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1. Method Overview

After the sample is dissolved in 2% nitric acid, it is injected into the graphite furnace of an atomic absorption spectrophotometer. After electrothermal atomization, it absorbs the resonance line at 247.6nm. Within a certain concentration range, the absorbance is proportional to the palladium content, and quantification is performed by comparison with the standard series.

2. 2. Instruments and Reagents

2.1 Instruments and Equipment

2.1.1 Detection Instruments

Graphite furnace atomic absorption spectrophotometer (Palladium hollow cathode lamp)

Argon gas 1 cylinder Purity ≥ 99.99%

Cooling circulating water system  (Rated water pump flow: 3.5L/min)

2.1.2 Pretreatment Equipment

Electronic balance

Ultrapure water system

Micropipette

Volumetric flask

Test tube Several

2.2 Reagents

2.2.1 Reagents

Nitric acid

2.2.2 Prepared Reagents

(2+98) Nitric acid solution Measure 20mL of nitric acid, slowly add it to 980mL of water, and mix well.

3. 3. Operation Process

3.1 Sample Treatment

3.1.1 Preparation of Test Solution

Accurately weigh 0.04g of the sample into a 10mL test tube, dilute to the mark with (2+98) nitric acid solution, mix well, and set aside as the sample test solution. Prepare a reagent blank solution simultaneously.

3.1.2 Preparation of Standard Solutions

1) Preparation of palladium standard intermediate solution:

Palladium standard solution (1.0μg/mL): Accurately pipette 0.1mL of the palladium standard solution (1000μg/mL) into a 100mL volumetric flask, dilute to the mark with (2+98) nitric acid solution, and shake well.

• Preparation of palladium standard series:

Accurately pipette 0.0, 0.1, 0.2, 0.3, and 0.4 mL of the palladium standard solution (1.0 μg/mL) into 10mL volumetric flasks respectively, dilute to the mark with (2+98) nitric acid solution to obtain palladium standard series solutions with concentrations of 0.0, 10.0, 20.0, 30.0, 40.0 ng/mL.

3.2 Sample Testing

1) Testing Conditions

Reference conditions for graphite furnace atomic absorption spectrophotometer detection

Element Palladium

Wavelength (nm) 247.6

Spectral bandwidth (nm) 0.2

Element lamp current (mA) 6

Background correction method Deuterium lamp

2) Sample Testing
Inject 15μL of the palladium standard series solutions into the graphite furnace in order of increasing mass concentration. After atomization, measure the absorbance. Plot a standard curve with mass concentration as the abscissa and absorbance as the ordinate. Read the data, input the sample weight, and check and record the results.

4. 결과 계산

어디:

X — Palladium content in the sample (mg/kg);

ρ– Mass concentration of palladium in the sample test solution(μg/L);

ρ0 — Mass concentration of palladium in the blank solution(μg/L);

V — Volume of the sample digestion solution after constant volume(mL);

m — Mass of the sample (g);

1000 — Conversion factor.