CN117470945A - ICP-MS method for measuring inorganic element content in honey - Google Patents

Abstract

The invention discloses an ICP-MS method for measuring the content of inorganic elements in honey, which utilizes an inductively coupled plasma tandem mass spectrometer (ICP-MS/MS) to measure the content of 19 inorganic elements in the honey, establishes a quicker, more accurate and more convenient detection method by a mass transfer method, utilizes a dynamic reaction mode (DRC) of a collision/reaction tank to form high-abundance interference-free cluster ions under the condition of ammonia gas, effectively eliminates the mass spectrum interference of each element, has linear correlation coefficients of more than 0.999 under the optimal test condition, has the standard adding recovery rate of 90.34-115.68% and relative standard deviation of 0.29-6.48% of an actual honey sample, and has the advantages of high accuracy, high precision, high analysis speed, low detection limit and no interference, and is suitable for high-throughput analysis of trace toxic elements in the honey.

Description

An ICP-MS method for determining the content of inorganic elements in honey

Technical field

The invention belongs to the technical field of food safety detection, and specifically relates to an ICP-MS method for determining the content of inorganic elements in honey.

Background technique

Honey is a natural nourishing food with rich nutrients and active functions. It is rich in sugars, trace amounts of organic acids, amino acids, minerals and various elements needed by the human body. However, elements that are harmful to the human body may be introduced due to environmental pollution during the production, processing, transportation, storage, and sales of honey. At the same time, there are large differences in the content of elements in honey from different types and regions. Therefore, accurately understanding the content of elements in honey is of great significance for improving honey quality, regulating honey ingredients, and achieving targeted production.

At present, the methods for detecting inorganic elements in honey include atomic absorption spectrometry (AAS), inductively coupled plasma optical emission spectroscopy (ICP-OES), electrochemical method (EA) or ICP-AES, etc. These methods all have certain shortcomings. For example, the detection limit of ICP-OES is relatively high, and AAS cannot simultaneously detect multiple elements. For ICP-MS/MS, the previous ICP-MS/MS method for testing inorganic elements in honey is basically the standard mode (Std .) or collision mode (KED). For Std., it is difficult to eliminate mass spectrum interference that is the same as the mass number of the element to be measured. For KED mode, it requires collision in the reaction cell, although it can reduce mass spectrum interference. But the test element also loses kinetic energy during the collision, causing deviations in the test results.

Contents of the invention

The technical problem to be solved by the present invention is to provide an ICP-MS method for measuring the content of inorganic elements in honey, so as to solve the technical problem of inaccurate measurement of the content of inorganic elements in honey.

In order to achieve the above object, the technical solution adopted by the present invention is to provide an ICP-MS method for determining the content of inorganic elements in honey, which includes the following steps:

S1: Prepare honey sample solution, blank solution and standard solution of elements to be measured;

S2: Determine the Q ₁ value of the first quadrupole: screen out the optimal isotope of each element to be measured based on the highest relative content of the isotope and the smallest relative interference. Q ₁ is the mass number of the optimal isotope of the element to be measured;

S3: Determine the _Q3 value of the third quadrupole: introduce the blank solution and the standard solution of 1 ppb of the element to be measured into the inductively coupled plasma tandem mass spectrometer, and screen out the optimal cluster ions, reagent gas flow rate and The non-dimensional suppression parameter q, Q ₃ is the mass number of the optimal cluster ion of the element to be measured;

Mass spectrum interference is due to the fact that some cluster ions or interfering elements have the same mass-to-charge ratio as the element to be measured. When ICP-MS/MS is used for detection and analysis, the spectra will overlap, making the intensity of the element to be measured not true. Therefore, in order to accurately understand the content of the element to be measured, it is necessary to eliminate the spectral overlap caused by mass spectrum interference as much as possible. Since most elements have isotopes, different isotopes can be selected to avoid mass spectrum interference, and the MSShift method can be combined to achieve the best elimination of mass spectrum interference. Non-mass spectrometry interference is divided into matrix interference and physical effects. In the present invention, matrix interference is mainly due to the difference between the solvent used in the prepared standard solution and the solvent of the element to be measured, which leads to a shift in spectral line intensity caused by different matrices. , so the internal standard element is added to correct the shift in signal intensity.

Determination of the mass number transfer of the element to be measured (MS Shift method), that is, Q ₃ =Q ₁ +x (x is the mass number brought by the reaction gas when the element to be measured collides with the reaction gas to form cluster ions). After the element to be measured and the interference enter Q ₂ (reaction cell) through Q ₁ , the element to be measured collides with the reaction gas to form cluster ions, while the interference does not react with the reaction gas and cannot pass through Q ₃ , so it is eventually annihilated. In Q ₂ , the new cluster ions formed by the element to be measured can pass through the set Q ₃ . Since the element to be measured and the reaction gas collide with each other in the reaction cell to form cluster ions, the content of the reaction gas in the reaction cell has an impact on the number of cluster ions formed. Since the reaction cell has a certain length, in order for the particle flow to have a specific movement trajectory and reach the detector, it is necessary to adjust the RF voltage of the quadrupole of the reaction cell. The present invention mainly changes the non-dimensional suppression parameter q of the RF voltage, that is, RPq; Since the mass numbers of the elements to be measured are different, the RPq value and reaction gas flow rate need to be adjusted separately according to different elements.

S4: Introduce the honey sample solution, blank solution and standard solution of the element to be measured into the inductively coupled plasma tandem mass spectrometer, based on the first quadrupole Q ₁ value determined in step S2 and the third quadrupole Q determined in step S3 Under the conditions of ₃ value, reaction gas flow rate and non-dimensional suppression parameter q, measure the average concentration A ₁ of the element in the blank solution and the average concentration A ₂ of the element in the honey sample solution, and calculate the actual content of the element to be measured in the honey sample. A ₀ :

In the formula, A ₀ is the actual content of the element to be measured in the honey sample, μg/g; A ₁ is the average concentration of the element in the blank solution, μg/mL; A ₂ is the average concentration of the element in the honey sample solution, μg/mL. ; V is the volume of the honey sample solution, mL; m is the mass of the weighed honey sample, g.

On the basis of the above technical solutions, the present invention can also make the following improvements:

Further, step S1 is specifically: mix the honey sample, perchloric acid and nitric acid in a ratio of 0.5-1g: 2-4mL: 10-20mL, add water after digestion to prepare a 50-100mL sample solution for later use; Mix acid and nitric acid at a volume ratio of 2-4mL:10-20mL. After digestion, add water to prepare a 50-100mL blank solution for later use; prepare a standard solution using 2wt% nitric acid solution and a standard stock solution with a concentration of 100mg/L of the element to be measured. .

Further, the digestion is carried out in three stages: first, the mixed solution is heated to 90-110°C in 12-17 minutes, and digested for 20-40 minutes; then, the temperature is continued to be raised to 140-160°C, in 8-10 minutes, and digested for 80-100 minutes; finally, Continue to raise the temperature to 180-200°C for 8-10 minutes and digest for 15-25 minutes.

Further, the elements to be measured are Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Mo, Ag, Cd, Sn, Sb, Ba and Pb.

Further, the reaction gas used in step S3 is NH ₃ .

Further, the reaction gas flow rate is 0.3-1.5mL/min.

Furthermore, the range of the non-dimensional suppression parameter q is 0.05-0.85.

Further, the parameters and setting values of the inductively coupled plasma tandem mass spectrometer in step S4 include: ICP radio frequency power is 1400-1600W, nebulizer air flow is 0.9-1mL/min, and auxiliary air flow is 1-1.5mL/min. , the plasma gas flow rate is 10-17mL/min, and the QID fixed voltage is -15~-10V.

The beneficial effects of the present invention are: the detection method of the present invention has a higher linear correlation coefficient, the linear correlation coefficients of other elements except Fe are all above 0.9999, and individual elements are above 0.99999; it has a lower detection limit; except The detection limits of other elements except Ag are far lower than the detection limits of the national standard GB 5009.268-2016. The standard recovery rate is 90.34-115.68%, and the relative standard deviation is 0.29-6.48%. Therefore, this method is suitable for trace and ultra-high levels. It has more advantages in trace detection.

Description of the drawings

Figure 1 is a schematic structural diagram of an inductively coupled plasma tandem mass spectrometer;

Figure 2 is a study diagram of the mass transfer of Fe element;

Figure 3 is the Q ₃ change diagram of Fe element;

Figure 4 is the reaction gas flow rate optimization diagram of Fe element;

Figure 5 is a detailed optimization diagram of the reaction gas flow rate of Fe element;

Figure 6 is the non-dimensional suppression parameter q optimization diagram of Fe element.

Detailed ways

Specific embodiments of the present invention are described below to facilitate those skilled in the art to understand the present invention. If specific conditions are not specified in the examples, the procedures should be carried out in accordance with conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not specified. Manufacturers are all conventional products that can be purchased commercially. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, various changes will be obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. , all inventions and creations utilizing the concept of the present invention are protected.

Example 1:

An ICP-MS method for determining the content of inorganic elements in acacia honey, including the following steps:

S1: Weigh 0.5191g acacia honey sample and place it in a polytetrafluoroethylene digestion tank, add 2mL perchloric acid and 10mL nitric acid in sequence, digest it in a fully automatic digestion instrument, and finally add water to prepare a 50mL sample solution for later use. ; Mix perchloric acid and nitric acid at a ratio of 2mL:10mL, then digest it in a fully automatic digestion instrument, and finally add water to prepare a 50mL blank solution for later use. The specific steps for digestion are shown in Table 1; use 2wt% nitric acid solution Prepare a standard solution with a standard stock solution of the element to be measured at a concentration of 100 mg/L. The concentrations of the standard solutions of elements Na and K are 100, 500, 1000, 2000 and 5000 μg/mL; elements V, Cr, Mn, Fe, Co, The concentrations of standard solutions of Ni, Cu, Zn, As, Sr, Mo, Ag, Cd, Sn, Sb, Ba and Pb are 1, 2, 5, 10 and 20 μg/mL;

Table 1 Digestion steps of fully automatic digestion instrument

Step number Digestion temperature (℃) Heating time (min) Digestion time(min) 1 100 15 30 2 150 8 90 3 190 8 20

S2: Determine the Q ₁ value of the first quadrupole: select the optimal isotope of each element to be measured based on the highest relative content of the isotope and the smallest relative interference. Q ₁ is the mass number of the optimal isotope of the element to be measured; the element to be measured The optimal isotopes and Q ₁ values are shown in Table 2;

S3: Determine the Q ₃ value of the third quadrupole: introduce the blank solution and the standard solution of 1 ppb of the element to be measured into the inductively coupled plasma tandem mass spectrometer (as shown in Figure 1). The reaction gas introduced is NH ₃ . Use Only the data and automatic optimization functions screen out the optimal cluster ions, reaction gas flow rate and non-dimensional suppression parameter q of each element to be tested. Q ₃ is the mass number of the optimal cluster ion of the element to be tested; the optimal value of the element to be tested is The cluster ions, Q ₃ value, optimal reaction gas flow rate and non-dimensional suppression parameter q are shown in Table 2;

Table 2 Corresponding data of elements to be measured

Taking the Fe element as an example and combining Figure 2-6, it can be seen from Figure 2 that the cluster ion ⁵⁶ Fe( ¹⁴ N ¹ H ₃ ) ₂ ⁺ of the Fe element has the highest intensity, so ⁵⁶ Fe( ¹⁴ N ¹ H ₃ ) ₂ ⁺ is the optimal cluster ion for Fe element.

As can be seen from Figure 3, the strong peaks of Fe element at different concentrations are gathered near mass number 90, so the _Q3 value of Fe element is 90.

It can be seen from Figure 4 that the changing trend of the reaction gas flow rate of the Fe element is to first increase and then decrease. The maximum intensity value appears around the reaction gas flow rate of 1.2mL/min. Therefore, automatic optimization is required to achieve the reaction gas flow rate value of 1.2mL/min. Continue to optimize within the small range of 1.2 (0.9-1.5), and the results are shown in Figure 5.

From Figure 5, it can be seen that the optimal reaction gas flow rate of Fe element is 1.1mL/min (automatic optimization optimal point selection principle: the point with the largest difference between the standard (Standard) and the background concentration (Composite) is the optimal point).

The non-dimensional suppression parameter q of the Fe element is screened through automatic optimization, with a range of 0.05-0.85 and a step size of 0.05. The results are shown in Figure 6. From Figure 6, it can be known that the optimal non-dimensional suppression parameter q of the Fe element is 0.3 .

S4: Introduce the honey sample solution, blank solution and standard solution of the element to be measured into the inductively coupled plasma tandem mass spectrometer. The parameters and setting values include: ICP radio frequency power is 1500W, atomizer air flow is 0.93mL/min, auxiliary gas The flow rate is 1.1mL/min, the plasma gas flow rate is 14mL/min, and the QID fixed voltage is -12V; based on the first quadrupole Q ₁ value determined in step S2 and the third quadrupole Q ₃ determined in step S3 Under the conditions of value, reaction gas flow rate and non-dimensional inhibition parameter q, after 20 measurements, the average concentration of elements A ₁ (μg/mL) in the blank solution was obtained. After 11 measurements, the average concentration of elements in the acacia honey sample solution was obtained. Concentration A ₂ (μg/mL), calculate the actual content A ₀ (μg/g) of the element to be tested in the acacia honey sample. The actual content of the element to be tested is shown in Table 3.

Table 3 Actual content of elements to be measured in acacia honey samples

element Blank sample (ppb) Honey sample (ppb) Actual content (ppb) Actual content (μg·kg ^-1 ) Na 448.413 618.023 169.610 16.337 K 31.155 3157.970 3126.815 301.177 V ND ND ND ND Cr ND ND ND ND Mn 0.109 2.338 2.228 0.215 Fe 8.195 37.555 29.359 2.828 Co ND ND ND ND Ni 0.144 0.186 0.042 0.004 Cu 0.826 1.651 0.825 0.079 Zn 0.023 0.151 0.128 0.012 As ND ND ND ND Sr 0.114 0.634 0.520 0.050 Mo ND ND ND ND Ag ND ND ND ND cd ND ND ND ND Sn ND 0.317 0.351 0.034 sb ND ND ND ND Ba 0.665 1.149 0.484 0.047 Pb 0.134 0.141 0.007 0.001

Note: ND means not detected, which means below the detection limit.

Example 2:

An ICP-MS method for determining the content of inorganic elements in acacia honey, including the following steps:

S1: Weigh 0.9862g acacia honey sample and place it in a polytetrafluoroethylene digestion tank, add 4mL perchloric acid and 20mL nitric acid in sequence, digest it in a fully automatic digestion instrument, and finally add water to prepare a 100mL sample solution for later use. ; Mix perchloric acid and nitric acid at a ratio of 4mL:20mL, then digest it in a fully automatic digestion instrument, and finally add water to prepare a 100mL blank solution for later use. The specific steps for digestion are shown in Table 1; use 2wt% nitric acid solution Prepare a standard solution with a standard stock solution of the element to be measured at a concentration of 100 mg/L. The concentrations of the standard solutions of elements Na and K are 100, 500, 1000, 2000 and 5000 μg/mL; elements V, Cr, Mn, Fe, Co, The concentrations of standard solutions of Ni, Cu, Zn, As, Sr, Mo, Ag, Cd, Sn, Sb, Ba and Pb are 1, 2, 5, 10 and 20 μg/mL;

S2: Determine the Q ₁ value of the first quadrupole: select the optimal isotope of each element to be measured based on the highest relative content of the isotope and the smallest relative interference. Q ₁ is the mass number of the optimal isotope of the element to be measured; the element to be measured The optimal isotopes and Q ₁ values are shown in Table 2;

S3: Determine the Q ₃ value of the third quadrupole: introduce the blank solution and the standard solution of 1 ppb of the element to be measured into the inductively coupled plasma tandem mass spectrometer. The reaction gas introduced is NH ₃ and filtered using the data-only and automatic optimization functions. Obtain the optimal cluster ion, reaction gas flow rate and non-dimensional suppression parameter q of each element to be tested. Q ₃ is the mass number of the optimal cluster ion of the element to be tested; the optimal cluster ion and Q ₃ value of the element to be tested. , the optimal reaction gas flow rate and non-dimensional suppression parameter q are shown in Table 2;

S4: Introduce the honey sample solution, blank solution and standard solution of the element to be measured into the inductively coupled plasma tandem mass spectrometer. The parameters and setting values include: ICP radio frequency power is 1400W, atomizer air flow is 1mL/min, and auxiliary air flow is 1.5mL/min, the plasma gas flow is 10mL/min, and the QID fixed voltage is -15V; based on the first quadrupole Q ₁ value determined in step S2 and the third quadrupole Q ₃ value determined in step S3 , reaction gas flow rate and non-dimensional suppression parameter q, after 10 measurements, the average concentration of elements A ₁ (μg/mL) in the blank solution was obtained. After 15 measurements, the average concentration of elements in the acacia honey sample solution was obtained. A ₂ (μg/mL), calculate the actual content of the element to be tested in the acacia honey sample, A ₀ (μg/g), and the actual content of the element to be tested is shown in Table 4.

Table 4 Actual content of elements to be measured in acacia honey samples

Note: ND means not detected, which means below the detection limit.

Example 3:

An ICP-MS method for determining the content of inorganic elements in Vitex honey, including the following steps:

S1: Weigh 0.5049g vitex honey sample and place it in a polytetrafluoroethylene digestion tank, add 2mL perchloric acid and 10mL nitric acid in sequence, digest it in a fully automatic digestion instrument, and finally add water to prepare a 50mL sample solution for later use. ; Mix perchloric acid and nitric acid at a ratio of 2mL:10mL, then digest it in a fully automatic digestion instrument, and finally add water to prepare a 50mL blank solution for later use. The specific steps for digestion are shown in Table 1; use 2wt% nitric acid solution Prepare a standard solution with a standard stock solution of the element to be measured at a concentration of 100 mg/L. The concentrations of the standard solutions of elements Na and K are 100, 500, 1000, 2000 and 5000 μg/mL; elements V, Cr, Mn, Fe, Co, The concentrations of standard solutions of Ni, Cu, Zn, As, Sr, Mo, Ag, Cd, Sn, Sb, Ba and Pb are 1, 2, 5, 10 and 20 μg/mL;

S2: Determine the Q ₁ value of the first quadrupole: select the optimal isotope of each element to be measured based on the highest relative content of the isotope and the smallest relative interference. Q ₁ is the mass number of the optimal isotope of the element to be measured; the element to be measured The optimal isotopes and Q ₁ values are shown in Table 2;

S3: Determine the Q ₃ value of the third quadrupole: introduce the blank solution and the standard solution of 1 ppb of the element to be measured into the inductively coupled plasma tandem mass spectrometer. The reaction gas introduced is NH ₃ and filtered using the data-only and automatic optimization functions. Obtain the optimal cluster ion, reaction gas flow rate and non-dimensional suppression parameter q of each element to be tested. Q ₃ is the mass number of the optimal cluster ion of the element to be tested; the optimal cluster ion and Q ₃ value of the element to be tested. , the optimal reaction gas flow rate and non-dimensional suppression parameter q are shown in Table 2;

S4: Introduce the honey sample solution, blank solution and standard solution of the element to be measured into the inductively coupled plasma tandem mass spectrometer. The parameters and setting values include: ICP radio frequency power is 1600W, atomizer air flow is 0.9mL/min, auxiliary gas The flow rate is 1mL/min, the plasma gas flow rate is 17mL/min, and the QID fixed voltage is -10V; based on the Q ₁ value of the first quadrupole determined in step S2 and the Q ₃ value of the third quadrupole determined in step S3 , reaction gas flow rate and non-dimensional inhibition parameter q, after 20 measurements, the average concentration of elements A ₁ (μg/mL) in the blank solution was obtained. After 10 measurements, the average concentration of elements in the acacia honey sample solution was obtained. (μg/mL), calculate the actual content A ₀ (μg/g) of the element to be measured in the vitex honey sample. The actual content of the element to be measured is shown in Table 5.

Table 5 Actual content of elements to be measured in Vitex honey samples

element Blank sample (ppb) Honey sample(ppb) Actual content (ppb) Actual content (μg·kg ^-1 ) Na 448.413 4275.954 3827.541 379.040 K 31.155 394.260 363.105 35.958 V ND ND ND ND Cr ND ND ND ND Mn 0.109 0.706 0.597 0.059 Fe 8.195 12.656 4.461 0.442 Co ND ND ND ND Ni 0.144 0.261 0.117 0.012 Cu 0.826 ND ND ND Zn 0.023 0.032 0.009 0.001 As ND ND ND ND Sr 0.114 1.041 0.928 0.092 Mo 0.028 0.043 0.015 0.001 Ag ND ND ND ND cd ND ND ND ND Sn ND ND ND ND sb ND ND ND ND Ba 0.665 1.175 0.510 0.051 Pb 0.134 ND ND ND

Note: ND means not detected, which means below the detection limit.

As can be seen from Table 3, acacia honey mainly contains Na, K, Mn, Fe, Ni, Cu, Zn, Sr, Ba and Pb. Among them, the beneficial elements are Na, K, Mn, Fe, Ni, Cu, Zn and Sr, and the harmful elements are Na, K, Mn, Fe, Ni, Cu, Zn and Sr. The elements are Ba and Pb. As can be seen from Table 5, vitex honey mainly contains Na, K, Mn, Fe, Ni, Cu, Zn, Sr, Mo and Ba, among which the beneficial elements are Na, K, Mn, Fe, Ni, Cu, Zn, Sr and Mo. , the harmful element is Ba. Comparing the content of each element in the two types of honey, it can be seen that different honey flower sources have an impact on the element content of honey. In particular, the Na and K elements with relatively high content have a difference of several ppm, while the differences of elements with lower content are relatively small. In addition to differences in content, there are also differences in types. For Vitex honey, it contains Mo which acacia honey does not have. Mo is an essential element such as flavin oxidase, aldehyde oxidase and nitrogenase, but excessive intake will also This leads to a reduction in enzyme activity; at the same time, for the harmful elements contained in the two honeys, their contents are below the limits of contaminants in food (the limits of some inorganic element contaminants in food refer to GB2762-2022). Due to the differences in element content and element types between the two honeys, it indicates that the two honeys have different levels of nutritional value.

Comparative ratio:

The reaction gas was replaced from NH ₃ to O ₂ , and the remaining conditions were the same as in Example 1. The products and interference conditions after the reaction between the element to be measured and O ₂ are as shown in Table 6.

Table 6 Products and interferences after the reaction between elements to be measured and O ₂

Because not all elements to be measured can react with _O2 , or the content of cluster ions formed after collision is too low, or the mass spectrum interference of some elements is severe, resulting in inaccurate measurement results of the content of the elements to be measured.

Experimental example:

In order to test the accuracy of the method of the present invention, under the optimal conditions tested in Example 1, the following data were tested:

1. Determine the detection limit of the element to be measured

Under the conditions of the Q ₁ value of the first quadrupole determined in step S2, the Q ₃ value of the third quadrupole determined in step S3, the reaction gas flow rate and the non-dimensional suppression parameter q, the standard solution of the element to be measured is used respectively. For quantitative analysis and testing of all elements to be measured, introduce the internal standard elements (Sc, Y, Rh and Re), blank solution and 1 ppb standard solution of the element to be measured into the inductively coupled plasma tandem mass spectrometer. Analyze the blank solution first, and then follow the steps The concentration of the standard solution of the element to be measured is detected in order from low to high, and finally the blank solution is used as the sample solution for 20 analyses; 3 times the standard deviation SD of the 20 blank solutions is used as the detection limit LOD:

LOD=3×SD.

The detection limits and lower detection limits of the elements to be tested are shown in Table 7:

Table 7 Detection limits and lower detection limits of elements to be measured

2. Determine the spike recovery rate and relative standard deviation of the element to be measured

(1) Under the conditions of the Q ₁ value of the first quadrupole determined in step S2, the Q ₃ value of the third quadrupole determined in step S3, the reaction gas flow rate and the non-dimensional suppression parameter q, use the value of the element to be measured The standard solution performs quantitative analysis and testing on all the elements to be measured. The internal standard elements (Sc, Y, Rh and Re), the blank solution and the standard solution of the element to be measured at 1ppb are introduced into the inductively coupled plasma tandem mass spectrometer. The blank solution is analyzed first. , and then detect the concentration of the standard solution of the element to be measured from low to high, and finally use the standard solution with the concentration closest to the detection limit LOD as the sample to analyze three times, and calculate the difference between the tested concentration and the concentration of the standard solution, that is, add Standard recovery rate ASRR:

In the formula: C ₀ is the actual concentration of the element to be measured in the standard solution, μg/mL; C ₁ is the concentration of the element to be measured in the blank solution, μg/mL; C ₂ is the test concentration of the element to be measured in the standard solution, μg/mL. mL.

(2) Calculate relative standard deviation RSD:

In the formula: It is the average concentration of three tests, μg/mL.

The spiked recovery rates and relative standard deviations of the elements to be tested are shown in Table 8:

Table 8 Spiked recovery rates and relative standard deviations of elements to be measured

element Sample concentration (ppb) Concentration after spike (ppb) Spiked recovery rate (%) The relative standard deviation(%) Na 642.000 1095.330 90.67 3.52 K 3232.000 5130.330 94.92 3.91 V 0.037 2.049 100.57 2.44 Cr 0.631 2.759 106.41 2.26 Mn 2.121 11.333 92.12 1.96 Fe 34.203 54.489 101.43 3.24 Co 0.036 1.916 94.01 1.43 Ni 0.169 2.160 99.57 0.66 Cu 1.650 3.457 90.34 6.48 Zn 3.304 4.999 98.28 3.29 As 0.084 2.397 115.68 1.66 Sr 1.407 3.267 93.02 2.16 Mo 0.080 1.908 91.39 0.43 Ag 0.064 2.109 102.24 0.90 cd 0.030 2.306 113.79 2.31 Sn 0.201 2.042 92.05 1.37 sb 0.149 2.149 100.00 0.29 Ba 1.251 3.064 90.63 1.38 Pb 0.243 2.252 100.45 0.46

Note: The spiked recovery rate is calculated by subtracting the sample concentration from the spiked concentration and then dividing it by the spiked concentration (the spiked amounts of different elements are inconsistent), and finally multiplied by 100%; the relative standard deviation is calculated by continuously detecting the same data three times, and then Divide the mean by the standard deviation and multiply by 100%.

Claims (8)

1. An ICP-MS method for determining the content of inorganic elements in honey, which is characterized in that it includes the following steps: S1: Prepare honey sample solution, blank solution and standard solution of elements to be measured; S2: Determine the Q ₁ value of the first quadrupole: screen out the optimal isotope of each element to be measured based on the highest relative content of the isotope and the smallest relative interference. Q ₁ is the mass number of the optimal isotope of the element to be measured; S3: Determine the _Q3 value of the third quadrupole: introduce the blank solution and the standard solution of 1 ppb of the element to be measured into the inductively coupled plasma tandem mass spectrometer, and screen out the optimal cluster ions, reagent gas flow rate and The non-dimensional suppression parameter q, Q ₃ is the mass number of the optimal cluster ion of the element to be measured; S4: Introduce the honey sample solution, blank solution and standard solution of the element to be measured into the inductively coupled plasma tandem mass spectrometer, based on the first quadrupole Q ₁ value determined in step S2 and the third quadrupole Q determined in step S3 Under the conditions of ₃ value, reaction gas flow rate and non-dimensional suppression parameter q, measure the average concentration A ₁ of the element in the blank solution and the average concentration A ₂ of the element in the honey sample solution, and calculate the actual content of the element to be measured in the honey sample. A ₀ : In the formula, A ₀ is the actual content of the element to be measured in the honey sample, μg/g; A ₁ is the average concentration of the element in the blank solution, μg/mL; A ₂ is the average concentration of the element in the honey sample solution, μg/mL. ; V is the volume of the honey sample solution, mL; m is the mass of the weighed honey sample, g. 2. The ICP-MS method for measuring the content of inorganic elements in honey according to claim 1, characterized in that, the step S1 is specifically: mixing honey sample, perchloric acid and nitric acid at 0.5-1g:2-4mL: Mix in a ratio of 10-20mL, add water after digestion to prepare a 50-100mL sample solution for later use; mix perchloric acid and nitric acid in a volume ratio of 2-4mL:10-20mL, add water after digestion to prepare a 50-100mL blank The solution is ready for use; prepare a standard solution using 2wt% nitric acid solution and a standard stock solution with a concentration of 100 mg/L of the element to be measured. 3. The ICP-MS method for measuring the content of inorganic elements in honey according to claim 2, characterized in that the digestion is divided into three stages: first, the mixed solution is heated to 90-110°C in 12-17 minutes, Digest for 20-40 minutes; then continue to raise the temperature to 140-160°C in 8-10 minutes and digest for 80-100 minutes; finally continue to raise the temperature to 180-200°C in 8-10 minutes and digest for 15-25 minutes. 4. The ICP-MS method for measuring the content of inorganic elements in honey according to claim 2, characterized in that: the elements to be measured are Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn , As, Sr, Mo, Ag, Cd, Sn, Sb, Ba and Pb. 5. The ICP-MS method for determining the content of inorganic elements in honey according to claim 1, characterized in that: the reaction gas used in step S3 is NH ₃ . 6. The ICP-MS method for determining the content of inorganic elements in honey according to claim 5, characterized in that: the flow rate of the reaction gas is 0.3-1.5mL/min. 7. The ICP-MS method for determining the content of inorganic elements in honey according to claim 1, characterized in that: the range of the non-dimensional inhibition parameter q is 0.05-0.85. 8. The ICP-MS method for measuring the content of inorganic elements in honey according to claim 1, characterized in that the parameters and setting values of the inductively coupled plasma tandem mass spectrometer in step S4 include: ICP radio frequency power is 1400 -1600W, the atomizer gas flow is 0.9-1mL/min, the auxiliary gas flow is 1-1.5mL/min, the plasma gas flow is 10-17mL/min, and the QID fixed voltage is -15~-10V.