Method for detecting heavy metals in shellfish

Abstract

The invention belongs to the technical field of aquatic product detection, and discloses a method for detecting heavy metals in shellfish, and the specific detection method is as follows: grinding edible parts of the shellfish to obtain a sample, mixing the sample with a digestion solution, and digesting through sectional microwave heating to obtain an object to be detected; heavy metal and dilute nitric acid are mixed, a heavy metal solution with the concentration of 0-50 micrograms / L is prepared, the obtained heavy metal solution is introduced into an inductively coupled plasma mass spectrometer, and a standard curve with the heavy metal ion concentration as the abscissa and the heavy metal ion abundance as the ordinate is obtained; the volume of a to-be-detected object is fixed to 50 mL with dilute nitric acid, then the to-be-detected object is introduced into the inductively coupled plasma mass spectrometer, the abundance of the heavy metal ions in the to-be-detected object is measured, and the concentration of the heavy metal ions in the to-be-detected object is obtained through calculation. The detection method disclosed by the invention is simple to operate, short in time consumption, safe, environment-friendly and accurate and reliable in detection result, and has practical significance for improving food safety.

Description

Technical Field

[0001] The invention relates to the technical field of aquatic product detection, and in particular to a method for detecting heavy metals in shellfish. Background Art

[0002] With the rapid growth of the world's population and economic development, a large number of toxic and harmful substances are directly or indirectly discharged into the ocean along with industrial wastewater and domestic sewage from coastal and riverside towns, and marine environmental pollution is becoming more and more serious. Marine organisms have a strong enrichment effect on many heavy metal elements. When the concentration of heavy metals reaches a certain value, it will have an adverse effect on the growth of marine organisms, leading to gene mutations and even death. At the same time, heavy metals can continue to accumulate in the human body through the food chain, seriously endangering human health.

[0003] In order to ensure people's health and life safety, it is necessary to measure the heavy metal content in aquatic products to ensure the quality of aquatic products. The commonly used methods for measuring the heavy metal content in aquatic products include flame atomic absorption, inductively coupled plasma mass spectrometry, atomic fluorescence spectrometry, etc. Among them, inductively coupled plasma mass spectrometry is widely used in the detection of heavy metal content in aquatic products because it can analyze multiple elements at the same time and has high sensitivity. When using inductively coupled plasma mass spectrometry to detect the heavy metal content in aquatic products, it is often necessary to pre-treat the sample to be tested. However, the pre-treatment used in the prior art has the problems of long time consumption, cumbersome steps, low efficiency, high blank value and high labor intensity of analysts, resulting in technical problems such as incomplete sample decomposition, complex process operation and long process time when detecting heavy metals in aquatic products.

[0004] Therefore, it is of great significance to develop a method for detecting heavy metals in shellfish that is simple in process and completely decomposes. Summary of the invention

[0005] In view of this, the present invention provides a method for detecting heavy metals in shellfish, the purpose of which is to solve the problems of incomplete sample decomposition, complex process operation and long process time existing in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for detecting heavy metals in shellfish, comprising the following steps:

[0008] (1) Grinding the edible part of the shellfish to obtain a sample, mixing the sample with a digestion solution and digesting it by segmented microwave heating to obtain an analyte;

[0009] (2) Drawing of heavy metal standard curve: heavy metals and dilute nitric acid are mixed to prepare a heavy metal solution with a concentration of 0 to 50 μg / L, and the obtained heavy metal solution is passed into an inductively coupled plasma mass spectrometer to obtain a standard curve with heavy metal ion concentration as the horizontal axis and heavy metal ion abundance as the vertical axis;

[0010] (3) The sample obtained in step (1) is diluted to 50 mL with dilute nitric acid and then introduced into an inductively coupled plasma mass spectrometer to determine the abundance of heavy metal ions in the sample, and the concentration of heavy metal ions in the sample is calculated.

[0011] Preferably, the segmented microwave heating in step (1) includes a first stage microwave heating and a second stage microwave heating;

[0012] In the first stage of microwave heating, the heating rate is 18-23°C / min, the heating temperature is 130-150°C, and the heating time is 4-6min;

[0013] In the second stage of microwave heating, the heating rate is 10-12°C / min, the heating temperature is 170-190°C, and the heating time is 12-16min.

[0014] Preferably, the ratio of the sample to the digestion solution in step (1) is 0.5-1 g: 4-5 mL;

[0015] The digestion solution comprises nitric acid and hydrogen peroxide, and the volume ratio of nitric acid to hydrogen peroxide is 5-7:1.

[0016] Preferably, the heavy metals in step (2) include lead, cadmium, mercury, arsenic, chromium, nickel, manganese, copper, zinc and iron.

[0017] Preferably, the concentration of heavy metals in the heavy metal solution in step (2) is 0 μg / L, 5 μg / L, 10 μg / L, 15 μg / L, 20 μg / L, 25 μg / L, 30 μg / L, 35 μg / L, 40 μg / L, 45 μg / L and 50 μg / L.

[0018] Preferably, the mass concentration of the dilute nitric acid in step (2) and step (3) is 1 to 3%.

[0019] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0020] The digestion in the detection method of the present invention adopts segmented microwave heating, that is, the heating temperature and heating time are adjusted in stages during the digestion process, first heating at a lower temperature to ensure uniformity, and then gradually increasing the temperature to speed up the digestion speed, which can effectively prevent the digestion unevenness generated during the digestion process;

[0021] The method for detecting heavy metals in shellfish of the present invention is simple to operate, short in time, safe and environmentally friendly. During the detection, other impurities in aquatic products have no effect on the detected samples. The standard curve is used for correction, and the detection results are accurate and reliable, which has practical significance for improving food safety. DETAILED DESCRIPTION

[0022] The present invention provides a method for detecting heavy metals in shellfish, comprising the following steps:

[0023] (1) Grinding the edible part of the shellfish to obtain a sample, mixing the sample with a digestion solution and digesting it by segmented microwave heating to obtain an analyte;

[0024] (2) Drawing of heavy metal standard curve: heavy metals and dilute nitric acid are mixed to prepare a heavy metal solution with a concentration of 0 to 50 μg / L, and the obtained heavy metal solution is passed into an inductively coupled plasma mass spectrometer to obtain a standard curve with heavy metal ion concentration as the horizontal axis and heavy metal ion abundance as the vertical axis;

[0025] (3) The sample obtained in step (1) is diluted to 50 mL with dilute nitric acid and then introduced into an inductively coupled plasma mass spectrometer to determine the abundance of heavy metal ions in the sample, and the concentration of heavy metal ions in the sample is calculated.

[0026] In the present invention, the segmented microwave heating in step (1) includes a first stage microwave heating and a second stage microwave heating;

[0027] In the first stage of microwave heating, the heating rate is preferably 18-23°C / min, more preferably 19-22°C / min, more preferably 20-21°C / min, the heating temperature is preferably 130-150°C, more preferably 135-148°C, more preferably 140-145°C, and the heating time is preferably 4-6 min, more preferably 4.5-5.5 min, more preferably 5 min;

[0028] In the second stage microwave heating, the heating rate is preferably 10-12°C / min, more preferably 10.5-11.5°C / min, more preferably 11°C / min, the heating temperature is preferably 170-190°C, more preferably 175-185°C, more preferably 180-182°C, and the heating time is preferably 12-16 min, more preferably 13-15 min, more preferably 14-14.5 min.

[0029] In the present invention, the dosage ratio of the sample to the digestion solution in step (1) is preferably 0.5-1 g: 4-5 mL, more preferably 0.6-0.9 g: 4-5 mL, and more preferably 0.7-0.8 g: 4.2-4.8 mL;

[0030] The digestion solution preferably includes nitric acid and hydrogen peroxide. The mass concentration of nitric acid is preferably 65-70%, more preferably 66-69%, and more preferably 67-68%. The volume ratio of nitric acid to hydrogen peroxide is preferably 5-7:1, more preferably 5.5-6.5:1, and more preferably 5.8-6:1.

[0031] In the present invention, the digestion in step (1) includes cooling and acid removal; the cooling temperature is preferably 20-30°C, more preferably 22-28°C, and more preferably 24-26°C; the acid removal temperature is preferably 120-140°C, more preferably 125-135°C, and more preferably 128-130°C, and the acid removal is completed when the digestion product is nearly dry.

[0032] In the present invention, the heavy metals in step (2) include lead, cadmium, mercury, arsenic, chromium, nickel, manganese, copper, zinc and iron.

[0033] In the present invention, the concentration of heavy metals in the heavy metal solution in step (2) is preferably 0 μg / L, 5 μg / L, 10 μg / L, 15 μg / L, 20 μg / L, 25 μg / L, 30 μg / L, 35 μg / L, 40 μg / L, 45 μg / L and 50 μg / L.

[0034] In the present invention, the mass concentration of the dilute nitric acid in step (2) and step (3) is preferably 1 to 3%, more preferably 1.2 to 2.8%, and even more preferably 1.8 to 2.2%.

[0035] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] In the embodiment of the present invention:

[0037] The inductively coupled plasma mass spectrometer was iCAP RQ Ultimate 3000, produced by Thermo Fisher, USA. The detection conditions of the inductively coupled plasma mass spectrometer were as follows: RF power 1400 W, plasma gas flow rate 15 L / min, nebulizer gas flow rate 0.92 L / min, lens voltage 7.00 V, auxiliary gas flow rate 1.2 L / min, detector analog level voltage 1800 V, detector pulse level voltage 900 V, sampling time 5 min;

[0038] The digester is a MARS6 microwave digestion system produced by CEM Corporation of the United States.

[0039] Example 1

[0040] The edible part of the mussel was ground to obtain a sample, 0.7 g of the obtained sample was placed in the inner tank of a microwave digestion instrument, 4.2 mL of a digestion solution (the volume ratio of nitric acid to hydrogen peroxide was 5.5:1, and the concentration of nitric acid was 68%) was added, the temperature was increased to 140°C at a heating rate of 20°C / min, and maintained for 5 minutes, and then the temperature was increased to 180°C at a heating rate of 10°C / min, and maintained for 15 minutes, thus completing the segmented microwave heating, and the heated product was cooled to 25°C, placed in an acid-dripping machine at 130°C to drive the acid until it was nearly dry, thus completing the digestion and obtaining the object to be tested;

[0041] Using dilute nitric acid with a mass concentration of 1.2% as a solvent, respectively prepare a standard solution of lead, a standard solution of cadmium, a standard solution of mercury, a standard solution of arsenic, a standard solution of chromium, a standard solution of nickel, a standard solution of manganese, a standard solution of copper, a standard solution of zinc and a standard solution of iron, wherein the concentrations of the above standard solutions all include 0 μg / L, 5 μg / L, 10 μg / L, 15 μg / L, 20 μg / L, 25 μg / L, 30 μg / L, 35 μg / L, 40 μg / L, 45 μg / L and 50 μg / L, and pass the obtained standard solutions into an inductively coupled plasma mass spectrometer to obtain a standard curve with the heavy metal ion concentration as the abscissa and the heavy metal ion abundance as the ordinate;

[0042] The sample was fixed to 50 mL with 1.2% dilute nitric acid, and then passed into an inductively coupled plasma mass spectrometer to determine the abundance of heavy metal ions in the sample. The obtained abundance was substituted into the standard curve to calculate the concentration of each heavy metal ion in the sample.

[0043] Example 2

[0044] The edible part of the mussel was ground to obtain a sample, 0.8 g of the obtained sample was placed in the inner tank of a microwave digestion instrument, 4.5 mL of a digestion solution (the volume ratio of nitric acid to hydrogen peroxide was 6:1, and the concentration of nitric acid was 69%) was added, the temperature was increased to 150°C at a heating rate of 18°C / min, and maintained for 6 minutes, and then the temperature was increased to 190°C at a heating rate of 10°C / min, and maintained for 16 minutes, thus completing the segmented microwave heating, and the heated product was cooled to 25°C, placed in an acid-dripping machine at 135°C to drive the acid until it was nearly dry, thus completing the digestion and obtaining the object to be tested;

[0045] Using 2% by mass nitric acid as a solvent, respectively prepare a standard solution of lead, a standard solution of cadmium, a standard solution of mercury, a standard solution of arsenic, a standard solution of chromium, a standard solution of nickel, a standard solution of manganese, a standard solution of copper, a standard solution of zinc and a standard solution of iron, wherein the concentrations of the above standard solutions all include 0 μg / L, 5 μg / L, 10 μg / L, 15 μg / L, 20 μg / L, 25 μg / L, 30 μg / L, 35 μg / L, 40 μg / L, 45 μg / L and 50 μg / L, and pass the obtained standard solutions into an inductively coupled plasma mass spectrometer to obtain a standard curve with heavy metal ion concentration as the abscissa and heavy metal ion abundance as the ordinate;

[0046] The sample was fixed to 50 mL with 2% dilute nitric acid, and then passed into an inductively coupled plasma mass spectrometer to determine the abundance of heavy metal ions in the sample. The obtained abundance was substituted into the standard curve to calculate the concentration of each heavy metal ion in the sample.

[0047] Example 3

[0048] The edible part of the mussel was ground to obtain a sample, 0.6 g of the obtained sample was placed in the inner tank of a microwave digestion instrument, 5 mL of a digestion solution (the volume ratio of nitric acid to hydrogen peroxide was 7:1, and the concentration of nitric acid was 70%) was added, the temperature was increased to 130°C at a heating rate of 23°C / min, and maintained for 4 minutes, and then the temperature was increased to 170°C at a heating rate of 12°C / min, and maintained for 12 minutes, thus completing the segmented microwave heating, and the heated product was cooled to 25°C, placed in an acid-dripping machine at 140°C to drive the acid until it was nearly dry, thus completing the digestion and obtaining the object to be tested;

[0049] Using dilute nitric acid with a mass concentration of 1.8% as a solvent, respectively prepare a standard solution of lead, a standard solution of cadmium, a standard solution of mercury, a standard solution of arsenic, a standard solution of chromium, a standard solution of nickel, a standard solution of manganese, a standard solution of copper, a standard solution of zinc and a standard solution of iron, wherein the concentrations of the above standard solutions all include 0 μg / L, 5 μg / L, 10 μg / L, 15 μg / L, 20 μg / L, 25 μg / L, 30 μg / L, 35 μg / L, 40 μg / L, 45 μg / L and 50 μg / L, and pass the obtained standard solutions into an inductively coupled plasma mass spectrometer to obtain a standard curve with the heavy metal ion concentration as the abscissa and the heavy metal ion abundance as the ordinate;

[0050] The sample was fixed to 50 mL with 1.8% dilute nitric acid, and then passed into an inductively coupled plasma mass spectrometer to determine the abundance of heavy metal ions in the sample. The obtained abundance was substituted into the standard curve to calculate the concentration of each heavy metal ion in the sample.

[0051] Comparative Example 1

[0052] The edible part of the mussel was ground to obtain a sample, 0.7 g of the obtained sample was placed in a microwave digestion inner tank, 4.2 mL of digestion solution (the volume ratio of nitric acid and hydrogen peroxide was 5.5:1) was added, the temperature was increased to 140°C at a heating rate of 20°C / min, and maintained for 5 minutes, then increased to 160°C at a heating rate of 13°C / min, and maintained for 8 minutes, and then increased to 180°C at a heating rate of 10°C / min, and maintained for 15 minutes, thus completing the segmented microwave heating, and the heated product was cooled to 25°C, placed in an acid-dripping machine at 130°C to drive the acid until it was nearly dry, thus completing the digestion and obtaining the object to be tested;

[0053] Using 1.2% dilute nitric acid as a solvent, respectively preparing a standard solution of lead, a standard solution of cadmium, a standard solution of mercury, a standard solution of arsenic, a standard solution of chromium, a standard solution of nickel, a standard solution of manganese, a standard solution of copper, a standard solution of zinc and a standard solution of iron, wherein the concentrations of the above standard solutions all include 0 μg / L, 5 μg / L, 10 μg / L, 15 μg / L, 20 μg / L, 25 μg / L, 30 μg / L, 35 μg / L, 40 μg / L, 45 μg / L and 50 μg / L, and passing the obtained standard solutions into an inductively coupled plasma mass spectrometer to obtain a standard curve with the heavy metal ion concentration as the abscissa and the heavy metal ion abundance as the ordinate;

[0054] The sample was fixed to 50 mL with 1.2% dilute nitric acid, and then passed into an inductively coupled plasma mass spectrometer to determine the abundance of heavy metal ions in the sample. The obtained abundance was substituted into the standard curve to calculate the concentration of each heavy metal ion in the sample.

[0055] It can be seen from the detection methods described in Examples 1 to 3 and Comparative Example 1 that both the detection method described in Comparative Example 1 and the detection method described in the present invention can detect the concentrations of various metal ions in mussels. The detection time of the detection method described in the present invention is significantly shorter, and the detection process is also relatively simple.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for detecting heavy metals in shellfish, characterized in that: The steps include: (1) Grinding the edible part of the shellfish to obtain a sample, mixing the sample with a digestion solution and digesting it by segmented microwave heating to obtain an analyte; (2) Drawing of heavy metal standard curve: heavy metals and dilute nitric acid are mixed to prepare a heavy metal solution with a concentration of 0 to 50 μg / L, and the obtained heavy metal solution is passed into an inductively coupled plasma mass spectrometer to obtain a standard curve with heavy metal ion concentration as the horizontal axis and heavy metal ion abundance as the vertical axis; (3) The sample obtained in step (1) is diluted to 50 mL with dilute nitric acid and then introduced into an inductively coupled plasma mass spectrometer to determine the abundance of heavy metal ions in the sample, and the concentration of heavy metal ions in the sample is calculated.

2. The method for detecting heavy metals in shellfish according to claim 1, characterized in that: The segmented microwave heating in step (1) includes first-stage microwave heating and second-stage microwave heating; In the first stage of microwave heating, the heating rate is 18-23°C / min, the heating temperature is 130-150°C, and the heating time is 4-6min; In the second stage of microwave heating, the heating rate is 10-12°C / min, the heating temperature is 170-190°C, and the heating time is 12-16min.

3. The method for detecting heavy metals in shellfish according to claim 2, characterized in that: The ratio of sample to digestion solution in step (1) is 0.5-1 g: 4-5 mL; The digestion solution comprises nitric acid and hydrogen peroxide, and the volume ratio of nitric acid to hydrogen peroxide is 5 to 7:

1.

4. The method for detecting heavy metals in shellfish according to claim 3, characterized in that: The heavy metals in step (2) include lead, cadmium, mercury, arsenic, chromium, nickel, manganese, copper, zinc and iron.

5. A method for detecting heavy metals in shellfish according to claim 2 or 4, characterized in that: The concentration of heavy metals in the heavy metal solution in step (2) is 0 μg / L, 5 μg / L, 10 μg / L, 15 μg / L, 20 μg / L, 25 μg / L, 30 μg / L, 35 μg / L, 40 μg / L, 45 μg / L and 50 μg / L.

6. The method for detecting heavy metals in shellfish according to claim 5, characterized in that: The mass concentration of the dilute nitric acid in step (2) and step (3) is 1 to 3%.