WO2020015041A1

WO2020015041A1 - Solid phase micro-extraction probe of nanogold modified wooden stick and use thereof

Info

Publication number: WO2020015041A1
Application number: PCT/CN2018/100677
Authority: WO
Inventors: 郭鹏然; 马旭; 潘佳钏; 雷永乾
Original assignee: 广东省测试分析研究所（中国广州分析测试中心）
Priority date: 2018-07-16
Filing date: 2018-08-15
Publication date: 2020-01-23
Also published as: CN109187775A; CN109187775B

Abstract

A solid phase micro-extraction probe of a nanogold modified wooden stick and use thereof. The solid phase micro-extraction probe of the nanogold modified wooden stick comprises a carrier and an adsorbing material, the carrier being a wooden stick material with a porous surface, the adsorbing material being gold nanoparticle, and the adsorbing material being adhered into the pores in the surface of the carrier by means of Van der Waals force. The preparation process for the solid phase micro-extraction probe of the nanogold modified wooden stick is simple and rapid, the preparation has low difficulty, the materials are conveniently obtained and have low cost, and the obtained solid phase micro-extraction probe has characteristics such as strong enrichment capacity and good reproducibility.

Description

Solid-phase microextraction probe with nano-gold modified wooden sign and application thereof

Technical field

The invention belongs to the field of environmental analytical chemistry, and relates to a solid-phase microextraction probe with a nano-gold modified wooden sign and its application.

Background technique

Mercury is a persistent toxic pollutant that has a great impact on human health. After the "Minamata disease" crisis broke out in Japan in the 1950s, the environmental pollution of mercury has attracted great attention worldwide. Human mercury exposure mainly comes from dietary mercury-contaminated water and mercury-contaminated fish. According to reports, about 50% of mercury levels in 100,000 lakes in Sweden exceed international health limits, leading the local government to advise pregnant women not to consume fish in Swedish lakes. It can be seen that the monitoring of mercury pollution in water bodies is very important, and it is the prerequisite for environmental assessment and effective treatment of it.

The content of mercury ions entering the water environment is extremely low, but can be converted into methylmercury with stronger toxicity and bioconcentration and amplification capacity under the action of microorganisms or photochemistry. Therefore, it is necessary to develop a rapid detection method for trace mercury ions in water. method. At present, atomic fluorescence spectroscopy and inductively coupled plasma mass spectrometry are the main instrumental methods for mercury detection. They have high sensitivity and good selectivity, but they are extremely expensive, bulky, require a dedicated carrier gas, and have poor portability, so they are not suitable for the scene. Or field applications.

Solid Phase Micro Extraction (SPME) is a sample pretreatment method that follows the principles of green chemistry. It has simple, fast, sensitive, and can be used in conjunction with portable instruments to achieve sample collection, separation, concentration and analysis. And other characteristics, very suitable for in-situ sampling and analysis of mercury in water. SPME technology has been successfully applied to the analysis of mercury in environmental, food and biological samples. However, due to the high cost of commercialized extraction heads (about 900 yuan / piece), limited service life (about 100 to 300 times), and the reduction of fiber coating extraction capabilities, the extraction heads cannot be replaced, and the entire extraction head needs to be scrapped. Disadvantages such as non-recyclability severely limit its application in daily environmental monitoring of mercury. To this end, some research groups at home and abroad have developed new SPME extraction fibers with higher adsorption properties and lower cost for probe preparation. Among them, gold nanoparticles, due to their unique physical and chemical characteristics, such as high specific surface area and significant amalgamation effect, have gradually become the preferred adsorption materials for preparing SPME probes for mercury. However, in the experiments, electroplating, spraying, vapor deposition and other techniques are usually used to form a gold layer on a stainless steel or other metal wire substrate. The preparation process is tedious and takes a long time (1 to 2 hours). The preparation cost is high. Such mercury-specific SPME probes are difficult to obtain on a large scale.

Summary of the invention

The purpose of the present invention is to provide a solid-phase microextraction probe with nano-gold modified wooden sign and its application. The solid-phase microextraction probe has a fast and simple preparation process, excellent performance, low price, and disposable use, and overcomes cross-contamination. problem.

In order to achieve the above-mentioned object, the technical solution of the present invention is as follows:

The invention provides a solid-phase microextraction probe with a nano-gold modified wooden sign, comprising a carrier and an adsorption material. The carrier is a wooden sign material with a porous surface, the adsorption material is gold nanoparticles, and the adsorption material passes Van der Waals forces are attached to the channels on the surface of the carrier. The tip diameter of the wooden sign carrier material is 0.3-0.5 mm.

The invention also provides a method for preparing a solid-phase microextraction probe with a nano-gold modified wooden sign, including the following steps:

(1) Nano-gold solution was prepared by reducing chloroauric acid with sodium borohydride;

(2) A wooden sign with a length of 2 to 5 cm and a tip diameter of 0.3 to 0.5 mm is selected as a carrier;

(3) The wooden sign described in step (2) is completely immersed in the nano-gold solution prepared in step (1), maintained for 1.0-20 minutes, and then taken out, and left at room temperature for 10-30 minutes to obtain the nano-gold modification. Solid-phase microextraction probe on wooden sign.

In practice, a commercial two-pointed wooden toothpick (with a length of about 5 cm, a diameter of about 2 mm, and a diameter of about 0.5 mm at the tip) was selected without any treatment, and two pieces of one-pointed wooden toothpicks were obtained as nano-gold particle carriers.

In the present invention, the above wooden toothpicks and nano-gold particles are selected as a supporting medium and a mercury selective adsorption material, respectively. Firstly, nano-gold particles are embedded in the three-dimensionally connected pores on the surface of the wooden sign by physical immersion to prepare a low-cost, good stability and strong enrichment ability suitable for the enrichment of mercury in the headspace of water. Sign a new solid-phase microextraction probe, and then perform headspace extraction and enrichment of mercury in water, and realize rapid detection of trace mercury in water by combining with a portable mercury detector.

Preferably, the specific preparation steps of the nano-gold solution described in step (1) are as follows: at room temperature, add ultrapure water and sodium citrate solution to chloroauric acid and stir for 5-10 minutes, then dropwise into the mixed solution. Add sodium borohydride solution, and the solution after adding sodium borohydride gradually changes from light yellow to wine red. After the solution after adding sodium borohydride becomes wine red, continue stirring for 7-15 minutes and stop stirring to obtain a nano-gold solution.

Preferably, the concentration of the nano-gold prepared by the sodium borohydride reduction method is 150-200 mg / L.

The invention also provides the application of the solid-phase microextraction probe of the nano-gold modified wooden sign, and is specifically applied to the determination of mercury ions in water samples. The method for measuring mercury ions in water samples provided by the present invention is very suitable for large-scale field application scenarios. The probes and portable instruments are easy to operate and can meet the needs of portable emergency monitoring of trace mercury in the wild, and have broad application potential. And marketing prospects.

Preferably, the determination of mercury ions in the water sample includes the following steps:

(1) Measure 5.0 ～ 10.0mL of mercury standard solution or test water sample into the headspace bottle, add 0.5 ～ 1.0mL of stannous chloride solution with a mass fraction of 1% to 10%, and quickly tighten the headspace bottle cap ;

(2) The prepared solid phase microextraction probe is pierced through the silica gel septum pad on the headspace bottle cap, and the length of the wooden sign carrier of the solid phase microextraction probe exposed outside the headspace bottle is 5.0 ～ 20mm, extract the headspace bottle at a shaking speed of 150 ～ 300r / min for 5.0 ～ 30min;

(3) Take out the solid-phase microextraction probe enriched in the headspace bottle and measure the mercury ion.

Preferably, the specific measurement step of step (3) is: taking out the solid-phase microextraction probe of the nano-gold modified wooden sign enriched in the headspace bottle, and transferring the solid-phase micro-extraction probe of the nano-gold modified wooden sign to The mercury sample was measured in a quartz sample boat of a portable mercury detector thermal desorption module. The thermal desorption temperature was set to 680 ° C to 740 ° C, the thermal desorption was 1 minute, and the air flow rate was 0.8 to 1.2 L / min. .

The beneficial effects of the present invention are:

(1) In the present invention, a new type of solid-phase microextraction probe is made by using nano-gold particles having super strong binding ability to mercury as an adsorbent, and embedding them into a three-dimensional communication channel on the surface of a commercial wooden toothpick by means of physical dipping. Extraction in headspace mode greatly improves the efficiency of mercury enrichment in water and the ability to resist matrix interference.

(2) The process for preparing a nano-gold modified wood sign solid-phase microextraction probe according to the present invention is simple, fast, low in preparation difficulty, convenient to obtain materials, and low in cost. The solid-phase microextraction probe prepared by the method has enrichment ability Strong and reproducible. In addition, the solid-phase microextraction probe prepared by the present invention is disposable and ready to use, convenient, fast, and easy to carry, and at the same time overcomes the problems of mercury residue on the probe and the like.

(3) The solid-phase microextraction probe prepared by the present invention is used in combination with a portable mercury detector, which is convenient to operate and can be applied to the on-site, fast, accurate, and portable emergency monitoring of mercury in water, and has broad application potential and market promotion prospects. .

Brief description of the drawings:

FIG. 1 is an SEM image of a wooden toothpick loaded with nano-gold particles in Example 1. FIG. A is an SEM image at a magnification of 20 times, FIG. B is an SEM image at a magnification of 100 times, and FIG. Figure;

2 is an energy spectrum of a wooden toothpick loaded with nano-gold particles on the surface of Example 1;

Figure 3 is the result of optimization of the extraction conditions of the microextraction probe of Example 4. Figure a is the influence of the oscillation speed on the extraction efficiency, figure b is the influence of the extraction temperature on the extraction efficiency, figure c is the investigation of the extraction equilibrium time, and figure d is the solution. Effect of pH and salinity on extraction efficiency;

FIG. 4 is an atomic absorption spectrum chart of eight standard solid phase extraction probes prepared in Example 1 combined with a portable mercury detector for headspace extraction to determine a standard concentration of 1 μg / L mercury standard solution.

detailed description

The present invention will be further illustrated with reference to specific examples. It should be understood that these embodiments are only used to illustrate the present invention, and are not used to limit the protection scope of the present invention. The improvements and adjustments made by a technician according to the present invention in actual applications still belong to the protection scope of the present invention.

Unless otherwise specified, the reagents, raw materials, and instruments used in the present invention can be obtained from publicly available sources.

Reagent: Mercury standard solution (1000mg / L, National Standard Center of China, China); chloroauric acid, sodium citrate, sodium borohydride, stannous chloride (Aladdin Chemical Co., Ltd., China).

Raw materials: wooden sign (birch toothpick).

Instrument: portable mercury analyzer, purchased from Lumex (Russia), model: RA-915 ⁺ (including PYRO-915 ⁺ thermal desorption module). The technical principle of instrumental mercury measurement is the use of high-frequency polarization Zeeman effect background correction technology, based on the principle of mercury atom absorption of 254nm resonance emission line, quantitative analysis of mercury.

Example 1

The preparation of a solid-phase microextraction probe with nano-gold modified wooden sign includes the following steps:

(1) Preparation of nano-gold solution using sodium borohydride to reduce chloroauric acid: First, all glassware is soaked with aqua regia to remove reducing substances that may remain on the container wall. At room temperature, accurately weigh 8.8 mg of chloroauric acid In a 50mL beaker, then add 30mL of ultrapure water and 1.0mL of sodium citrate (sodium citrate concentration: 40mmol / L) solution. After vigorous stirring for 5min, add 0.5mL of the newly prepared solution dropwise to the above mixed solution. Sodium borohydride (sodium borohydride concentration is 40mmol / L) solution. After adding sodium borohydride to the mixed solution, the color of the solution gradually changed from light yellow to purple gray and finally wine red. After turning into wine red, continue stirring for 10 minutes and then stop That is, a nano-gold solution is obtained. The synthesized nano-gold solution is allowed to stand at room temperature for 2 hours and stored at 4 ° C. The concentration of the nano-gold synthesized by the above method is 167 ± 3.2 mg / L.

(2) Select a commercial two-pointed wooden toothpick (5.0cm in length and 2.0mm in diameter) without any treatment, and break it from the middle to obtain two segments of one-pointed wooden toothpick as the nano-gold particle carrier;

(3) The toothpick obtained in step (2) was completely immersed in the nano-gold solution obtained in step (1), kept for 1.0 min, and then taken out, and allowed to air-dry at room temperature for 10 min to obtain a solid-phase microextraction probe for the nano-gold modified wooden sign needle.

FIG. 1 is a scanning electron microscopy (SEM) image of the solid-phase microextraction probe prepared in this example, which shows that at a magnification of 100 × (FIG. 1B), the surface of the wooden sign is wrinkled and porous, and the diameter of the tip is 0.5mm. At a magnification of 500 × (Figure 1C), the porous structure of the wooden sign is more obvious, and it can be seen that particulate matter is distributed in the pores. FIG. 2 is the energy spectrum (EDS) of the solid-phase microextraction probe prepared in this example. Elemental analysis of the prepared solid-phase microextraction probe by EDS can clearly see the signal of gold, and at the same time can be seen The mass percentage of gold is 1.45%, which proves that gold nano-particle clusters are attached to the wood-wood signature matrix.

Example 2

It is the same as Embodiment 1, except that:

The specific step of step (1) is to prepare a nano-gold solution by reducing chloroauric acid with sodium borohydride: First, all glassware is soaked with aqua regia to remove reducing substances that may remain on the container wall. At room temperature, accurately weigh 8.8 mg of chloroauric acid was placed in a 50 mL beaker, and then 30 mL of ultrapure water and 1.0 mL of a solution of sodium citrate (sodium citrate concentration: 40 mmol / L) were added to the beaker. After vigorously stirring for 10 minutes, was added dropwise to the above mixed solution. 0.5mL of freshly prepared sodium borohydride (sodium borohydride concentration is 40mmol / L) solution. After adding sodium borohydride to the mixed solution, the color of the solution gradually changes from light yellow to purple gray and finally wine red. Continue stirring for 15min and stop, to get nano gold solution;

The specific step of step (3) is to completely immerse the toothpick obtained in step (2) in the nano-gold solution obtained in step (1), keep it for 20 minutes, then take it out, and leave it to stand for 30 minutes at room temperature to air dry to obtain a solid gold-modified wooden sign. Phase microextraction probe.

Example 3

Headspace extraction and micro-extraction probes combined with a portable mercury detector for the determination of mercury ions in environmental water samples

Headspace extraction includes the following steps:

(1) Measure 5 mL of mercury standard solution or water sample to be tested in a 20 mL universal screw-top headspace bottle, add 1.0 mL of stannous chloride 5% by weight stannous chloride hydrochloric acid solution, and quickly tighten the top Empty bottle cap

(2) Quickly pierce the solid-phase microextraction probe of the nano-gold modified wooden sign prepared in Example 1 through the silica gel septum pad on the headspace bottle cap, wherein the length of the solid-phase microextraction probe exposed in the headspace is 15.0mm;

(3) Place the headspace bottle on a reciprocating shaker, and extract at room temperature for 10 min at a shaking speed of 250 r / min.

Analysis of portable mercury detector with micro-extraction probe:

Take out the solid-phase microextraction probe enriched in the headspace bottle and transfer it to the quartz sample boat of the thermal desorption module of the portable mercury detector. Carrier gas type: air; carrier gas flow rate: 1.0L / min; absorption line wavelength: 253.7nm; total detection optical path: 40cm; integration time: 30s, external standard method for quantification.

Example 4

Study on Optimization of Headspace Extraction Conditions

2 μg / L of mercury ions were added to ultrapure water to study the effects of different extraction conditions (oscillation speed, extraction temperature, extraction time, solution pH and solution salinity) on extraction efficiency (Figure 3). The extraction efficiency is expressed in terms of the peak area.

In this example, the extraction efficiency was studied at different oscillation speeds (0 rpm, 60 rpm, 120 rpm, 150 rpm, 180 rpm, 210 rpm, 240 rpm, 270 rpm, 300 rpm). As shown in Figure 3a, the extraction efficiency increases with increasing oscillation speed.

This embodiment simultaneously studies the extraction efficiency at different extraction temperatures (25 ° C, 35 ° C, 45 ° C, 55 ° C, 65 ° C, 75 ° C). As shown in Figure 3b, an appropriate increase in temperature is conducive to the improvement of extraction efficiency, but when it reaches a certain temperature (55 ° C), it continues to increase the extraction efficiency but decreases, indicating that the partition coefficient between the microextraction probe and mercury vapor is reduced.

This example also investigated the effect of extraction time (Figure 3c). The extraction efficiency increased with the increase of extraction time, and reached a dynamic equilibrium at 10 minutes.

This example finally studies the extraction efficiency of the solution pH (4, 5, 6, 7, 8, 9) and salinity conditions (0, 1%, 3%, 5%, 10%, 15%, 20%). Impact. As shown in Figure 3d, pH and salinity have no significant effect on extraction efficiency.

Example 5

Study on the Performance of Headspace Extraction Method

Mercury ions were added to ultrapure water at a concentration range of 0.2 to 10 μg / L, and the linear range, minimum detection limit, and limit of quantification of the extraction method were studied. The results show that the method of the invention has a good linear relationship and the correlation coefficient (r ² ) is 0.9999. The minimum detection limit and the limit of quantification were 0.06 μg / L and 0.19 μg / L, respectively (determined by the peak concentration at 3 times and 10 times the standard deviation of the blank solution for 11 consecutive measurements). Table 1 compares the performance of this method and other instrumental methods for direct measurement of mercury. The results show that the solid-phase microextraction probe used in this method combined with a portable mercury detector can achieve or exceed the mercury measurement capabilities of conventional laboratory instruments. . In addition, because the solid-phase microextraction technology involved in this method integrates sample sampling, extraction, and pre-enrichment, it does not require the use of relatively complicated equipment such as chemical vapor generation and gas-liquid separators, which further improves the portability of experimental equipment And field performance.

Table 1

1 μg / L of mercury ion was added to ultrapure water to study the reproducibility between different probes. Eight different microextraction probes were prepared by the method described in Example 1. The experimental results shown in Figure 4 The method has good reproducibility, and the RSDs are 2.1%.

In this embodiment, the anti-interference ability of the micro-extraction probe is also studied, and 15 kinds of ions such as alkali metal, alkaline earth metal and transition metal ions widely present in environmental water are used as matrix interference. These cations in the water can easily form a metal state or corresponding metal colloids to adsorb mercury during the reduction derivatization process, thereby affecting the extraction efficiency. The concentration of mercury ion in the experiment was 2 μg / L, and the concentration of other 15 kinds of interference ions (potassium, calcium, sodium, magnesium, iron, aluminum, nickel, copper, zinc, manganese, cobalt, chromium, cadmium, antimony and arsenic) was 5 mg / At L, the recovery of mercury ions was examined. The experimental results show that the headspace extraction recovery of mercury ions is 92.9% -101.8% in the presence of interfering ions.

The above results show that the microextraction probe of the present invention meets the analysis requirements for trace mercury ions in environmental water bodies.

Example 6

Study on Extraction Capability of Water Samples in Real Environment

Take the solid-phase microextraction probe prepared in Example 1 and use the extraction conditions in Example 3 to extract standard water samples GBW080042 and GSB07-3173-2014 and tap water, lake water, seawater, and tannery with a mercury spiked concentration of 1 μg / L. Wastewater, the measurement results are shown in Table 2:

Table 2

From the experimental results in Table 2, it can be seen that the measured values of the standard water samples are in good agreement with the certified values. No mercury ions were detected in the tap water, lake water, sea water, and wastewater. When the sample spiked concentration was 1 μg / L, the spiked recovery rate was It is 91.3% to 106%, which indicates that the solid-phase microextraction probe prepared in Example 1 is suitable for the determination of mercury in water samples in different matrix environments.

The detailed description above is a specific description of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or change that does not depart from the present invention should be included in the patent protection of this case. In range.

Claims

A solid-phase microextraction probe with a nano-gold modified wooden sign is characterized in that it includes a carrier and an adsorption material, the carrier is a wooden sign material, the adsorption material is gold nanoparticles, and the adsorption material passes Van der Waals forces are attached to the channels on the surface of the carrier.
The method for preparing a solid-phase microextraction probe of a nano-gold modified wooden sign according to claim 1, comprising the following steps:

(1) Nano-gold solution was prepared by reducing chloroauric acid with sodium borohydride;

(2) A wooden sign with a length of 2 to 5 cm and a tip diameter of 0.3 to 0.5 mm is selected as a carrier;

(3) The wooden sign described in step (2) is completely immersed in the nano-gold solution prepared in step (1), maintained for 1.0-20 minutes, and then taken out, and left at room temperature for 10-30 minutes to obtain the nano-gold modification. Solid-phase microextraction probe on wooden sign.
The method for preparing a solid-phase microextraction probe of a nano-gold modified wooden sign according to claim 2, characterized in that the specific preparation steps of the nano-gold solution in step (1) are as follows: After adding ultrapure water and sodium citrate solution to the acid and stirring for 5-10 minutes, add the sodium borohydride solution dropwise to the above mixed solution. The solution after adding sodium borohydride gradually changes from light yellow to finally wine red. After the solution of sodium hydride becomes wine red, stirring is continued for 7-15 minutes and stirring is stopped to obtain a nano-gold solution.
The method for preparing a solid-phase microextraction probe of a nano-gold modified wooden sign according to claim 3, wherein the concentration of the nano-gold prepared by the sodium borohydride reduction method is 150-200 mg / L.
Application of the solid-phase microextraction probe of the nano-gold modified wooden sign according to claim 1.
The application of the solid-phase microextraction probe of the nano-gold modified wooden sign according to claim 5, wherein the solid-phase microextraction probe is used for the determination of mercury ions in water samples.
The application of the solid-phase microextraction probe of the nano-gold modified wooden sign according to claim 6, wherein the determination of mercury ions in the water sample comprises the following steps:

(1) Measure 5.0 to 10.0 mL of a standard mercury solution or a water sample to be measured into a headspace bottle, and add 0.5 to 1.0 mL of a stannous chloride solution with a mass fraction of 1% to 10%;

(2) pierce the prepared solid-phase microextraction probe of the nano-gold modified wood sign through the silica gel septum pad on the headspace bottle cap, and the solid-phase micro-extraction probe of the nano-gold modified wood sign The length of the wooden sign carrier exposed outside the headspace bottle is 5.0 ～ 20mm, and the headspace bottle is extracted at a shaking speed of 150 ～ 300r / min for 5.0 ～ 30min;

(3) Take out the solid-phase microextraction probe of the nano-gold modified wooden sign enriched in the headspace bottle, and measure the mercury ion.
The application of the solid-phase microextraction probe of the nano-gold modified wooden sign according to claim 7, characterized in that the specific measurement step of step (3) is: removing the enriched nano-gold modified wooden sign from the headspace bottle. Solid-phase micro-extraction probe, transfer the nano-gold-modified wooden sign solid-phase micro-extraction probe to the quartz sample boat of the thermal desorption module of the portable mercury detector, measure the mercury ion, and set the thermal desorption temperature of 680 ℃ ～ 740 ℃, air flow rate 0.8 ～ 1.2L / min.