Trace detection method of heavy metals and application thereof

Abstract

The invention belongs to the technical field of trace detection, and discloses a heavy metal trace detection method and application thereof. The detection method; comprising the following steps: preparing a quality sample; mixing the quality sample with the sample to be tested according to a specific proportion; using X-ray fluorescence spectrometer to detect trace heavy metals; and using standard curve to realize quantitative analysis of heavy metals. For the purpose of detecting heavy metal elements in tea, the application of this invention can shorten the detection time, avoid the use of a large amount of acid liquor, improve the environmental protection performance, and lower the detection cost, moreover, the obtained standard curve by this invention has high correlation and accurate detection results.

Claims

1. A trace detection method of heavy metals, comprising steps as follows: 1) Preparing a quality control sample; 2) Mixing the quality control sample with a sample to be tested; 3) Using X-ray fluorescence spectrometer for detection of trace heavy metals; wherein the heavy metals include As, Pb, Cd, Cr, Cu, Zn and Ni; wherein in step 2, when a heavy metal element detected is As, a mass ratio of the quality control sample to the sample to be detected is 20:0.27, a standard curve is y=0.9817x−0.0697, and a correlation coefficient is 0.9992; when the heavy metal element detected is Pb, the mass ratio of the quality control sample to the sample to be detected is 20:0.27, a standard curve is y=0.9596x+0.0333, and a correlation coefficient is 0.9984; when the detected heavy metal element is Cd, the mass ratio of the quality control sample to the sample to be detected is 50:1.6, a standard curve is y=1.0133x−0.0214, and a correlation coefficient is 0.9995; when the detected heavy metal element is Cr, the mass ratio of the quality control sample to the sample to be detected is 10:0.076, a standard curve is y=1.0055x−0.0346, and a correlation coefficient is 0.9943; when the heavy metal element detected is Cu, the mass ratio of the quality control sample to the sample to be detected is 100:24, a standard curve is y=0.9777x−0.6403, and a correlation coefficient is 0.9965; when the heavy metal element detected is Zn, the mass ratio of the quality control sample to the sample to be detected is 100:35, a standard curve is y=1.0666x−4.5605, and a correlation coefficient is 0.9920; when the heavy metal element detected is Ni, the mass ratio of quality control sample to sample to be detected is 100:5.4, a standard curve is y=1.0051x−0.8094, and a correlation coefficient is 0.9924.

2. The trace detection method of heavy metals as claimed in claim 1, wherein in step 3, test conditions of the X-ray fluorescence spectrometer are described as follows: current range of X-ray tube is 0˜0.2 mA, voltage range is 0˜70 KV, test time range is 0˜10 min, collimator is φ5 mm, an optical filter system, containing 4 optical filters, wherein, the optical filter is optimized by heavy metal detection and is automatically switched, target excitation, containing a Micro X-ray window.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 illustrates the standard curve of heavy metals in tea.

DETAILED DESCRIPTION OF EMBODIMENTS

(2) Trace detection method of heavy metals, comprising the following steps:

(3) 1) preparing a quality sample;

(4) 2) mixing the quality sample with the sample to be tested according to a specific proportion;

(5) 3) using X-ray fluorescence spectrometer to detect trace heavy metals.

(6) According to this invention, the preparation steps of the quality sample in step 1) are as follows: as shown in Table 1, each single standard solution is added to the tea quality sample of GBW 08505, after the addition, the quality sample is freeze-dried, and ground at −4° C., evenly mixed and bottled for later use. According to the standard requirements of “CNAS-G017-2018 General Principles and Statistical Methods of Standard Reference Materials/Standard Samples”, carrying out the homogeneity test, stability test, uncertainty evaluation, data evaluation, etc. on the quality samples, setting value on the new quality samples for the use laboratory internal control.

(7) TABLE-US-00002 TABLE 1 Quality of addition standard of each element As Pb Cd Cr Cu Zn Ni Single standard solution 1000 1000 1,000 1000 1000 1000 1000 (mg/L) Content of quality sample 20 50 10 20 100 100 100 after spiked standard solution (mg/kg) Spike mass of single 0.1894 0.4894 0.09968 0.192 0.838 0.613 0.9239 standard solution (mg)

(8) According to this invention, the heavy metals include As, Pb, Cd, Cr, Cu, Zn and Ni.

(9) According to this invention, in step 2,

(10) when the heavy metal element detected is As, the mass ratio of quality control sample to sample to be detected is 20:0.27;

(11) when the heavy metal element detected is Pb, the mass ratio of the quality control sample to the sample to be detected is 20:0.27;

(12) when the detected heavy metal element is Cd, the mass ratio of the quality control sample to the sample to be detected is 50:1.6;

(13) when the detected heavy metal element is Cr, the mass ratio of the quality control sample to the sample to be detected is 10:0.076;

(14) when the heavy metal element detected is Cu, the mass ratio of the quality control sample to the sample to be detected is 100:24;

(15) when the heavy metal element detected is Zn, the mass ratio of the quality control sample to the sample to be detected is 100:35;

(16) when the heavy metal element detected is Ni, the mass ratio of quality control sample to sample to be detected is 100:5.4.

(17) According to this invention, in step 3, the test conditions of X-ray fluorescence spectrometer are described as follows: current range of X-ray tube is 0˜0.2 mA, voltage range is 0˜70 KV, test time range is 0˜10 min, collimator is φ5 mm, the optical filter system, containing 4 optical filters, wherein, the optical filter is optimized by heavy metal detection and can be automatically switched, the target excitation, containing a Micro X-ray window.

(18) Drawing of Standard Curve:

(19) The standard curve is based on the standard content of the sample to be tested and the content measured by the instrument, wherein, the two contents shows a linear relationship with the different spike mass. The higher the linear correlation, the more accurate the determination.

(20) As shown in Table 2, adding the quality sample to the sample to be tested, fully mixing, then measuring the content of each element with X-ray fluorescence instrument, setting the determined value as the ordinate, setting the theoretical standard content, which is calculated after adding the spiking solution, as the abscissa, drawing the standard curve, fitting the linear equation, and calculating the spiked recovery (see FIG. 1, Table 3 and Table 4 for details).

(21) TABLE-US-00003 TABLE 2 Quality of spiked quality control samples (unit: g) No. As Pb Cd Cr Cu Zn Ni  1 0.01 0.01 0.01 0.01 0.01 0.01 0.01  2 0.02 0.02 0.02 0.02 0.02 0.02 0.02  3 0.05 0.05 0.05 0.05 0.05 0.05 0.05  4 0.1 0.1 0.1 0.1 0.1 0.1 0.1  5 0.2 0.2 0.2 0.2 0.2 0.2 0.2  6 0.3 0.3 0.3 0.3 0.3 0.3 0.3  7 0.5 0.5 0.5 0.5 0.5 0.5 0.5  8 1 1 1 1 1 1 1  9 1.3 1.3 1.3 1.3 1.3 1.3 1.3 10 1.8 1.8 1.8 1.8 1.8 1.8 1.8 11 3.5 3.5 3.5 3.5 3.5 3.5 3.5 12 5 5 5 5 5 5 5

(22) TABLE-US-00004 TABLE 3 Standard curve and correlation coefficient of heavy metals in tea correlation coefficient No. Standard curve R2 As y = 0.9817x − 0.0697 0.9992 Pb y = 0.9596x + 0.0333 0.9984 Cd y = 1.0133x − 0.0214 0.9995 Cr y = 1.0055x − 0.0346 0.9943 Cu y = 0.9777x − 0.6403 0.9965 Zn y = 1.0666x − 4.5605 0.9920 Ni y = 1.0051x − 0.8094 0.9924

(23) TABLE-US-00005 TABLE 4 Spike recovery value of heavy metals (As, Pb, Cd, Cr, Cu, Zn, Ni) in tea (unit: %) No As Pb Cd Cr Cu Zn Ni  1 104.18 85.82 114.81 92.89 97.30 93.94 96.62  2 101.69 90.64 106.46 110.44 96.70 93.59 93.48  3 95.76 91.33 101.00 108.21 94.94 92.58 96.27  4 93.37 92.55 104.70 102.00 94.15 93.73 96.49  5 87.28 96.29 94.89 94.33 92.86 93.33 98.47  6 88.98 94.75 96.00 94.50 91.87 93.07 92.98  7 91.93 102.00 98.94 92.29 97.06 100.22 85.71  8 93.58 103.45 95.55 97.07 95.45 93.82 89.76  9 92.37 93.98 98.88 102.53 100.80 101.21 88.28 10 99.02 96.80 98.41 96.98 95.20 97.69 105.12 11 96.64 97.54 101.70 107.10 95.85 97.14 94.69 12 98.56 94.30 101.69 96.56 96.77 100.74 102.47

(24) This invention also provides the application of of trace detection method of heavy metals.

(25) The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, but not all of them. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in the field without creative labor are within the scope of the present invention.

EMBODIMENT 1

(26) 30 tea samples were randomly determined by ICP-MS and X-ray fluorescence instrument, and the relative phase differences between the two independent determination results were calculated, and the results respectively were As 0.34-13.35%, Pb 0.70-11.34%, Cd 0.73-14.97%, Cr 0.61-9.66%, Cu 0.15-7.05%, Zn 0.38-13.20%, Ni 0.28-9.52%, average<20%, meeting the requirements of GB 5009.268 for precision. (The relative phase difference of two independent determination results, when the content>1 mg/kg, the relative phase difference 10%; When the relative phase difference of content≤1 mg/kg and >0.1 mg/kg, the relative phase difference is ≤15%; When the content is ≤0.1 mg/kg, the relative phase difference is ≤20%).

(27) TABLE-US-00006 TABLE 5.1 Determination content (mg/kg) and relative phase difference (%) of tea samples As Pb Cd Cr No ICPMS XRF RSD % ICPMS XRF RSD % ICPMS XRF RSD % ICPMS XRF RSD %  1 0.1901 0.2032 −6.66 0.7687 0.8456 −9.53 0.0527 0.0554 −4.95 2.3843 2.3223 2.64  2 0.0934 0.1009 −7.70 0.4748 0.5210 −9.28 0.1779 0.1878 −5.40 0.7438 0.7220 2.97  3 0.0877 0.1000 −13.15 0.5320 0.5543 −4.10 0.1613 0.1778 −9.71 0.7346 0.7301 0.61  4 0.0676 0.0760 −11.76 0.0675 0.0700 −3.68 0.0222 0.0253 −12.99 0.9603 1.0012 −4.17  5 0.0962 0.1103 −13.70 0.0698 0.0770 −9.86 0.0231 0.0268 −14.97 1.2691 1.2234 3.67  6 0.0772 0.0801 −3.74 0.0888 0.0987 −10.55 0.0217 0.0245 −11.97 1.2512 1.2121 3.17  7 0.0522 0.0560 −7.05 0.5416 0.5454 −0.70 0.0344 0.0339 1.52 0.9402 1.0111 −7.27  8 0.0700 0.0711 −1.54 0.0406 0.0450 −10.19 0.0221 0.0237 −6.97 0.9149 0.9238 −0.97  9 0.0335 0.0355 −5.82 0.0199 0.0222 −11.07 0.0488 0.0500 −2.48 0.7583 0.8019 −5.58 10 0.0946 0.1023 −7.78 0.1084 0.1145 −5.52 0.0286 0.0301 −5.17 1.2650 1.2323 2.62 11 0.1035 0.1131 −8.87 0.1613 0.1789 −10.33 0.0300 0.0321 −6.74 1.3297 1.2444 6.63 12 0.1172 0.1180 −0.72 0.1413 0.1567 −10.34 0.0320 0.0311 2.98 1.0087 1.1111 −9.66 13 0.1180 0.1298 −9.50 0.2040 0.1976 3.17 0.0309 0.0311 −0.73 1.3035 1.2345 5.44 14 0.1087 0.1212 −10.87 0.2599 0.2500 3.87 0.0322 0.0345 −6.96 1.3393 1.2988 3.07 15 0.1245 0.1278 −2.63 0.1267 0.1345 −6.00 0.0307 0.0298 3.10 1.1802 1.2020 −1.83 16 0.1583 0.1781 −11.76 0.1433 0.1345 6.35 0.0297 0.0321 −7.64 1.1273 1.2023 −6.44 17 0.0700 0.0789 −11.88 0.0500 0.0560 −11.34 0.0176 0.0200 −12.77 1.1184 1.1987 −6.93 18 0.1066 0.1100 −3.15 0.0165 0.0180 −8.41 0.0348 0.0333 4.35 1.0053 1.0924 −8.30 19 0.1954 0.2000 −2.32 0.6696 0.6634 0.93 0.1262 0.1187 6.09 1.3884 1.2901 7.34 20 0.2105 0.2000 5.11 0.1748 0.1699 2.85 0.0972 0.0893 8.43 1.4202 1.2998 8.86 21 0.2774 0.2765 0.34 0.3066 0.2900 5.58 0.0399 0.0387 3.03 1.2716 1.2998 −2.19 22 0.2618 0.2521 3.79 0.3266 0.3000 8.48 0.0386 0.0376 2.60 1.3766 1.2898 6.51 23 0.0791 0.0800 −1.11 0.0908 0.1001 −9.78 0.0412 0.0378 8.62 1.0621 1.1213 −5.42 24 0.0768 0.0679 12.33 0.1300 0.1200 8.03 0.0392 0.0411 −4.81 1.0221 1.1010 −7.43 25 0.0795 0.0876 −9.64 0.0465 0.0502 −7.75 0.0248 0.0265 −6.81 1.4714 1.4747 −0.22 26 0.1243 0.1421 −13.35 0.0755 0.0801 −5.91 0.0279 0.0300 −7.42 1.3612 1.4721 −7.83 27 0.1196 0.1234 −3.10 0.1302 0.1221 6.43 0.0287 0.0300 −4.58 1.2247 1.3434 −9.24 28 0.1202 0.1234 −2.65 0.0820 0.0890 −8.18 0.0269 0.0289 −7.00 1.0938 1.1829 −7.83 29 0.1110 0.1098 1.05 0.1474 0.1348 8.93 0.0251 0.0277 −9.71 0.9152 1.0000 −8.85 30 0.1322 0.1298 1.81 0.1321 0.1348 −2.00 0.0458 0.0444 3.11 1.1379 1.1111 2.38

(28) TABLE-US-00007 TABLE 5.2 Determination content (mg/kg) and relative phase difference (%) of tea samples NO Cu Zn Ni  1 ICPMS XRF RSD % ICPMS XRF RSD % ICPMS XRF RSD %  2 99.85 100.00 −0.15 0.9444 0.9121 3.48 25.58 23.45 8.70  3 56.98 57.11 −0.23 0.1416 0.1421 −0.38 39.78 38.77 2.57  4 58.15 62.23 −6.78 0.2587 0.2433 6.15 41.01 39.01 5.00  5 61.31 62.33 −1.65 0.3930 0.4123 −4.79 17.91 17.23 3.87  6 64.87 60.11 7.61 0.4438 0.4189 5.77 22.34 20.92 6.55  7 68.53 70.23 −2.46 0.5576 0.5328 4.55 23.05 22.22 3.66  8 54.89 58.90 −7.05 0.1481 0.1298 13.20 25.41 23.44 8.06  9 61.49 65.34 −6.07 0.0776 0.0809 −4.11 25.31 23.01 9.52 10 71.64 68.99 3.77 0.2593 0.2345 10.06 32.42 30.98 4.53 11 72.15 70.10 2.88 0.6226 0.5789 7.27 21.17 23.01 −8.34 12 76.77 73.21 4.75 0.6281 0.5982 4.88 22.12 23.89 −7.67 13 69.83 71.34 −2.13 0.3347 0.3143 6.28 26.44 24.88 6.08 14 73.32 71.98 1.84 0.9550 1.0010 −4.70 24.17 24.87 −2.86 15 71.70 73.45 −2.42 0.5109 0.5347 −4.55 25.15 25.55 −1.59 16 70.35 73.21 −3.98 0.4467 0.5001 −11.28 29.33 30.99 −5.49 17 70.22 73.20 −4.15 0.8682 0.8989 −3.47 28.65 30.31 −5.63 18 59.70 60.54 −1.40 0.3976 0.3876 2.54 20.94 23.03 −9.51 19 58.77 61.10 −3.90 0.7239 0.7014 3.15 25.99 26.79 −3.02 20 73.01 70.22 3.90 0.7980 0.8123 −1.78 38.30 40.34 −5.18 21 73.46 74.32 −1.17 0.9794 0.9432 3.77 38.77 40.98 −5.54 22 72.86 75.27 −3.25 2.1031 1.9879 5.63 26.26 26.33 −0.28 23 76.01 75.99 0.02 1.9324 1.9989 −3.38 26.49 25.13 5.27 24 62.77 65.44 −4.16 0.6838 0.7089 −3.60 17.16 16.77 2.32 25 63.35 65.01 −2.58 1.0923 0.9898 9.84 17.15 17.98 −4.70 26 95.04 98.10 −3.17 0.8633 0.9001 −4.17 18.27 19.99 −8.97 27 85.83 90.13 −4.88 0.4891 0.4678 4.45 24.86 23.23 6.78 28 81.70 83.33 −1.97 0.8274 0.8023 3.08 23.94 21.83 9.21 29 70.19 72.43 −3.14 0.3092 0.3210 −3.74 17.93 19.15 −6.56 30 65.30 68.01 −4.06 0.8801 0.9032 −2.59 17.48 18.43 −5.27

(29) In this specification, each embodiment is described in a progressive way, and the differences between each embodiment and other embodiments are highlighted, so the same and similar parts of each embodiment can be referred to each other. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Many modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.