CN107543747B - Rapid microwave-assisted filtering device and method - Google Patents
Rapid microwave-assisted filtering device and method Download PDFInfo
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- CN107543747B CN107543747B CN201710738456.1A CN201710738456A CN107543747B CN 107543747 B CN107543747 B CN 107543747B CN 201710738456 A CN201710738456 A CN 201710738456A CN 107543747 B CN107543747 B CN 107543747B
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Abstract
A sample pretreatment device and a method for simultaneously carrying out rapid auxiliary filtration on a plurality of samples by using microwave energy in a dynamic mode belong to the technical field of rapid microwave auxiliary filtration devices. The device consists of a filtrate storage tank, a first multi-path peristaltic pump and a second multi-path peristaltic pump which are provided with the same number of passages, a microwave oven, a filtrate tube, a pipeline pressure sensor, a filter, a two-position three-way valve body, a waste liquid collecting tank, a filtrate collecting tube, a first vacuum cavity, a second vacuum cavity, a vacuum pump, a connecting pipeline and a connecting accessory; the flow velocity of the filtrate entering the filtering tube and sucking the filtering tube is controlled by controlling the flow velocity of the two multi-path peristaltic pumps, so that static microwave-assisted filtering, dynamic microwave-assisted filtering and static/dynamic microwave-assisted mixed filtering can be realized, and the phenomena of reverse running, acceleration of flow velocity and the like of the filtered filtrate in a pipeline, which are caused by thermal expansion of the filtered filtrate after microwave irradiation, can be avoided. Can filter a plurality of samples simultaneously and get, improve the efficiency of handling the sample.
Description
Technical Field
The invention belongs to the technical field of rapid microwave-assisted filtering devices, and particularly relates to a sample pretreatment device and a sample pretreatment method for simultaneously performing rapid assisted filtering on a plurality of samples by using microwave energy in a dynamic mode.
Background
With the rapid development of global economy, the accompanying environmental pollution has gradually affected human health through the accumulation of organisms in the food chain. Therefore, people pay more attention to detecting and monitoring the content of heavy metal elements in grains. The detection and analysis of heavy metals in grain is a very challenging subject, and the heavy metal elements and other inorganic/organic components in grain are in a combined state, so how to completely separate the heavy metal elements from a matrix and integrate the heavy metal elements into a solution for measurement by methods such as atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry and the like is a difficult problem which is widely researched.
Because the traditional wet digestion method has complex operation process, the high temperature in the digestion process easily causes volatile element volatilization loss and the pollution of concentrated acid steam to the environment under an open system, the grain sample is digested by adopting a microwave-assisted digestion method, and the microwave-assisted digestion method can be divided into a high-pressure closed microwave-assisted digestion method, a microwave-induced combustion method, a focused microwave acid steam digestion method, a microwave-assisted ultraviolet radiation digestion method and the like:
1) the high-pressure closed microwave-assisted digestion method utilizes microwave energy to digest a sample in a closed container under high-temperature and high-pressure conditions. It has the advantages of high heating speed, less pollution, less volatile element evaporation loss, etc. However, concentrated acid still needs to be used in the digestion process, a closed container for digestion needs to be opened after the temperature is reduced to room temperature, the solution obtained by digestion still needs to be subjected to evaporation, centrifugation and filtration processes for instrument testing, and potential harm is caused to operators if high-temperature and high-pressure equipment is improperly operated;
2) the microwave-induced combustion method utilizes heat energy generated by microwaves to ignite a sample in a pure oxygen-containing container, and organic matters in the sample are decomposed through combustion. Although the whole process does not need the participation of concentrated acid, the residue still needs proper acid solution dissolution and subsequent treatment, and meanwhile, the flux of the treated sample is less, and the measurement of volatile elements is influenced;
3) the focused microwave acid vapor digestion method is to utilize microwave energy to heat an acid solution to evaporate the acid solution and utilize the evaporated acid vapor to digest a sample, and the consumption of the digestion solution is small, so background interference caused by the acid solution is eliminated, and a detection line is reduced, but the problems of acid vapor generated in the operation and long operation time are also problems to be solved;
4) the microwave-assisted ultraviolet digestion method simultaneously utilizes the combined action of microwave energy and ultraviolet radiation to carry out digestion treatment on the sample. Although the use amount of concentrated acid is small and the digestion effect of a sample which is not easy to be processed by a common ultraviolet digestion method is good, the problems that an instrument is complex, the operation is complex, the flux of the processed sample is small, the measurement of volatile elements is influenced and the like exist.
The microwave-assisted digestion method widely used at present has the defects of complex device, small sample processing flux, influence on measurement of volatile elements, complicated steps of acid evaporation, filtration, transfer and the like of digestion solution before the next detection and the like. The multi-channel dynamic microwave-assisted filtration method has the characteristics of rapid filtration, small reagent dosage, no use of concentrated acid filtration agent, short filtration time, good effect on volatile elements, capability of simultaneously processing a plurality of samples and the like.
Disclosure of Invention
The invention aims to provide a rapid microwave-assisted filtering device and a rapid microwave-assisted digestion method, which are used for solving the problems that most of the existing microwave-assisted digestion methods are complex in device, small in sample processing flux, influenced in measurement of volatile elements, and still need to perform complicated steps such as acid evaporation, filtration and transfer before next detection.
The rapid microwave-assisted filtering device consists of a filtering liquid storage tank 1, a first multi-path peristaltic pump 31 and a second multi-path peristaltic pump 32 which are provided with the same number of passages, a microwave oven 4, a filtering pipe 5, a pipeline pressure sensor 6, a filter 7, a two-position three-way valve body 8, a waste liquid collecting tank 11, a filtering liquid collecting pipe 12, a first vacuum cavity 9, a second vacuum cavity 10, a vacuum pump 13, a pipeline and connecting accessories;
the liquid filtering and taking tank 1 is positioned at the foremost end of the rapid microwave-assisted filtering and taking device, the first multi-path peristaltic pump 31 is positioned at the right side of the liquid filtering and taking tank 1, and a plurality of input passages of the first multi-path peristaltic pump are respectively connected with the liquid filtering and taking tank 1 through the second pipeline 202, the first connecting accessory 2 and the first pipeline 201; the microwave oven 4 is positioned at the right side of the first multi-path peristaltic pump 31 and the second multi-path peristaltic pump 32, and the upper end of the filtering tube 5 positioned in the cavity of the microwave oven 4 is respectively connected with a plurality of output channels of the first multi-path peristaltic pump 31 through a third pipeline 203; the pressure sensor 6 is positioned below the microwave oven 4, and the lower end of the filtering pipe 5 is connected with the upper end of the pipeline pressure sensor 6 through a fourth pipeline 204; the lower end of the pipeline pressure sensor 6 is respectively connected with a plurality of input channels of the second multi-channel peristaltic pump 32 through a fifth pipeline 205; the second multi-path peristaltic pump 32 is positioned above the first multi-path peristaltic pump 31; the filter 7 is positioned at the right side of the microwave oven 4, and the upper end of the filter is connected with a plurality of output channels of the second multi-channel peristaltic pump 32 through a sixth pipeline 206; the two-position three-way valve body 8 is positioned below the filter 7, and the inlet at the upper end of the two-position three-way valve body is connected with the lower end of the filter 7 through a seventh pipeline 207; the first vacuum cavity 9 and the second vacuum cavity 10 are positioned at the lower side of the two-position three-way valve body 8, a waste liquid collecting tank 11 is arranged in the first vacuum cavity 9, a filtered liquid collecting pipe 12 is arranged in the second vacuum cavity 10, the waste liquid collecting tank 11 is connected with a first valve body outlet at the lower end of the two-position three-way valve body 8 through an eighth pipeline 208, a second connecting accessory 14 and a tenth pipeline 210, and the filtered liquid collecting pipe 12 is connected with a second valve body outlet at the lower end of the two-position three-way valve body through a ninth pipeline 209; the vacuum pump 13 is located at the very end of the whole apparatus and is connected to the first vacuum chamber 9 and the second vacuum chamber 12 through an eleventh line 211, all the liquid connection lines satisfying the communicating vessel principle. The number of the leaching pipes 5, the pipeline pressure sensor 6, the filter 7, the two-position three-way valve body 8, the second pipeline 202, the third pipeline 203, the fourth pipeline 204, the fifth pipeline 205, the sixth pipeline 206, the seventh pipeline 207, the eighth pipeline 208, the ninth pipeline 209 and the leaching liquid collecting pipes 12 is the same as that of the multi-way peristaltic pump channels.
The connection mode of a plurality of passages from the outlets of the plurality of passages of the first multi-path peristaltic pump 31 to the upper end of the filtering tube 5 and a plurality of passages from the lower end of the filtering tube 5 to the second multi-path peristaltic pump 32 realizes the control of the flow rate of the filtering liquid entering the filtering tube and sucking out the filtering tube by controlling the flow rate of the two multi-path peristaltic pumps, can realize static microwave-assisted filtering, dynamic microwave-assisted filtering and static/dynamic microwave-assisted mixed filtering, and can avoid the phenomena of reverse movement, accelerated flow rate and the like of the filtering liquid in the pipeline caused by the heated expansion of the filtering liquid after microwave irradiation;
the filtering pipe, the connecting pipeline and the connecting accessories are all made of plastic materials and do not absorb microwave energy;
the first multi-path peristaltic pump 31 and the second multi-path peristaltic pump 32 are both purchased from Baoding Shenchen Pump industry Co., Ltd, and have the model number of BT10N/MC6, and can drive 6 pump tubes to pump liquid at the same speed and direction through a single peristaltic pump shaft, wherein the rotating speed range is 0.5-150 rpm, and the flow range is 0.0046-7.03 mL min-1；
The microwave oven 4 is a customized product, the interior of the microwave oven is designed to be a flat plate type, the microwave power can be adjusted and continuously output, the power output range is 0-2000W, and the volume of the cavity is 50-100L;
the filtration tube 5 is purchased from Tianjin Bonner Aijiel technology ltd, and is a FCH004I type hand-screwed purification column product, and consists of a column head and a column tube, wherein the column head and a main tube can be sealed by hand (high pressure resistance: 180psi), an upper sieve plate and a lower sieve plate (the diameter of the sieve plate is 10-40 mu m, and the thickness is 1-3 mm) can be plugged in the column, and other types of filtration tubes can be adopted according to different application methods; the filtering tube is a device for containing samples, so that the filtering liquid and the samples can be fully mixed under the cooperation of the whole system, and microwave irradiation can be fully received, so that the powder samples can not flow out along with the filtering liquid in the filtering process, and the aim of improving the filtering/extracting efficiency is fulfilled;
the pipeline pressure sensor 6 is purchased from American OMEGA company, the model is PX309 customized type, a self-contained connector can be connected with a pipeline system, the measuring range is 5-10000 psi, and the working temperature is-40-85 ℃; the pressure in the pipeline can be monitored, and the phenomenon of leakage caused by overhigh pressure in the system due to pipeline blockage is avoided;
the filter 7 can further ensure the cleanliness of the collected filtrate, and sieve plates with different apertures (such as 10-40 μm) and thicknesses (1-3 mm) can be arranged in the filter according to different filtered samples, so as to ensure the cleanliness of the filtrate; for relatively clean samples, SPE empty columns can be used as substitutes;
the two-position three-way valve body 8 is purchased from high-sand electric (Suzhou) limited company, is of the type WTB-3K-M6G, is driven by 24V direct current, and is provided with 1 valve body inlet and 2 valve body outlets (a first valve body outlet and a second valve body outlet), wherein the valve body keeps the valve body inlet communicated with the first valve body outlet when not electrified, and is switched to be communicated with the second valve body outlet after being electrified;
and a first valve body outlet and a second valve body outlet of the two-position three-way valve body 8 are respectively connected with a waste liquid collecting tank 11 and a filtrate collecting pipe 12 which are arranged in the two vacuum cavities. By controlling the power-on (open and close) state of the two-position three-way valve body 8, waste liquid exceeding the collection amount required by the experimental method in the system pipeline flushing process and the filtration/extraction process can be introduced into the waste liquid collection tank 11 through the eighth pipeline 208, the second connecting accessory 14 and the tenth pipeline 210; the energization (opening and closing) state of the two-position three-way valve body 8 is controlled, and the filtered liquid can also be guided into the filtered liquid collecting pipe 12 through the ninth pipeline 209, so that the separation of the waste liquid and the filtered liquid is realized, and the possibility of pollution to the collected filtered liquid is avoided;
the liquid path connecting pipelines are all Polytetrafluoroethylene (PTFE) pipes with the inner diameter of 0.8mm and the outer diameter of 1.2mm, and the residue of filtrate in the pipelines can be reduced due to special materials and smaller inner diameter;
the filter 7 can be replaced by a commercially available Solid-Phase Extraction (SPE) cartridge/empty cartridge: the commercially available SPE cartridge can be selected from products with different bonded silica gel fillers such as C18, C8 and the like according to the target filter extract; the SPE hollow column can adopt different specifications such as 1mL, 3mL and 6mL according to different methods, and is matched with sieve plates with different pore diameters (10-40 μm) to be filled with extraction fillers such as self-made sulfonated resin and the like. The on-line separation, enrichment and/or purification treatment of the filtered liquid is realized by replacing the filler and/or the sieve plate in the filter 7.
The first connecting accessory 2 and the second connecting accessory 14 are made of polytetrafluoroethylene blocks and are regular hexagonal prisms; the schematic structural diagram is shown in fig. 2, and it can be seen from the top view that the projection is a regular hexagon with a side length of 25mm, and there are 6 connecting holes perpendicular to each side surface, and the connecting holes are respectively connected with the second pipeline 202 (or the eighth pipeline 208); as seen from the front view, the thickness of the pipe is 30mm, and 1 connecting hole is arranged perpendicular to the top surface of the regular hexagonal prism and is connected with the first pipeline 201 (or the tenth pipeline 210); as can be seen from the isometric view, the 7 holes are communicated with each other in the first connecting accessory 2 and the second connecting accessory 14, and play the roles of dividing the liquid path into 1 and 6 and combining the liquid path into 1; by connecting and removing the first connecting accessory 2, the multi-channel pumping of the same filtrate and the pumping of different filtrates by different channels can be realized;
the liquid circuit pipeline connection all adopts a standard microfluidic connection kit produced by Beion fluid company: a gasket (polytetrafluoroethylene, internal diameter 1.2mm), a flange joint (PP) and a joint sleeve connection (PP), which can withstand pressures up to 200Mpa and chemical corrosion;
a method for filtering by using the rapid microwave-assisted filtering device comprises the following steps:
(1) firstly, a lower sieve plate with the aperture of 10-40 mu m and the thickness of 1-3 mm is placed in a filtering tube 5 and compacted, then a sample is weighed and transferred into the filtering tube, an upper sieve plate with the aperture of 10-40 mu m and the thickness of 1-3 mm is placed in the filtering tube 5 and compacted, and then the filtering tube 5 is connected into a pipeline and placed in a cavity of a microwave oven 4;
(2) preparation of the system: sequentially turning on the power supplies of the first multi-path peristaltic pump 31, the second multi-path peristaltic pump 32, the microwave oven 4, the two-position three-way valve 8 and the vacuum pump 13 and setting working parameters thereof to enable the pumps to be in a standby state;
(3) filtering: filling the filtrate into a filtrate storage tank 1, sequentially starting a vacuum pump 13, a first multi-path peristaltic pump 31 and a second multi-path peristaltic pump 32 to enable the filtrate to enter a pipeline, starting a microwave oven 4 to perform microwave irradiation after the filtrate infiltrates a sample in a filtrate tube 5, and sequentially closing the first multi-path peristaltic pump 31, the second multi-path peristaltic pump 32, a two-position three-way valve body 8, the microwave oven 4 and the vacuum pump 13 when the filtrate with a required volume is collected in a filtrate collection tube 12, thereby realizing rapid microwave-assisted filtration of the sample.
Compared with the prior art, the rapid microwave-assisted filtering device disclosed by the invention has the following advantages:
1. the device can accurately control the flow velocity of the filtered liquid entering and exiting the filtering pipe during filtering, so that the use of dilute acid solution (generally hydrochloric acid aqueous solution, nitric acid aqueous solution and diluted aqua regia are used as filtering solution) to replace concentrated acid solution in the traditional digestion method becomes possible;
2. the filtering efficiency of the volatile elements is obviously improved because a dynamic filtering mode is adopted;
3. complex operations such as transferring, acid dispelling and the like which are necessary in the traditional digestion process are avoided;
4. a plurality of samples can be filtered simultaneously, so that the efficiency of sample treatment is improved;
5. the required filtering liquid volume is small, so that the background interference caused by acid liquor is reduced;
6. static microwave-assisted filtration, dynamic microwave-assisted filtration and static/dynamic microwave-assisted hybrid filtration of samples can be realized by controlling different flow rates of two peristaltic pumps in the system.
(1) Static microwave-assisted filtration: firstly, the running speed of a first multi-path peristaltic pump 31 is higher than that of a second multi-path peristaltic pump 32, so that the purpose that a sample in a filtering pipe 5 is immersed by a filtering liquid is achieved, then the first multi-path peristaltic pump 31 and the second multi-path peristaltic pump 32 stop working simultaneously, a microwave oven 4 is started to perform microwave irradiation on the sample, and at the moment, a static microwave-assisted filtering process is performed in the filtering pipe 5;
(2) the dynamic microwave-assisted filtration process: firstly, the running speed of a first multi-path peristaltic pump 31 is higher than that of a second multi-path peristaltic pump 32, so that the purpose that a sample in a filtering pipe 5 is immersed by a filtering liquid is achieved, then the first multi-path peristaltic pump 31 and the second multi-path peristaltic pump 32 start to work at the same speed, a microwave oven 4 is started to perform microwave irradiation on the sample, and at the moment, a dynamic microwave-assisted filtering process is performed in the filtering pipe 5;
(3) static/dynamic microwave assisted hybrid filtration process: firstly, the running speed of the first multi-path peristaltic pump 31 is made to be higher than that of the second multi-path peristaltic pump 32, so that the purpose that a sample in the filtering pipe 5 is immersed by the filtering liquid is achieved, then the first multi-path peristaltic pump 31 and the second multi-path peristaltic pump 32 stop working at the same time, the microwave oven 4 is started to carry out microwave irradiation on the sample, after the specific irradiation time, the first multi-path peristaltic pump 31 and the second multi-path peristaltic pump 32 are started to work at the same speed, and at the moment, a static/dynamic microwave-assisted hybrid filtering process is carried out in the filtering pipe 5.
Drawings
FIG. 1: the device of the invention has a schematic overall structure;
FIG. 2: a schematic view of the first attachment accessory 2 and the second attachment accessory 14; wherein (a) is a front view; (b) is a top view; (c) is a perspective view;
Detailed Description
Example 1: constitution example of rapid microwave auxiliary filtering device
Referring to fig. 1, a filtration liquid storage tank 1 is located at the foremost end of the device, a first multi-path peristaltic pump 31 is located at the right side of the storage tank 1, and input channels 1 to 6 of the first multi-path peristaltic pump are connected with the filtration liquid storage tank 1 through a second pipeline 202, a first connecting accessory 2 and a first pipeline 201; the microwave oven 4 is positioned at the right side of the first multi-path peristaltic pump 31, and the upper end of the filtering pipe 5 positioned in the cavity of the microwave oven 4 is connected with No. 1 to No. 6 output passages of the first multi-path peristaltic pump 31 through a third pipeline 203; the lower end of the filtering pipe 5 is connected with the upper end of the pipeline pressure sensor 6 through a fourth pipeline 204; the lower end of the pipeline pressure sensor 6 is connected with No. 1 to No. 6 input channels of the second multi-way peristaltic pump 32 through a fifth pipeline 205; the filter 7 is positioned at the right side of the microwave oven 4, and the upper end of the filter is connected with No. 1 to No. 6 output passages of the second multi-path peristaltic pump 32 through a sixth pipeline 206; the two-position three-way valve body 8 is positioned below the filter 7, and the inlet at the upper end of the two-position three-way valve body is connected with the lower end of the filter 7 through a seventh pipeline 207; the first vacuum cavity 9 and the second vacuum cavity 10 are positioned at the lower side of the two-position three-way valve body 8, wherein the first vacuum cavity 9 is provided with a waste liquid collecting tank 11, the second vacuum cavity 10 is provided with a filtered liquid collecting pipe 12, the waste liquid collecting tank 11 is connected with a first valve body outlet at the lower end of the two-position three-way valve body 8 through an eighth pipeline 208, a second connecting accessory 14 and a tenth pipeline 210, and the filtered liquid collecting pipe 12 is connected with a second valve body outlet at the lower end of the two-position three-way valve body 8 through a ninth pipeline 209; the vacuum pump 13 is located at the extreme end of the instrument and is connected to the first vacuum chamber 9 and the second vacuum chamber 10 via an eleventh line 211, all fluid connections satisfying the communicating vessel principle.
The number of the filtering pipes 5, the pipeline pressure sensor 6, the filter 7, the two-position three-way valve body 8, the second pipeline 202, the third pipeline 203, the fourth pipeline 204, the fifth pipeline 205, the sixth pipeline 206, the seventh pipeline 207, the eighth pipeline 208, the ninth pipeline 209 and the filtering liquid collecting pipes 12 is 6, and is the same as that of the multi-way peristaltic pump channels.
Example 2: the device is used for filtering various metal elements in the standard rice sample
According to the method, a multi-channel rapid filtering method is adopted to determine the content of a plurality of metal elements (Cu, Mn, Zn, Ni and Cd) in a standard rice sample (GBW (E)100348-100362 purchased from a institute for analysis and test of the Steel research institute), and the specific operation steps are as follows:
and (3) processing of a sample: the standard sample does not need special treatment;
the packing of the leaching tube 5 (part 7 can be purchased as a finished product, or the solid-phase extraction cartridge itself can be purchased as a packing, part 7 not being described indicating that the solid-phase extraction cartridge used in part 7 in the present method of use is a solid-phase extraction cartridge): firstly, a lower sieve plate (with the aperture of 30 mu m and the thickness of 1.5mm) is placed in a filtering tube and compacted, then a 0.2g standard rice sample is weighed and transferred into the filtering tube, an upper sieve plate (with the aperture of 30 mu m and the thickness of 1.5mm) is placed in the filtering tube and compacted, and then the filtering tube is connected into a pipeline and placed in a microwave cavity;
preparation of the system: the power supply of the first multi-path peristaltic pump 31, the second multi-path peristaltic pump 32, the microwave oven 4, the two-position three-way valve 8 and the vacuum pump 13 is sequentially turned on, and the working parameters are set to be in a standby state, for example, the flow rate of the peristaltic pump is set to be 1.0mL min in the embodiment-1The power of the microwave oven is 350W; the flow rate of the vacuum pump 13 is 20L min-1；
Filtering: according to the method, a 20% (v/v) nitric acid aqueous solution is used as a filtering liquid, the filtering liquid is filled into a filtering liquid storage tank 1, then a vacuum pump 13, a first multi-path peristaltic pump 31 and a second multi-path peristaltic pump 32 are sequentially started to enable the filtering liquid to enter a pipeline, after the filtering liquid soaks a standard rice sample in a filtering pipe 5, a microwave oven 4 is started to perform microwave irradiation (dynamic microwave-assisted filtering is performed in the embodiment, the purpose is to keep the dynamic balance of the filtering liquid in the filtering pipe as much as possible, so that the filtered target filtering liquid is transferred out of the filtering pipe as soon as possible to avoid the loss of easily pyrolyzed elements), and when 10mL of filtering liquid is collected in a filtering liquid collecting pipe 12, the first multi-path peristaltic pump 31, the second multi-path peristaltic pump 32, the microwave oven 4 and the vacuum pump 13 are sequentially closed;
detection of heavy metal components: the filtrate collection tube 12 was removed from the second vacuum chamber 10, and the filtrate was diluted to 25mL with deionized water and centrifuged, and after passing through a 0.45 μm acid-resistant filter, detected by ICP-OES.
Flushing of the system: after filtration, replacing the filtration tube 5 with a clean empty tube, starting the first multi-path peristaltic pump 31, the second multi-path peristaltic pump 32 and the vacuum pump 13, switching the two-position three-way valve body 8 to the outlet position of the first valve body, and adopting 50% ethanol water solution (volume ratio) and pure deionized water for 2mL min-1The system pipeline is washed in sequence, and the washing liquid enters the waste liquid collecting tank 11.
The filtration rate: calculated as follows, data are shown in table 1:
CMTDMAL: the concentration of heavy metal (Cu, Mn, Zn, Ni and Cd) elements in a standard rice sample measured by the rapid microwave-assisted leaching device is measured
CReference: the concentration of heavy metal (Cu, Mn, Zn, Ni and Cd) elements in the same standard rice sample is measured by a national standard method (GB 5009.15-2014)
TABLE 1 measurement of national Standard Rice flour sample (GBW (E)100357)
| Element(s) | CReferencemg kg-1 | CMTDMALmg kg-1 | Percent leaching/percent |
| Cu | 4.3±0.2 | 3.61±0.2 | 84.0 |
| Cd* | 2.16±0.06 | 1.46±0.05 | 67.6 |
| Mn | 14.0±0.4 | 11.9±0.3 | 85.0 |
| Zn | 22.1±0.3 | 17.4±0.6 | 78.7 |
| Ni | 1.06±0.08 | 0.89±0.05 | 84.0 |
*All values in the standard tables are mean (n-3) ± standard deviation (mg kg-1 dry basis)
Example 3: the device is used for filtering various metal elements in the rice samples sold on the market
In order to verify the practical application effect of the method, the method is adopted to test the practical sample and compare the practical sample with the national standard method (GB 5009.15-2014). Table 2 shows the results of comparing the metallic elements Cu, Mn, Zn, Ni and Cd in three rice samples purchased from local markets, measured by the national standard method (GB 5009.15-2014) and the rapid microwave-assisted extraction device according to the present invention. The specific operation steps are as follows:
and (3) processing of a sample: grinding a rice sample purchased from a local supermarket into powder, and sieving the powder by a 40-mesh sieve to be detected;
filling of the straining tube 5: first, a lower sieve plate (aperture 30 μm, thickness 1.5mm) was placed in the straining tube and compacted, then a 0.2g rice flour sample was weighed and transferred into the straining tube, and then an upper sieve plate (aperture 30 μm, thickness 1.5mm) was placed in the straining tube and compacted. Then the filter taking pipe is connected into the pipeline and is arranged in the microwave cavity;
preparation of the system: the power supply of the first multi-path peristaltic pump 31, the second multi-path peristaltic pump 32, the microwave oven 4, the two-position three-way valve 8 and the vacuum pump 13 is sequentially turned on, and the working parameters are set to be in a standby state, for example, the flow rate of the peristaltic pump is set to be 1.0mL min in the embodiment-1The power of the microwave oven is 350W; the flow rate of the vacuum pump 13 is 20L min-1；
Filtering: according to the method, a 20% (v/v) nitric acid aqueous solution is used as a filtrate, the filtrate is filled into a filtrate storage tank 1, then a vacuum pump 13, a first multi-path peristaltic pump 31 and a second multi-path peristaltic pump 32 are sequentially started to enable the filtrate to enter a pipeline, after the filtrate soaks a rice sample in a filtrate tube 5, microwave irradiation of a microwave oven 4 is started, and when 10mL of filtrate is collected in a filtrate collection tube 12, the first multi-path peristaltic pump 31, the second multi-path peristaltic pump 32, the microwave oven 4 and the vacuum pump 13 are sequentially closed;
detection of heavy metal components: the filtrate collection tube was removed from the vacuum chamber, and the filtrate was diluted to 25mL with deionized water and centrifuged, and passed through a 0.45 μm acid-resistant filter and detected by ICP-OES.
Flushing of the system: after filtration, replacing the filtration tube 5 with a clean empty tube, starting the first multi-path peristaltic pump 31, the second multi-path peristaltic pump 32 and the vacuum pump 13, switching the two-position three-way valve body 8 to the outlet position of the first valve body, and adopting 50% ethanol water solution (volume ratio) and pure deionized water for 2mL min-1The system pipeline is washed in sequence, and the washing liquid enters the waste liquid collecting tank 11.
Comparative samples and methods: detecting the same sample by adopting a national standard GB 5009.15-2014;
the filtration rate: calculated as follows:
CMTDMAL: the concentration of heavy metal (Cu, Mn, Zn, Ni and Cd) elements in a commercial rice sample measured by the rapid microwave-assisted leaching device is measured
CReference: the concentration of heavy metal (Cu, Mn, Zn, Ni and Cd) elements in a commercial rice sample is measured by a national standard method (GB 5009.15-2014)
As shown in Table 2, the leaching rates of the method for the three heavy metal elements of Cu, Mn and Zn are between 59.5% and 94.5%, and the contents of the two heavy metal elements of Cd and Ni are below the lower limit of the method.
Table 2: application of method in detection of several actual rice samples
Therefore, compared with the prior art, the rapid microwave-assisted leaching device has the advantages of short leaching time, simplicity and convenience in operation, avoidance of adopting concentrated acid as a leaching solution, capability of treating a plurality of samples simultaneously, easiness in realizing automation, online purification of the leaching solution and the like, and has higher leaching rate on thermally decomposable analytes.
Claims (1)
1. The utility model provides a quick microwave-assisted filters gets device which characterized in that: the device comprises a filtrate storage tank (1), a first multi-path peristaltic pump (31) and a second multi-path peristaltic pump (32) which are provided with the same number of passages, a microwave oven (4), a filtrate tube (5), a pipeline pressure sensor (6), a filter (7), a two-position three-way valve body (8), a waste liquid collecting tank (11), a filtrate collecting tube (12), a first vacuum cavity (9), a second vacuum cavity (10), a vacuum pump (13), a connecting pipeline and connecting accessories;
a plurality of input passages of the first multi-path peristaltic pump (31) are respectively connected with the filtrate storage tank (1) through a second pipeline (202), a first connecting accessory (2) and a first pipeline (201); the upper end of a filtering pipe (5) positioned in the cavity of the microwave oven (4) is respectively connected with a plurality of output passages of the first multi-path peristaltic pump (31) through a third pipeline (203); the lower end of the filtering pipe (5) is connected with the upper end of the pipeline pressure sensor (6) through a fourth pipeline (204); the lower end of the pipeline pressure sensor (6) is respectively connected with a plurality of input channels of the second multi-channel peristaltic pump (32) through a fifth pipeline (205); the upper end of the filter (7) is connected with a plurality of output channels of the second multi-channel peristaltic pump (32) through a sixth pipeline (206); an inlet at the upper end of the two-position three-way valve body (8) is connected with the lower end of the filter (7) through a seventh pipeline (207); a waste liquid collecting tank (11) is arranged in the first vacuum cavity (9), a filtered liquid collecting pipe (12) is arranged in the second vacuum cavity (10), the waste liquid collecting tank (11) is connected with a first valve body outlet at the lower end of the two-position three-way valve body (8) through an eighth pipeline (208), a second connecting accessory (14) and a tenth pipeline (210), and the filtered liquid collecting pipe (12) is connected with a second valve body outlet at the lower end of the two-position three-way valve body through a ninth pipeline (209); the vacuum pump (13) is connected with the first vacuum cavity (9) and the second vacuum cavity (10) through an eleventh pipeline (211); the number of the filtering pipes (5), the pipeline pressure sensor (6), the filter (7), the two-position three-way valve body (8), the second pipeline (202), the third pipeline (203), the fourth pipeline (204), the fifth pipeline (205), the sixth pipeline (206), the seventh pipeline (207), the eighth pipeline (208), the ninth pipeline (209) and the filtering liquid collecting pipe (12) is the same as that of the multi-way peristaltic pump channels;
the first connecting accessory (2) and the second connecting accessory (14) are formed by processing polytetrafluoroethylene blocks, each surface vertical to the first connecting accessory is provided with a connecting hole, and the number of the connecting holes is 6, and the connecting holes are respectively connected with the second pipeline (202) or the eighth pipeline (208); the top surface is vertical to the top surface and is provided with 1 connecting hole which is connected with the first pipeline (201) or the tenth pipeline (210); the 7 holes are communicated with each other in the first connecting accessory (2) or the second connecting accessory (14) to play a role of dividing the liquid path into 1 part and 6 parts or combining the liquid path into 1 part;
the filtering liquid storage tank (1) is positioned at the foremost end of the rapid microwave-assisted filtering device, and the second multi-path peristaltic pump (32) is positioned above the first multi-path peristaltic pump (31); the microwave oven (4) is positioned at the right side of the first multi-path peristaltic pump (31) and the second multi-path peristaltic pump (32); the pressure sensor (6) is positioned below the microwave oven (4), the filter (7) is positioned on the right side of the microwave oven (4), the two-position three-way valve body (8) is positioned below the filter (7), the first vacuum cavity (9) and the second vacuum cavity (10) are positioned on the lower side of the two-position three-way valve body (8), and the vacuum pump (13) is positioned at the tail end of the whole device;
the pressure in the filtering pipe (5) is monitored through the pressure sensor (6), so that the filtering liquid is prevented from collapsing and leaking due to pipeline blockage; the switching of the discharge of the waste liquid to the waste liquid collecting tank (11) through a tenth pipeline (210) and the discharge of the filtrate to the filtrate collecting pipe (12) through a ninth pipeline (209) is realized through the opening and closing of the two-position three-way valve; the online separation, enrichment and/or purification treatment of the filtered liquid is realized by replacing the filler and/or the sieve plate in the filter (7); by connecting or removing the first connecting accessory (2), the multi-channel pumping of the same filtrate or the pumping of different filtrates by different channels is realized; static microwave-assisted filtration, dynamic microwave-assisted filtration or static/dynamic microwave-assisted mixed filtration of a sample is realized by controlling the pumping speed of a first multi-path peristaltic pump (31) and a second multi-path peristaltic pump (32);
the method for filtering by using the rapid microwave-assisted filtering device comprises the following steps:
(1) firstly, a lower sieve plate with the aperture of 10-40 mu m and the thickness of 1-3 mm is placed in a filtering tube (5) and compacted, then a sample is weighed and transferred into the filtering tube, an upper sieve plate with the aperture of 10-40 mu m and the thickness of 1-3 mm is placed in the filtering tube (5) and compacted, and then the filtering tube (5) is connected into a pipeline and placed in a cavity of a microwave oven (4);
(2) preparation of the system: sequentially turning on a power supply of a first multi-path peristaltic pump (31), a second multi-path peristaltic pump (32), a microwave oven (4), a two-position three-way valve body (8) and a vacuum pump (13), and setting working parameters of the two-position three-way valve body and the vacuum pump to enable the two-position three-way valve body and the vacuum pump to be in a standby state;
(3) filtering: the filter liquid is filled into the filter liquid storage tank (1), then the vacuum pump (13), the first multi-path peristaltic pump (31) and the second multi-path peristaltic pump (32) are sequentially started, the filter liquid enters the pipeline, after the filter liquid soaks the sample in the filter tube (5), the microwave oven (4) is started to perform microwave irradiation, when the filter liquid with the required volume is collected in the filter liquid collecting tube (12), the first multi-path peristaltic pump (31), the second multi-path peristaltic pump (32), the two-position three-way valve body (8), the microwave oven (4) and the vacuum pump (13) are sequentially closed, and therefore the rapid microwave auxiliary filter of the sample is achieved.
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| CN101226119B (en) * | 2008-01-30 | 2010-06-02 | 吉林大学 | Dynamic loop microwave auxiliary clear-up device |
| CN101797448B (en) * | 2010-04-12 | 2012-06-06 | 吉林大学 | High-flux dynamic microwave-assisted extraction device |
| CN203737232U (en) * | 2014-03-17 | 2014-07-30 | 柯中炉 | Microwave reaction device |
| CN205176043U (en) * | 2015-11-14 | 2016-04-20 | 中国科学院合肥物质科学研究院 | Water sample automatic acquisition and digestion instrument |
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