Applications

Determination of Copper in Nylon (Flame Atomic Absorption Spectrometry)

September 9, 2025

1. Method Overview

After the sample is digested and treated, it is atomized by flame, and the absorbance is measured at a wavelength of 324.8 nm. Within a certain concentration range, the absorbance value of copper is proportional to its content, and quantification is performed by comparison with the standard series.

2. Instruments and Reagents

2.1 Instruments and Equipment

2.1.1 Testing Instruments

Serial No.	Name	Quantity	Technical Requirements	Accessories
1	Flame Atomic Absorption Spectrophotometer	1 set	–	Copper Hollow Cathode Lamp
2	Air Compressor	1 set	Rated discharge pressure: 0.3 MPa	–
3	Acetylene Gas	1 cylinder	Purity ≥ 99.99%	–

2.1.2 Sample Pretreatment Equipment

Serial No.	Name	Quantity	Technical Requirements	Accessories
1	Electronic Balance	1 set	Sensitivity: 0.1 mg	–
2	Quartz Crucibles	Several	Volume: 100 mL	–
3	Adjustable Electric Heater	1 set	Power: 2000 W	–
4	Muffle Furnace	1 set	Rated temperature: 1000 ℃	–
5	Adjustable Hot Plate	1 set	Temperature range: Room temperature ~ 300 ℃	–
6	Micropipettes	1 each	Volume ranges: 100 μL ~ 1000 μL; 1000 μL ~ 5000 μL	–
7	Volumetric Flasks	Several	Volume: 100 mL	–
8	Colorimetric Tubes	Several	Volume: 25 mL	–

2.2 Reagents

2.2.1 Raw Reagents

Serial No.	Name	Technical Requirements	Remarks
1	Sulfuric Acid	Guaranteed Reagent (GR)	–
2	Nitric Acid	MOS Grade	–

2.2.2 Prepared Reagents

Serial No.	Name	Preparation Method	Remarks
1	Nitric Acid Solution (1+9)	Measure 10 mL of nitric acid, add it to 90 mL of water, and mix well.	–

2.3 Reference Standards

2.3.1 Stock Solution

Serial No.	No.	Name	Technical Requirements	Remarks
1	GBW08615	Copper Single-Element Standard Solution	Concentration: 1000 μg/mL	National Institute of Metrology, China

3. Operation Procedure

3.1 Sample Preparation

3.1.1 Preparation of Test Solution

Sample Pretreatment
Weigh 1.0 g of solid sample (accurate to 0.0001 g) into a quartz crucible, add 1 mL of sulfuric acid, heat gently on an adjustable electric heater for carbonization until no smoke is produced. Transfer the crucible to a muffle furnace and ash at 550 ℃ for 3–4 hours. Cool and take out the crucible. For samples with incomplete ashing, add a few drops of nitric acid, place the crucible on an adjustable hot plate, heat at 150 ℃, and carefully evaporate to dryness. Then transfer it back to the muffle furnace at 550 ℃ and continue ashing for 1–2 hours until the sample is completely ashed. Cool and take out the crucible, add 5 mL of nitric acid solution (1+9), place it on an adjustable hot plate, and heat at 150 ℃ to dissolve the sample. Cool the solution, transfer it to a 25 mL colorimetric tube with water, and dilute to the marked volume. Conduct a reagent blank test simultaneously.
Preparation of Sample Test Solution
Accurately pipette 5 mL of the original sample solution into a 25 mL colorimetric tube, add 0.25 mL of nitric acid, dilute to the marked volume with deionized water, and shake well. Conduct a blank test simultaneously—except for not adding the sample, the type and amount of reagents added to the blank test solution are the same as those of the test solution.

3.1.2 Preparation of Standard Solutions

Preparation of Copper Standard Series:
Pipette 0 μL, 25 μL, 50 μL, 100 μL, and 150 μL of copper standard solution (1000 μg/mL) respectively into 100 mL volumetric flasks. Add 1 mL of nitric acid, dilute to the marked volume with deionized water, and mix well. The concentrations of this standard series are: 0 μg/mL, 0.25 μg/mL, 0.50 μg/mL, 1.00 μg/mL, and 1.50 μg/mL.

3.2 Sample Testing

Testing Conditions
Reference Conditions for Flame Atomic Absorption Spectrophotometer Detection

Parameter	Specification
Wavelength	324.7 nm
Spectral Bandwidth	0.4 nm
Element Lamp Current	3.0 mA
Burner Height	6 mm
Fuel Gas Flow Rate	1600 mL/min
Air Compressor Pressure	0.22 MPa

Sample Testing
Introduce the copper standard series solutions into the flame atomizer in ascending order of concentration, and determine their absorbance values. Plot a standard curve with the mass concentration of copper in the standard series solutions as the abscissa and the corresponding absorbance values as the ordinate.

Under the same experimental conditions as those for determining the standard solutions, introduce the blank solution and the sample test solution into the flame atomizer respectively. After atomization, determine their absorbance values, and perform quantification by comparison with the standard series.