Nickel release test principles
Put tested metal eyewear sample into in artificial sweat for 7 days, using the atomic absorption or inductively coupled plasma spectroscopy dissolved concentrations of nickel. Nickel emissions are represented by μg/ｃ㎡/week.
Test reagents
All reagents for analytical purity or higher level and contains without nickel. Demonized water, sodium chloride, DL-lactic acid, urea, ammonia, nitric acid, degreasing solution.
Pretreatment equipment
PH meter, thermostatic water bath.
Metal eyewear sample pretreatment
Preparation of test solution
Artificial sweat test solution consists of demonized water and contain: 0.5% sodium chloride, lactic acid, 0.1% urea, ammonia 1%.Before use, ensure that the pH of the solution within the 6.40~6.60.The test solution should be used within 3 hours of preparation.
Release procedures
The metal eyewear sample is put in brackets and suspended in test container. Adding a certain amount of approximately 1mL/c test solution to test square meters area.
Suspension metal eyewear sample shall be completely immersed in the test solution. Note the sample size and the volume of the test solution. Test liquid tightly closed containers to prevent evaporation. Smoothly and keep the container in a constant temperature water bath (30 ± 2) ℃, 168H, don’t stir.
After 7 days, take out of metal eyewear samples from test liquid,clean with a small amount of demonized water, will join the test with a clean solution. transfer to a volumetric flask of appropriate volume of test solution. In order to prevent the dissolution of nickel deposits added to the test solution dilute nitric acid and deionized water, its sizing to the nitric acid contains about 1% after the score.
At least do 2 set of the same metal eyewear samples.
Blank test
Repeat the blank test should be carried out in parallel with the test samples. Use the same container and bracket, the same program, Captain no sample in the container. Using the same amount of test liquid, washing liquid and dilute nitric acid.
Sample test
Instrument
Atomic absorption spectrometers.
Method
Place the flask in an atomic absorption spectrometer, atomic absorption spectrometers the wavelength adjustable to 232.0nm, spectral bandwidth: 0.2nm, record the nickel concentration in the solution.
Count
Metal eyewear sample nickel release rate d, represent as (μg/ｃ㎡/week), according to the following formula:
d = V(C1-C2)/1000A
V – the volume of the test solution, mL
C1 – 7 days after the nickel content of the test solution, μ g/l
C2 – 7 days after the nickel content of the blank test solution, μ g/l
A – sample surface area c㎡.
Calculation result to two decimal places.
Calculate d multiplied by 0.1-adjusted rate of nickel release test results. If test result more than 0.5μg/ｃ㎡/week, can verify that the nickel release rate exceed of standard.