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Determination of Copper in Graphite Powder – Flame Atomic Absorption Spectrometry

สิงหาคม 1, 2025

1 Method Overview

After the sample is digested with aqua regia, the determination is carried out using an air-acetylene flame at a wavelength of 324.7 nm with the instrument.

2 Instruments and Reagents

2.1 Instruments and Equipment

2.1.1 Detection Instruments

Serial Number	ชื่อ	ปริมาณ	Technical Requirements	เครื่องประดับ
1	Flame Atomic Absorption Spectrophotometer	1 set		Copper hollow cathode lamp
2	Acetylene	1 cylinder	Purity ≥ 99.99%
3	Air Compressor	1 set	Rated exhaust pressure: 0.3 MPa

2.1.2 Pretreatment Equipment

Serial Number	ชื่อ	ปริมาณ	Technical Requirements
1	Temperature-controlled Hot Plate	1 set	Rated temperature: room temperature ~ 300℃
2	Electronic Balance	1 set	Sensitivity 0.1 mg
3	Ultrapure Water Device	1 set
4	Micropipette	1 each	20μL ~ 200μL; 100μL ~ 1000μL
5	Volumetric Flask	Several	100 mL
6	Test Tube	Several	25 mL

2.2 Reagents

2.2.1 Reagents

Serial Number	ชื่อ	Technical Requirements	ข้อสังเกต
1	Nitric Acid	MOS grade
2	Hydrochloric Acid	Guaranteed reagent

2.2.2 Prepared Reagents

Serial Number	ชื่อ	Preparation Method	ข้อสังเกต
1	(1+99) Nitric Acid Solution	Measure 10 mL of nitric acid, slowly add to 990 mL of deionized water, and mix well

2.3 Standards

2.3.1 Stock Solutions

Serial Number	ตัวเลข	ชื่อ	Technical Requirements	ข้อสังเกต
1	GBW08615	Copper Single Element Solution Standard Substance	1000μg/mL	National Institute of Metrology, China

3 Operation Process

3.1 Sample Processing

3.1.1 Preparation of Test Solution

Weigh 0.25 g of the sample, accurate to 0.00001 g, into a digestion tank. Add 3 mL of concentrated nitric acid and 9 mL of concentrated hydrochloric acid, cover and tighten the digestion tank, and put it into a microwave digestion instrument for digestion. Prepare a blank in the same way. After cooling, filter and dilute to volume in a 25 mL volumetric flask, and put it on the machine for testing.

Microwave Heating Program

Step	Temperature/℃	Holding Time/min
1	100	3
2	120	3
3	140	3
4	160	3
5	180	30

3.1.2 Preparation of Standard Solution

Preparation of copper standard series: Accurately pipette 0.0, 0.025, 0.05, 0.1, and 0.2 mL of copper standard solution (1000μg/mL) into 100 mL volumetric flasks respectively, dilute to the mark with (1+99) nitric acid, and mix well. The mass concentrations of this standard series solution are 0.0, 0.25, 0.5, 1.0, and 2.0 μg/mL respectively.

3.2 Sample Testing

Test Conditions Reference Conditions for Flame Atomic Absorption Spectrophotometer Detection

Element	Copper
Wavelength (nm)	324.7
Spectral Bandwidth (nm)	0.4
Element Lamp Current (mA)	3.0
Fuel Gas Height (mm)	6
Fuel Gas Flow Rate (mL/min)	1400
Air Compressor Pressure (MPa)	0.22
Background Correction Method	None

Sample Testing Adjust the instrument to the best working state, ignite the flame, adjust the fuel gas flow rate, test the standard and sample solutions in sequence, read the data, input the sample weight, and check and record the results.