Mercury atomic fluorescence analyzer using water as carrier and mercury atomic fluorescence analysis method

Abstract

The present invention discloses a mercury atomic fluorescence analysis method and a mercury atomic fluorescence measuring instrument using water as a carrier, which belongs to the atomic fluorescence analysis in the field of analytical chemistry. The method includes the steps of sampling and infusion, reaction of a test solution and a reducing agent in a reactor to atomize mercury, generation of mercury atomic fluorescence and fluorescence detection, and in the conventional sampling and infusion process, water is used to replace HCl and a reducing agent as a carrier, so that the mercury test solution and reagent are pushed into the reactor by water to complete the reaction. The present invention uses water as a carrier, effectively overcomes the memory effect in mercury determination, improves the determination sensitivity and accuracy, and saves a large amount of high-purity HCl and reducing agent NaBH4 at the same time, greatly reduces the analysis cost, and significantly improves the operating environment, which is an innovation of mercury atomic fluorescence analysis technology.

Description

Technical Field

[0001] The invention belongs to the field of analytical chemistry and relates to atomic fluorescence analysis of mercury. It breaks through the traditional infusion mode and corresponding technology in atomic fluorescence analysis of mercury, and specifically relates to the improvement of the existing mercury atomic fluorescence analysis method and instrument. Background Art

[0002] Atomic fluorescence analysis has been widely used for the determination of trace amounts of Hg. The basic principle is that mercury ions react with a strong reducing agent (usually potassium borohydride or sodium borohydride) in an acidic medium (usually hydrochloric acid) to be reduced to mercury atoms, while producing a large amount of hydrogen. Mercury atoms are excited to a high-energy state by the radiation of a specific frequency from the excitation light source. Since the high energy level is extremely unstable, the excited atoms emit fluorescence of a characteristic wavelength in the form of light radiation during the de-excitation process. The fluorescence intensity is related to the concentration of mercury, and the concentration of mercury is obtained by measuring its fluorescence signal through a detector (usually a photomultiplier tube).

[0003] The mercury atomic fluorescence analyzer designed according to the above principle mainly includes an infusion system, a vapor generation system (or reactor), an atomizer, an excitation light source and a detection system. The mercury test solution and the reducing agent are transported through the infusion system and carried by the carrier liquid (also called carrier fluid) into the reactor for chemical reaction to generate mercury atomic vapor and hydrogen, which enter the atomizer under the carrier gas (usually argon) and are then excited to generate fluorescence for detection.

[0004] In the atomic fluorescence analysis of mercury, HCl and NaBH4 (or KBH4) have always been used as carriers for mercury test solution and reagents, respectively. This technology has the following defects: the infusion system has a serious memory effect. Especially after measuring high-concentration mercury samples, the capillary that transports the mercury test solution needs to be cleaned many times with blank solution before the next sample can be measured, which is time-consuming and may even require the entire infusion system to be replaced; the infusion process requires the continuous use of a large amount of acid carrier fluid, which not only pollutes the operating environment, but also corrodes the detection instrument. At the same time, the carrier process consumes a large amount of high-purity HCl and relatively expensive reducing agents, which also increases the detection cost. Summary of the invention

[0005] The object of the present invention is to provide a mercury atomic fluorescence analyzer using water as a carrier and an improved mercury atomic fluorescence analysis method, so as to effectively solve the above-mentioned problems in mercury atomic fluorescence analysis.

[0006] The mercury atomic fluorescence analysis method using water as a carrier flow of the present invention comprises the steps of sampling and infusion, reaction of a mercury test solution and a reducing agent in a reactor to atomize mercury, generation of mercury atomic fluorescence and fluorescence detection, and is characterized in that in the conventional sampling and infusion process, water is used instead of HCl and a reducing agent as a carrier flow, so that the mercury test solution and the reducing agent are carried by water and pushed into the reactor to complete the reaction.

[0007] Specifically, the sampling and infusion process is to firstly take samples, that is, to simultaneously introduce a mercury test solution with a certain acidity and a reducing agent (reagent) with a certain concentration, and then infuse, that is, to use pure water as a carrier to push the mercury test solution and the reducing agent into the reactor.

[0008] The sampling time is 4-5 seconds, and the infusion time is 8-10 seconds.

[0009] In the above-mentioned mercury atomic fluorescence analysis method using water as carrier, the acidity of the mercury test solution is in the range of 5%-10% of the hydrochloric acid concentration. The concentration range of the mercury test solution that can be measured by the mercury atomic fluorescence analysis method using water as carrier is 0-5ng / ml, and even when the Hg concentration is as low as 0-0.5ng / ml and lower than 0.1ng / ml (such as 0.04ng / ml), it can be measured.

[0010] The present invention also provides a mercury atomic fluorescence measuring instrument using water as a carrier current, comprising an infusion system, a reactor, an atomizer, a mercury hollow cathode lamp and a detector, etc., and is characterized in that: the infusion system comprises: a test solution bottle for holding a mercury test solution to be tested, the test solution bottle is connected to the reactor through a sample inlet tube; a reagent bottle for holding a reducing agent, the reagent bottle is connected to the reactor through a reagent inlet tube; a water bottle for holding pure water, the water outlet of the water bottle is connected to the sample inlet tube inlet and the reagent inlet tube inlet respectively through a water inlet tube, and the water inlet is controlled by switching the water inlet tube; and the infusion system does not contain a supporting device for infusing an acid solution for the carrier current.

[0011] Based on the mercury atomic fluorescence analyzer set up above, the present invention further provides a mercury atomic fluorescence analysis method using water as a carrier fluid, comprising the following steps:

[0012] Step 1: prepare a series of Hg standard solutions of different concentrations, sample solutions to be tested and NaBH4 solutions. Put the standard solutions and sample solutions as mercury test solutions into the test solution bottle, put the NaBH4 solution as a reducing agent into the reagent bottle; and put pure water as carrier water into the water bottle.

[0013] Step 2: Make a standard curve: After the instrument enters the working state,

[0014] 1) Connect the sample inlet tube to the test solution bottle interface containing the standard blank solution, connect the reagent inlet tube to the reagent bottle interface, and add liquid;

[0015] 2) Switch the sample inlet tube and the reagent inlet tube to be connected with the water inlet tube, suck the carrier water into the sample inlet tube and the reagent inlet tube, and use the carrier water to push the blank solution and the reducing agent;

[0016] 3) The reactor, atomizer, and mercury hollow cathode lamp are working, and the detector obtains a blank fluorescence value;

[0017] 4) Replace the test solution bottles containing standard solutions of different concentrations in order from low to high concentrations, repeat steps 1)-3), and sequentially measure the fluorescence value corresponding to each solution in the standard series;

[0018] 5) draw a fluorescence value-concentration standard curve;

[0019] Step 3, sample determination: replace the test solution bottle containing the sample solution, repeat steps 1) to 3) in step 2 to determine and obtain the fluorescence value corresponding to the sample solution, and obtain the concentration value of mercury in the sample solution through the fluorescence value-concentration standard curve in step 5). In step 3, it is preferred to wash the sample injection tube with water before replacing the test solution bottle containing the sample solution.

[0020] Wherein: the sampling and liquid inlet time in step 1) is 4-5 seconds; the time from the completion of switching the water inlet pipe in step 2) to the step 3) the detector obtaining the fluorescence value is 8-10 seconds.

[0021] Based on the above mercury atomic fluorescence analyzer using water as a carrier current, the present invention further provides a simplified mercury atomic fluorescence analyzer using water as a carrier current. In the simplified instrument, the sample inlet tube and the reagent inlet tube of the infusion system are both liquid inlet capillaries, one end of the liquid inlet capillary is connected to the reactor, and the other end is a free end inserted into the solution of the test solution bottle or the reagent bottle; the water bottle is changed to two water cups, one water cup is used to hold cleaning water, and the other water cup is used to hold carrier water, and the free end of the liquid inlet capillary can be swapped between the two water cups.

[0022] Specifically, two liquid inlet capillaries (one for mercury test solution and the other for reducing agent) are respectively connected to the reactor through peristaltic pumps, and the peristaltic pumps are used to control the delivery speed and infusion volume of mercury test solution, reducing agent and carrier water into the liquid inlet capillaries.

[0023] Based on the simplified mercury analyzer with water as carrier flow, the present invention provides a matching mercury atomic fluorescence analysis method with water as carrier flow, including the following operations:

[0024] Operation 1. Prepare the mercury standard series solution and sample solution as mercury test solution as required, prepare NaBH4 solution as reducing agent, prepare two cups of pure water, one as cleaning water and the other as carrier water;

[0025] Operation 2. Start the instrument and adjust it to the required working state;

[0026] Operation 3. Make a standard curve:

[0027] A1) Sampling: insert the two inlet capillary ends into the standard blank solution and NaBH4 solution respectively to take samples, and the peristaltic pump stops working after 4-5 seconds;

[0028] A2) Replacement: Take out the two capillary ends and place them in a cup of cleaning water to clean them (clean the outer wall of the capillary), and then transfer them to another cup of flowing water to complete the replacement operation;

[0029] A3) Carrier current measurement: the peristaltic pump is restarted, so that the carrier water entering the capillary carries the mercury test solution and the reducing agent into the reactor respectively, the reactor, the atomizer, and the mercury hollow cathode lamp are operated, and the detector measures the blank fluorescence signal and records the fluorescence value of the blank solution;

[0030] A4) After the blank fluorescence signal reaches stability, replace the blank solution with the standard solution, repeat the operations of A1) to A3) to measure the fluorescence signals of the standard series solutions in order from low to high concentrations and record the fluorescence values;

[0031] A5) Prepare fluorescence value-concentration standard curve;

[0032] Operation 4. Determine the sample: Determine the sample solution according to the operations of A1)-A3) to obtain the sample fluorescence value, obtain the concentration of mercury in the sample solution from the fluorescence value-concentration standard curve of step A5), and calculate the content of the measured element in the sample after inputting relevant parameters. In operation 4, preferably, before determining the sample solution, clean the liquid inlet capillary with cleaning water.

[0033] In the above operation 3, the sampling / delay / switch time / measurement time is 4-5 / 0 / 2-3 / 8-10 seconds respectively, that is, A1) sampling time is 4-5 seconds, delay is zero second, A2) swap time is 2-3, A3) current measurement time is 8-10 seconds.

[0034] By adopting the above scheme, the present invention creatively uses water as the carrier in the atomic fluorescence analysis process of mercury, ending the history of using HCl and NaBH4 as the carrier for more than 30 years. Experiments have shown that the infusion technology using water instead of HCl and reducing agent as carrier current is used in mercury atomic fluorescence analysis, which can not only detect trace or trace amounts of Hg in the test solution, but also overcome the technical prejudice that it is impossible to use water as carrier current in atomic fluorescence analysis in the general understanding; at the same time, unlike HCl and NaBH4 as carrier current for mercury measurement, ultrapure water does not contain the measured component, and will not undergo any chemical reaction with the mercury test solution or reducing agent during the infusion process, and there are no large amounts of bubbles (caused by the generation of hydrogen by the acid and the reducing agent) adhering to the tube wall of the flow path, and all infusion flow paths can be flushed most thoroughly while carrying the current, so that the memory effect in mercury atomic fluorescence measurement can be effectively overcome, the measurement sensitivity and accuracy are improved, and even Hg can be measured when the concentration is lower than 0.1ng / ml (such as 0.04ng / ml in Example 3); in addition, using water as carrier current also saves a large amount of high-purity HCl and reducing agent NaBH4 used as carrier liquid, the analysis cost is greatly reduced, and the operating environment is also significantly improved.

[0035] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1A A schematic diagram of a dual-channel atomic fluorescence analysis device combined with a water carrier infusion system;

[0037] Figure 1B It is a schematic diagram of the structure of the mercury atomic fluorescence analyzer using water as the carrier current of the present invention;

[0038] Figure 2 It is a simplified infusion system and infusion schematic diagram in the mercury atomic fluorescence analysis using water as carrier fluid of the present invention;

[0039] Figure 3 This is a picture of Hg measured by the mercury atomic fluorescence analyzer of the present invention using water as the carrier current in Example 1, frame A is the peak curve (fluorescence value-time), frame B is the standard curve of Hg concentration 1-5 ng / mL (fluorescence value-concentration);

[0040] Figure 4 The peak curve of Hg / As (A, fluorescence value-time) and the standard curve of 0.2-1.0 ng / mL Hg and 10-50 ng / mL As mixed solution (B, fluorescence value-concentration) were simultaneously measured by a dual-channel atomic fluorescence analyzer with water as carrier in Example 2;

[0041] Figure 5 This is a picture of Example 3 of measuring Hg in rice using the mercury atomic fluorescence analyzer of the present invention using water as the carrier current. Frame B is the peak curve (fluorescence value-time), and frame C is the 0.1-0.5 ng / mL Hg standard curve (fluorescence value-concentration). DETAILED DESCRIPTION

[0042] The invention provides a mercury atomic fluorescence analysis method using water as carrier and a mercury atomic fluorescence measuring instrument.

[0043] Based on atomic fluorescence analysis technology, conventional atomic fluorescence analysis devices usually include an infusion system, a reactor, an atomizer, an excitation light source and a detector (see the relationship between the components). Figure 1A As shown, Figure 1A The dual-channel atomic fluorescence analysis device designed by the applicant can be used to simultaneously measure Hg and As). The basic structure of the mercury atomic fluorescence measurement instrument based on the atomic fluorescence analysis principle is similar to this, except that the excitation light source is a single mercury hollow cathode lamp (see Figure 1B As shown), a mercury test solution (test solution) and a reducing agent (reagent) are introduced into the reactor by an infusion system, and hydrochloric acid and a reducing agent are used as carriers during the introduction process.

[0044] The design idea of ​​the present invention is to use water instead of HCl and reducing agent (reagent) as carrier flow in the conventional mercury atomic fluorescence analysis infusion process. After the test solution and reagent are respectively input from the liquid aspiration capillary into their respective sample storage loops, both capillaries use pure water as carrier flow, and the test solution and reagent in each sample storage loop are pushed into the reactor for reaction under the carrier of water. At the same time, the pure water as carrier flow also cleans the pipeline of the infusion system.

[0045] According to the above design ideas, the structure of the mercury atomic fluorescence analyzer using water as carrier current of the present invention is shown in Figure 1B As shown, the infusion system includes: a test solution bottle for holding the mercury test solution to be tested, the test solution bottle is connected to the reactor through a sample inlet tube; a reagent bottle for holding a reducing agent, the reagent bottle is connected to the reactor through a reagent inlet tube; a water bottle for holding pure water, the water outlet of the water bottle is connected to the sample inlet tube inlet and the reagent inlet tube inlet respectively through a water inlet tube, and the water inlet is controlled by switching the water inlet tube. The unique design of the infusion system is that the infusion system does not include a supporting device for infusing the carrier hydrochloric acid, so it is clearly distinguished and significantly different from the known infusion system. The infusion system, together with a conventional mercury atomic fluorescence analyzer including a reactor, an atomizer, a hollow cathode lamp and a detector, constitutes the mercury atomic fluorescence analyzer with water as the carrier of the present invention.

[0046] According to the above design ideas, in the mercury atomic fluorescence analysis method of the present invention, a test solution of a certain acidity and a reagent of a certain concentration are first introduced simultaneously during the infusion process (called inlet solution), and then the test solution and the reagent are pushed (carrier push) into the reactor for reaction using pure water as a carrier, and the vapor after the reaction is atomized by an atomizer, and then the fluorescence signal of mercury is obtained through an excitation light source (mercury hollow cathode lamp) and a detector (called determination), and then the concentration of mercury in the test solution is obtained. The infusion process does not use hydrochloric acid as a carrier, and the carrier of the reagent is also replaced by pure water, which is significantly different from the known infusion system and beyond conventional imagination.

[0047] In the method of the present invention, the acidity (HCl%) of the test solution is 5%-10%, and the concentration of the reducing agent NaBH4 (or KBH4) is 0.2%. The concentration of mercury that can be measured is below 5ng / ml, and even when the Hg concentration is as low as below 0.5ng / ml and below 0.1ng / ml (such as 0.04ng / ml), it can be measured.

[0048] Specific, combined Figure 1B As shown, the specific steps of the mercury atomic fluorescence analysis method using water as the carrier flow can be:

[0049] Step 1: Prepare a series of standard solutions with different concentrations of mercury, prepare the sample solution to be tested, prepare NaBH4 solution, put the standard solution and sample solution (collectively referred to as mercury test solution, referred to as test solution) into the test solution bottle, put the NaBH4 solution (referred to as reagent) into the reagent bottle; put pure water (as carrier water) into the water bottle.

[0050] Step 2, prepare standard curve: 1) connect the sample injection tube to the interface of the test solution bottle containing standard blank solution (acid solution with Hg concentration of 0), connect the reagent inlet tube to the interface of the reagent bottle, and inject liquid (4-5 seconds); 2) switch the sample injection tube and the reagent inlet tube to be connected with the water inlet tube, suck the carrier water into the sample injection tube and the reagent inlet tube, and push the blank solution and reagent with the carrier; 3) the reactor, atomizer, and excitation light source work, and the detector records the blank fluorescence value (8-10 seconds from switching to completion of detector detection); 4) replace the test solution bottles containing standard solutions of different concentrations in order from low to high concentration, repeat steps 1)-3), sequentially measure and obtain the fluorescence value corresponding to each concentration standard solution in the standard series; 5) draw a mercury fluorescence value-concentration standard curve.

[0051] Step 3, sample determination: Replace the test solution bottle containing the sample solution, repeat steps 1)-3) to determine and obtain the fluorescence value corresponding to the sample solution, and convert the concentration value of mercury in the sample solution through the fluorescence value-concentration standard curve. In order to avoid the residue of high-concentration mercury standard solution in the tube, it is best to wash the injection tube with water before replacing the sample solution (compared with the previous operation with acid as the carrier current, washing is not necessary, and even if washing, the amount of washing water used is much less), which can better eliminate the memory effect of mercury.

[0052] The present invention uses water as the carrier of the mercury atomic fluorescence analyzer, and the simplified infusion system is shown in Figure 2 As shown, it includes: a test solution bottle for holding a test solution and a reagent bottle for holding a reducing agent, the test solution bottle and the reagent bottle are respectively connected to the reactor through a liquid inlet capillary inserted into the liquid in the bottle, that is, one end of the liquid inlet capillary is connected to the reactor, and the other end is a free end inserted into the solution of the test solution bottle or the reagent bottle; two water bottles for holding pure water, one (water cup 1) holds cleaning water for cleaning the capillary, and the other (water cup 2) holds carrier water as the carrier. A peristaltic pump can be used in the infusion process of mercury atomic fluorescence analysis. After the test solution and reagent are respectively input into the sample storage loop (called "sampling") through two capillaries under the action of the peristaltic pump, the front section (free end) of the two capillaries near the head end is transferred into the cleaning pure water in the water cup 1 to clean the solution attached to the outer wall (see Figure 2 Then the two capillary tips (free ends) are transferred into the water cup 2 (see Figure 2 The free end of the capillary is transferred from the test solution bottle or reagent bottle to water cup 1, and then from water cup 1 to water cup 2 (called "re-insertion"), and the test solution and reagent in the sample ring are pushed into the reactor with pure water. Similarly, the reactor, atomizer, and excitation light source (mercury hollow cathode lamp) work, that is, the mercury atomic vapor produced by the chemical reaction in the reactor is input into the atomizer and excited by the radiation of the mercury hollow cathode lamp. The emitted fluorescent signal is detected by the detector to obtain the concentration of mercury in the test solution.

[0053] The time control in the mercury atomic fluorescence analysis using water as the carrier flow using the simplified infusion system is: sampling / delay / replacement (capillary) / determination: 4-5 / 0 / 2-3 / 8-10 (seconds). That is, the time for sucking the test solution and reagent (i.e. sampling) is 4-5 seconds, the delay is usually zero seconds, the capillary is taken out of the test solution and reagent, first placed in water cup 1 for a while and then transferred to water cup 2 (i.e. replacement), and the time is generally 2-3 seconds. The time for the carrier water in water cup 2 to push the test solution and reagent in the sample loop until the end of the determination is 8-10 seconds, and the fluorescence signal of mercury is measured during this period of time.

[0054] The specific operations of the detection instance are:

[0055] Operation 1. Prepare the mercury standard series solution and NaBH4 solution and related reagents as required. The sample solution must be prepared in advance. Place the test solution bottle containing the test solution, the reagent bottle containing the NaBH4 solution and two cups of pure water in the sample tray.

[0056] Operation 2. Turn on the power of the atomic fluorescence instrument, confirm the test conditions, light the hollow cathode lamp and preheat for 5-10 minutes. Open the valve of the Ar gas cylinder, adjust the Ar gas pressure to 0.3MPA, and open the exhaust device of the atomizer.

[0057] Operation 3. Make a standard curve:

[0058] 1) Sampling: insert the two inlet capillary ends (free ends) into the standard blank solution in the test bottle and the NaBH4 solution in the reagent bottle respectively, click the "blank" button of the instrument, the infusion system executes the infusion program, and the peristaltic pump stops working after sampling for 4-5 seconds;

[0059] 2) Immediately take out the free ends of the two capillaries from the test solution bottle and the reagent bottle, first place them in the cleaning water of cup 1 to clean them to remove the attached solution, and then transfer them to the pure water of cup 2 to complete the insertion (the insertion time is 2-3 seconds). After the two capillaries are inserted into cup 2, the peristaltic pump is restarted;

[0060] 3) The carrier water in the water cup 2 enters the two capillaries respectively under the action of the peristaltic pump, and the carrier water and the reagent enter the reactor. The reactor, the atomizer, and the excitation light source work, and the detector measures the fluorescence signal of the standard blank solution and records the blank fluorescence value (the time from the carrier to the end of the measurement is 8-10 seconds);

[0061] 4) After the blank fluorescence signal is stable, the standard solution is used as the test solution, and steps 1) to 3) are repeated to measure the fluorescence signals of the standard series solutions in order from low to high concentrations and record the fluorescence values; the peak curve of the fluorescence signal (fluorescence value-time) can be generated synchronously;

[0062] 5) Input the concentration of the standard solution, take the average value of each concentration of the standard solution, and make a fluorescence value-concentration standard curve.

[0063] Operation 4. Determine the sample: clean the inlet capillary inserted into the test solution bottle with water (to avoid the residue of high concentration mercury standard solution in the tube, but cleaning is not necessary here), click the "Sample Test" button of the instrument, first determine the sample blank until it is stable, use the sample solution as the test solution and then determine the fluorescence signal of each sample solution according to 1)-3) of operation 3, and obtain the concentration of mercury in the sample solution from the fluorescence value of the sample and the fluorescence value-concentration standard curve in 5) of operation 3. After entering the relevant parameters, calculate the mercury content in the sample.

[0064] The above describes the determination of mercury as a single element by atomic fluorescence using water as the carrier. In practical applications, mercury can also be measured together with other elements, such as using Figure 1A The dual-channel atomic fluorescence analysis device with a combined water carrier infusion system is shown. Figure 1B or Figure 2 The same as shown, one of the two excitation light sources is a mercury excitation light source. When determining multiple elements containing mercury, prepare a standard mixed solution of different concentrations of each element, and use two excitation light sources to excite based on a single infusion, reaction, and atomization process. The detector obtains the fluorescence signals of different elements respectively, and the standard curves of the corresponding elements are prepared respectively. Then, according to the above steps and operations, the concentration of each element in each sample test solution is determined and the content of each element to be measured in the sample is calculated.

[0065] The present invention is further described below in conjunction with specific examples, which are provided for illustrative purposes only and are not intended to limit the present invention. The concentration of reagents in the examples is expressed as a percentage by mass.

[0066] Example 1: Analysis of Hg in associated uranium ore

[0067] Test samples: associated uranium minerals

[0068] This embodiment utilizes Figure 1B The water shown is the carrier of the mercury atomic fluorescence analyzer (the infusion system uses Figure 2 shown).

[0069] Preparation of mercury standard curve: First prepare a 50ng / ml Hg standard solution. Take 0, 1, 2, 3, 4, and 5ml of this standard solution in a 50ml plastic quantitative bottle, add 5ml of 50% HCl to each, and dilute to the scale with water. The Hg concentration in the obtained series of standard solutions is 0, 1, 2, 3, 4, and 5ng / ml. According to the operating procedure, measure the fluorescence signal of the blank and standard series solutions. The peak curve of Hg can be found in Figure 3 A signal spectrum similar to Gaussian distribution was obtained. A fluorescence signal-concentration standard curve was prepared based on the fluorescence signal of the standard solution (see Figure 3 (B).

[0070] Sample solution preparation and determination:

[0071] Weigh a certain ore sample and record it in Table 1, place it in a 50ml tetrafluoroethylene sample tube, add 5ml of 50% aqua regia, boil and decompose it in a water bath for 1 hour, transfer it to a 50ml centrifuge tube with water, add 5ml of 50% HCl, dilute it to the scale with water, shake it well, use the sample solution as the test solution, and measure the fluorescence signal of the sample solution according to the operation process. In view of the high Hg concentration of the standard solution of 5ng / ml, the injection capillary can be washed with water before inserting the sample solution to completely remove the mercury residue in the capillary. The Hg concentration is obtained from the standard curve and converted into the Hg content in the sample. The determination results of the sample solution and Hg in the sample are shown in Table 1.

[0072] Table 1. Determination results of Hg in ores

[0073] G(g) Fluorescence intensity Concentration (ng / ml) Test solution volume (ml) Sample content (μg / g) 0.1161 5046 1.699 50 0.528 0.2357 7264 2.447 50 0.521 0.1846 5645 1.901 50 0.517 0.1940 6038 2.033 50 0.524

[0074] From the data in the table, it can be seen that when the sample weight (G) varies greatly and the HCl concentration is 5%, the mercury analyzer using water flow can quickly determine the Hg in the ore. The measured Hg content in the samples is almost the same and consistent with the comparison results of multiple laboratories.

[0075] In this determination operation, only pure water (18.2MΩ.cm) is consumed without hydrochloric acid as a carrier, and the sampling time is reduced by about 50% compared with the conventional method. The NaBH4 solution is only needed to participate in the reaction, which saves more than 75% compared with conventional detection. The sample weight in the table is random. It can be seen that the concentration of mercury in the solution is high or low and the determination can still be completed and consistent results can be obtained. It can be seen that using water as a carrier eliminates the memory effect. Even after the high-concentration standard solution is determined, the infusion system is cleaned with carrier water, and the determination of other concentration sample solutions is not affected.

[0076] Example 2: Simultaneous determination of Hg / As in soil

[0077] Test sample: Soil

[0078] Since the content of As in soil is much higher than that of Hg, the existing atomic fluorescence spectrometer has not been able to simultaneously measure Hg and As in such samples. Figure 1A The dual-channel atomic fluorescence analysis device shown in the figure can realize the simultaneous detection of Hg and As elements in the same sample.

[0079] Preparation of standard curve: Prepare a mixed standard solution containing 500ng / ml As and 10ng / ml Hg in advance. Take 0, 1, 2, 3, 4, 5ml of this standard solution in 50ml plastic quantitative bottles, add 5ml of 5% Vc-5% thiourea solution and 10ml of 50% HCl, dilute with water to the scale, and the Hg concentration in the obtained series of standard solutions is 0, 0.2, 0.4, 0.6, 0.8, 1.0ng / ml, and the As concentration is 0, 10, 20, 30, 40, 50ng / ml.

[0080] Select the dual-channel method and simultaneously measure the fluorescence signals of Hg and As in the blank and standard series solutions according to the above operation process to prepare the standard curves of 0.2-1.0 ng / ml Hg and 10-50 ng / ml As of the mixed standard solution respectively. Figure 4 The A amplitude is the peak curve of Hg / As. Figure 4 Panel B is the standard curve of the mixed standard solution of Hg and As (the signal of the standard curve is calculated based on the spectrum area, and the blank area has been subtracted).

[0081] Preparation and determination of sample solution: 0.1-0.2g of soil sample was placed in a 50ml tetrafluoroethylene sample tube, 50% aqua regia was added to each sample and boiled in a water bath for 1 hour, then transferred to a 50ml plastic quantitative bottle with water, 5% Vc-5% thiourea solution 5ml and 50% HCl 10ml were added to each sample, and diluted to the scale with water, after shaking, the sample solution was used as the test solution, and the fluorescence signals of Hg and As were determined according to the operation process, and the concentrations of the corresponding elements were obtained according to their respective standard curves to calculate their respective contents in the sample. The determination results are shown in Table 2.

[0082] Table 2. Simultaneous determination results of soil Hg / As

[0083]

[0084] The data show that the atomic fluorescence method and device using water as carrier current solves the difficulty of simultaneously determining Hg and As in soil. It can also be seen that the Hg concentrations in the six samples (standard samples) vary greatly. The results of the samples tested from top to bottom in Table 2 are consistent with the recommended values, indicating that the mercury atomic fluorescence analysis method and device using water as carrier current eliminates the serious memory effect in the determination of Hg.

[0085] In this embodiment, two elements coexist in the test solution, the delivery system only needs to complete the test solution delivery once, and the detection of the dual-channel detection system is also completed once. In this measurement operation, water is used as the carrier fluid without the need for hydrochloric acid. Each time the NaBH4 solution is analyzed, only 100ml-250ml of it needs to be prepared for the reaction, and the time and cost of the entire testing process are greatly reduced.

[0086] Example 3: Analysis of Hg in Rice

[0087] Test sample: Rice

[0088] Preparation of mercury standard curve: First prepare a 5ng / ml Hg standard solution. Take 0, 1, 2, 3, 4, and 5ml of this standard solution in a 50ml plastic quantitative bottle, add 5ml of 50% HCl to each, and dilute to the scale with water. The Hg concentrations in the obtained series of standard solutions are 0, 0.1, 0.2, 0.3, 0.4, and 0.5ng / ml. According to the operating procedures, measure the fluorescence signals of the blank and standard series solutions. The changes in signal intensity with concentration are shown in Table 4, and the peak curve is shown in Table 4. Figure 5 In panel B, a fluorescence signal-concentration standard curve was prepared based on the fluorescence signal of the standard solution (see Figure 5 (C).

[0089] Sample solution preparation and determination:

[0090] Weigh 0.3-0.5g of rice sample, place in 50ml tetrafluoroethylene sample tube, add 5ml of 50% aqua regia, boil and decompose in a water bath for 1 hour, transfer to 20ml centrifuge tube with water, dilute to scale with water, measure the fluorescence signal of sample solution (in view of the maximum Hg concentration of standard solution is only 0.5ng / ml, water is used as carrier current to remove the residual Hg in the tube, and the injection capillary does not need to be cleaned before inserting the sample solution), obtain the concentration of Hg from the standard curve and convert it into the content of Hg in the sample. The determination results of Hg in rice sample are shown in Table 3.

[0091] Table 3. Determination results of Hg in rice (ng / g)

[0092]

[0093] From the data in the table, it can be seen that the content of Hg in rice is extremely low, and it is difficult to obtain accurate results using general analytical methods. However, the four rice samples were measured using this instrument, and the results of the two parallel measurements were almost the same and consistent with the recommended values. Obviously, the atomic fluorescence spectrometer using water as the carrier current of the present invention provides a reliable analytical means for detecting Hg in rice.

[0094] Table 4 Determination data of Hg standard solution

[0095]

Claims

1. A mercury atomic fluorescence analysis method using water as carrier fluid, comprising the steps of sampling and infusion, a mercury test solution and a reducing agent reacting in a reactor to atomize mercury, generating mercury atomic fluorescence and fluorescence detection, characterized in that: In the conventional sampling and infusion process, water is used instead of HCl and reducing agent as carrier fluid, so that the mercury test solution and reducing agent are carried by water and pushed into the reactor to complete the reaction; The sampling and infusion process is to first take samples, that is, introduce mercury test solution and reducing agent with certain acidity at the same time, and then infuse, that is, use pure water as carrier to push the mercury test solution and reducing agent into the reactor respectively; the certain acidity of the mercury test solution refers to the hydrochloric acid concentration of 5%-10%.

2. The mercury atomic fluorescence analysis method using water as carrier fluid according to claim 1, characterized in that: The sampling time is 4-5 seconds and the infusion time is 8-10 seconds.

3. The mercury atomic fluorescence analysis method using water as carrier fluid according to claim 2, characterized in that: The Hg concentration range of the mercury test solution determined by this method is 0-5 ng / mL.

4. The mercury atomic fluorescence analysis method using water as carrier fluid according to claim 2, characterized in that: This method can determine the Hg concentration of mercury test solution in the range of 0-0.5 ng / mL.

5. The mercury atomic fluorescence analysis method using water as carrier fluid according to claim 2, characterized in that: The Hg concentration range of the mercury test solution determined by this method is as low as less than 0.1 ng / mL.

6. A mercury atomic fluorescence analyzer using water as carrier fluid, comprising an infusion system, a reactor, an atomizer, a mercury hollow cathode lamp and a detector, characterized in that: The infusion system comprises: A test solution bottle for containing the mercury test solution to be tested, the test solution bottle being connected to the reactor through a sample injection tube; A reagent bottle for containing a reducing agent, the reagent bottle being connected to the reactor through a reagent inlet pipe; A water bottle for holding pure water, the water outlet of the water bottle is connected to the inlet of the sample tube and the inlet of the reagent tube through the water inlet pipe, and the water inlet is controlled by switching the water inlet pipe; and The infusion system does not contain a supporting device for infusing the carrier acid.

7. The mercury atomic fluorescence spectrometer using water as carrier fluid according to claim 6, characterized in that: The sample inlet tube and the reagent inlet tube are both liquid inlet capillaries, one end of the liquid inlet capillary is connected to the reactor, and the other end is a free end inserted into the solution in the test solution bottle or the reagent bottle. The water bottle is changed to two water cups, one water cup is used to hold cleaning water, and the other water cup is used to hold carrier water. The free end of the liquid inlet capillary can be swapped between the two water cups.

8. The mercury atomic fluorescence spectrometer using water as carrier fluid according to claim 7, characterized in that: Two liquid inlet capillaries are respectively connected to the reactor through peristaltic pumps, and the peristaltic pumps control the conveying speed and infusion volume of mercury test solution, reducing agent and carrier water into the liquid inlet capillaries.

9. A method for mercury atomic fluorescence analysis using water as a carrier fluid, using the mercury atomic fluorescence analyzer of claim 6, comprising the following steps: Step 1, prepare a series of standard solutions of Hg with different concentrations, sample solutions to be tested and NaBH4 solutions, put the standard solutions and sample solutions as mercury test solutions into the test solution bottle, put the NaBH4 solution as a reducing agent into the reagent bottle; and put pure water as carrier water into the water bottle; Step 2: Make a standard curve: 1) Connect the sample inlet tube to the test solution bottle interface containing the standard blank solution, connect the reagent inlet tube to the reagent bottle interface, and add liquid; 2) Switch the sample inlet tube and the reagent inlet tube to be connected with the water inlet tube, suck the carrier water into the sample inlet tube and the reagent inlet tube, and use the carrier water to push the blank solution and the reducing agent; 3) The reactor, atomizer, and mercury hollow cathode lamp are working, and the detector obtains a blank fluorescence value; 4) Replace the test solution bottles containing standard solutions of different concentrations in order from low to high concentrations, repeat steps 1)-3), and sequentially measure and obtain the fluorescence value corresponding to each solution in the standard series; 5) draw a standard curve of mercury fluorescence value-concentration; Step 3, sample determination: replace the test solution bottle containing the sample solution, repeat steps 1)-3) in step 2, determine and obtain the fluorescence value corresponding to the sample solution, and obtain the concentration value of mercury in the sample solution through the fluorescence value-concentration standard curve in step 5).

10. The mercury atomic fluorescence analysis method using water as carrier fluid according to claim 9, characterized in that: In step 3), before replacing the test solution bottle containing the sample solution, the sample injection tube is cleaned with water.

11. The mercury atomic fluorescence analysis method using water as carrier fluid according to claim 9 or 10, characterized in that: The time for sampling and liquid entry in step 1) is 4-5 seconds; the time from the inhalation of carrier water in step 2) to the acquisition of fluorescence value by the detector in step 3) is 8-10 seconds.

12. A mercury atomic fluorescence analysis method using water as a carrier fluid, using the mercury atomic fluorescence analyzer according to claim 7 or 8, comprising the following operations: Operation 1. Prepare the mercury standard series solution and sample solution as mercury test solution as required, prepare NaBH4 solution as reducing agent, prepare two cups of pure water, one as cleaning water and the other as carrier water; Operation 2. Start the mercury atomic fluorescence analyzer and adjust it to the required working state; Operation 3. Make a standard curve: A1) Sampling: insert the free ends of the two inlet capillaries into the standard blank solution and NaBH4 solution respectively to take samples, and the peristaltic pump stops working after 4-5 seconds; A2) Replacement: Take out the free ends of the two capillaries and place them in a cup of cleaning water to clean them, and then transfer them to another cup of carrying water to complete the replacement operation; A3) Carrier flow measurement: The peristaltic pump is restarted, so that the carrier water entering the capillary carries the mercury test solution and the reducing agent into the reactor respectively, the reactor, the atomizer, and the excitation light source work, and the detector measures the blank fluorescence signal and records the fluorescence value of the blank solution; A4) After the blank fluorescence signal reaches stability, replace the blank solution with the standard solution, repeat the operations of A1) to A3) to measure the fluorescence signals of the standard series solutions in order from low to high concentrations and record the fluorescence values; A5) Prepare fluorescence value-concentration standard curve; Operation 4. Determine the sample: Determine the sample solution according to A1)-A3) in Operation 3 to obtain the sample fluorescence value. From the fluorescence value-concentration standard curve in A5), obtain the concentration of mercury in the sample solution. After inputting relevant parameters, calculate the content of the measured element in the sample.

13. The mercury atomic fluorescence analysis method using water as carrier fluid according to claim 12, characterized in that: In operation 4, before measuring the sample solution, the inlet capillary is cleaned with cleaning water.

14. The mercury atomic fluorescence analysis method using water as carrier fluid according to claim 12 or 13, characterized in that: The sampling / delay / switching / measurement times are 4-5 / 0 / 2-3 / 8-10 seconds respectively, that is, A1) sampling time is 4-5 seconds, delay is zero second, A2) switching time is 2-3 seconds, A3) current measurement time is 8-10 seconds.

Images