CN111537643B - Method for detecting content of heavy metal organic compounds in water in plastic pipeline - Google Patents

Abstract

The invention discloses a method for detecting the content of heavy metal organic compounds in water in a plastic pipeline, which connects a liquid chromatography device with the plastic pipeline, wherein all sections of the plastic pipeline are connected through a liquid pump, the sections of the plastic pipeline form a circularly closed pipeline, one end of the plastic pipeline is provided with a reversing valve, the reversing valve is respectively connected with the liquid chromatography device and the middle section of the plastic pipeline, and the detection step comprises the following steps: firstly, opening the reversing valve to fill water into the plastic pipeline, then switching the reversing valve to open the liquid pump to enable tap water to enter a liquid chromatography device, measuring the content values of the heavy metal organic compounds at different time points respectively to obtain the functional relation between the content values of the heavy metal organic compounds and time, and obtaining the migration time of the heavy metal organic compounds corresponding to the content threshold value through the functional relation; the method can judge the mobility of the metal stabilizer in the water pipe, and provides information support for water pollution treatment and improvement of plastic pipe manufacturing process.

Description

A kind of detection method of heavy metal organic compound content in water of plastic pipe

technical field

The invention relates to the field of liquid detection, in particular to a method for detecting the content of heavy metal organic compounds in water in plastic pipes.

Background technique

The analysis and detection of organic lead compounds at home and abroad mainly focus on textiles, food and environmental samples, and the detection of organic lead compounds in plastic products is still less. Polyvinyl chloride (PVC) is a polymer with poor thermal stability. Usually, hydrogen chloride gas will escape and degrade at temperatures above 160°C. In order to avoid and reduce the thermal degradation and discoloration of polyvinyl chloride in the process of processing and molding, it is necessary to add a certain heat stabilizer. Organolead compounds are widely used as heat stabilizers for polyvinyl chloride due to their high transparency, good thermal stability, and outstanding heat resistance. However, organolead compounds are extremely harmful to organisms, which are manifested in the following: the central nervous system can cause leukoedema, the oxidative phosphorylation process in cellular energy utilization is blocked, the thymus gland and lymphatic system are inhibited, and cellular immunity is affected. Obstruction, hormone secretion inhibition causes diabetes and hyperlipidemia and so on. Toxicity to humans, local irritation to skin, respiratory tract, cornea, and systemic poisoning or even death through skin or brain edema.

As stabilizers for PVC plastics, organic lead compounds are widely used in municipal and building water supply and drainage, gas, heating and heating, agricultural water-saving irrigation and other fields. They are also a class of environmental endocrine disrupting substances, which can affect biological reproduction by Function and interference with the secretion of hormones in organisms lead to adverse reproductive and genetic consequences.

However, the impact of plastic pipes on water quality safety has certain concealment, extensiveness and hysteresis. When the accumulation of long-term effects exceeds the tolerance threshold, problems such as food security and residents' health caused by water quality safety will gradually be exposed, affecting human health. Therefore, it is necessary to efficiently detect the content of heavy metal organic compounds in the water of plastic pipes to determine the stability of metals. The migration rate of the agent in the water pipe can provide information support for water pollution control and the improvement of plastic pipe manufacturing process.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for detecting the content of heavy metals and organic compounds in water in plastic pipes, which can efficiently detect the content of heavy metals and organic compounds in water in plastic pipes to determine the mobility of metal stabilizers in water pipes, thereby preventing water pollution. Provide information support for governance and improvement of plastic pipe manufacturing processes.

The present invention provides specific technical solutions as follows:

A method for detecting the content of heavy metals and organic compounds in water in plastic pipes, characterized in that a liquid chromatography device is connected to a plastic pipe, the plastic pipes are connected in the form of equal-length sections, and each section of the plastic pipe is connected with each other. They are all connected by a liquid pump, and the multiple segments of the plastic pipeline are formed into a closed loop pipeline. The liquid chromatography device is also provided with a timer and a flowmeter, and one end of the plastic pipeline is provided with A reversing valve, the reversing valve is respectively connected with the liquid chromatography device and the middle section of the plastic pipeline, and the other ends of the liquid chromatography device and the middle section are connected to the plastic through a tee Other segments of the pipeline are connected, and the detection steps are as follows:

a. First, open the reversing valve to make the plastic pipe communicate with the interior of the liquid chromatography device, and inject tap water into the liquid chromatography device to fill the plastic pipe with water;

b. Switch the reversing valve so that the plastic pipe is disconnected from the interior of the liquid chromatography device, and turn on one of the suction pumps, so that tap water only flows in each section of the plastic pipe, At the same time, the timer starts to work;

c. When the timer reaches the set first time T1, switch the reversing valve to communicate with the liquid chromatography device, and the liquid chromatography device detects the first content value of heavy metal organic compounds in the tap water H1, and record it;

d. When the timer reaches the set second time T2, switch the reversing valve to communicate with the liquid chromatography device, and the liquid chromatography device detects the second content value of heavy metal organic compounds in the tap water. H2, and record it, wherein the T2-T1≥T1;

e. Determine whether H2-H1 is greater than 1%×H1, if H2-H1≥1%×H1, continue to measure the content value Hn of heavy metal organic compounds at the set nth time Tn, wherein the Tn-T(n -1)≥T1, and obtain the curve diagram of heavy metal organic compound content value H and time T; if 0.1%×H1＜H2-H1＜1%×H1, then turn on the second pump and continue to measure the set The content value Hn of heavy metal organic compounds at the nth time Tn, if 0.1%×H(n-1)<Hn-H(n-1)<1%×H(n-1), then continue to open the following Measure with n pumping pumps until Hn-H(n-1)≥1%×H(n-1); if H2-H1＜0.1%×H1, turn on all pumping pumps, and put all pumping Increase the speed of the pump, and set the time as Tn-T(n-1)≥T(n-1) and continue to measure the content value Hn of heavy metal organic compounds at the set nth time Tn until Hn-H (n-1)≥1%×H(n-1);

f. A threshold value Hm of the content value of heavy metal organic compounds is also set in the liquid chromatography device, and through the obtained curve diagram of the content value H of heavy metal organic compounds and time T, the content value H and time T of heavy metal organic compounds are obtained. The functional relationship between, through which the heavy metal organic compound migration time Tm corresponding to the threshold Hm is obtained;

g. In the above-mentioned content measurement step, when Hn≧Hm, the liquid chromatography device sends out an alarm reminder, and records the time Tn at this moment, where Tn is Tm.

Further, the liquid chromatography device includes a low-speed pump, a multi-component pump, a column temperature box, a column switching valve, a sampling valve, an ultraviolet detector, a sampling loop, a suction column, and a separation column; the detection method also includes:

(1) Sampling: turn on the low-speed pump to make the tap water enter the sampling ring, and at the flow rate of V1, transport Ta for a period of time, flush the sampling ring and make the sample fill the sampling ring;

(2) Suction collection: switch the column switching valve, turn on the multi-component pump, wash and activate the suction collection column with 100% methanol, 50% methanol aqueous solution, 100% water in sequence, the flow rate is V1, and wash the time Ta respectively; then 60% Methanol aqueous solution is used as the mobile phase for suction and collection, and the water sample in the sampling loop is introduced into the suction and collection column at the flow rate V2, and the suction and collection time Tb, the analyte is absorbed and collected on the suction and collection column, the flow rate V2>V1, the time Tb< Ta;

(3) Sampling and elution: switch the column switching valve and the sampling valve, set the temperature of the column oven to 30 °C, and the multi-component pump delivers a certain volume ratio V (methanol): V (H20) = 90:10 (including 0.05% trifluoroacetic acid) mobile phase, the flow rate was adjusted to V1, flowed through the adsorption column, washed the analyte on the adsorption column, separated by the separation column and passed through the ultraviolet detector, and obtained 210nm recorded by the ultraviolet detector. The chromatogram under the wavelength can indirectly measure the content of heavy metal organic compounds in water.

Further, before the step (1), a solution of heavy metal organic compounds with a fixed standard concentration is added to the port of the injection valve.

Preferably, the heavy metal organic compound detected by the liquid chromatography device is an organic lead compound.

Preferably, the organic lead compound is at least one of diphenyl lead chloride, tetraphenyl lead, tetraethyl lead, and tetrabutyl lead.

Further, the ultraviolet detector records a chromatogram at a wavelength of 210 nm, and obtains the content of each component of the compound through the peak areas generated by different compounds in the chromatogram, thereby obtaining the content of heavy metal organic compounds in water.

Further, the inlet end of the low-speed pump is connected to the outlet end of the reversing valve, the outlet end of the low-speed pump is connected to the sampling ring, and the other end of the sampling ring is connected to the inlet of the column switching valve. The outlet end of the column switching valve is connected to the low-speed pump and the multi-component pump respectively, and the other end of the multi-component pump is connected to the suction column, the suction column and the column switching valve The column temperature box is also connected between them, the suction column is connected with the inlet of the injection valve, the outlet of the injection valve is connected with the separation column, and the separation column is connected with the ultraviolet detector. connected, and the end of the ultraviolet detector is connected with the three-way.

Further, each part of the components of the liquid chromatography device is communicated with each other through a polyetheretherketone pipe.

Further, the inner diameter of the plastic pipe is larger than the inner diameter of the polyetheretherketone pipe.

The beneficial effects of the present invention are as follows:

In the detection method of the present invention, a liquid pump and a liquid chromatography device are arranged in the circulating plastic pipeline, and the liquid chromatography device and the middle section of the plastic pipeline are connected in parallel through a reversing valve, taking into account some of the metal stabilizer in the plastic pipeline. The migration rate of heavy metal organic compounds is not constant, and the migration time is long. Through the control of the reversing valve, phased measurement is realized to improve the detection accuracy of the liquid chromatography device; in addition, the heavy metal organic compounds are regularly and intermittently detected in water by setting the time. Compound content, the functional relationship between the heavy metal organic compound content value H and the time T can be obtained through multiple measurement statistics, and then the time it takes for the heavy metal organic compound content to exceed the standard state can be calculated, that is, the migration time of heavy metal organic compounds can be obtained. The mobility of the stabilizer in the water pipe provides information support for water pollution control and the improvement of the plastic pipe manufacturing process; the invention adopts the water circulation measurement of the plastic pipe to realize the ultra-long period water pipe detection under real civil conditions, and controls the concentration through the concentration comparison method. The different working states of each pump in the pipeline can change the water flow to simulate the long-term mobility of the metal stabilizer in the water pipeline in the real state, thus greatly shortening the detection time and improving the detection efficiency; The control can eliminate the interference of the pump and improve the flow rate, and ensure the accuracy of the liquid chromatography device to absorb and detect the content of heavy metal organic compounds.

Description of drawings

For ease of description, the present invention is described in detail by the following specific embodiments and accompanying drawings.

FIG. 1 is a schematic structural diagram of a structural diagram of a device for detecting heavy metals and organic compounds in water in a plastic pipe according to the present invention.

FIG. 2 is a chromatogram obtained by detection by the liquid chromatography device of the present invention.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

It is to be understood that the terms "top", "bottom", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" The orientation or positional relationship indicated by , "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific specification in the description. Orientation, construction and operation in a particular orientation, and therefore should not be construed as limiting the invention.

Furthermore, the terms "first", "second" and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature.

The present invention will be described in further detail below in conjunction with the embodiments given in the accompanying drawings:

Example 1

Referring to Fig. 1, a method for detecting the content of heavy metals and organic compounds in water in a plastic pipe 1 is characterized in that, the liquid chromatography device 2 is connected with the plastic pipe 1, and the plastic pipe 1 is connected in the form of equal length segments, so Each segment of the plastic pipeline 1 is connected by a liquid pump 3, and the multiple segments of the plastic pipeline 1 are formed into a closed loop pipeline, and a timer is also provided on the liquid chromatography device 2. and flowmeter, one end of the plastic pipe 1 is provided with a reversing valve 4, and the reversing valve 4 is respectively connected with the liquid chromatography device 2 and the middle section of the plastic pipe 1, and the liquid chromatography The device 2 and the other end of the middle section are connected to other sections of the plastic pipe 1 through a tee.

Considering that it is necessary to measure the content of heavy metal organic compounds in the plastic pipe 1, and then obtain the migration rate of the metal stabilizer, this is a relatively difficult factor to determine. It is stipulated as 24h in the "Safety Evaluation Standards for Protective Materials and Protective Materials", but the setting of the test period in the actual civil pipeline water quality testing process can be relatively flexible, such as 8h, 24h, 48h, 72h, etc., and the longest period is 14d. Considering Due to the design of the circulating pipeline plus the pump 3 adopted in the present invention, the detection period can be shortened accordingly.

Therefore, in this embodiment, a tentative detection is firstly performed, and the time interval is set to be relatively short. The specific detection steps are as follows:

a. First, open the reversing valve 4 to make the plastic pipe 1 communicate with the liquid chromatography device 2, and inject tap water into the liquid chromatography device 2 so that the plastic pipe 1 is filled with water ;

b. Switch the reversing valve 4, so that the plastic pipe 1 is disconnected from the interior of the liquid chromatography device 2, and one of the suction pumps 3 is turned on, so that the tap water is only in each of the plastic pipes 1. Intra-segment flow, while the timer starts working;

c. When the timer reaches the set first time T1=5min, switch the reversing valve 4 to communicate with the liquid chromatography device 2, and the liquid chromatography device 2 detects heavy metal organic compounds in tap water The first content value H1 of , and record it;

d. When the timer reaches the set second time T2=10min, switch the reversing valve 4 to communicate with the liquid chromatography device 2, and the liquid chromatography device 2 detects heavy metal organic compounds in tap water. The second content value H2 of , and record it;

e. Determine whether the H2-H1 is greater than 1%×H1, if H2-H1≥1%×H1, it means that there is still a gap in the content value, and you can continue to measure the set nth time Tn (where Tn=16min, 25min , 35min, 50min . The difference is not big, indicating that the migration of the metal stabilizer has become stable, that is, the detection is terminated, and the curve diagram of the heavy metal organic compound content H and time T is obtained;

If 0.1%×H1＜H2-H1＜1%×H1, it means that the difference range before and after the content value is not obvious enough. Continuing the measurement is very likely to cause errors. At this time, turn on the second pump 3 and continue to measure the set first The content value Hn of heavy metal organic compounds at the n time Tn, if 0.1%×H(n-1)<Hn-H(n-1)<1%×H(n-1), then continue to open the next nth Each pump 3 is used for measurement until Hn-H(n-1)≥1%×H(n-1), and the tap water flow can be rapidly increased by opening multiple pumps 3. The increase in flow is equivalent to the daily n times of the water flow in the civil water pipe, which means that the migration time of the metal stabilizer in the pipe is also greatly shortened. This operation can increase the variation of the content value before and after the same set time until it meets the content in the above steps. value difference, at this time, recording Hn will avoid measurement error;

If H2-H1<0.1%×H1, this situation indicates that the mobility of the metal stabilizer is very low, and it is difficult to measure accurately in the follow-up. At this time, all the pumping pumps 3 need to be turned on, and all the pumping pumps 3 Increase the rotation speed and set the time to Tn-T(n-1)≥T(n-1) and continue to measure the content value Hn of heavy metal organic compounds at the set nth time Tn until Hn-H(n -1)≥1%×H(n-1), through the above operation, the pump 3 can be operated at the maximum power, which greatly increases the flow of tap water, and at the same time prolongs the setting time of the intermittent detection before and after, to achieve the maximum Expand the detection gap of content value to reduce the subsequent measurement error;

f. The liquid chromatography device 2 is also set with a threshold value Hm of the content value of heavy metal organic compounds, and through the obtained curve diagram of the content value H of heavy metal organic compounds and time T, obtain the content value H and time of heavy metal organic compounds The functional relationship between T, through which the metal compound migration time Tm corresponding to the threshold Hm is obtained;

g. In the above-mentioned content measurement step, when Hn≧Hm, the liquid chromatography device 2 sends out an alarm reminder, and records the time Tn at this moment, where Tn is Tm.

Example 2

In the case that the detection effect of metal stabilizer mobility is not good, the initial time setting value is extended, and the corresponding detection steps are adjusted as follows:

c. When the timer reaches the set first time T1=10min, switch the reversing valve 4 to communicate with the liquid chromatography device 2, and the liquid chromatography device 2 detects heavy metal organic compounds in tap water The first content value H1 of , and record it;

d, when the timer reaches the set second time T2=20min, switch the reversing valve 4 to communicate with the liquid chromatography device 2, and the liquid chromatography device 2 detects heavy metal organic compounds in tap water. The second content value H2 of , and record it;

e. Determine whether the H2-H1 is greater than 1%×H1. If H2-H1≥1%×H1, it means that there is still a gap in the content value, and you can continue to measure the set nth time Tn (where Tn=40min, 60min , 90min, 120min . The difference is not big, indicating that the migration of the metal stabilizer has become stable, that is, the detection is terminated, and the curve diagram of the heavy metal organic compound content value H and time T is obtained; the remaining steps are the same as in Example 1.

Example 3

Continue to expand the setting time, by sacrificing time in exchange for measurement accuracy, the corresponding detection steps are adjusted as follows:

c. When the timer reaches the set first time T1=30min, switch the reversing valve 4 to communicate with the liquid chromatography device 2, and the liquid chromatography device 2 detects heavy metal organic compounds in tap water The first content value H1 of , and record it;

d, when the timer reaches the set second time T2=60min, switch the reversing valve 4 to communicate with the liquid chromatography device 2, and the liquid chromatography device 2 detects heavy metal organic compounds in tap water. The second content value H2 of , and record it;

e. Determine whether the H2-H1 is greater than 1%×H1. If H2-H1≥1%×H1, it means that there is still a gap in the content value, and you can continue to measure the set nth time Tn (where Tn=100min, 180min , 270min, 360min . The difference is not big, indicating that the migration of the metal stabilizer has become stable, that is, the detection is terminated, and the curve diagram of the heavy metal organic compound content value H and time T is obtained; the remaining steps are the same as in Example 1.

Example 4

Further, the liquid chromatography device 2 includes a low-speed pump 5, a multi-component pump 8, a column thermostat 9, a column switching valve 7, a sampling valve 11, an ultraviolet detector 13, a sampling loop 6, a suction column 10, and a separation column. 12; the inlet end of the low-speed pump 5 is connected to the outlet end of the reversing valve 4, the outlet end of the low-speed pump 5 is connected to the sampling ring 6, and the other end of the sampling ring 6 is connected to the column The inlet end of the switching valve 7 is connected, the outlet end of the column switching valve 7 is respectively connected with the low-speed pump 5 and the multi-component pump 8, and the other end of the multi-component pump 8 is connected with the suction column 10, so the The column thermostat 9 is also connected between the suction column 10 and the column switching valve 7, the suction column 10 is connected to the inlet of the sampling valve 11, and the outlet of the sampling valve 11 is connected to the inlet of the sampling valve 11. The separation column 12 is connected, the separation column 12 is connected with the ultraviolet detector 13, and the end of the ultraviolet detector 13 is connected with the tee. Wherein, the components of the liquid chromatography device 2 communicate with each other through a polyetheretherketone pipe 14 . The use of polyetheretherketone tube 14 has good stability, and it is not easy to produce other compounds that dissolve in water.

Further, the inner diameter of the plastic pipe 1 is set to be larger than the inner diameter of the polyether ether ketone pipe 14, so as to ensure that under the action of the low-speed pump 5, the flow rate of the tap water matches the water flow path in the pipe, in addition to the detection process. Reducing the pipe diameter in the middle can increase the contact area between the tap water per unit volume and the adsorption column 10, thereby improving the absorption rate of heavy metal organic compounds by the adsorption column 10 and improving the accuracy of concentration detection.

Consider that the present invention detects heavy metal organic compounds, especially detects organic lead compounds to reduce its harm to human body, so the detection method adopted by liquid chromatography device 2 is as follows:

(1) sampling: turn on the low-speed pump 5 and make the tap water enter the sampling ring 6, with the flow rate of 1L/min, transport 8min, rinse the sampling ring 6 and make the sample fill the 1L sampling ring 6;

(2) Suction collection: switch column switching valve 7, turn on multi-component pump 8, wash and activate suction collection column 10 with 100% methanol, 50% methanol aqueous solution, 100% water in sequence, adding methanol solution in stages can increase the organic concentration of heavy metals in the water pipe For the separation efficiency of the compounds, the flow rate was set at 1L/min, and washed for 8min respectively; then 60% methanol aqueous solution was used as the mobile phase for suction and collection, and 1L of the water sample in the sampling loop 6 was introduced into the collection column 10 at a flow rate of 2.5L/min. The suction time is 5min, and the object to be tested is collected on the suction column 10;

(3) Sampling and elution: switch the column switching valve 7 and the sampling valve 11, the temperature of the column oven 9 is set to 30° C. to maintain the stability of methanol, and the multi-component pump 8 delivers the volume ratio V (methanol): The mobile phase of V(H20)=90:10 (containing 0.05% trifluoroacetic acid), the flow rate is set to 1L/min, flows through the suction column 10, washes the analyte on the suction column 10, and then passes through the suction column 10. The separation column 12 passes through the ultraviolet detector 13 after separation, and obtains a chromatogram recorded by the ultraviolet detector 13 at a wavelength of 210 nm, and indirectly measures the content of heavy metal organic compounds in water. Adding trifluoroacetic acid can better shield the residual polar surface on the stationary phase and prevent methanol or heavy metal organic compounds from being adsorbed by other substances in the pipeline, which is equivalent to a tail sweeping agent. In addition, the ultraviolet wavelength of trifluoroacetic acid is less than 200nm, and a small amount of trifluoroacetic acid Acetic acid can effectively adjust the acidity of the mobile phase, so that the peak shape of heavy metal organic compounds is not disturbed by the solvent peak, and it also shortens the retention time of heavy metal organic compounds. The ultraviolet detector 13 is set to detect heavy metal organic compounds with a wavelength of 210 nm, which improves the detection accuracy.

Preferably, the heavy metal organic compound detected by the liquid chromatography device 2 is an organic lead compound.

Preferably, the organic lead compound is at least one of diphenyl lead chloride, tetraphenyl lead, tetraethyl lead, and tetrabutyl lead.

Further, the ultraviolet detector records a chromatogram at a wavelength of 210 nm, and obtains the content of each component of the compound through the peak areas generated by different compounds in the chromatogram, thereby obtaining the content of heavy metal organic compounds in water in proportion.

In order to improve the accuracy of the detection of the content of organic lead compounds and eliminate the interference of other substances in the tap water and the migration of other substances in the plastic pipe 1, a fixed standard concentration can be added to the port of the sampling valve 11 before the sampling step (1) above. If the standard stock solution of 3 organic lead compounds is added, the concentrations of tetraphenyl lead are 0.2, 0.4 and 0.6 mg/L; the concentrations of tetraethyl lead are 0.4, 0.8 and 1.2 mg, respectively. /L, the concentrations of tetrabutyl lead are 0.8, 1.6 and 2.4 mg/L, respectively, so that the UV detector 13 can measure the wavelength of similar organolead compounds, and the organic lead compounds migrated out of the plastic pipe 1 can be accurately obtained through the standard concentration comparison. content of lead compounds.

Example 5

Taking into account the detection accuracy of organic lead compounds and improving the degree of absorption as much as possible, the detection flow rate can be appropriately reduced, and the detection steps of the present embodiment are adjusted as follows:

(1) sampling: turn on the low-speed pump 5 to make the tap water enter the sampling ring 6, with the flow rate of 0.2L/min, convey 3min, flush the sampling ring 6 and make the sample fill the 1L sampling ring 6;

(2) Suction collection: switch column switching valve 7, turn on multi-component pump 8, wash and activate suction collection column 10 with 100% methanol, 50% methanol aqueous solution, 100% water in sequence, adding methanol solution in stages can increase the organic concentration of heavy metals in the water pipe For the separation efficiency of the compounds, the flow rate was set at 0.2L/min, and washed for 3min respectively; then 60% methanol aqueous solution was used as the mobile phase for adsorption and collection, and 1L of the water sample in the sampling loop 6 was introduced into the collection column 10 at a flow rate of 0.5L/min. , the suction time is 2min, and the object to be tested is collected on the suction column 10;

(3) Sampling and elution: switch the column switching valve 7 and the sampling valve 11, the temperature of the column oven 9 is set to 30° C. to maintain the stability of methanol, and the multi-component pump 8 delivers the volume ratio V (methanol): The mobile phase of V(H20)=90:10 (containing 0.05% trifluoroacetic acid), the flow rate is set to 0.2L/min, flows through the suction column 10, and the analyte on the suction column 10 is washed off, After separation by the separation column 12, the ultraviolet detector 13 obtains a chromatogram recorded by the ultraviolet detector 13 at a wavelength of 210 nm, and the content of heavy metal organic compounds in the water is indirectly measured.

In addition, a fixed standard concentration of organic lead compound solution can be added to the port of the sampling valve 11 before the above sampling step (1), such as adding three standard stock solutions of organic lead compounds, which are respectively the concentration of tetraphenyl lead were 0.05, 0.1 and 0.15mg/L; the concentrations of tetraethyl lead were 0.1, 0.2 and 0.3mg/L, and the concentrations of tetrabutyl lead were 0.2, 0.4 and 0.6mg/L, respectively, which moderately reduced the concentration of the fixed standard solution. Concentration, in order to match the content of organic lead compounds in the water of the plastic pipe 1 to be tested as much as possible.

In this embodiment, as shown in FIG. 2 , the chromatogram of the organic lead compounds is sequentially obtained by the liquid chromatography device 2 . Further, according to the detection data, the following linear equation table is obtained:

The content value of the organolead compound can be detected and obtained through the above chromatogram and the relationship of the linear equation, and the above steps e to g are repeated to obtain the functional relationship between the content value and the time, and the required amount of the organolead compound migration can be obtained when the migration amount exceeds the standard. Time, and then reflect the mobility of the metal stabilizer in the plastic pipe, which can indirectly judge the service life or maximum service life of the plastic pipe, and provide a basis for improvement in the process production of industrial plastic pipes.

The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and the descriptions in the above-mentioned embodiments and the description are only for illustrating the present invention. principle, without departing from the spirit and scope of the present invention, the present invention will also have various changes and improvements, these changes and improvements all fall within the scope of the claimed invention, and the claimed scope of the present invention is determined by the appended rights Requirements and their equivalents are defined.

Claims (9)

1. the detection method of heavy metal organic compound content in the water in plastic pipeline, it is characterized in that, liquid chromatography device is connected with plastic pipeline, described plastic pipeline is connected with the form of isometric section, and each part of described plastic pipeline is connected. The sections are all connected by a pumping pump, and the multiple sections of the plastic pipe are formed into a closed loop pipeline. The liquid chromatography device is also provided with a timer and a flowmeter. One end of the plastic pipe is A reversing valve is provided, and the reversing valve is respectively connected with the liquid chromatography device and the middle section of the plastic pipeline, and the other end of the liquid chromatography device and the middle section is connected to the other end through a tee. The other sections of the plastic pipe are connected, and the steps of the detection method include: First, open the reversing valve to make the plastic pipe communicate with the interior of the liquid chromatography device, and inject tap water into the liquid chromatography device to fill the plastic pipe with water; Switch the reversing valve, so that the plastic pipe is disconnected from the interior of the liquid chromatography device, and one of the suction pumps is turned on, so that the tap water only flows in each section of the plastic pipe, and all the The timer starts working; When the timer reaches the set first time T1, switch the reversing valve to communicate with the liquid chromatography device, and the liquid chromatography device detects the first content value H1 of heavy metal organic compounds in the tap water, and recorded; When the timer reaches the set second time T2, switch the reversing valve to communicate with the liquid chromatography device, and the liquid chromatography device detects the second content value H2 of heavy metal organic compounds in the tap water, and record, wherein the T2-T1≥T1; Determine whether H2-H1 is greater than 1%×H1, if H2-H1≥1%×H1, continue to measure the content value Hn of heavy metal organic compounds at the set nth time Tn, wherein the Tn-T(n-1 )≥T1, and obtain the curve diagram of heavy metal organic compound content H and time T; if 0.1%×H1＜H2-H1＜1%×H1, then turn on the second pump and continue to measure the set nth The content value Hn of heavy metal organic compounds at time Tn, if 0.1%×H(n-1)<Hn-H(n-1)<1%×H(n-1), then continue to open the next nth Measure the pump until Hn-H(n-1)≥1%×H(n-1); if H2-H1＜0.1%×H1, turn on all the Increase the rotation speed and set the time to Tn-T(n-1)≥T(n-1) and continue to measure the content value Hn of heavy metal organic compounds at the set nth time Tn until Hn-H(n -1)≥1%×H(n-1); The liquid chromatography device is also set with a threshold value Hm for the content value of heavy metal organic compounds, and through the obtained curve diagram of the content value H of heavy metal organic compounds and time T, the difference between the content value H of heavy metal organic compounds and time T is obtained. The functional relationship of , obtains the heavy metal organic compound migration time Tm corresponding to the threshold Hm through the functional relationship; In the above-mentioned content measurement step, when Hn≧Hm, the liquid chromatography device sends out an alarm reminder, and records the time Tn at this moment, where Tn is Tm. 2. detection method as claimed in claim 1 is characterized in that, described liquid chromatography device comprises low-speed pump, multi-component pump, column thermostat, column switching valve, sampling valve, ultraviolet detector, sampling loop, suction collector column and separation column; the detection step of the liquid chromatography device comprises: (1) Sampling: turn on the low-speed pump to make the tap water enter the sampling ring, and at the flow rate of V1, transport Ta for a period of time, flush the sampling ring and make the sample fill the sampling ring; (2) Suction collection: switch the column switching valve, turn on the multi-component pump, wash and activate the suction collection column with 100% methanol, 50% methanol aqueous solution, 100% water in sequence, the flow rate is V1, and wash the time Ta respectively; then with 60% Methanol aqueous solution is used as the mobile phase for suction and collection, and the water sample in the sampling loop is introduced into the suction and collection column at the flow rate V2, the suction and collection time Tb, the analyte is absorbed and collected on the suction and collection column, the flow rate V2 > the flow rate V1, the time Tb < the time Ta; (3) Sampling and elution: switch the column switching valve and the sampling valve, set the temperature of the column oven to 30°C, and the multi-component pump delivers a mobile phase with a certain volume ratio of methanol:H ₂ O =90:10, in which H ₂ O contains 0.05% trifluoroacetic acid, the flow rate is adjusted to V1, flows through the adsorption column, washes the analyte on the adsorption column, and is separated by the separation column and passes through the ultraviolet detector to obtain a wavelength of 210 nm recorded by the ultraviolet detector. The chromatogram below can indirectly measure the content of heavy metal organic compounds in water. 3 . The detection method according to claim 2 , wherein a solution of heavy metal organic compounds with a fixed standard concentration is added to the port of the injection valve before the step (1). 4 . 4. The detection method according to claim 1 or 3, wherein the heavy metal organic compound detected by the liquid chromatography device is an organic lead compound. 5. The detection method according to claim 4, wherein the organic lead compound is at least one of diphenyl lead chloride, tetraphenyl lead, tetraethyl lead, and tetrabutyl lead. 6. detection method as claimed in claim 3 is characterized in that, described ultraviolet detector records the chromatogram under 210nm wavelength, through the peak area that different compounds produce in the chromatogram, obtains the content of each component of compound, thereby seeks. The content of heavy metal organic compounds in the obtained water. 7. The detection method according to claim 2 or 3, wherein the inlet end of the low-speed pump is connected with the outlet end of the reversing valve, and the outlet end of the low-speed pump is connected with the sampling ring, The other end of the sampling ring is connected to the inlet end of the column switching valve, the outlet end of the column switching valve is respectively connected to the low-speed pump and the multi-component pump, and the other end of the multi-component pump is connected to the suction pump. The collection column is connected, the column temperature box is also connected between the suction-collection column and the column switching valve, the suction-collection column is connected with the inlet of the injection valve, and the outlet of the injection valve is connected with the inlet of the injection valve. The separation column is connected, the separation column is connected with the ultraviolet detector, and the end of the ultraviolet detector is connected with the tee. 8 . The detection method according to claim 7 , wherein each component of the liquid chromatography device is communicated with each other through a polyether ether ketone pipe. 9 . 9 . The detection method according to claim 8 , wherein the inner diameter of the plastic pipe is larger than the inner diameter of the polyether ether ketone pipe. 10 .

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