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Detection of heavy metal content in soil environment

2022-06-24 14:23:18   

Application Overview

  In recent decades, with the rapid development of the China's industrialization, urbanization, and agricultural modernization, the pollution problems occur frequently. The quality of the cultivated soils is worrying, which brings the new threats and challenges to China's economic and social development.

   According to the newly issued"GB15618-2018 the Soil Quality: Pollution Risk Control Standard of the Agricultural Soils",the content of the heavy metals must be measured in the soils is defined as "risk screening value" and "risk control value". they are of great significance for the heavy metal emigration. Therefore, an analytical instrument that can clearly distinguish these two values becomes a necessary condition for the detection of the heavy metals in soils.

   Ancoren combines the advanced design concept with the cutting-edge technology of X-ray fluorescence spectrometry. Through the focused excitation of cadmium, the detection limit of cadmium that is difficult to analyze by XRF reaches an unprecedented level of 0.06 mg/kg, becoming the first X-ray fluorescence spectrometry in the world that can accurately detect the low content of cadmium in soil.

   The portable high-sensitivity XRF, such as PHECDA series, can meet the needs of laboratories and the on-site detection for the heavy metals. The method is simple, fast and high for the pretreatment of the sample, the analysis speed and the precision.


Demand for heavy metal detection in soil environment


  "GB15618-2018 the Soil Quality: Pollution Risk Control Standard of the Agricultural Soil"stipulates basic testing items such as cadmium, mercury, arsenic, lead, chromium, copper, nickel, and zinc in agricultural land soil, among which cadmium, mercury, arsenic, Five heavy metals such as lead and chromium stipulate the risk screening value and risk control value.

Table of risk screening value and risk control value of heavy metals in agricultural land soil   Unit：mg/kg

Pollutants Items	Cd	Hg	As	Pb	Cr	Cu	Ni	Zn
Risk screening value	0.3	0.5	25	70	150	50	60	200
Risk control value	1.5	2.0	100	400	800	-	-	-
Detection Limit	0.06	1.0	0.3	0.4	1.0	1.0	1.0	1.0

   

     If an analytical instrument can accurately analyze dozens of the heavy metals and completely distinguish the different of the "risk screening value" and "risk control value", it will become a necessary choice.

 
    The portable high-sensitivity XRF, such as PHECDA series developed by Ancoren Co., Ltd. can meet the above requirements, so it will be an excellent instrument to analyze the heavy metals.

 

Sample pretreatment


Performance Data
(1)Linearity
    The fast fundamental parameter method (Fast FP) establishes a mathematical model of the physical phenomena that comes from the X-rays incident to detected by a detector. Meanwhile, it takes advantage of a large number of calculations to eliminate matrix absorption-enhancement effects, correctly calculates and subtracts background interference, getting excellent linearity in a wide content range for the national standard sample.



























(2)Repeatability
      The standard sample GBW(E)070003 was tested for repeatability by PHECDA-ECO, and the results are as follows:

Elements	Cr	Ni	Co	V	Zn	As	Pb	Cu	Cd
GBW（E）070003 Certified	127±7	59.8±3.6	20.3±2.9	101±8	106±8	15.7±1.1	59.8±3.6	54.2±3.6	0.32±0.06
1	131.92	67.99	18.82	95.20	109.69	16.43	57.15	58.46	0.38
2	132.88	68.95	21.59	95.70	111.24	16.68	58.08	59.53	0.30
3	133.78	68.44	24.84	96.19	110.14	16.11	58.66	59.18	0.39
4	134.09	68.48	26.94	95.09	111.45	16.46	57.92	59.61	0.37
5	134.88	68.70	25.69	95.13	110.44	16.40	58.85	59.80	0.36
6	132.79	69.06	24.79	95.13	110.99	16.59	58.14	59.37	0.41
7	131.53	68.89	26.29	95.02	111.18	15.87	59.17	59.70	0.32
8	131.23	68.90	24.45	95.34	112.04	16.01	59.24	58.89	0.45
9	134.37	69.57	26.06	94.97	111.67	15.93	59.27	59.32	0.31
10	131.96	69.39	26.73	95.14	111.68	16.02	58.56	59.25	0.39
11	131.25	69.13	25.57	94.99	111.27	15.92	59.41	59.96	0.34
12	132.54	68.85	25.74	95.04	110.7	16.36	58.43	58.99	0.37
13	135.21	67.74	22.51	95.54	110.48	16.43	57.69	59.06	0.38
14	134.36	68.85	23.46	95.49	112.44	16.03	58.31	59.56	0.4
SD	1.38	0.49	2.26	0.34	0.76	0.27	0.66	0.40	0.04
Avg	132.79	68.86	24.71	95.26	111.07	16.22	58.59	59.37	0.37
RSD	1.0%	0.7%	9.2%	0.4%	0.7%	1.7%	1.1%	0.7%	11.2%

 

 

    The portable high-sensitivity X-ray fluorescence spectrometer PHECDA series can achieve the same repeatability as laboratory instruments for soil heavy metal analysis. Even if the content of cadmium is about 0.3mg/kg, the RSD value reaches 10%, which is the guarantee for accurate detection of soil heavy metals.

（3） Accuracy

Sample ID	Cr	Ni	Co	V	Zn	As	Pb	Cu	Cd
GBW(E) 070004	54.1±6.5	28.5±3.4	15.4±2.1	75.5±5.9	116±10	220±11	91.4±6.4	180±10	0.5±0.07
Measured Value	56.01	28.58	14.91	75.44	116.43	212.6	99.27	198.37	0.59
GBW(E) 070005	89.9±3.2	60.8±3.9	26.2±2.6	103±6	618±30	87.2±3.2	325±17	187±11	1.97±0.33
Measured Value	98.86	69.17	28.57	95.38	632.1	90.54	352.14	188.25	1.73
GBW(E) 070006	104±8	8.7±3.1	-3.75	140±8	37.9±5.4	606±53	60±5.0	18.9±2.4	0.07±0.02
Measured Value	116.61	11.85	21.23	134.55	36.31	611.89	62.39	15.02	0.09
GBW(E) 070007	35±5.5	18.6±3	13±2.2	76.4±5.6	153±9	32.6±3.3	73.9±5.2	309±12	0.53±0.07
Measured Value	34.54	15.04	8.18	75.1	144.02	29.77	71.91	304.55	0.77
GBW(E) 070008	84.3±9.4	333±25	25.6±2.7	88±7.1	301±20	74.6±7.1	675±27	290±16	0.49±0.06
Measured Value	79.84	331.39	25.76	80.03	270.38	84.09	686.17	254.94	0.63
GBW(E) 070009	99±11	83.3±7.4	23.8±3.2	158±12	982±78	841±98	1141±59	854±44	4.08±0.37
Measured Value	113.03	98.95	24.46	105.38	975.01	740.62	1048.74	732.88	4.26
GBW(E) 070010	87±11	55.2±4.4	24.5±2.5	110±7	158±8	200±22	110±9	209±10	0.47±0.07
Measured Value	89.96	62.53	32.31	94.35	151.35	188.89	104.36	202.84	0.38

 

   The portable high-sensitivity X-ray fluorescence spectrometer PHECDA-ECO analyzes GBW series standard samples, and the analysis results are within the error range, and in the 10-minute "quantitative analysis" mode, it has excellent accuracy.  


（4）HS XRF® vs. ICP MS

ICP-MS and Wet digestion are the standard method for the element detection. By comparing the results of the actual samples by ICP-MS, the HS XRF have excellent data consistency. The PHECDA also does not require complex sample treatment. The analysis method is simple and reliable.





Method principle

(1)Hardware core technology
Monochromatic excitation

The X-ray tube incident spectrum is focused on sample by hyperbolic bent crystal monochromatization, which reduces the X-ray tube continuous scattered ray background interference, and increases the SDD detector to accept the fluorescence ray intensity of the sample elements, thus enhancing the signal-to-noise ratio of the elemental characteristic fluorescence peaks and improving the sensitivity.

(2)Software core technology
Fast fundamental parameter method（Fast FP2.0®）
A library of fundamental parameters and advanced mathematical models are used for the calculation of interferences between elements to be measured, matrix effects and absorption enhancement effects between elements, background deduction, etc. A small number of measured value samples are used to further correct the calculation bias and improve the accuracy of element quantification and sample adaptability.





Features and advantages
   
   Ultra-low limit of detection

The detection limit of PHECDA, a high-sensitivity XRF, is less than 1.0mg/kg for all metals in soils. Especially, the detection limit of Cd that is difficult to analyze for XRF is 0.06mg/kg. The apparatus meets the limit demands for eight heavy metals in the basic project according to"GB15618-2018 the Soil Quality: Pollution Risk Control Standard of the Agricultural Soil". The apparatus can clearly distinguish "risk screening value" and "risk control value".


   Stability

The patented fixation system can eliminate the displacement of the optical path after factory tuning. Mono-wavelength excitation can eliminate the effects from the baseline background and the data repeatability meets the laboratory standards.


  Rapid analysis

The preparation of the samples is simple, and the treatment of the samples can be completed in a few minutes. The rapid screening analysis is 180seconds/sample. The quantitative analysis is 600seconds / sample.


  Extensive adaptability

The fast fundamental parameter method eliminates the X-ray interference between the matrix and the elements by accurate calculation, can be suitable for the analysis of various matrix samples.

  
   Portability

The auxiliary equipment such as gas vacuum is not required, so as to ensure the apparatus for the on-site detection.


Original statement:
This article is the original work of ancoren company except for the quotation. If it is forwarded and quoted, the source must be indicated, otherwise it may involve infringement. For more detailed technical information, please consult the staff of Ancoren.

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