
The concentration of amphetamine storing solution is 1.0mmol/L, and storing solution is hidden in refrigerator and cooled and preserved;
The cyclic voltammetry experiment of amphetamine standard solution:
With 10.0mmol/L, the NaH of pH 10.0
2PO
4-Na
2HPO
4Buffer solution is electrolyte as a setting, and in scan round 5-10 week, sweep interval is 0-1.35V, the cyclic voltammetry curve when record is stablized; Then scan round 2-4 week in the back-ground electolyte that contains the 1.0mmol/L amphetamine, sweep interval is similarly 0-1.35V, the cyclic voltammetry curve when record is stablized; The cyclic voltammetry curve of amphetamine and the cyclic voltammetry curve of back-ground electolyte are contrasted, determine with preliminary whether amphetamine has electrochemical activity and electrochemical activity interval thereof.
4), peace non-invention standard solution testing conditions and optimization thereof, and under this condition and optimal conditions, carry out the investigation of the range of linearity and detectability
Select the constant potential mode of operation, change-detection current potential between 0.95-1.35V; 5.0-50.0mmol/L between change NaH
2PO
4-Na
2HPO
4Buffer concentration changes NaH between the 3.0-12.0
2PO
4-Na
2HPO
4PH value of buffer solution; 2-10s changes sample injection time and sample introduction high pressure between the 10-15kV; Change between the 10-20kV and separate high pressure.
Aspects such as overall sensitivity, peak shape, reappearance determine that the testing conditions of symmetrical no obvious peak broadening of highly sensitive, peak shape and favorable reproducibility is a top condition, top condition is to detect current potential 1.20V, sample injection time 3s, sample introduction high pressure 10kV, separate high pressure 15kV, NaH
2PO
4-Na
2HPO
4Buffer concentration 10.0mmol/L, pH 10.0.
5), blank urine sample and contain the preparation process of the urine sample of amphetamine standard items
Get healthy people's urine,, use 10.0mmol/L afterwards, the NaH of pH 10.0 through 0.22 μ m membrane filtration
2PO
4-Na
2HPO
410 times of buffer solution dilutions are as blank urine sample; The 1.0mmol/L amphetamine is dissolved in being made in the blank urine sample contains amphetamine concentration and be respectively 1.0 * 10
-5Mol/L, 1.5 * 10
-5Mol/L and 2.0 * 10
-5The urine sample of mol/L.
6), blank urine sample and contain the detection of the urine sample of amphetamine standard items
Under these conditions, obtain blank urine sample and contain the electrophoresis pattern of the urine sample of amphetamine standard items.
The detection method of amphetamine involved in the present invention relatively has following characteristics with other analytical approachs:
1. cost is low, and is simple to operate.Capillary electrophoresis amperometric detects only needs a capillary, a high-voltage power supply, and a potentiostat and some laboratory common chemical reagent can be finished analysis task; Compare with some very sensitive detection methods such as mass spectrum and laser-induced fluorescence (LIF), operate simplyr, instrument cost is also lower.
2. lack analysis time, can satisfy the quantitative requirement of amphetamine fast qualitative.Whole electrophoresis process can be controlled in the 10min, owing to save the necessary step of deriving in other most of methods, makes that the processing time of sample is shorter.
3. highly sensitive, the range of linearity is wide.This method is limited to 3.3 * 10 to the detection of amphetamine
-9Mol/L is than low 2 orders of magnitude of the most frequently used ultraviolet detection method detectability, suitable with the sensitiveest laser-Induced Fluorescence Detection result.The range of linearity is 1.0 * 10
-8Mol/L-1.0 * 10
-5Mol/L crosses over three orders of magnitude.
The present invention is applied to the capillary electrophoresis amperometric detection technique detection of amphetamine in the aqueous solution first.Capillary electrophoresis amperometric detects combined apparatus and is assembled voluntarily by the inventor laboratory, and device as shown in Figure 1.Whole device comprises a high-voltage power supply, a capillary, an electrochemical investigating pond, a potentiostat and corresponding data processing software.Adopting traditional three-electrode system, is working electrode with the carbon fiber microdisk electrode, and platinum filament is to the utmost point, and Ag/AgCl is a contrast electrode, and buffer solution uses NaH
2PO
4-Na
2HPO
4Phosphate buffer.
Description of drawings
Fig. 1 is the installation drawing that capillary electrophoresis amperometric detects combined system.Among the figure: 1. working electrode; 2. contrast electrode; 3. to electrode; 4. kapillary; 5. high pressure P t silk; 6. runtime buffer solution; 7. screw; 8. high-voltage earthing end; 9. galvanochemistry potentiostat; 10. high direct voltage.
Fig. 2 is the electrophoresis pattern of amphetamine standard solution, and standard solution concentration is 1.0 * 10
-5Mol/L.
Fig. 3 is the electrophoresis spectrogram that has added the urine sample of amphetamine standard solution.Wherein A is blank urine sample, and B, C, D contain amphetamine concentration to be respectively 1.0 * 10
-5Mol/L, 1.5 * 10
-5Mol/L and 2.0 * 10
-5The urine sample of mol/L.
Embodiment
Following examples capillary electrophoresis amperometric pick-up unit (as shown in Figure 1).Detect current potential 1.20V, sample injection time 3s, sample introduction high pressure 10kV separates high pressure 15kV, NaH
2PO
4-Na
2HPO
4Buffer concentration 10.0mmol/L, pH 10.0; Working electrode is diameter 33 μ m carbon fiber microdisk electrodes; To the utmost point is platinum filament, and contrast electrode is Ag/AgCl, and three-electrode system is installed in the electrochemical investigating pond relevant position.Capillary column internal diameter 25 μ m.Capillary column endpiece alignment work electrode surface adopts the styletable detecting pattern.The stainless-steel pipe of capillary outlet end one side parcel makes solution ground connection as the earth polar, adopts the electrokinetic injection method.
The detection of embodiment 1 amphetamine standard items
To the detection of amphetamine standard items, used instrument as previously mentioned, it is as follows to detect step:
1. the preparation of amphetamine standard solution
Amphetamine storing solution concentration is 1.0mmol/L.Storing solution is kept at refrigerator and cooled and hides.
2.10.0mmol/L, the NaH of pH 10.0
2PO
4-Na
2HPO
4The preparation of buffer solution
Elder generation's compound concentration is the Na of 100.0mmol/L
2HPO
4Solution and concentration are the NaOH solution of 1.0mol/L, follow the Na with 100.0mmol/L
2HPO
4Solution dilution to concentration is 10.0mmol/L, and the NaOH solution with 1.0mol/L is adjusted to pH 10.0 with it afterwards.
3. the detection of amphetamine standard items
Detecting current potential 1.20V; Buffer concentration 10.0mmol/L, pH value 10.0; Sample injection time 3s, sample introduction voltage 10kV; Separate under the top condition of high pressure 15kV, 5min obtains detecting with interior amphetamine, and under optimal detection condition, the detectability of amphetamine standard items is 3.3 * 10 simultaneously
-9Mol/L, the range of linearity is 1.0 * 10
-8-1.0 * 10
-5Mol/L crosses over three orders of magnitude.The electrophoresis pattern of amphetamine standard items as shown in Figure 2, the electrophoresis peak that is amphetamine that asterisk indicated.
In experimentation,, need kapillary and working electrode are carried out suitable processing for guaranteeing to obtain higher signal response and quite good detecting reappearance.
Disposal route capillaceous is: kapillary spends the night with the flushing of 0.1mol/L NaOH solution before using for the first time.In experimentation, use secondary water between twice sample introduction successively, 0.1mol/L NaOH solution, secondary water and electrophoretic buffer flushing capillary column, flush time is respectively 2min, 2min, 2min and 2min.
The disposal route of working electrode is: 10.0mmol/LK is used in the little dish work of 33 μ m carbon fibers before use
3Fe (CN)
6Solution characterizes, and when obtaining typical microelectrode serpentine shape cyclic voltammogram, shows that working electrode is in good condition.With working electrode scan round 10-20 week in detection cell buffer solution, sweep interval is-0.1-1.20V, to remove the electrode surface pollutant, the activation working electrode surface in the experimentation.
The detection of amphetamine in embodiment 2 urine samples
To the detection of amphetamine in the urine sample, used instrument as previously mentioned, it is as follows to detect step:
1.10.0mmol/L, the NaH of pH 10.0
2PO
4-Na
2HPO
4The preparation of buffer solution
Elder generation's compound concentration is the Na of 100.0mmol/L
2HPO
4Solution and concentration are the NaOH solution of 1.0mol/L, follow the Na with 100.0mmol/L
2HPO
4Solution dilution to concentration is 10.0mmol/L, and the NaOH solution with 1.0mol/L is adjusted to pH 10.0 afterwards.
2. blank urine sample and the preparation process that contains the urine sample of amphetamine standard items are:
Get healthy people's urine,, use 10.0mmol/L, the NaH of pH 10.0 through 0.22 μ m membrane filtration
2PO
4-Na
2HPO
410 times of buffer solution dilutions are as blank urine sample; The amphetamine storing solution is dissolved in makes in the blank urine sample that to contain amphetamine concentration be 1.0 * 10
-5-2.0 * 10
-5The urine sample of mol/L.
3. blank urine sample and contain the detection of the urine sample of amphetamine
What determine: detect current potential 1.20V by standard items; NaH
2PO
4-Na
2HPO
4Buffer concentration 10.0mmol/L, pH10.0; Sample injection time 3s, sample introduction voltage 10kV; Separate under the optimal detection condition of high pressure 15kV, obtain blank urine sample and contain the electrophoresis pattern (Fig. 3) of the urine sample of amphetamine.Asterisk indicated is the electrophoresis peak of amphetamine.
In experimentation,, need kapillary and working electrode are carried out suitable processing for guaranteeing to obtain higher signal response and quite good detecting reappearance.
Disposal route capillaceous is: kapillary spends the night with the flushing of 0.1mol/L NaOH solution before using for the first time.In experimentation, use secondary water between twice sample introduction successively, 0.1mol/L NaOH solution, secondary water and damping fluid flushing capillary column, flush time is respectively 2min, 2min, 2min and 4min.
The disposal route of working electrode is: 10.0mmol/LK is used in the little dish work of 33 μ m carbon fibers before use
3Fe (CN)
6Solution characterizes, and when obtaining typical microelectrode serpentine shape cyclic voltammogram, shows that working electrode is in good condition.With working electrode scan round 10-20 week in detection cell buffer solution, sweep interval is-0.1-1.20V, in addition with electrode ultrasonic 0.5-1.5min in ultrasonic cleaner in the experimentation.