The method for detecting L-type Tryptophan concentration in solution
Technical field
The present invention relates to heterogeneous amino acid detection techniques fields.It is more particularly related to which a kind of be based on amino
Graphite alkene quantum dot and the electrochemical sensing of beta cyclodextrin modification utilize L-type tryptophan in differential pulse voltammetry detection solution
The method of concentration.
Technical background
Tryptophan is the precursor substance that auxin biosynthesis is important in plant, and structure is similar to heteroauxin,
It is generally existing in higher plant.Tryptophan synthetic auxin can be passed through.This product is important nutritional agents.It may participate in animal body
The update of plasma proteins, and riboflavin can be promoted to play a role, the synthesis of niacin and ferroheme is additionally aided, can be dramatically increased
Pregnant animal fetus internal antibody, cow and sow to lactation period have promotion galactogogue action.It is raw when livestock and poultry lack tryptophan
Long to stagnate, weight loss, Fat Accumulation reduces, sire orchiatrophy.It is used as the control agent of bark favus in medicine.
Since the outer rim of beta cyclodextrin is hydrophilic and inner cavity is hydrophobic, thus it can provide a hydrophobic combination as enzyme
Position, as the various objects appropriate of main body envelope, such as organic molecule, inorganic ions and gas molecule.Its inner cavity is hydrophobic
And the characteristic of external hydrophilic make its can according to Van der Waals force, hydrophobic interaction power, the intermolecular matching effect of Subjective and Objective etc. with
Many organic and inorganic molecule forms inclusion compound and molecular assembled system, becomes chemistry and the interested research pair of chemical research person
As.The molecular recognition of this selective tetra-inclusion complex, that is, usually said, as a result, forming Subjective and Objective inclusion complex.Beta cyclodextrin
It is the ideal host molecule similar to enzyme found so far, and itself just has the characteristic of catalator.Therefore, catalysis,
In the fields such as separation, food and drug, beta cyclodextrin, which receives, greatly to be paid attention to and is widely applied.
The method that the amino acid of existing detection various configuration has cyclic voltammetric and AC impedance, these methods are only to it
A kind of middle index is used as according to carrying out qualitative and quantitative analysis simultaneously, for example, cyclic voltammetric only using the size of current signal as
The amino acid of various configuration is distinguished, AC impedance is using resistance value size as distinguishing, and accuracy is lower, and sensitivity is also low, inspection
Limit for height out.
Summary of the invention
It is an object of the invention to solve at least the above problems or defect, and provide the advantages of at least will be described later.
It is a still further object of the present invention to provide a kind of methods of L-type Tryptophan concentration in detection solution, can be quick
And in quantitative detection solution L-type tryptophan content, establish a kind of simple, quickly and sensitivity and the high L-type color of accuracy
Propylhomoserin detection method.
It is a still further object of the present invention to provide the preparation methods of working electrode, using by amination graphene quantum dot
With beta cyclodextrin modified glassy carbon electrode as working electrode, the method for preparation work electrode is simple.
In order to realize these purposes and other advantages according to the present invention, L-type tryptophan in a kind of detection solution is provided
The method of concentration, wherein include: the linear equation of preparatory building L-type tryptophan, using by working electrode, reference electrode and auxiliary
The three-electrode system for helping electrode to constitute is detected to obtain phase by differential pulse voltammetry to the L-type tryptophan in solution to be measured
Parameter is answered, the linear equation that relevant parameter substitutes into the L-type tryptophan is obtained into the concentration of L-type tryptophan in solution to be measured;
Wherein, the working electrode is that glass-carbon electrode obtains after amination graphene quantum dot and beta cyclodextrin modification
Modified glassy carbon electrode.
Preferably, in the detection solution in the method for L-type Tryptophan concentration, the preparation of the modified glassy carbon electrode
Method includes:
Reference electrode, auxiliary electrode and glass-carbon electrode are immersed and contain 1.5~2.5mg/mL amination graphene quantum dot
In the mixed solution of 1.5~2.5mg/mL beta cyclodextrin, it is drying to obtain using taking-up after the completion of the scanning of cyclic voltammetric method described
Modified glassy carbon electrode;
Wherein, sweep parameter is arranged are as follows: initial potential 0V, maximum potential 1V, minimum point 0V, final current potential 0V, scanning
Rate 0.1V/s, scanning times 100 times, sensitivity 10-4A/V, waiting time 2s.
Preferably, the line of L-type tryptophan is constructed in advance in the method for L-type Tryptophan concentration in the detection solution
Property equation the following steps are included:
Step 1: compound concentration is the standard solution of at least 4 parts L-type tryptophans of 7.0~30.0 μm of ol/L;
Step 2: being detected, being obtained to every part of standard solution using differential pulse voltammetry using the three-electrode system
To the differential pulse voltammetry curve of every part of standard solution, the differential pulse voltammetry of every part of standard solution is recorded respectively in the process
The peak value of current strength in curve;
Step 3: using the peak value of the corresponding current strength of differential pulse voltammetry curve of resulting every part of standard solution as
Ordinate draws standard curve as abscissa using the concentration of every part of standard solution and the linear equation of L-type tryptophan is calculated.
Preferably, in the detection solution in the method for L-type Tryptophan concentration, using the three-electrode system, benefit
The solution to be measured containing unknown concentration L-type tryptophan is detected with differential pulse voltammetry, obtains the difference of solution to be measured
Pulse Voltammetry curve finds out the peak parameters of the corresponding current strength of differential pulse voltammetry curve of solution to be measured, and will be described
Peak value substitutes into the linear equation of the L-type tryptophan, and the concentration of L-type tryptophan in solution to be measured is obtained after calculating.
Preferably, in the detection solution in the method for L-type Tryptophan concentration, L-type tryptophan in the step 1
Standard solution configuration method are as follows: to pH be 6.5~7.5, concentration is 10mmol/L phosphate buffer solution and concentration is
The L-type tryptophan solution of 0.01mol/L mixes, and then preparing L-type Tryptophan concentration respectively is 7.0 × 10-6mol/L、10.0×
10-6mol/L、15.0×10-5mol/L、3.0×10-54 standard solution of mol/L.
Preferably, in the detection solution in the method for L-type Tryptophan concentration, the step 2 specifically includes following
Step:
1) three-electrode system is respectively implanted in 4 standard solution, stirs 1min at room temperature at 20~30 DEG C,
Static 1min;
2) differential pulse map is scanned, setting scanning initial potential is -0.1V, and termination current potential is 0.6V, and current potential increment is
0.004V, Sample Width 0.0167s, amplitude 0.05V, pulse width 0.05V, sensitivity 10-4A/V, waiting time 2s;
3) peak value for measuring and recording the current strength of 4 standard solution respectively establishes 4 standard solution
Differential pulse voltammetry curve.
Preferably, in the detection solution in the method for L-type Tryptophan concentration, the amination graphene quantum dot
It is obtained after concentrated by rotary evaporator by the amination graphene quantum dot that concentration is 1mg/mL.
Preferably, in the detection solution in the method for L-type Tryptophan concentration, before the modified glassy carbon electrode use
By pretreatment, pretreatment the following steps are included:
Modified glassy carbon electrode is placed on the polishing cloth containing 0.3 μm of granularity of polishing powder and is polished to mirror surface, then will
The H that glass-carbon electrode is sequentially placed into methanol, concentration is 0.5mol/L2SO425~35s of ultrasound is distinguished in solution and ultrapure water, and every
The modified glassy carbon electrode is obtained with 0.5~1.5min of ultrapure water after secondary ultrasound.
Preferably, in the detection solution in the method for L-type Tryptophan concentration, reference electrode is Ag/AgCl electrode,
Auxiliary electrode is platinum electrode.
The invention has the following advantages:
Firstly, work is made using amination graphene quantum dot and beta cyclodextrin modified glassy carbon electrode in the method for the invention
Make electrode, constructs relevant sensing interface as three-electrode system sensor for detecting, tryptophan configuration is carried out using current potential
Carry out qualitative, quantified using peak point current out, improve the sensitivity and accuracy of detection L-type tryptophan, it is minimum can be with
Detect 8.5 × 10-7The L-type tryptophan of mol/L.
Secondly, the Electrochemical Detection L-type color ammonia that method of the invention is repaired as amination graphene quantum dot and beta cyclodextrin
A kind of method of acid, greatly reduces testing cost, simple to operate;
Finally, a step of the invention quickly detects L-type tryptophan, after the completion of the preparation of three-electrode system sensor, it is only necessary to several points
Clock can realize that a step detects L-type tryptophan.
Detailed description of the invention
Fig. 1 is the differential pulse voltammetry curve of the L-type tryptophan standards solution of various concentration in the embodiment of the present invention 1
Figure;
Fig. 2 is the canonical plotting of L-type tryptophan in the embodiment of the present invention 1.
Specific embodiment
Elaborate below with reference to embodiment to the present invention, with enable those of ordinary skill in the art refering to this specification after
It can implement accordingly.
It should be noted that experimental method described in following embodiments is unless otherwise specified conventional method, institute
Reagent and material are stated, unless otherwise specified, is commercially obtained.
The term definition involved in the present invention arrived:
Unless otherwise defined, otherwise all technologies used herein and scientific term all have with it is of the art
Those of ordinary skill usually understands identical meaning.Although the usable and described herein in practice or test of the invention
Similar or equivalent any method, apparatus and material, but preferred method, device and material will now be described.
" working electrode " is also known as Electrode, refers to that studied reaction occurs on this electrode.In general, to work
The basic demand of electrode is: working electrode can be solid, be also possible to liquid, and miscellaneous solid material that can be conductive is equal
It can serve as electrode.It is affected due to the reaction that the electrochemical reaction studied will not be occurred by electrode itself, and can be
It is measured in biggish potential areas;Electrode must not react with solvent or electrolyte component;Electrode area should not be too
Greatly, electrode surface preferably should be uniform smooth, and can carry out surface cleaning etc. by simple method.Using solid electrode
When, in order to guarantee the reproducibility of experiment, it has to be noted that suitable electrode pre-treatment step is established, to guarantee redox, surface
Pattern and reproducible state there is no adsorbing contaminant.
A kind of method of L-type Tryptophan concentration in detection solution passes through differential pulse voltammetry pair using three-electrode system
L-type tryptophan in solution to be measured is detected, and obtains L-type tryptophan in solution to be measured according to the linear equation of L-type tryptophan
Concentration, the working electrode in three-electrode system is glass-carbon electrode after the amination graphene quantum dot and beta cyclodextrin modification
The modified glassy carbon electrode arrived.Three-electrode system is made of working electrode, reference electrode and auxiliary electrode.
The present invention is to be detected using Differential Pulse Voltammetry to L-type tryptophan, and Differential Pulse Voltammetry is linearly being swept
Retouch on waveform, be superimposed the fixed continuous impulse of an amplitude constant and pulsewidth, in scanning process, base current potential from initial potential scan to
Terminate current potential, before potential pulse starts and at the end of carry out current sample, by the difference of the two sample rate currents to current potential
Mapping, as DPV curve are mainly used for electrochemical analysis, and background current caused by reducing because of oxidation of impurities reduction reaction has
Better detection sensitivity and lower detectable limit, relative to other methods, cost is relatively low for the Differential Pulse Voltammetry, behaviour
Make simple.
The method of L-type Tryptophan concentration in the detection solution, comprising the following steps:
Step 1: preparing the working electrode and building three-electrode system, compound concentration is the more of 7.0~30.0 μm of ol/L
The standard solution of part L-type tryptophan;
Step 2: using the three-electrode system, using differential pulse voltammetry to the every part of standard prepared in step 1
Solution is detected, and the differential pulse voltammetry curve of every part of standard solution is obtained, and it is molten to record every part of standard respectively in the process
The peak value of current strength in the differential pulse voltammetry curve of liquid;
Step 3: with the corresponding current strength of differential pulse voltammetry curve of every part of standard solution obtained in step 2
Peak value draws standard curve as abscissa using the concentration of every part of standard solution and calculates linear equation as ordinate;
Step 4: using the three-electrode system, using differential pulse voltammetry to containing unknown concentration L-type tryptophan
Solution to be measured is detected, and the differential pulse voltammetry curve of solution to be measured is obtained, by the differential pulse voltammetry curve of solution to be measured
The peak value of corresponding current strength substitutes into linear equation obtained in step 3, and L-type tryptophan in solution to be measured is calculated
Concentration.
Embodiment 1:
Preparation work electrode: reference electrode, auxiliary electrode and glass-carbon electrode are immersed and contain 2mg/mL amination graphene
In the mixed solution of quantum dot and 2mg/mL beta cyclodextrin, it is drying to obtain using taking-up after the completion of the scanning of cyclic voltammetric method described
Modified glassy carbon electrode;
Wherein, sweep parameter is arranged are as follows: initial potential 0V, maximum potential 1V, minimum point 0V, final current potential 0V, scanning
Rate 0.1V/s, scanning times 100 times, sensitivity 10-4A/V, waiting time 2s.
Working electrode pretreatment: modified glassy carbon electrode is placed on the polishing cloth upthrow containing 0.3 μm of granularity of polishing powder
Glass-carbon electrode is then sequentially placed into methanol, concentration to mirror surface as the H of 0.5mol/L by light2SO4Surpass respectively in solution and ultrapure water
Sound 30s, and the modified glassy carbon electrode is obtained with ultrapure water 1min after each ultrasound.
A kind of method of L-type Tryptophan concentration in detection solution, comprising the following steps:
Step 1: preparing the working electrode and building three-electrode system, compound concentration is the 4 of 7.0~30.0 μm of ol/L
The standard solution of part L-type tryptophan;
Wherein, working electrode, that is, modified glassy carbon electrode is the preparation method comprises the following steps: by after reference electrode, auxiliary electrode and pretreatment
Glass-carbon electrode immerse in the mixed solution containing 2mg/mL amination graphene quantum dot and 2mg/mL beta cyclodextrin, using following
It is taken out after the completion of the scanning of ring voltammetric method and is drying to obtain modified glassy carbon electrode, sweep parameter setting are as follows: initial potential 0V, highest electricity
Position 1V, minimum point 0V, final current potential 0V, sweep speed 0.1V/s, scanning times 100 times, sensitivity 10-4A/V, waiting time
For 2s;
Wherein, in the step 1 L-type tryptophan standard solution configuration method are as follows: be added into phosphate buffer solution dense
Degree is the L-type tryptophan standards solution of 0.01mol/L, prepares L-type Tryptophan concentration respectively and is followed successively by 7.0 × 10-6Mol/L's is molten
Liquid a, 15.0 × 10-5The solution b of mol/L, 1.0 × 10-5The solution c of mol/L, 3.0 × 10-5Total 4 marks of the solution d of mol/L
Quasi- solution;Wherein the pH of the phosphate buffer solution is 7.0, concentration 10mmol/L;
Step 2: using the three-electrode system, using differential pulse voltammetry to the every part of standard prepared in step 1
Solution is detected, and the differential pulse voltammetry curve of every part of standard solution is obtained, and it is molten to record every part of standard respectively in the process
The peak value of current strength in the differential pulse voltammetry curve of liquid;
Wherein, the step 2 specifically includes the following steps:
The three-electrode system is respectively implanted in 4 standard solution by step 2.1, and 2min is stirred at room temperature, quiet
Only 2min;
Step 2.2, scanning differential pulse map, setting scanning initial potential are -0.1V, and termination current potential is 0.6V, current potential
Increment is 0.004V, Sample Width 0.0167s, amplitude 0.05V, pulse width 0.05V, sensitivity 10-4A/V, waiting time
For 2s;
Step 2.3, measure and record respectively 4 standard solution current strength peak value, establish 4 standards
The differential pulse voltammetry curve of solution, Fig. 1 show the differential pulse voltammetry curve of 4 standard solution.
Step 3: with the corresponding electricity of differential pulse voltammetry curve of solution a, b, c, d standard solution obtained in step 2
The peak value of intensity of flow is drawn standard curve as abscissa using the concentration of L-type tryptophan in solution a, b, c, d and is counted as ordinate
Calculate linear equation;For example, using the peak value of the corresponding current strength of differential pulse voltammetry curve of solution a as ordinate, with solution a
The concentration of middle L-type tryptophan is abscissa, can determine that a point on standard curve is changed into solution a by the above method
Solution b, c, d determine the point of the other three on standard curve by solution b, c, d, draw standard curve as shown in Figure 2;
Obtain linear equation by Fig. 2 standard curve: Y=-0.01318-0.00192X, Y is current value (I) in formula, and I is
The peak value of the corresponding current strength of differential pulse voltammetry curve of every part of standard solution, unit are μ A;X is L-type in standard solution
Tryptophan concentration (c), unit are μm ol/L, coefficient R2It is 0.9963.Modified electrode is limited to the detection of L-type tryptophan
8.5×10-7mol/L;
Step 4: using the three-electrode system, using differential pulse voltammetry to containing unknown concentration L-type tryptophan
Solution to be measured is detected, and the differential pulse voltammetry curve of solution to be measured is obtained, and calculates the dense of L-type tryptophan in liquid to be detected
Degree: it is substituted into using the peak value of the current strength of the corresponding solution to be measured of the differential pulse voltammetry curve of solution to be measured as Y value linear
In equation, the concentration of L-type tryptophan in liquid to be detected is calculated.
Although the embodiments of the present invention have been disclosed as above, but its is not only in the description and the implementation listed
With it can be fully applied to various fields suitable for the present invention, for those skilled in the art, can be easily
Realize other modification, therefore without departing from the general concept defined in the claims and the equivalent scope, the present invention is simultaneously unlimited
In specific details.