CN111239212A

CN111239212A - Ciprofloxacin detection method

Info

Publication number: CN111239212A
Application number: CN202010150218.0A
Authority: CN
Inventors: 郭佩佩; 黄家怿; 刘海峰; 陈艺; 潘明; 刘红刚; 谢秋波; 孟祥宝
Original assignee: GUANGZHOU JIANKUN NETWORK TECHNOLOGY DEVELOPMENT CO LTD; Guangdong Modern Agricultural Equipment Research Institute
Current assignee: GUANGZHOU JIANKUN NETWORK TECHNOLOGY DEVELOPMENT CO LTD; Guangdong Modern Agricultural Equipment Research Institute
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2020-06-05
Anticipated expiration: 2040-03-06
Also published as: CN111239212B

Abstract

The invention relates to the technical field of chemical analysis and detection, in particular to a ciprofloxacin detection method. The invention discloses a ciprofloxacin detection method, which comprises the following steps: step 1: dispersing graphene oxide and Nafion by using isopropanol to prepare mixed turbid liquid containing graphene oxide and Nafion solution, and dropwise coating the mixed turbid liquid on a working area of a screen printing electrode to obtain a modified screen printing electrode; step 2: inserting the modified electrode into a B-R buffer solution containing potassium chloride with the pH value of 8.0, and connecting three electrode wires; and step 3: sequentially adding Mn into the B-R buffer solution²⁺And (3) measuring the standard solutions of the ions and the ciprofloxacin by adopting a differential pulse stripping voltammetry method to obtain a corresponding stripping voltammetry curve. The method solves the problems that the existing ciprofloxacin detection method is complicated in process, low in sensitivity, and environment-friendly in related modified materials or reagents, and has the characteristics of simplicity in preparation, easiness in operation, high detection speed, strong anti-interference performance and the like.

Description

Ciprofloxacin detection method

Technical Field

The invention relates to the technical field of chemical analysis and detection, in particular to a ciprofloxacin detection method.

Background

Ciprofloxacin is a fluoroquinolone antibiotic compound medicine, is a third-generation quinolone antibacterial medicine, has broad-spectrum antibacterial activity and good bactericidal effect, and is widely applied to livestock breeding for preventing and treating diseases and the like. After being used by animals, the medicament is generally discharged with excrement, urine or waste water in the form of medicament original form or metabolites thereof, so that the pollution to water, soil and the like is caused, the ecological balance of the environment is destroyed, and finally, potential harm is inevitably brought to the food safety and the human health of people.

At present, methods commonly used for detection include high performance liquid chromatography, gas chromatography, nuclear magnetic resonance spectroscopy, immunological detection methods and the like, but the required technology and equipment are complex or expensive, and the sample pretreatment is complicated. Therefore, the development of a simple, efficient, rapid and cheap detection technology is significant. The electrochemical detection analysis method has the characteristics of high sensitivity, low detection limit, simple and portable equipment, low price and the like, and has good application prospect in the field of antibiotic detection.

The substrate electrode in the prior art usually adopts a traditional solid electrode, pretreatment such as electrode polishing, ultrasonic cleaning and the like is carried out for multiple times before each modification, the process is complicated, the subsequent field real-time detection is not facilitated, and some detection methods adopt the combination of toxic heavy metals and antibiotics to indirectly detect the antibiotics, so that the environment is polluted to a certain extent; in some detection methods, a plurality of modification materials are involved, the preparation steps are multiple, the sensitivity is not high, and the like, so that the existing method for electrochemically detecting ciprofloxacin has the limitations of complex and complicated preparation process, environmental friendliness, low sensitivity and the like, and technical personnel are urgently needed to solve the problems.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a ciprofloxacin detection method.

The technical scheme adopted by the invention is as follows:

the invention provides a ciprofloxacin detection method, which comprises the following steps:

step 1: dispersing graphene oxide and Nafion by using isopropanol to prepare a mixed suspension containing graphene oxide and Nafion solution, ultrasonically dispersing until the solution is uniform and stable, and dropwise coating a proper amount of the mixed suspension on a working area of a screen printing electrode to obtain a modified screen printing electrode;

step 2: inserting the modified screen printing electrode into a B-R buffer solution containing potassium chloride, and respectively connecting an auxiliary electrode, a working electrode and a reference electrode in the screen printing electrode by using electrode wires;

and step 3: adding Mn into the B-R buffer solution²⁺Ion stripping of Mn-containing by differential pulse stripping voltammetry²⁺The solution of the ions is tested to obtain Mn²⁺After differential pulse stripping voltammogram (i.e., a blank curve) of the ions; then respectively adding ciprofloxacin standard solutions with different concentrations, and measuring the ciprofloxacin standard solutions by adopting a differential pulse stripping voltammetry method to obtain Mn²⁺And (3) a stripping voltammogram with the change of ion oxidation peak current along with the concentration of the ciprofloxacin solution.

And 4, step 4: and analyzing and detecting the content of the ciprofloxacin in the milk sample by adopting a standard addition method.

The invention adopts a screen printing electrode which is low in price, disposable and highly integrated as a substrate electrode, the screen printing electrode is modified after simple combination of graphene oxide and Nafion, a small amount of divalent manganese ions necessary for human life bodies are added into a solution, the oxidation peak of the manganese ions is detected by a differential pulse stripping voltammetry method, ciprofloxacin is detected according to the principle that the higher the current of the oxidation peak is, the higher the concentration of ciprofloxacin is, the electrochemical response is greatly improved, the detection sensitivity is enhanced, and the screen printing electrode can be used together with a portable electrochemical detection instrument to realize on-site instant detection.

The substrate electrode adopted by the invention is different from the traditional solid electrode, such as the commonly used glassy carbon electrode, not only needs complicated pretreatment such as polishing and the like, but also needs to be provided with a separate reference electrode and an auxiliary electrode, and the modifier adopted by the invention is used for the glassy carbon electrode, so that the detection sensitivity is lower than that of the modified electrode taking a screen-printed electrode as the substrate, and the subsequent field instant application is not facilitated. The substrate electrode provided by the invention is a screen printing electrode, is low in price and disposable, adopts a highly integrated structure of an auxiliary electrode, a reference electrode and a working electrode as the substrate electrode, does not need multiple polishing and cleaning, is simple and convenient in pretreatment process, and is beneficial to subsequent on-site real-time monitoring.

Preferably, step 1 is preceded by rinsing the electrode with distilled water.

Preferably, the washing time is 1-5 min.

The impurities on the surface of the electrode can be effectively removed by adopting distilled water to wash the electrode before detection, the electrode is prevented from being polluted, and the accuracy and the sensitivity of detection are enhanced.

Preferably, the concentration of the graphene oxide in the step 1 is 0.5-2.0 mg/mL; more preferably, the concentration of the graphene oxide is 1.5 mg/mL.

Preferably, the concentration of the Nafion solution in the step 1 is 0.01-0.05%; more preferably, the concentration of the Nafion solution is 0.01%.

According to the invention, the graphene oxide and Nafion solution are compounded and used for modifying the electrode, so that the preparation steps of the modified electrode are greatly simplified, the preparation process is environment-friendly and high in stability, and the composite modified material can greatly improve the conductivity of the electrode and promote the electron transfer rate on the surface of the electrode.

Preferably, the concentration of the potassium chloride in the step 2 is 0.01-0.1 mol/L; more preferably, the potassium chloride concentration is 0.05 mol/L.

Preferably, the pH value of the B-R buffer solution in the step 2 is 6.0-9.0; more preferably, the pH of the B-R buffer solution is 8.0.

Preferably, Mn is mentioned in step 3²⁺The concentration of the ions is 1 mu mol/L-100 mu mol/L; more preferably, Mn is described in step 3²⁺The concentration of the ions was 10. mu. mol/L.

Mn of the present invention compared to the concentration range of ciprofloxacin detection of the prior art²⁺The use of the ions can effectively improve the sensitivity and the range of ciprofloxacin concentration detection, so that the detection result is more accurate.

Preferably, the voltage scanning range of the differential pulse stripping voltammetry in the step 3 is-1.0V.

In the present invention, Nafion is a perfluorosulfonic acid resin. The B-R buffer solution is a mixed solution of boric acid, acetic acid and phosphoric acid.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, the electrode is modified after the graphene oxide and the Nafion are simply mixed, the electrode modification method and conditions are simple and convenient, the preparation process is environment-friendly, and the stability is high.

(2) The modified electrode prepared by the method can be used for detecting ciprofloxacin in the presence of interfering substances such as glucose, NaCl, ascorbic acid, glycine and the like, the oxidation peak current is basically not influenced, and the anti-interference capability is strong;

(3) because the oxidation-reduction response of directly detecting ciprofloxacin is weak and the sensitivity is low, the method establishes a method for enhancing metal Mn²⁺The method for indirectly detecting ciprofloxacin by using the ion peak current effectively improves the sensitivity of ciprofloxacin detection, and the detection method provided by the invention has the advantages of short time consumption, high sensitivity, low detection limit and convenience in operation.

Drawings

FIG. 1 is a diagram of a process for preparing a modified screen-printed electrode according to an embodiment of the present invention;

FIG. 2 is a differential pulse stripping voltammetry curve obtained by detecting B-R buffer solutions containing different substances by using a modified screen-printed electrode according to an embodiment of the present invention;

FIG. 3 is a differential pulse stripping voltammogram obtained by detecting ciprofloxacin with different concentrations by modifying a screen-printed electrode in examples 3-10 of the present invention;

FIG. 4 is a differential pulse stripping voltammogram obtained by detecting ciprofloxacin with different concentrations by modifying a screen-printed electrode in example 11 of the present invention;

FIG. 5 is a standard working curve obtained by linear fitting of ciprofloxacin concentration and manganese ion oxidation peak response values in an embodiment of the present invention;

in the figure: 1. an auxiliary electrode; 2. a working electrode; 3. a reference electrode; 4. mixed suspension of graphene oxide and Nafion solution; 5. a microsyringe; 6. modifying the screen printing electrode; A. example 2 stripping voltammogram; B. example 1 stripping voltammogram; C. example 5 stripping voltammogram.

Detailed Description

The invention is described in further detail below with reference to the figures and the specific embodiments. In the present specification, the terms "upper", "inner", "middle", "left", "right" and "one" are used for clarity of description only, and are not used to limit the scope of the present invention, and the relative relationship between the terms and the modifications may be regarded as the scope of the present invention without substantial technical changes.

Example 1

The modification process is shown in FIG. 1, and comprises the following steps:

step 1: washing the screen printing electrode for 1-5 min by using distilled water;

step 2: dispersing Graphene Oxide (GO) and a Nafion solution by using isopropanol to prepare a mixed suspension 4 containing 1.5mg/mL graphene oxide and a Nafion solution with the concentration of 0.01%, ultrasonically dispersing for 20min until the solution is uniform and stable, then dropwise coating 5 mu L of the mixed suspension on a working area of a screen printing electrode by using a microsyringe 5, and naturally airing to obtain a modified screen printing electrode 6 (GO-Nafion/SPCE).

And step 3: the modified screen-printed electrode 6 was inserted into a B-R buffer solution containing 0.05mol/LKCl, wherein the pH of the B-R buffer solution was 8.0. The auxiliary electrode 1, the working electrode 2 and the reference electrode 3 are respectively connected by electrode wires. And testing the B-R buffer solution by adopting a differential pulse stripping voltammetry within the range of-1.0V to obtain a stripping voltammetry curve of the B-R buffer solution (blank supporting solution).

Example 2

The present embodiment differs from embodiment 1 only in that: mn with the concentration of 10 mu mol/L is added into the B-R buffer solution²⁺Ions are dissolved out of Mn by adopting differential pulse stripping voltammetry within the range of-1.0 to 1.0V²⁺And testing the ionic B-R buffer solution to obtain a corresponding stripping voltammetry curve.

Examples 3 to 10

The differences between the embodiments 3-10 and the embodiment 1 are only: mn with the concentration of 10 mu mol/L is added into the B-R buffer solution²⁺Ions and 1 to 8 mu mol/L ciprofloxacin (wherein, the concentration of the ciprofloxacin in the examples 3 to 10 is gradually increased), and Mn is added in the range of-1.0 to 1.0V by adopting differential pulse stripping voltammetry²⁺And testing the ions and B-R buffer solution of ciprofloxacin to obtain a corresponding stripping voltammetry curve.

Example 11

The present embodiment 11 differs from embodiment 1 only in that: mn with the concentration of 50 mu mol/L is added into the B-R buffer solution²⁺Ions and ciprofloxacin of 5, 25 and 50 mu mol/L are added, and differential pulse stripping voltammetry is adopted to carry out on Mn-containing substances within the range of-1.0 to 1.0V²⁺And testing the ions and B-R buffer solution of ciprofloxacin to obtain a corresponding stripping voltammetry curve.

Example 12

The standard addition method is used for detecting the ciprofloxacin in the milk, the standard addition recovery rate is 98%, and the detection method has high accuracy and reliability for detecting the ciprofloxacin in an actual sample.

Comparative example 1

The method is characterized in that the detection of ciprofloxacin with different concentrations is realized by preparing a silver disulfide/reduced graphene oxide modified glassy carbon electrode and utilizing a differential pulse voltammetry method. The traditional solid electrode is adopted, pretreatment such as electrode polishing, ultrasonic cleaning and the like is carried out for multiple times before each modification, and the preparation process is complex, so that the subsequent field real-time detection is not facilitated.

Comparative example 2

After the graphene is electrodeposited, electropolymerization hematoxylin is carried out to modify a glassy carbon electrode, sensitive quantitative determination is carried out on ciprofloxacin by adopting a square wave voltammetry method and a current-time technology, and a good linear relation exists in a range of 0.5-45.0 mu mol/L. However, the electrode preparation steps are complicated, the linear correlation coefficient is slightly low, and the measurement sensitivity is poor.

Comparative example 3

Adding divalent cadmium ions or copper ions into a sample to be detected containing the fluoroquinolone antibiotics to form an antibiotic-heavy metal complex solution, selecting a glassy carbon electrode as a working electrode, detecting the complex solution by adopting a voltammetry method, and calibrating the concentration of the antibiotics according to the principle that the smaller the peak current value is, the higher the concentration of the fluoroquinolone antibiotics is. The method adopts the combination of toxic heavy metal ions and antibiotics to indirectly detect the antibiotics, has certain pollution to the environment, and has the detection principle that the smaller the peak current value is, the higher the antibiotic concentration is, so that the detection method has larger limitation and is not beneficial to the improvement of the detection sensitivity.

Performance testing

The performance test was performed for example 1, example 2 and example 5 (ciprofloxacin solution concentration 3. mu. mol/L). As shown in FIG. 2, the curve B of example 1 containing only the blank supporting solution, i.e., the B-R buffer solution, showed no peak around + 0.37V; while in example 2 the B-R buffer solution was added with Mn²⁺Weak peaks appear in the A curve after the ions are ionized; the C curve of the ciprofloxacin solution added in the example 5 is obviously increased in the peak current of +0.37V, the peak shape is sharp, the peak shape is better, and the addition of Ciprofloxacin (CIP) to Mn is proved²⁺Has a certain enhancing effect, Mn²⁺The ion oxidation peak and the ciprofloxacin have stronger response sensitivity.

Adding Mn with the concentration of 10 mu mol/L²⁺Then, the mixture is added respectively at a concentration of1. 2, 3, 4, 5, 6, 7, 8 μmol/L ciprofloxacin, examples 3-10 were obtained and the corresponding stripping voltammograms were obtained, as shown in FIG. 3, and found at Mn²⁺When the ion concentration was kept constant, the peak intensity of +0.37V was significantly increased as the ciprofloxacin concentration was increased, indicating that Mn was present²⁺The presence of the ions increases the response sensitivity of ciprofloxacin concentrations.

As shown in FIG. 4, Mn was added at a concentration of 50. mu. mol/L²⁺Thereafter, ciprofloxacin concentrations of 0, 5, 25, and 50. mu. mol/L were added to obtain example 11 and corresponding stripping voltammograms, which were also found to be Mn²⁺Under the condition that the ion concentration is kept constant, the intensity of an oxidation peak is obviously increased along with the increase of the ciprofloxacin concentration, which shows that Mn is contained in the manganese ion and ciprofloxacin solution with higher concentration²⁺The presence of ions can still improve the response sensitivity of ciprofloxacin concentrations.

As shown in FIG. 5, the concentration of ciprofloxacin solution was plotted on the abscissa with Mn²⁺The ion peak current value is an ordinate, linear fitting is carried out, and the modified electrode pair Mn is found to be increased along with the increase of the ciprofloxacin concentration²⁺The current response of (2) is gradually increased, the oxidation peak current value and the ciprofloxacin concentration have good linear relation in the range of 1-8 mu mol/L, the linear equation is that I (mu A) is 1.92c (mu mol/L) +1.19, and the linear correlation coefficient is 0.993, so that the ciprofloxacin solution concentration and Mn are shown to be²⁺The ionic oxidation peak current is in good linear relation according to Mn²⁺The indirect detection of the ciprofloxacin is realized by the principle that the stronger the ionic peak current response (oxidation peak response value) is, the higher the ciprofloxacin concentration is, the electrochemical response is greatly improved, the detection sensitivity is enhanced, and the method can be used together with a portable electrochemical detection instrument to realize the on-site instant detection.

As shown in table 1, when the modified electrode prepared in the example of the present invention was placed in a ciprofloxacin solution, the current value was 11.01 μ a, and the modified electrode had almost no influence on the peak current detected in an environment where the modified electrode coexisted with interferents such as high-concentration glucose, sodium chloride, ascorbic acid, glycine, and the like, which indicates that the electrode prepared by the method of the present invention has good specificity and extremely strong anti-interference performance.

Table 1 test results of anti-interference performance of modified electrode prepared in the embodiment of the present invention

Additive material	concentration/(μmol/L)	Multiple of	Current value/(μ A)	Detection error/%)
					Ciprofloxacin	5	/	11.01	/
Glucose	50	10	11.34	2.99
					Sodium chloride	500	100	10.85	-1.45
Ascorbic acid	500	100	11.19	1.63
					Glycine	500	100	11.47	4.18

In conclusion, the invention adopts the substrate electrode which is low in price, disposable and highly integrated with three electrodes, utilizes graphene oxide and Nafion to carry out simple composite modification on the screen printing electrode, and adds a trace of Mn of human life bodies into the solution²⁺Ion, detection of Mn by differential pulse stripping voltammetry²⁺Ion according to Mn²⁺The indirect detection of the ciprofloxacin is realized by the principle that the higher the ionic oxidation peak current is, the higher the ciprofloxacin concentration is, the electrochemical response is greatly improved, the detection sensitivity is enhanced, and the method can be used together with a portable electrochemical detection instrument to realize the on-site instant detection.

The embodiments of the present invention are not limited thereto, and according to the above-mentioned contents of the present invention, the present invention can be modified, substituted or combined in other various forms without departing from the basic technical idea of the present invention.

Claims

1. A ciprofloxacin detection method is characterized by comprising the following steps:

step 1: dispersing graphene oxide and Nafion by using isopropanol to prepare a mixed suspension containing graphene oxide and Nafion solution, ultrasonically dispersing until the solution is uniform and stable, and then dripping the solution on a working area of a screen printing electrode to obtain a modified screen printing electrode;

step 2: inserting the modified electrode into a B-R buffer solution containing potassium chloride, and respectively connecting an auxiliary electrode, a working electrode and a reference electrode in the screen-printed electrode by using electrode wires;

and step 3: adding Mn into the B-R buffer solution²⁺Ion stripping of Mn-containing by differential pulse stripping voltammetry²⁺The solution of the ions is tested to obtain Mn²⁺After differential pulse stripping voltammetry curve of ions; then respectively adding ciprofloxacin standard solution, and measuring by adopting differential pulse stripping voltammetry to obtain Mn²⁺A stripping voltammetry curve of which the ion oxidation peak current changes along with the concentration of ciprofloxacin solution;

2. A ciprofloxacin detection method according to claim 1, further comprising rinsing the screen printed electrode with distilled water before step 1.

3. A ciprofloxacin detection method according to claim 2, wherein the time for flushing is 1-5 min.

4. A ciprofloxacin detection method according to claim 1, wherein the concentration of the graphene oxide in step 1 is 0.5-2.0 mg/mL; preferably, the concentration of the graphene oxide is 1.5 mg/mL.

5. A ciprofloxacin detection method according to claim 1, wherein the concentration of the Nafion solution in step 1 is 0.01% -0.05%; preferably, the concentration of the Nafion solution is 0.01%.

6. A ciprofloxacin detection method according to claim 1, wherein the concentration of the potassium chloride in step 2 is 0.01-0.1 mol/L; preferably, the concentration of the potassium chloride is 0.05 mol/L.

7. A ciprofloxacin detection method according to claim 1, wherein the pH value of the B-R buffer solution in the step 2 is 6.0-9.0; preferably, the pH value of the B-R buffer solution is 8.0.

8. A ciprofloxacin detection method according to claim 1, wherein said Mn in step 3 is²⁺The concentration of the ions is 1 mu mol/L-100 mu mol/L; preferably, Mn is mentioned in step 3²⁺The concentration of the ions was 10. mu. mol/L.

9. A ciprofloxacin detection method according to claim 1, wherein the voltage sweep range of the differential pulse stripping voltammetry in step 3 is-1.0V.