Marine sediment heavy metal determination method based on rapid digestion

Abstract

The invention discloses a marine sediment heavy metal determination method based on rapid digestion. The marine sediment heavy metal determination method comprises the following steps: S1, digestion; the method comprises the following steps: weighing a standard sample, putting the standard sample into a polypropylene volumetric tube, wetting the sample, adding mixed acid, and digesting in a graphite digestion instrument; the exterior of the polypropylene volumetric tube is sealed; s2, detecting; cooling and quantifying after digestion is completed, taking supernate, diluting and detecting; preparing a calibration solution by adopting the digestion blank solution so as to eliminate a matrix effect caused by acid for digestion; 103Rh, 115In and 209Bi are selected as internal standard elements, and the on-line internal standard concentration is 50 [mu] g / L. According to the method, the polypropylene volumetric tube and the graphite digestion instrument are adopted for digestion, the digestion time is obviously shortened, the digestion temperature is reduced, the pretreatment efficiency is improved, and meanwhile, by optimizing the calibration solution preparation method and the conditions such as internal standard elements and internal standard concentration, it is ensured that the accuracy and precision of the method meet the test requirements.

Description

Technical Field

[0001] This invention belongs to the field of marine monitoring technology, specifically relating to a method for determining heavy metals in marine sediments based on rapid digestion. Background Technology

[0002] Heavy metals, as a class of environmental pollutants with long-term persistence, have become one of the main factors affecting sediment quality due to their prominent toxicity and persistence. The accumulating toxic substances and increasing organic matter in sediments can eventually migrate to benthic habitats and enter the food chain, posing a significant threat to ecosystems and human health. Therefore, conducting detection and safety risk assessment of heavy metal content in marine sediments is of great practical significance. Currently commonly used methods for heavy metal analysis include polarography, atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS).

[0003] Chinese invention CN 113109323A, entitled "Determination of Major Heavy Metal Elements in Marine Sediments," discloses a technical solution for determining major heavy metal elements in marine sediments. The procedure is as follows: Marine sediment samples are acid-digested to obtain a digest solution, which is then introduced into an inductively coupled plasma optical emission spectrometer (ICP-OES) via a peristaltic pump. A carrier gas carries the sample into an atomization system to form an aerosol, which then enters the axial channel of the torch. In a high-temperature, inert argon atmosphere, the aerosol particles are fully evaporated, atomized, excited, and ionized. The excited atoms and ions emit high-intensity atomic and ionic spectral lines. Through a spectroscopic system, photoelectric conversion, signal detection, and data processing, the content of each element is finally determined.

[0004] However, this technical solution still has the following shortcomings: 1. Although this method can achieve complete digestion of most sediment samples, the actual operation steps are relatively cumbersome and time-consuming, and the instrument operation during microwave digestion is relatively complicated, which is not conducive to the efficient pretreatment of large batches of marine sediment samples.

[0005] 2. The digestion vessel needs to be acid-washed and reused. This process may introduce exogenous contamination and affect the accuracy of the analytical results.

[0006] 3. Marine sediments have a complex composition, and the complete digestion process introduces a large number of anions (such as chloride and fluoride ions), which can interfere with subsequent analyses.

[0007] 4. When using inductively coupled plasma mass spectrometry (ICP-MS) to detect such samples, the matrix effect often leads to deviations in the detection results, resulting in measured values ​​that are too high or too low. Summary of the Invention

[0008] The purpose of this application is to overcome the aforementioned shortcomings of the prior art and provide a method for determining heavy metals in marine sediments based on rapid digestion. This method uses polypropylene volumetric tubes and a graphite digester for digestion, significantly shortening the digestion time and reducing the digestion temperature, thus improving pretreatment efficiency. Simultaneously, by optimizing the calibration solution preparation method and the internal standard element and concentration, the accuracy and precision of this method are ensured to meet testing requirements.

[0009] To achieve the aforementioned objectives, this application provides a method for determining heavy metals in marine sediments based on rapid digestion, comprising the following steps: S1. Dissolve; The standard sample was weighed and placed in a polypropylene volumetric tube. After wetting the sample, a mixed acid was added, and then the sample was placed in a graphite digester for digestion. The polypropylene volumetric tube was sealed to improve its sealing performance and internal pressure. S2. Detection; After digestion, the solution was cooled and quantified. The supernatant was diluted and then analyzed. A calibration solution was prepared using a digestion blank solution to eliminate the matrix effect caused by the acid used in digestion. 103 Rh、 115 In and 209 Bi was used as the internal standard element, and the online internal standard concentration was 50 μg / L.

[0010] Specifically, this detection is based on the fact that the ion counting rate (CPS, Counts Per Second) is proportional to the concentration of that element in the sample. Calibration: A calibration curve is established by measuring a series of calibration solutions with known concentrations. Calculation: Then, the signal intensity of the unknown sample is measured, and the actual content of each element in the sample can be accurately calculated using the calibration curve.

[0011] This invention establishes optimal rapid digestion conditions suitable for ICP-MS determination of heavy metals in marine sediments by systematically studying the effects of key parameters such as digestion system, digestion pressure, calibration solution preparation method, and internal standard element and concentration on the digestion effect of marine sediment samples.

[0012] Compared with traditional methods, this method has the following advantages: it eliminates the acid removal step, making the process simpler and more efficient; the digestion process is simplified, effectively reducing human error; it uses low-cost disposable polypropylene quantitative tubes for digestion, avoiding cross-contamination that may occur due to the reuse of digestion tubes; the sealing method of the volumetric tubes has been optimized and improved, further enhancing operational efficiency; and by optimizing the preparation method of the calibration solution and the conditions such as the internal standard element and internal standard concentration, it is ensured that the method meets the testing requirements in terms of accuracy and precision.

[0013] Preferably, during digestion, PTFE tape and adhesive tape are used to wrap and seal the upper part of the polypropylene volumetric tube and its cap to improve the tube's sealing and internal pressure. PTFE tape is very flexible and can fill tiny gaps, forming an effective airtight and watertight seal. This is crucial for volumetric tubes requiring precise measurement, preventing leakage. Adhesive tape provides quick and secure fixation and wrapping, focusing on mechanical protection and temporary / unpressurized sealing. More preferably, PTFE tape is first wrapped to ensure a seal, and then adhesive tape is wrapped around the outer layer for final fixation.

[0014] Preferably, when detecting Cr, Ni, Cu, Cd, and Pb, the mixed acid in S1 is nitric acid and hydrofluoric acid; when detecting Cr, Ni, Cu, Cd, Pb, and Zn, the mixed acid in S1 is a mixture of HCl, HNO3, and HF, with a volume ratio of HCl:HNO3:HF of 3:1:1. The inventors have found through extensive experimentation that the above-mentioned volume ratio of combined acids exhibits good dissolution performance for heavy metals in marine sediments. During sample digestion, the amount of acid can be appropriately increased or decreased according to the sample volume.

[0015] Preferably, the digestion temperature is 120–130°C, and the digestion time is 0.8–1.2 h. The low digestion temperature and short time significantly improve operational efficiency and are beneficial for the pretreatment of large batches of marine sediment samples. Heating and reflux are required during the digestion process.

[0016] The combination of acids with the above-mentioned volume ratio, as well as the digestion temperature and time, resulted in a thorough digestion of heavy metals without residue, and good reproducibility of heavy metal detection.

[0017] Preferably, in step S2, the quantitative method is weighing, using 0.5% HNO3 to dilute the digestion solution to 400-600 times its original weight. Considering that the heating process may affect the volumetric tube graduations, this invention changes the quantitative method from fixed volume to weighing, i.e., diluting the digestion solution to a specified multiple with 0.5% HNO3. Before testing, the supernatant (which is the digestion solution) is taken and further diluted by 2 times with 0.5% HNO3, and then measured. The dilution factor is increased during the pretreatment process to reduce the influence of the matrix.

[0018] In this article, 0.5% HNO3 refers to a 0.5% (v / v) nitric acid solution.

[0019] Preferably, the collection, preparation, storage, and transportation of the standard samples are carried out in accordance with the relevant provisions of GBW07314 and GBW07333; specifically, the standard samples are commercially available. The weight ratio of the standard sample to the mixed acid is 1:50-70. The weight ratio of the standard sample to the digestion mixed acid is a parameter that needs careful optimization. This invention adjusts the ratio based on the sample characteristics and the specific acid system to achieve a better digestion effect.

[0020] Preferably, all reagents used are of analytical grade, and the standard sample described in S1 is wetted with ultrapure water. The purity of these reagents significantly reduces the impact of impurities on the detection results.

[0021] Preferably, the calibration solution is prepared by digesting a blank solution, including the following steps: 1. Take the same volume of ultrapure water as the standard sample in the same process, and put it into a polypropylene volumetric tube that is exactly the same as the standard sample. Add the same type and volume of mixed acid and digest it under the same conditions. After digestion, dilute to the same volume as the standard sample with 0.5% HNO3 to obtain a digestion blank solution. 2. Using the digestion blank solution as a solvent, dilute and prepare a series of calibration solutions of known concentrations.

[0022] The above-mentioned method for preparing calibration solutions eliminates background contamination introduced during the experiment and ensures measurement accuracy through matrix matching.

[0023] If the blank value is too high, focus on verifying the reagent blank and the entire sample analysis process. Prioritize the use of high-purity reagents, or purify existing reagents to effectively reduce background interference introduced by the reagents. The range of the standard curve can be adjusted according to the content of the analyte in the sample, or the sample digestion solution can be diluted to ensure that the content of the analyte is within the range of the standard curve while maintaining the linearity of the standard curve.

[0024] Preferably, the graphite digester is a DS-360 porous graphite digester with a temperature control accuracy of ±0.2℃, manufactured by Guangzhou Gedana Instruments Co., Ltd. The polypropylene volumetric tube is a disposable polypropylene volumetric tube made of transparent polymer material polypropylene, with a softening temperature of 160℃.

[0025] This invention employs ICP-MS to accurately determine six elements—Cr, Ni, Cu, Zn, Cd, and Pb—in marine sediments. Compared to existing technologies, the key advantage of this method is that the measured components are completely consistent with the controlled elements specified in the national standard "Marine Sediment Quality" (GB18668-2002). Therefore, the measurement results can provide a basis for classifying the quality of marine sediments, thereby providing crucial data support for studying the distribution patterns of heavy metals, assessing potential ecological risks, and ultimately serving the technical decision-making of marine environmental protection and management departments.

[0026] Compared with the prior art, this application has the following technical effects: ① Simplified process, high efficiency and convenience: The acid removal step in the traditional method is eliminated, which significantly shortens the pretreatment time; the entire digestion process is streamlined, which effectively reduces human error that may be caused by multiple operations.

[0027] ② Avoid contamination and control costs: The digestion process uses disposable polypropylene metering tubes, which are not only inexpensive, but also fundamentally avoid cross-contamination problems that may be caused by the reuse of digestion containers.

[0028] ③ Targeted optimization for matrix interference: In response to the problem that marine sediments are complex in composition and that full digestion can easily introduce interfering substances such as chloride ions and fluoride ions, which can lead to significant matrix effects in ICP-MS analysis (manifested as results that are too high or too low), this invention improves pretreatment efficiency while systematically optimizing the preparation method of calibration solutions and the selection of internal standard elements and concentrations, thereby effectively ensuring the accuracy and precision of analytical results.

[0029] Repeatability experiments were conducted on marine sediment standard materials GBW07314 and GBW07333. The determination results of the six major metallic elements all fell within the standard value range, with a method recovery rate of 95.4%–109.2% and a relative standard deviation between 0.00% and 3.22%. These data indicate that the accuracy and precision of this invention meet the requirements of routine analytical testing, providing reliable technical support for the monitoring, evaluation, and management of my country's marine ecological environment. Attached Figure Description

[0030] none Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the present invention will now be further described in conjunction with specific embodiments.

[0032] In the following description, the embodiments of this application are for illustrative purposes and not for limiting purposes, so as to provide a thorough understanding of the embodiments. However, those skilled in the art will understand that the embodiments of this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known preparation methods have been omitted so as not to obscure the description of the embodiments of this application with unnecessary details. Unless otherwise specified, the raw materials used in the following embodiments and comparative examples are all commercially available.

[0033] It should also be understood that the term "and / or" as used in the specification of embodiments of this application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" means two or more.

[0034] This section only introduces content related to the inventive points; other details can be obtained from relevant technologies and will not be described in detail here. The following embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0035] The instrument used in this embodiment is an ICP-MS 7900 inductively coupled plasma mass spectrometer (Agilent Technologies, USA). The Agilent 7900 ICP-MS is equipped with a copper-based nickel cone, a glass concentric nebulizer, and an integrated sample introduction system (ISIS 3). The RF power is 1550 W, the sampling depth is 9 mm, the carrier gas flow rate is 1.07 L / min, the dilution gas flow rate is 0.20 L / min, the number of scans is 100, and each sample is read three times. Before detection, the instrument measurement parameters of the ICP-MS are adjusted using instrument tuning fluid to ensure the instrument is operating at its optimal condition.

[0036] DS-360 porous graphite digester (temperature control accuracy ±0.2℃, Guangzhou Gedana Instrument Co., Ltd.), QUINTIX35-1CN electronic balance (sensitivity 0.01 mg, Sartorius, Germany), Milli-Q Advantage A10 ultrapure water system (resistivity greater than 18.25 MΩ·cm, Millipore, USA).

[0037] The reagents used in this application's embodiments are as follows: The sediment standard samples used in the experiments are sediment composition analysis standard materials GBW07314 (nearshore marine sediments) and GBW07333 (Yellow Sea marine sediments), both of which are commercially available. All reagents used in the experiments are of analytical grade (Guangdong Guangshi Reagent Technology Co., Ltd.), and the experimental water is ultrapure water. Disposable 50 ml volumetric tubes were used in the experiments. All other glassware was soaked in (1+3) HNO3 solution for 24 hours and then rinsed three times with tap water and ultrapure water before use. (1+3) HNO3 solution refers to a solution prepared by mixing 1 volume of nitric acid and 3 volumes of ultrapure water.

[0038] The test calibration solutions used in the experiment were prepared from Agilent mixed standard solutions in 0.5% HNO3 at concentration levels of 0.5%, 1, 2, 5, 10, 20, 50, 100, 200, 500, and 1000 μg / L.

[0039] Example 1: A method for determining heavy metals in marine sediments based on rapid digestion, comprising: S1. Dissolution Weigh approximately 0.1000 g of sediment standard sample (GBW07314 nearshore marine sediment) and place it in a 50 mL polypropylene volumetric tube. After wetting it with a small amount of ultrapure water, add 3 mL of HCl, 1 mL of HNO3 and 1 mL of HF in sequence. Then screw on the matching cap and seal the outside with PTFE tape and adhesive tape. Subsequently, place the volumetric tube in a graphite digester, heat it to 125℃, and reflux it for 1 h.

[0040] S2. Detection After digestion, the solution is cooled to room temperature, and the volumetric tube is taken out for quantification. Considering that the heating process will have a certain impact on the scale of the volumetric tube, the present invention changes the quantification method from fixed volume to weighing, that is, the digestion solution is diluted to 50 g with 0.5% HNO3, and before detection, the supernatant is taken and diluted 2 times with 0.5% HNO3 for testing.

[0041] ① Plotting the calibration curve The calibration solution was prepared using a digestion blank solution. The dilution factor was increased during pretreatment (1000-fold dilution before measurement) to reduce matrix influence. However, considering that the rapid digestion pretreatment process does not include an acid removal step, this invention uses a digestion blank solution to prepare the calibration solution to eliminate the matrix effect caused by the acid used in digestion. The steps include: 1. Take the same volume of ultrapure water as the standard sample in the same process, and put it into a polypropylene volumetric tube that is exactly the same as the standard sample. Add the same type and volume of mixed acid and digest it under the same conditions. After digestion, dilute to the same volume as the standard sample with 0.5% HNO3 to obtain a digestion blank solution. 2. Using the digestion blank solution as a solvent, dilute and prepare a series of calibration solutions of known concentrations. The calibration solutions are prepared from Agilent mixed standard solutions in 0.5% HNO3 medium at concentration levels of 0.5%, 1, 2, 5, 10, 20, 50, 100, 200, 500, and 1000 μg / L.

[0042] The calibration series solutions were measured according to the reference operating conditions of the inductively coupled plasma atomic emission spectrometer, and the calibration curve was plotted based on the measurement results.

[0043] ② Selection of internal standard element and internal standard concentration choose 103 Rh、 115 In and 209 Bi was used as the internal standard element, and the online internal standard concentration was 50 μg / L.

[0044] Example 2: To verify the broad-spectrum nature of the method, an additional marine sediment standard material (GBW07333 Yellow Sea marine sediment) from a different sea area was selected for testing. The specific operating steps are as described in Example 1 above.

[0045] Comparative Example 1: Compared to Example 1, the internal standard element and concentration are different, but everything else is the same. The internal standard element is... 45 Sc and 72 When the internal standard concentration of Ge is 50 μg / L 45 The recovery rate of Sc exceeds 800%. 72 Ge recovery rates were between 180% and 200%, however, at the same internal standard concentration, 103 Rh、 115 In and 209 The recoveries of the three internal standards (Bi) remained stable within the range of 70%–130%. The internal standards were: 45 Sc and 72 When the internal standard concentration of Ge is 500 μg / L 45 The recovery rate of Sc was 125%. 72 The Ge recovery rate is 110%. At this point, the analytical results of the standard substance are within the standard value range. However, if the internal standard concentration is too high, it will cause the detector to saturate, which will manifest as signal distortion or failure to accurately reflect the actual concentration, and may even shorten the instrument life.

[0046] Comparative Example 2: Compared to Example 1, in the S1 digestion process, the polypropylene volumetric tube was not sealed with PTFE tape or adhesive tape, while all other aspects remained the same. In the rapid digestion method S1, without sealing the polypropylene volumetric tube with PTFE tape or adhesive tape, the recoveries of the standard substances Cr and Zn were 82.7% and 92.0%, respectively. If PTFE tape and adhesive tape were used to seal the polypropylene volumetric tube, the recoveries of the standard substances Cr and Zn increased from 82.7% and 92.0% to 93.0% and 95.7%, respectively.

[0047] Comparative Example 3: The microwave digestion method was employed, with the following specific steps: Approximately 0.1000 g of sediment standard sample was accurately weighed into a polytetrafluoroethylene (PTFE) digestion vessel. After wetting with a small amount of ultrapure water, 3 mL of HCl, 6 mL of HNO3, and 2 mL of HF were added according to Table 1, ensuring thorough mixing of the sample and digestion solution. The digestion vessel was then placed in the microwave digestion apparatus after being mounted on the digestion vessel holder. Digestion was initiated using the following program: ① 120℃ for 3 min, ② 160℃ for 3 min, ③ 190℃ for 25 min. After the program was completed, the vessel was cooled. Once the temperature inside the vessel had dropped to room temperature, the pressure was slowly released, and the vessel lid was opened. The digestion vessel was transferred to a graphite digestion apparatus to remove the acid. After the acid was completely removed, a small amount of diluted nitric acid solution was added, and the mixture was gently heated for extraction. The digestion solution was then transferred to a 50 mL colorimetric tube and brought to a final volume for analysis. The digestion process takes approximately 1 hour, with a cooling time of about 1 hour. After the temperature inside the vessel drops to room temperature, acid removal is required, which takes about 1 hour. After the acid is completely removed, a small amount of diluted nitric acid solution is added, followed by gentle heating for extraction. The total digestion time is no less than 3 hours, and commonly used microwave digesters in laboratories can typically only pretreat 10 samples simultaneously. However, the DS-360 porous graphite digester used in this invention can pretreat 36 samples simultaneously, with a total digestion time of no more than 1.5 hours. Furthermore, the rapid digestion method, using a closed system, achieves recovery rates for the six elements comparable to those using microwave digestion.

[0048] Measurement results: The content of each element in the standard samples of Example 1, Comparative Examples 2 and 3 was determined, and the recovery rate of the standard substances was calculated. The results are shown in Table 1. The results of Example 1 and Example 2 were all within the certificate reference range of the standard reference substances. To demonstrate the good accuracy of the method of the present invention, eight parallel tests were performed, and the standard deviation and relative standard deviation (RSD%) of the eight tests were calculated. The results are shown in Table 2.

[0049] Recovery rate of standard substance = (test value / standard value) × 100% The formula for calculating standard deviation (σ) is as follows:

[0050] In the formula: N is the total number of data points; Xi is the i-th data point. μ is the population mean. The formula for calculating the relative standard deviation (RSD) is as follows:

[0051] In the formula: x k This represents the result of the k-th test performed on the standard substance. This represents the average value of tests conducted on the standard substance. Si This represents the standard deviation of the test for the reference material.

[0052] Table 1. Effects of different treatments on the recovery rate of standard reference GBW07314.

[0053] Table 2. Detection results of two marine sediment standard materials in Examples 1 and 2.

[0054] Table 1 shows that during the rapid digestion process, wrapping the upper part of the polypropylene volumetric tube and the cap with PTFE tape and adhesive tape improved the tube's sealing and internal pressure. The results indicate that using a closed system in the rapid digestion method increased the recoveries of Cr and Zn from 82.7% and 92.0% to 93.0% and 95.7%, respectively, while the recovery rate of Cd increased from 91.0% to 96.7%. The recoveries of each element were comparable to those achieved using microwave digestion, demonstrating that a closed system optimizes the effectiveness of the rapid digestion method.

[0055] As shown in Table 2, the optimized rapid digestion method of this invention is suitable for the determination of heavy metals in marine sediments. Repeatability tests revealed that the detection results for the six major metallic elements were all within the standard range, with recoveries ranging from 95.4% to 109.2%, standard deviations from 0.00 to 0.64 mg / kg, and relative standard deviations from 0.00% to 3.22%. The method is accurate, reliable, rapid, and efficient, meeting the needs for heavy metal testing in marine sediment samples, especially large batches.

[0056] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A method for determining heavy metals in marine sediments based on rapid digestion, characterized in that, Includes the following steps: S1. Dissolve; The standard sample was weighed and placed in a polypropylene volumetric tube. After wetting the sample, a mixed acid was added, and then the sample was placed in a graphite digester for digestion. The polypropylene volumetric tube was sealed to improve its sealing performance and internal pressure. S2. Detection; After digestion, the solution was cooled and quantified. The supernatant was then diluted and analyzed. The calibration solution was prepared using a digestion blank solution to eliminate the matrix effect introduced by the acid used in the digestion; [Selection] 103 Rh、 115 In and 209 Bi was used as the internal standard element, and the online internal standard concentration was 50 μg / L.

2. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, During the digestion process, PTFE tape and adhesive tape are used to wrap and seal the upper part of the polypropylene capacity tube and the cap to improve the tube's sealing performance and internal pressure.

3. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, When detecting Cr, Ni, Cu, Cd, and Pb, the mixed acid mentioned in S1 is nitric acid and hydrofluoric acid; when detecting Cr, Ni, Cu, Cd, Pb, and Zn, the mixed acid mentioned in S1 is a mixture of HCl, HNO3, and HF, with a volume ratio of HCl:HNO3:HF of 3:1:

1.

4. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, During the digestion process, the digestion temperature is 120–130℃ and the digestion time is 0.8–1.2 h.

5. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, In S2, the quantitative method is weighing, and the digestion solution is diluted with 0.5% HNO3 to 400-600 times the original weight; And / or, Before testing, take the supernatant and dilute it twice with 0.5% HNO3, then measure it on the instrument.

6. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, The collection, preparation, storage and transportation of the standard samples shall be carried out in accordance with the relevant provisions of GBW07314 and GBW07333, and the weight ratio of the standard sample to the mixed acid shall be 1:50-70.

7. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, All reagents used were of analytical grade, and the standard samples described in S1 were wetted with ultrapure water.

8. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, The calibration solution is prepared by digesting the blank solution, including the following steps:

1. Take the same volume of ultrapure water as the standard sample in the same process, and put it into a polypropylene volumetric tube that is exactly the same as the standard sample. Add the same type and volume of mixed acid and digest it under the same conditions. After digestion, dilute to the same volume as the standard sample with 0.5% HNO3 to obtain a digestion blank solution.

2. Using the digestion blank solution as a solvent, dilute and prepare a series of calibration solutions of known concentrations.

9. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, The graphite digestion apparatus used is the DS-360 multi-hole graphite digestion apparatus, with a temperature control accuracy of ±0.2℃, manufactured by Guangzhou Gedana Instrument Co., Ltd.

10. The method for determining heavy metals in marine sediments based on rapid digestion as described in claim 1, characterized in that, The polypropylene capacity tube is a disposable polypropylene capacity tube made of transparent polymer material polypropylene, with a softening temperature of 160℃.

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