Rainwater contains trace amount of heavy metals in case of unpolluted region unless and until there are other factors like long range transport and presence of point source. Therefore, I would like to know if any method exists by which we can extract the heavy metals in rainwater.
You may collect your samples and analyze them using ICP or AAS.
Thank you sir Aiman..but problem is if we directly analyze rainwater using ICP-OES then very few heavy metals were detected and most of those showed concentration below detection limit.
Hi,
As pranamika said, direct analysis of metal in rain water is kind difficult. for carrying smooth analysis of the metal in rain water needs the pre-concentration of the the rain water sample.
1000ml water sample compressed (evaporated) up to 25ml under acidic condition at 100centigrade temp.
ICP and AAS are the instrumental methods of analysis. before going that we need to prepare the sample includes pre-concentratio for liquid samples and digestion for solid samples.
Yes Bhagawan Dheeravath is right, concentrate the samples by evaporation.
If anybody is interested in direct analysis of rain water without any chemical treatment or pre-concentration total reflection X-ray fluorescence (TXRF) spectrometry is the great technique. As TXRF have detection limit in ng/g or ppb range one can use this technique for rain water analysis.
Just for your information here is two references:
1. ANALYTICAL CHEMISTRY, VOL. 57, NO. 14, DECEMBER 1985
2. Pramana; February 2011, Volume 76, Issue 2, pp 361-366 OR DOI:10.1007/s12043-011-0035-1
In our lab have this instrument and I am working on this so for any other information you can write me
Thank you very much for your suggestion Veer sir....I will be grateful if I get support from you..
Dear Pranamika,
the best choice would be to use an ICP-MS, as these technique has better detection limits than ICP-OES or AAS.
Yes, AAS and ICP will be a good choice for multiple heavy metal element analysis and you have lots of samples to run. If you have predetermined selected heavy metals to analyse, there are water quality analysis commercial kits available in the market as well.
Chances to have heavy metal element in rain water is very less untill unless the rain water come in contact with earth surface and interacted to soil and minerals and others. However Atomic Absorption Spectrometer and Inductivily Coupled Plasma mass spectrometer is knownand appropriate techniques for analysis of metal trace elements
Most require the use of expensive instrumentation as said above, however, as also mentioned by Mr. Noik, Hach makes some pretty good kits depening on how low you need to detect to.
Kits are useful for preliminary test before jumping into instrumentation to minimize and/or avoid cost overrun, but this depend on what the lab have. :) Agree, with Mr. Finke, Hach has a pretty good kits. I'm using them for my routine WQ test and monitoring.
I do not know if Dr. Pranamika Bhuyan is lucky enough to be able to afford expensive tools such as TXRF. I have only a graphite furnace AAS with Zeeman effect for background correction, so my preparation technique is aimed at this type of instrument. As we all know rainwater, if not originate from highly polluted atmosphere, contain very low concentrations of trace elements. As regards the analysis with AAS is therefore required a sample concentration of at least 50 to 1. This is possible because there are no significant quantities of organic substances that could interfere in the measurement phase. You can weigh exactly 100 ml. of sample in a Teflon container spotlessly clean (the glass is not recommended because it can yield Pb). The best system of evaporation is to freeze the samples and then subjecting them to lyophilization until completely dry but in the absence of this technique it is possible to dry the sample in a thermostatic oven without exceeding 70 ° C. As a last step, after cooling of the container, add exactly 2 ml. of pure 1% HNO3, cover to prevent further evaporation and leave a few minutes with gentle shaking to ensure that the solution is in contact with the walls of the container. You can then proceed to the measurement with AAS.
I apologize for my bad English :)
Thank you very much Sergio sir for your suggestion. Actually I was searching for such type of technique only. I will try to follow the procedure for my samples.
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