Determination of lead in compound fertilizer by AA-1800 atomic absorption spectrometry - Master's thesis

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Determination of Lead in Compound Fertilizer by AA-1800 Atomic Absorption Spectrometer

Key words: atomic absorption spectrometer; compound fertilizer;

;

This standard specifies the determination of lead in compound fertilizers by atomic absorption spectrometry.

Atomic absorption spectrometry

Subject content and scope of application

This standard specifies the determination of lead in compound fertilizers by atomic absorption spectrometry.

This standard applies to the determination of lead content is less than

25Î¼g/mL

Sample solution.

Reference Standard

GB 602

Preparation of standard solution for determination of chemical reagent impurities

GB 6682

Analytical laboratory water specifications and test methods

Method summary

Lead in the sample solution, in the air

Atomization in the acetylene flame, the resulting atomic vapor, absorbs the characteristic wavelength emitted from the lead hollow cathode lamp

283.3nm

The amount of light absorbance is proportional to the atomic concentration of lead in the flame.

Reagents and materials

Analytically pure reagents are used in the analysis unless otherwise stated. The water used should be consistent with

GB 6682

Medium and third grade water specifications.

4.1

hydrochloric acid

(GB 622)

Solution:

c(HCl)=0.5mol/L

. measure

42mL

hydrochloric acid

(p1.19)

Dilute to

Mix well;

4.2

Lead standard solution:

0.1mg/mL

. press

GB 602

(4.82)

Formulated, this solution

1mL

Lead

100Î¼g

;

4.3

Dissolved acetylene

(GB 6819)

, or the same specifications of acetylene.

equipment

General laboratory instruments, equipment and:

5.1 AA-1800C

Atomic absorption spectrophotometer: equipped with air

Acetylene burner and lead hollow cathode lamp.

Analysis step

6.1

Drawing of the working curve

By table

As shown, the lead standard solution is placed separately

One

100mL

Hydrochloric acid solution in volumetric flask

(4.1)

Dilute to the mark and mix.

table

Lead standard solution

(4.2)

volume,

Corresponding lead content,

Gg/mL

5.0

10.0

15.0

20.0

25.0

5.0

10.0

15.0

20.0

25.0

Note: The preparation of the standard series solution can be adjusted according to the amount of lead in the sample and the sensitivity of the instrument.

Before performing spectrophotometry, according to the nature of the element to be tested, refer to the instrument manual for the spectral bandwidth, lamp current, burner height, air used for the measurement.

The acetylene flow ratio is selected for optimal working conditions.

Then, at the wavelength

283.3nm

Use air

Acetylene oxide flame with lead content

The standard solution is the reference solution, adjusted

Atomic absorption spectrophotometer

After the absorbance was zero, the absorbance of each standard solution was measured. After each measurement, the burner was washed with a water spray.

Lead content of each standard solution

(Î¼g/mL)

For the abscissa, the corresponding absorbance is plotted on the ordinate and the working curve is drawn.

6.2

Determination

The test solution is not diluted

(GB/T

14539.1

5.2

Article

)

Or pipetting a certain amount of test solution into a volumetric flask and using a hydrochloric acid solution

(4.1)

Dilution as a sample solution for measurement

(

The lead content of the solution to be tested must be less than

25Î¼g/mL)

Determine the absorbance of the test solution under the same conditions as the standard series solution, and find the corresponding lead concentration on the working curve.

(Î¼g/mL)

Expression of analysis results

7.1

When the test solution directly measures the absorbance without dilution, lead

(Pb)

content

, expressed in mass percent, by type

(1)

Calculation:

...................................................

(1)

In the formula:

â”€ the concentration of lead in the sample solution detected by the working curve,

?g/mL

;

â”€ the quality of the sample,

;

200

â”€ the total volume of the test solution,

7.2

After taking a certain amount of test solution and diluting it to a certain volume, when measuring the absorbance, lead (

)content

, expressed in mass percent, by formula (

) Calculation:

................................................

(2)

In the formula:

â”€ the concentration of lead in the sample solution detected by the working curve,

Gg/mL

;

â”€ the quality of the sample,

;

200

â”€ the total volume of the test solution,

;

â”€ draw a certain amount of test solution,

;

â”€ the total volume of the sample solution,

;

Allowable difference

Taking the arithmetic mean of the parallel determination results as the measurement result;

The relative deviation of the parallel determination results should be consistent with the table.

Claim:

table

Lead content, %

Allow relative deviation, %

0.005

0.0020

0.0001

100

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