SL/T 220-1998 Determination of trace copper, zinc, cadmium and lead in water - Flow injection atomic absorption spectrophotometry SL/T 220-98
Some standard content:
Industry Standard of the People's Republic of China
SL/T220--98
Determination of the trace amounts of Copper, Zinc, Cadmium and Lead in Water (Flow injection atomic absorption spectrometry)1998-07-20Promulgated
Ministry of Water Resources of the People's Republic of China
Implemented on 1998-09-01
Industry Standard of the People's Republic of China
Determination of the trace amounts of Copper, Zinc, Cadmium and Lead in Water (Flow injection atomic absorption spectrometry) : Notice on the approval of the release of "Determination of trace copper, zinc, cadmium and lead in water - Flow injection atomic absorption spectrophotometry" SL/T220--98
Editor: Liaoning Provincial Water Environment Monitoring Center Songliao River Basin Water Environment Monitoring Center
Approving department: Ministry of Water Resources of the People's Republic of China Effective date: September 1, 1998
Ministry of Water Resources of the People's Republic of China
Notice on the approval of the release of "Determination of trace copper, zinc, cadmium and lead in water - Flow injection atomic absorption spectrophotometry" SL/T220--98
Water Science and Technology [1998] No. 291
According to the Ministry's plan for the formulation and revision of technical standards for water resources and hydropower, the "Determination of trace copper, zinc, cadmium and lead in water - Flow injection atomic absorption spectrophotometry" was formulated by the Ministry's Hydrology Bureau and Liaoning Provincial Water Environment Monitoring Center as the main editor. After review and approval, it is a water conservancy industry standard and is now published. The name and number of the standard are: "Determination of trace copper, zinc, lead in water - Flow injection atomic absorption spectrophotometry" SL/T220--98
This standard shall be implemented from September 1, 1998. During the implementation process, each unit should pay attention to summarizing experience. If there are any problems, please inform the Ministry of Hydrology Department in writing, and it will be responsible for interpretation. The standard text is published and distributed by China Water Resources and Hydropower Press. July 20, 1998
"Determination of trace copper, zinc, lead in water - Flow injection atomic absorption spectrophotometry" is compiled based on domestic and foreign analytical technology research, according to the characteristics of the water conservancy industry and the actual situation of water environment monitoring development in the water conservancy system. The relevant specific issues are explained as follows.
This standard technically follows the following specifications: - SL01-97 "Regulations on the Preparation of Water Conservancy and Hydropower Technical Standards"; - GB1.4-88 "Regulations on the Preparation of Chemical Analysis Methods in the Guidelines for Standardization Work".
The main contents of this standard include:
How to use flow injection analysis technology to connect the sampling, enrichment, elution and other processes together to form an online pre-enrichment analysis system; How to eliminate interference;
How to select reagents, experimental water and prepare various solutions; How to draw a standard curve;
Detailed provisions are made on the operating conditions of the atomic absorption spectrophotometer; Detailed provisions are made on the pretreatment of water samples. This standard interpretation unit: Hydrology Department of the Ministry of Water Resources This standard editor unit: Liaoning Water Environment Monitoring Center Songliao River Basin Water Environment Monitoring Center
Main drafters of this standard: Li Xuchun, Li Qingshan, Guo Dongming, Luan Tianxin, Jia Guozhen, Guan Awei, Sun Xiaocheng
Precision and accuracy
Precautions
1 General
1.1 Principle of the method
Workflow: See Figure 1.1.1.
(a) Enrichment state
(b) Elution state
Figure 1.1.1 Schematic diagram of flow injection analysis workflow P—peristaltic pump: V—sampling column; C—ion exchange column; S—water sample, B—re-flushing solution; E—salt solution; W-waste liquid; AAS—atomic absorption spectrophotometerHO
1.1.2 Working principle: Water sample and buffer solution are introduced into the system by the peristaltic pump of the flow injection analyzer, mixed by the three-way pipe in the combination block, and then injected into the ion exchange column for online enrichment by the sampling valve. After timed enrichment, switch the sampling column, and use hydrochloric acid solution to reversely elute the copper, zinc, and lead enriched on the ion exchange column into the atomic absorption flame for determination. Compare the absorbance value of the heavy metals in the water sample with the absorbance value of the standard solution to determine the content of copper, zinc, and lead in the water sample. 1.2 Interference and Elimination
When the concentration of magnesium in the water sample is higher than 50mg/L, and the concentration of calcium and sodium is higher than 200mg/L, it interferes with the determination of cadmium; when the concentration of calcium is higher than 200mg/L and the concentration of magnesium is higher than 100mg/L, it interferes with the determination of copper and lead. In this case, the sample dilution method can be used to reduce or eliminate the interference, or the standard addition method can be used to determine and calculate the results. 1.3 Scope of Application
The detection limits of this method for copper, zinc, radium, and lead are 0.001, 0.001, 0.001, and 0.01mg/L, respectively. The determination range of the method is 0.001~0.050mg/L for copper, 0.001~0.040mg/L for zinc, 0.001~0.040mg/L for cadmium, and 0.01~0.70mg/L for lead.
This method is applicable to the determination of low concentrations of steel, zinc, pot and lead in surface water, groundwater and wastewater samples.
2 Instruments
Atomic absorption spectrophotometer.
Flow injection analyzer: 60r/min rotating pump speed. Ion exchange column: 4mmX30mm organic glass tube, filled with 200mg401 chelating resin (80-100 mesh) in the middle, and 100 mesh nylon mesh or glass wool at both ends. 2. 0.4
Hollow cathode lamp and atomic absorption supporting equipment. Common laboratory equipment.
3 Reagents
Unless otherwise specified, chemical reagents of analytical grade or higher than analytical grade that meet national standards are used during analysis. The experimental water should meet the secondary water specified in the national standard GB6682-92 "Specifications and Test Methods for Water Use in Analytical Laboratories". The water used to prepare zinc standard solution, hydrochloric acid solution and acetic acid ammonium buffer solution should be sub-boiling distilled water. 3.0.1 Hydrochloric acid (HCI), p=1.19g/mL
Nitric acid (HNO), e=1.42g/mL.
Perchloric acid (HCIO), p=1.764g/mL. Hydrochloric acid solution, c(HCI)=2mol/L.
0.2% (V/V) nitric acid solution.
1+1 nitric acid solution.
Ammonium acetate buffer solution: Weigh 19.5g ammonium acetate (NH.Ac), dissolve in 500mL water, and adjust pH to 9-10 with concentrated ammonia water, seal and store in refrigerator. 3.0.8 Copper, zinc, saw, lead standard stock solution: Weigh 0.1250g of spectrally pure copper, zinc, and lead, respectively, and place them in 50mL beakers, add 5mL (1+1) nitric acid to dissolve each, and then transfer them to 500mL volumetric flasks, dilute with water to the mark, shake and set aside. This standard solution contains 0.25mg of copper, zinc, radium, and lead per liter. 3.0.9 Copper, zinc, radium, and lead standard working solutions: Take 0.25mg/mL of copper, zinc, radium, and lead standard stock solutions respectively, and dilute them step by step into four standard working solutions containing 2.5g/mL of copper, 2.5g/mL of zinc, and 25μg/mL of lead.
3.0.10 Preparation of standard curve solutions: Take 0, 0.50, 1.00, 2.00, 3.00, and 4.00mL of copper, zinc, radium, and lead standard working solutions, and put them into 6 250mL volumetric flasks respectively, and dilute to the mark with distilled water. The content of this standard series converted into copper, zinc, and radium is 0, 1.25, 2.50, 5.00, 7.50, and 10.0g; the content of lead is 0, 12.5, 25, 50, 75, and 100μg. 3.0.11401 integrated resin: soak 401 integrated resin (80/100 mesh) with 2mol/L hydrochloric acid, and take 0.2g of resin to load the column when using. 3.0.12 Acetylene gas, purity 99.9%.
4 Steps
41 Experimental preparation
Adjust the atomic absorption spectrophotometer operating conditions according to Table 4.1.1. Table 4.11
Atomic absorption spectrophotometer operating conditions
Lamp currentWww.bzxZ.net
Duty cycle
Air flow
(L/min)
Acetylene flow
(L/min)
Flame type
4.1.2According to Figure 1.1.1 As shown in the flow injection analysis workflow diagram, connect the three pump tubes of the flow injection analyzer end pump, push the pressure block, and then connect the flow injection analyzer pipeline interface to the atomic absorption spectrophotometer (AAS), turn on the power, and turn on the instrument switch.
4.2 Calibration curve drawing
Insert a polytetrafluoroethylene tube on the flow injection analyzer olefin pump into the ammonium acetate buffer solution (3.0.7) of pH 9~10, a polytetrafluoroethylene tube into the hydrochloric acid solution (3.0.4), and another polytetrafluoroethylene tube into the standard curve solution (3.0.10) of different concentrations in sequence (from dilute to concentrated). The end pump draws the standard curve solution and buffer solution at a flow rate of 7.5mL/min and 0.8mL/min, and after mixing through the three-way pipe in the combination block, it is injected into the ion exchange column for adsorption and enrichment for 90S through the sampling chest, as shown in Figure 1.1.1 (a). At this time, deionized water enters the atomic absorption flame, and its recorded signal is the baseline. Then switch the sampling valve to the elution state, see Figure 1.1.1 (b). Use 2mol/L hydrochloric acid solution at a flow rate of 4.2mL/min to reversely elute the ion exchange column for 20S, and elute the heavy metals in the 5
sample on the column into the atomic absorption flame. At the measurement wavelengths of copper, zinc, and lead at 324.7, 213.9, 228.8, and 283.3nm, use the distilled water as a reference to measure the absorbance, and draw a calibration curve for the absorbance versus the copper, zinc, antimony, and lead content (g). 4.3 Water sample pretreatment
4.3.1 For groundwater and clean surface water without suspended matter, add nitric acid immediately after the sample arrives to acidify it to a pH less than 2. Generally, add 1.5mL of concentrated nitric acid per liter of water sample, and this water sample can be directly measured.
4.3.2 For water samples containing a large amount of suspended matter, microorganisms and organisms, filter with a 0.45μm organic microporous filter membrane, add nitric acid to the filter to acidify to a pH less than 2, and bring it back to the laboratory for determination as soon as possible.
4.3.3 For surface water and industrial wastewater containing high organic matter, digestion should be carried out, that is, add 5.0mL of concentrated nitric acid to every 100mL of water sample, place it on a hot plate to heat and digest until it evaporates to about 10mL, add 2.0mL of perchloric acid (depending on the content of organic matter) after cooling, and continue to heat and digest until the liquid is clear and transparent. After cooling, use 0.2% nitric acid solution to digest the residue, and filter it with rapid quantitative filter paper to allow all copper, zinc, lead and lead to enter the test solution, and then dilute it with water to a certain volume for analysis and determination. 44 Water sample determination
Take a certain volume (depending on the amount of copper, zinc, cadmium and lead in the water sample) of the sample solution and blank solution (distilled water) treated in step 4.3, and insert the polytetrafluoroethylene tube of the flow injection analyzer into the sample solution, buffer solution and hydrochloric acid solution respectively. The following steps are the same as those for drawing the calibration curve. The water sample determination conditions should also be the same as those for drawing the calibration curve.
The blank sample is prepared from the actual sample. The absorbance of the sample measurement minus the absorbance of the blank, and the content of copper, zinc, cadmium and lead (g) is found from the standard curve. 6
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