Identification of hazardous wastes, identification of leaching toxicity, inductively coupled plasma mass spectrometry (3)

(7) Calculation and expression of results

(1) The results of aqueous samples are expressed in ug/L, and the results of solid samples are expressed in mg/kg dry weight

(2) For results with a value lower than 10, 2 significant digits are reserved; for results with a value equal to or greater than 10, 3 significant digits are reserved

(3) The result of the sample extract is expressed in ug/L.

(4) The solid sample is reported and converted into dry sample mass ratio w (mg/kg), with 3 significant figures reserved, unless otherwise specified

In the formula, p——the concentration of the test substance in the extract, ug/L;

V——The volume of extraction liquid, L;

m——the mass of the sample to be extracted, kg

The analysis result of MDL that is lower than the estimated solid method detection limit (MDL) or adjusted according to the dilution (to complete the analysis) will not be reported

(5) The solid mass fraction ws(%) in the solid sample is calculated by formula (2):

Where m is _dry ——the quality of the sample _{dried at} 60℃;

m _wet -the quality of the sample before drying

Note: If the data user, project or laboratory requires that the percentage of solids be determined after drying at 105°C, take another sample (greater than 20g) and re-operate according to the steps of solid sample processing (total recoverable analytes), at 103~ Dry at 105°C to constant weight

(6) The results of the quality monitoring samples during the analysis period can provide a reference for the quality of the sample data and should be provided together with the sample results

(8) Quality assurance and quality control

(1) All laboratories using this method should implement the specified quality control procedures

(2) Linear calibration range: The upper limit of the linear calibration range suitable for each element is established by measuring the signal response of the standard solutions of three different mass concentrations.

(3) Quality control sample (QCS): The average of the three measurements of QCS used to verify the calibration standard must be within ±10% of its standard value

(4) Laboratory reagent blank (LRB): When analyzing a set of samples of the same matrix, at least one laboratory reagent blank should be inserted for every 20 or fewer samples

(5) Laboratory fortified blank (LFB): At least one laboratory fortified blank must be analyzed for each batch of samples

(6) If the element recovery rate falls outside the specified range and the laboratory performance is normal, the recovery problem encountered by the enhanced sample should be caused by the matrix of the enhanced sample rather than a system problem

(7) Internal standard response: The internal standard response during the entire sample analysis process and the ratio of the internal standard to the signal response of each analysis element should be monitored
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The deviation of the absolute response value of any internal standard cannot exceed 60% to 125% of the initial response in the calibration blank
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(9) Matters needing attention

(1) a laboratory vessel for the determination of trace elements in terms of pollution and loss is the primary consideration, glassware used in the analysis must be made in HN03 _.
3 (1 + 1) solution immersion 24h, heat or HN03 _.
3 swing After washing, rinse with deionized water before use
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For new utensils, the corresponding blank inspection should be done before they can be used
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(2) Corresponding blank experiment should be done for each bottle of reagent used, especially hydrochloric acid should be carefully checked
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When preparing standard solutions and samples, use the same bottle of reagents as much as possible
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(3) The standard series used must be prepared each time and measured under the same conditions as the sample
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(4) The sample processing of trace elements must ensure a clean laboratory operating environment
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In the determination of trace elements, the sample container will bring positive and negative errors to the sample determination results through the following ways:

① Pollution caused by surface desorption or leaching;

② Reduce the element mass concentration through the adsorption process
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All reusable laboratory utensils (glass, quartz , polyethylene , PTFE, FEP and other materials) should be fully cleaned until they meet the analysis requirements
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(5) The performance of the instrument must be checked and the instrument calibrated before the sample measurement
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In order to confirm the reliability of the calibration, after each calibration, after every 10 samples are analyzed and the analysis running program is finished, the calibration blank and standard must be back-tested
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The back-tested value of the calibration standard can be used to judge whether the calibration is valid
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The deviation of the mass concentration of all the elements to be tested in the standard solution should be within ±10%
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If the back-test result is not within the specified range, the instrument must be recalibrated (the response signal of the back-tested instrument during the calibration check can be used for re-calibration, but it must be confirmed before continuing the sample analysis)
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If the continuous calibration check exceeds the ±15% deviation range, the 10 samples analyzed before must be retested after calibration
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If the calibration drift is caused by the sample matrix, it is recommended to re-measure the 10 samples previously measured in a group of 5 samples to avoid similar drift
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(6) Use internal standard method to correct interference caused by instrument drift or sample matrix
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The characteristic mass interference should also be corrected
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Regardless of whether hydrochloric acid is added or not , all samples must be corrected for chloride interference, because chloride ions in environmental samples are common components
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(7) If more than one isotope is selected for a analyte element, the calculated mass concentration or isotope ratio of different isotope can provide useful information for the analyst to check possible mass spectrum interference
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When measuring the mass concentration of elements, both major and minor isotopes must be considered
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In some cases, the sensitivity of the secondary isotope may be lower than the recommended primary isotope or more likely to be interfered.
Therefore, the difference between the two results does not indicate that there is a problem with the calculation of the primary isotope
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