CN105954349B - A kind of method of qualitative analysis graphene oxide - Google Patents

Abstract

A method for qualitatively analyzing graphene oxide, used for the determination of graphene oxide in aqueous solution or in chlorella, the steps are as follows: 1) preparing graphene oxide solution; 2) setting MDALI-TOF-MS test conditions; 3) Analysis of the tested sample: use MDALI-TOF-MS to measure the charge-to-mass ratio of the graphene oxide solution to be tested, and analyze the mass spectrum of the graphene oxide solution. According to the eleven characteristics of the graphene oxide MDALI-TOF-MS mass spectrum peak, qualitatively confirming the presence of graphene oxide. The beneficial effects of the invention are: the method is simple to operate, has a low detection limit, which can reach 0.01 mg/L, and has good repeatability, and is suitable for qualitative detection of graphene oxide in solution.

Description

A kind of method of qualitative analysis graphene oxide

technical field

The invention belongs to the field of analytical chemistry, and in particular relates to a method for qualitatively analyzing graphene oxide.

technical background

Graphene is a two-dimensional nanomaterial with only one layer of atomic thickness that is exfoliated from graphite materials and composed of carbon atoms. Graphene oxide flakes are the product of graphite powder after chemical oxidation and exfoliation. It is a non-traditional soft material with the characteristics of polymers, colloids, films and amphiphilic molecules. The current test methods for graphene oxide generally use atomic force microscope or transmission electron microscope to conduct qualitative analysis of graphene oxide nanomaterials, and use UV-visible spectrophotometer or ultraviolet spectrometer to conduct semi-quantitative analysis of graphene oxide. However, none of the above methods can quickly realize the qualitative determination of graphene oxide nanomaterials. Due to the existence of the above reasons, it has become a research focus to invent a new method for qualitative analysis of graphene oxide. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is a new type of soft ionization biological mass spectrometry developed in recent years, which is very simple and efficient both in theory and in design. Using MDALI-TOF-MS to detect the prepared graphene oxide solution, the graphene oxide can be quickly and easily qualitatively analyzed.

Contents of the invention

The purpose of the present invention is to address the above-mentioned problems and provide a method for qualitatively analyzing graphene oxide. The method uses matrix-assisted laser desorption ionization time-of-flight mass spectrometry to detect the prepared graphene oxide solution, which can rapidly analyze graphene oxide. , Simple qualitative analysis.

Technical scheme of the present invention:

A method for qualitative analysis of graphene oxide, used for the determination of graphene oxide in aqueous solution, the steps are as follows:

1) Preparation of a solution of graphene oxide

Graphene oxide was added to ultrapure water to prepare an aqueous solution of graphene oxide with a concentration of 100 mg/L, ultrasonically crushed in an ice bath with an ultrasonic instrument for 2 hours, and vigorously shaken and mixed once every 15 minutes during the ultrasonic process, and then the The aqueous solution of gained graphene oxide is diluted into the graphene oxide solution sample that concentration is 0.01,0.03,0.05,0.1,0.3,0.5,1.0,3.0,5.0,10.0mg/L;

2) Qualitative analysis of graphene oxide in solution using MADLI-TOF-MS

①Set MDALI-TOF-MS conditions

The instrument parameters used for detection are: nitrogen laser light source, laser wavelength 377nm; negative ion operation mode; spectrometer settings: high voltage, ion source 1: 19.00kv, ion source 2: 16.65kv, matrix suppression: off, lens (Lens): 8.5 kv; setting mass range 0-800Da; digital converter setting: trigger level 1000mv, laser frequency 100.0Hz;

②Determination of graphene oxide

Measure the mass-to-charge ratio (m/z) of the graphene oxide solution prepared in step 1) with MDALI-TOF-MS, analyze the mass spectrum of the graphene oxide solution, and the m/z of graphene oxide is at 23.7 (C ₂ ⁻ ) , 35.7(C ₃ ^- ), 47.7(C ₄ ^- ), 59.7(C ₅ ^- ), 71.7(C ₆ ^- ), 83.7(C ₇ ^- ), 95.7(C ₈ ^- ), 107.7(C ₉ ^- ), Eleven peaks appeared at 119.7 (C ₁₀ ^- ), 131.7 (C ₁₁ ^- ), and 143.7 (C ₁₂ ^- ), which are the characteristic peaks of the graphene oxide MDALI-TOF-MS mass spectrum. According to the signals of these eleven peaks Appearance, qualitatively confirm the existence of graphene oxide;

③ Reproducibility experiment

Get the 1.0mg/L graphene oxide aqueous solution prepared in step 1), measure 6 times according to the method for measuring graphene oxide in step 2) ②, take the MDALI-TOF-MS instrument field of view at each measurement The graphene oxide signal was measured at 5 points each in the Middle East, West, South, North and Central, and its reproducibility was analyzed.

The beneficial effects of the invention are: the method is easy to operate, has a low detection limit, which can reach 0.01 mg/L, and has good repeatability, and is suitable for qualitative detection of graphene oxide in solution.

Description of drawings

Figure 1 is a mass spectrogram of ultrapure water.

Figure 2 is a graphene oxide solution mass spectrum.

Figure 3 is the mass spectrogram of Chlorella.

Fig. 4 is the mass spectrogram of graphene oxide in chlorella.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1:

A method for qualitative analysis of graphene oxide, used for the determination of graphene oxide in aqueous solution, the steps are as follows:

1) Preparation of a solution of graphene oxide

Use an analytical balance to weigh 10mg of graphene oxide, add it to a 100mL volumetric flask, add ultrapure water to the scale line, and make a 100mg/L solution. 15min, shake vigorously to mix once. Take the sample prepared in step 1, dilute it into a graphene oxide solution with a concentration of 0.01, 0.03, 0.05, 0.1, 0.3, 0.5, 1.0, 3.0, 5.0, 10.0 mg/L, and measure its charge-to-mass ratio.

2) Using MADLI-TOF-MS to measure the mass spectrum of graphene oxide nanomaterials in solution

①Set MDALI-TOF-MS conditions: nitrogen laser source, laser wavelength 377nm; negative ion operation mode; spectrometer settings: high voltage, ion source 1 (Ion source 1): 19.00kv, ion source 2 (Ion source 2): 16.65 kv, matrix suppression (Matrix suppression): off, lens (Lens): 8.5kv; set mass range 0-800Da, digitizer settings: trigger level: 1000mv, laser frequency 100.0Hz.

② Sample solution detection: Take 1 μL of the detection sample prepared in step 1) and add it on the special sample target for MDALI-TOF-MS, and let it dry naturally at room temperature before use. Afterwards, carefully place the loaded sample plate in the plate hole, with the added sample facing up, "close the lid, vacuumize" and open the instrument control software Flexcontrol, adjust the instrument parameters, and save the collected mass spectrometry data. Biotyper software for analysis and identification. Analyze the mass spectrum of the graphene oxide solution and compare it with the mass spectrum of high-purity water to qualitatively determine the existence of graphene oxide.

Figure 1 is a mass spectrogram of ultrapure water. The figure shows: ultrapure water at m/z at 23.7(C ₂ ^- ), 35.7(C ₃ ^- ), 47.7(C ₄ ^- ), 59.7(C ₅ ^- ), 71.7(C ₆ ^- ), 83.7(C ₇ ^- ), 95.7 (C ₈ ^- ), 107.7 (C ₉ ^- ), 119.7 (C ₁₀ ^- ), 131.7 (C ₁₁ ^- ), 143.7 (C ₁₂ ^- ) did not appear peak signals.

Figure 2 is a graphene oxide solution mass spectrum. The figure shows that the m/z of the graphene oxide solution is at 23.7 (C ₂ ^- ), 35.7 (C ₃ ^- ), 47.7 (C ₄ ^- ), 59.7 (C ₅ ^- ), 71.7 (C ₆ ^- ), 83.7 ( Eleven peak signals appeared at C ₇ ^- ), 95.7(C ₈ ^- ), 107.7(C ₉ ^- ), 119.7(C ₁₀ ^- ), 131.7(C ₁₁ ^- ), 143.7(C ₁₂ ^- ).

3. Reproducibility experiment: get the prepared graphene oxide aqueous solution, measure 6 times, and get 5 points for each measurement, analyze and obtain its reproducibility.

Example 2:

A method for qualitatively analyzing graphene oxide, used for the determination of graphene oxide in chlorella, the steps are as follows:

1) Toxic culture of Chlorella, specifically implemented according to the following steps: Use an analytical balance to weigh 5 mg of graphene oxide, add it to a 50 mL volumetric flask, add sterilized BG-11 medium, and set the volume to the mark, Prepare a 100 mg/L solution, and use an ultrasonic instrument to sonicate in an ice bath for 2 hours. During the sonication process, shake vigorously and mix once every 15 minutes. Take the sample prepared in step 1, dilute it into a graphene oxide solution with a concentration of 1.0 mg/L, and cultivate Chlorella for 96 hours.

2) Determination by MADLI-TOF-MS

Chlorella sample pretreatment: take 5 mL of chlorella liquid, centrifuge at 10,000 rpm for 5 minutes, and wash with BG-11 culture medium for 3 times. Pour off the supernatant, and freeze-thaw three times with liquid nitrogen. Add 1 mL of ultrapure water, break the chlorella cells with a cell disruptor for 5 minutes, and then shake with a vortex shaker for 10 minutes to prepare a chlorella homogenate.

①Set MDALI-TOF-MS conditions: nitrogen laser source, laser wavelength 377nm; negative ion operation mode; spectrometer settings: high voltage, ion source 1 (Ion source 1): 19.00kv, ion source 2 (Ion source 2): 16.65 kv, matrix suppression (Matrix suppression): off, lens (Lens): 8.5kv; set mass range 0-800Da, digitizer settings: trigger level: 1000mv, laser frequency 100.0Hz.

② Sample liquid detection: Take 1 μL of the chlorella sample homogenate prepared in step 1) and add it on the sample target dedicated to MDALI-TOF-MS, and let it dry naturally at room temperature before use. Afterwards, carefully place the loaded sample plate in the plate hole, with the added sample facing up, "close the lid, vacuumize" and open the instrument control software Flexcontrol, adjust the instrument parameters, and save the collected mass spectrometry data. Biotyper software for analysis and identification. The mass spectrum of the graphene oxide solution was analyzed and compared with the mass spectrum of Chlorella cultured without graphene oxide exposure.

Figure 3 is the mass spectrogram of Chlorella. The figure shows that the m/z in the blank Chlorella homogenate is 23.7(C ₂ ^- ), 35.7(C ₃ ^- ), 47.7(C ₄ ^- ), 59.7(C ₅ ^- ), 71.7(C ₆ ^- ) , 83.7 (C ₇ ^- ), 95.7 (C ₈ ^- ), 107.7 (C ₉ ^- ), 119.7 (C ₁₀ ^- ), 131.7 (C ₁₁ ^- ), 143.7 (C ₁₂ ^- ) did not appear peak signals.

Fig. 4 is the mass spectrogram of graphene oxide in chlorella. The figure shows that the m/z of the chlorella homogenate added with graphene oxide is 23.723.7 (C ₂ ^- ), 35.7 (C ₃ ^- ), 47.7 (C ₄ ^- ), 59.7 (C ₅ ^- ) , 71.7(C ₆ ^- ), 83.7(C ₇ ^- ), 95.7(C ₈ ^- ), 107.7(C ₉ ^- ), 119.7(C ₁₀ ^- ), 131.7(C ₁₁ - ), 143.7(C ₁₂ ^- ) Eleven peak signals appeared.

It can be seen from Figures 3-4 that the presence of graphene oxide can be detected in Chlorella cultured by exposure to graphene oxide.

③ Reproducibility experiment: Take the prepared chlorella biological sample, measure 6 times, and take 5 points for each measurement, and analyze to obtain its reproducibility.

The above experimental results show that this method is convenient for measurement, and this experimental method can be used not only for quick and easy qualitative determination of graphene oxide in solution but also in biological samples.

Claims (1)

1. A method for qualitative analysis of graphene oxide, used for the determination of graphene oxide in aqueous solution, is characterized in that the steps are as follows: 1) Preparation of a solution of graphene oxide Graphene oxide was added to ultrapure water to prepare an aqueous solution of graphene oxide with a concentration of 100 mg/L, ultrasonically crushed in an ice bath with an ultrasonic instrument for 2 hours, and vigorously shaken and mixed once every 15 minutes during the ultrasonic process, and then the The aqueous solution of gained graphene oxide is diluted into the graphene oxide solution sample that concentration is 0.01,0.03,0.05,0.1,0.3,0.5,1.0,3.0,5.0,10.0mg/L; 2) Qualitative analysis of graphene oxide in solution using MADLI-TOF-MS ①Set MDALI-TOF-MS conditions The instrument parameters used for detection are: nitrogen laser light source, laser wavelength 377nm; negative ion operation mode; spectrometer settings: high voltage, ion source 1: 19.00kv, ion source 2: 16.65kv, matrix suppression: off, lens (Lens): 8.5 kv; setting mass range 0-800Da; digital converter setting: trigger level 1000mv, laser frequency 100.0Hz; ②Determination of graphene oxide Measure the mass-to-charge ratio of the graphene oxide solution prepared in step 1) with MDALI-TOF-MS, analyze the mass spectrum of the graphene oxide solution, and the m/z of graphene oxide is at 23.7 (C ₂ ⁻ ), 35.7 (C ₃ ^- ), 47.7(C ₄ ^- ), 59.7(C ₅ ^- ), 71.7(C ₆ ^- ), 83.7(C ₇ ^- ), 95.7(C ₈ ^- ), 107.7(C ₉ ^- ), 119.7(C ₁₀ ^- ), 131.7 (C ₁₁ ^- ), 143.7 (C ₁₂ ^- ), there are 11 peaks, which are the characteristic peaks of the graphene oxide MDALI-TOF-MS mass spectrum. According to the appearance of these eleven peak signals, the oxidation the presence of graphene; ③ Reproducibility experiment Get the 1.0mg/L graphene oxide aqueous solution prepared in step 1), measure 6 times according to the method for measuring graphene oxide in step 2) ②, take the MDALI-TOF-MS instrument field of view at each measurement The graphene oxide signal was measured at 5 points each in the Middle East, West, South, North and Central, and its reproducibility was analyzed.