This experiment is from the official website of College of Chemistry, Qingdao University of Science and Technology.
Operation method
Determination of copper in materials by flame atomic absorption spectrometry experiment
Principle
Copper is atomic absorption analysis often and the easiest to determine the element, in a slightly poorer air - acetylene flame is very little interference in the determination of the copper standard series of solutions as the horizontal coordinate; to the corresponding absorbance as the vertical coordinate, drawing a working curve for a straight line through the origin, according to the absorbance of the specimen solution measured under the same conditions in the working curve, you can find out the concentration of copper in the test solution; and then can be calculated in the original sample of copper content. According to the absorbance of the sample solution measured under the same conditions, the concentration of copper in the test solution can be found on the working curve; and then the copper content in the original sample can be calculated. In atomic absorption, in order to reduce the difference between the test solution and the standard and the error caused by; or in order to eliminate some chemical and ionization interference can be used to join the standard method. For example, the atomic absorption method for the determination of trace copper in nickel-plated solution, due to the high concentration of salt in the solution, if the standard curve method, due to the difference between the test solution and the standard solution, will make the results low, this is due to the spray of high concentration of salt, the atomization efficiency is low, and thus the absorption value is reduced. To eliminate this effect, the standard addition method can be used. Pipette 10mL of plating solution in four 50mL volumetric flasks, respectively, in 0, 1, 2, 3 volumetric flasks were added to 0, 1, 2, 3 μl / mL of Cu2 + diluted to the scale with distilled water. The absorbance of the same element is measured under the same conditions, plotted, and the copper content in the test solution is found from the graph. This method is also called "direct extrapolation". The concentration of the element to be measured in the test solution can also be calculated. Set the concentration of the element to be tested in the sample for Cx, measured its absorbance for Ax, the sample solution added to the standard solution concentration Co, the total concentration of the element to be tested in this solution Cx + Co; measured its absorbance for Ao, according to Beer's law Ax = KCxAo = K (Co + Cx) will be compared to the above two standard addition can also be used for
Materials and Instruments
Hydrochloric Acid (Superior Purity) Nitric Acid (Superior Purity) Copper Standard Solution (1000ppm) Sample Master Element Solution Move 1. Sample handling Caveat The value of the absorbance of the standard series on one side is the vertical coordinate, and the concentration is the horizontal coordinate to draw the working curve. According to the absorbance of the test solution on the working curve to find the copper content of the test solution Cx, and then according to the following formula to find out the percentage of copper in the metal material CU% = (Cx × 100 × f) / (w × 10 ^ 6) where f is the number of times of dilution For more product details, please visit Aladdin Scientific website.
TAS-990 Atomic Absorption Spectrophotometer Air compressor Copper hollow cathode lamp Pipette Volumetric flasks
Accurately weigh 0.5~1g of sample, add 10ml (1+1)HCl or 10ml (1+1)HNO3, heat to dissolve, and then set in 100ml volumetric flask, and process the blank at the same time.
2. Standard series preparation
Prepare 100μg/ml transition solution first, take 1 2 3 4ml of transition solution in volumetric flask, add the corresponding amount of the main element of the metal material and each volumetric flask, and add the acid corresponding to the samples to be fixed to the scale.
3. Measurement
(1) Turn on the instrument according to the steps of instrument software, burn the lamp for 15-30 minutes, turn on the air compressor, pressure P=2.5 kg/cm2, turn on the acetylene P=0.5 kg/cm2, turn on the acetylene P=0.5 kg/cm2, turn on the air compressor.
P=0.5 kg/cm2
(2) Ignition After ignition, spray deionized water and burn for 5 minutes until the signal is stable. After finishing, enter the blank 1,2,3,4 standard series in order to make curve and wait for the absorbance signal to drop down and then enter the sample for testing. If over the line can be diluted 4 measurement is completed, spray deionized water for 5 minutes and then turn off the acetylene, air compressor and software programs and the host computer.