CN105606590A - Method for simultaneously determining contents of various elements in soil or deposits - Google Patents

Abstract

The invention relates to detection technology for element contents, and provides a method for simultaneously determining contents of arsenic, cadmium, lead, vanadium, zinc, manganese and phosphor in soil or deposits. The method mainly comprises the following steps: (1) 0.1g of a grinded drying soil sample is accurately weighed and placed in a TFM microwave digestion pot, a certain proportion of aqua regia and hydrofluoric acid are added, and a solution is allowed to stand; (2) an appropriate microwave digestion program is set, and microwave digestion is carried out for the solution in the step (1); (3) after the microwave digestion program ends, an acid-driving device is used for heating and evaporating the digestion solution in the step (2) to a dry state, and total transfer, volumetric flask preparation, and filtering are carried out; (4) ICP-OES is used for determining contents of arsenic, cadmium, lead, vanadium, zinc, manganese and phosphor in the clear liquor in the step (3); (5) ICP-MS is used for determining contents of elements in the clear liquor in the step (3) which do not reach detection limits in the step (4) once more. The method has the advantages of simple steps, simplified operation, saved soil samples, reduced personal error, minimized environment interference, and improved working environments.

Description

A method for simultaneously determining the content of multiple elements in soil or sediment

technical field

The invention relates to detection technology of element content.

Background technique

my country's current monitoring standards for soil or natural water sediments are mainly "Technical Specifications for Soil Environment Monitoring" (HJ/T166-2004) issued by the former State Environmental Protection Administration, and "Lead, Cadmium, Vanadium, Phosphorus, etc." issued by the Ministry of Water Resources. "Determination of 34 Elements" (SL394-2007) and "Marine Monitoring Regulations" (GB17378-2007) jointly promulgated by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China and the National Standardization Administration Atomic Fluorescence Method" (GB/T22105-2008). These standards use electric hot plate (most elements) or water bath (arsenic) digestion method to pre-treat soil or sediment samples. These methods are complicated to operate, large in sampling volume, time-consuming and labor-intensive, and cause great pollution to the surrounding environment. These standards have different regulations on the determination methods of different elements. If you want to investigate the content of various elements such as arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus in a soil or sediment sample, you need to measure it many times. The operation is complicated, time-consuming and labor-intensive, and there are many interference factors. In recent years, the United States Environmental Protection Agency (US-EPA) recommends the use of microwave digestion method for pretreatment of soil or sediment, which has the advantages of rapid digestion, high recovery rate and low environmental pollution. With reference to this law, my country has formulated the Microwave Digestion Method for Pretreatment of Heavy Metals in Marine Sediments and Marine Organisms (HY/T132-2010), but it is only applicable to the five elements of copper, lead, cadmium, zinc and chromium. In terms of element determination methods, the U.S. Environmental Protection Agency (US-EPA) recommends the use of inductively coupled plasma spectrometer (ICP-OES) or inductively coupled plasma mass spectrometer (ICP-MS), which can determine multiple elements at one time , and has the advantages of fast analysis speed, wide linear range and high precision, but the former has a higher upper limit of determination than the latter, and the latter has a lower detection limit than the former. In order to be in line with international standards and improve the efficiency and accuracy of determining the content of various elements, the present invention combines the microwave digestion method with ICP-OES/ICP-MS to simultaneously measure arsenic, cadmium, lead, vanadium in soil or sediment , zinc, manganese and phosphorus element content, and optimize the operation steps and condition parameters, thus expanding the scope of application of the digestion method and simplifying the element determination operation.

Contents of the invention

In order to solve the problems of complicated digestion steps of existing soil or sediment samples, narrow scope of application and complicated element determination methods, the present invention proposes the following technical solutions:

(1) Get the dry sample of the soil to be tested and grind until all can pass through a 100-mesh nylon sieve;

(2) Accurately weigh 0.1000 ± 0.0010g of ground dry soil sample to be tested, place it in a TFM polytetrafluoroethylene microwave digestion tank, add a certain proportion of aqua regia (premium grade pure concentrated nitric acid and superior grade pure concentrated hydrochloric acid) The volume ratio is 1:3) and hydrofluoric acid (excellent grade), let it stand still, and at the same time use the digestion solution without adding soil samples as a blank control;

(3) The temperature and time parameters of the microwave digestion program are set, and the solution in the above step (2) is subjected to microwave digestion. The specific microwave digestion program is as follows:

(4) After the microwave digestion program is over, use an acid catcher to heat and evaporate the digestion solution obtained in the above step (3) to a dry state, then transfer it to a volumetric flask for constant volume, and then pass it through a 0.45 μm mixed fiber filter membrane to filter;

(5) Utilize ICP-OES to measure the content of arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus in the clear dilute solution that above-mentioned step (4) obtains;

(6) Using ICP-MS to re-determine the contents of the elements in the clear dilute solution obtained in the above step (4) that have not reached the detection limit in the above step (5).

The features of the present invention are:

1. The inventive method effectively shortens the digestion time and the measurement time, simplifies the sampling times and reduces the sampling volume, saves soil samples and improves the working environment;

2. The method of the present invention can measure multiple elements only by performing one digestion process, saving sampling volume and preventing cross-contamination;

3. The TFM microwave digestion tank adopted by the method of the present invention is suitable for the determination of trace soil samples, ensuring the stability of the results of repeated use and the reproducibility of trace soil samples;

4. The microwave digestion program adopted by the method of the present invention is not only suitable for measuring volatile elements such as arsenic, but also for difficult to digest elements such as lead and cadmium, and can ensure the recovery rate of multiple elements at the same time;

5. The method of the present invention combines ICP-OES and ICP-MS for the determination of element content, and the content of various elements in different concentration ranges can be determined at one time, so as to avoid repeated sampling, digestion and dilution operations, and reduce human error , reduce environmental interference, and ensure the stability of the measurement results.

Description of drawings

Figure 1 is a flow chart of "simultaneous determination of arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus in soil or sediment", and the comprehensive results A and B are the measured values of the contents of various elements.

detailed description

1. GSS-15 standard soil sample (GBW07429, Yangtze River plain area)

The present embodiment applies the method of the present invention to the determination of metal elements and phosphorus elements in soil samples, and the specific determination steps are as follows:

(1) Accurately weigh 0.1000±0.0010g of the ground dry soil sample to be tested, place it in a 10mL TFM polytetrafluoroethylene microwave digestion tank, add 6mL of high-grade pure aqua regia (the volume ratio of concentrated nitric acid and concentrated hydrochloric acid is 1: 3) and 2mL of high-grade pure hydrofluoric acid, let it stand for 10 minutes, and use the digestion solution without adding soil samples as a blank control;

(2) The temperature and time parameters of the microwave digestion program are set, and the solution in the above step (1) is subjected to microwave digestion. The specific microwave digestion program is as follows:

(3) After the microwave digestion program is over, use an acid catcher to heat and evaporate the digestion solution in the TFM microwave digestion tank to the dry state, transfer all the obtained soil digestion solution to a volumetric flask for constant volume, and then pass through a 0.45 μm mixing Fibrous filter membrane for filtration;

(4) Utilize ICP-OES to measure the manganese and phosphorus content in the clear dilute solution that above-mentioned step (3) obtains;

(5) Utilize ICP-MS to measure the content of arsenic, cadmium, lead, vanadium and zinc in the clear dilute solution that above-mentioned step (3) obtains;

(6) Measure four parallel soil samples at the same time to calculate the average recovery rate and relative standard deviation.

The measurement results are shown in Table 1 and Table 2:

Table 1 Statistics of ICP-OES measurement results of GSS-15 standard soil samples

Table 2 GSS-15 standard soil sample ICP-MS measurement results statistics

2. GSD-4a standard soil sample (GBW07304a, Tongling limestone and skarn mineralized area, Anhui)

The present embodiment applies the method of the present invention to the determination of metal elements and phosphorus elements in natural water system sediment samples, and the specific determination steps are as follows:

(1) Accurately weigh 0.1000±0.0010g of the ground dry soil sample to be tested, place it in a 10mL TFM polytetrafluoroethylene microwave digestion tank, add 6mL of high-grade pure aqua regia (the volume ratio of concentrated nitric acid and concentrated hydrochloric acid is 1: 3) and 2mL of high-grade pure hydrofluoric acid, let it stand for 10 minutes, and use the digestion solution without adding soil samples as a blank control;

(2) The temperature and time parameters of the microwave digestion program are set, and the solution in the above step (1) is subjected to microwave digestion. The specific microwave digestion program is as follows:

(3) After the microwave digestion program is over, use an acid catcher to heat and evaporate the digestion solution in the TFM microwave digestion tank to the dry state, transfer all the obtained soil digestion solution to a volumetric flask for constant volume, and then pass through a 0.45 μm mixing Fibrous filter membrane for filtration;

(4) Utilize ICP-OES to measure the iron, manganese and phosphorus content in the clear dilute solution that above-mentioned step (3) obtains;

(5) Utilize ICP-MS to measure the arsenic, cadmium, chromium, copper, nickel, lead, vanadium, zinc content in the clarification dilute solution that above-mentioned step (3) obtains;

(6) Measure four parallel soil samples at the same time to calculate the average recovery rate and relative standard deviation.

The measurement results are shown in Table 3 and Table 4:

Table 3 GSD-4a standard soil sample ICP-OES measurement results statistics

Table 4GSD-4a standard soil sample ICP-MS measurement results statistics

Claims (8)

1. a method of simultaneously measuring multiple element content in soil or deposit, is characterized in that following steps:

(1) get antecedent soil moisture sample to be measured, be ground to whole energy by 100 order nylon mesh;

(2) accurately take and get ground antecedent soil moisture sample to be measured 0.1000 ± 0.0010g, be placed in 10mLTFM polytetrafluoroethylene (PTFE) microwave and disappearSeparate in tank, add a certain proportion of chloroazotic acid (volume ratio of the pure red fuming nitric acid (RFNA) of top grade and the pure concentrated hydrochloric acid of top grade is 1:3) and the pure hydrofluoric acid of top grade, leave standstill,Do blank with the digestion solution that does not add soil sample simultaneously;

(3) the temperature and time parameter of micro-wave digestion program is set, the solution in above-mentioned steps (2) is carried out to micro-wave digestion;

(4), after micro-wave digestion EP (end of program), utilize the digestion solution heating evaporation dry state extremely to the greatest extent of catching up with sour device that above-mentioned steps (3) is obtained, then completePortion transfers to and in volumetric flask, carries out constant volume, then filters by the composite fibre filter membrane of 0.45 μ m;

(5) utilize arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content in the clarification dilute solution that ICP-OES obtains above-mentioned steps (4) to carry outMeasure;

(6) utilize ICP-MS to contain the element that does not reach detection limit in the clarification dilute solution that above-mentioned steps (4) is obtained in above-mentioned steps (5)Amount is measured again.

2. the method for simultaneously measuring arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content in soil or deposit according to claim 1, its spyLevy and be: carrying out the digestion solution that disposable micro-wave digestion pretreatment process obtains can survey multiple element by above machine.

3. the method for simultaneously measuring arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content in soil or deposit according to claim 1, its spyLevy and be: take antecedent soil moisture sample to be measured 0.1000 ± 0.0010g, sample weighting amount is few, save soil sample.

4. the method for simultaneously measuring arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content in soil or deposit according to claim 1, its spyLevy and be: use TFM polytetrafluoroethylene (PTFE) micro-wave diminishing pot to hold strong acid dissolution liquid and carry out High-temperature Digestion, the micro-wave diminishing pot acid corrosion-resistant of this materialHigh temperature resistant, under HTHP, deformation behavior is little, permeability is little, restorative good and there is very high surface smoothness, ensure that nonexpondable result is steadyThe reappearance that qualitative and micro-soil sample is measured.

5. the method for simultaneously measuring arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content in soil or deposit according to claim 1, its spyLevy and be: add chloroazotic acid and hydrofluoric acid as strong acid dissolution liquid, to ensure that the metallic element that plumbous and these difficulties of cadmium are cleared up clears up completely, and guarantee mensurationThe reappearance of result.

6. the method for simultaneously measuring arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content in soil or deposit according to claim 1, its spyLevy and be: in the 4th step of micro-wave digestion program, design temperature is 190 DEG C, and the setting retention time is 30min, ensure on the one hand plumbous and these difficulties of manganeseThe metallic element of clearing up is cleared up completely, prevents again that on the other hand excess Temperature from producing shadow to the assay of this more volatile metalloid element of arsenicRing.

7. the method for simultaneously measuring arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content in soil or deposit according to claim 1, its spyLevy and be: after micro-wave digestion EP (end of program), utilize and catch up with sour device by the dry state extremely to the greatest extent of digestion solution heating evaporation in TFM micro-wave diminishing pot, to preventThe interference that amount strong acid is measured ICP-MS.

8. the method for simultaneously measuring arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content in soil or deposit according to claim 1, its spyLevy and be: first with ICP-OES, arsenic, cadmium, lead, vanadium, zinc, manganese and phosphorus content are measured, used if content does not reach the element of detection limitICP-MS measures again, and the disposable like this various constituent contents that can measure variable concentrations scope, to avoid repeating sampling, to clear upWith dilution operation, and reduce human error, reduce environmental disturbances, ensure the stability of measurement result.