I determined the concentration of hexavalent chromium with spectrophotometer uv - vis with diphenylcarbazide, after the extraction with base solution from metal plating. for calculating the amount of cr6+ in the plating, which weight do i have to use? The weight of the sample that I extracted or just weight of the plating?
according to ROHS, the maximum amount of cr6+ is 0.1% or 1000 ppm. which weight to calculate the amount of cr6+ in metal plating to compare the data with the the maximum permitted concentrations from ROHS?
I used this equation to calculate:
ppm = (cons of sample from calibration curve x volume of Volumetric flask x dilution factor)/weight
is that right?
Not if you understand, but, the concentration corresponding to the sample obtained. Report the amount of chromium in the sample, possibly because the plate does not contain chromium. Example: the amount of mercury in the paint of toys, does not take into account the whole toy you consider is paint covering the toy.
To calculate the percent of chromium, based on the number of samples used / dissolved/extracted. In order for accurate results, samples should be taken a few parts, and the results obtained were calculated statistically.
Make a calibration plot with standard, then put the absorbance (concentration) of unknown and you will find the concentration.
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