Heavy Metal Analysis Technology - AAS & ICP-MS

I believe that most people know about the sinister side of heavy metals. Here are a few examples:

• Mercury poisoning - the emergence of Minamata disease in Japan
• Lead poisoning - a decades old problem 
• Cadmium poisoning - the Itai-itai disease in Japan
• Arsenic poisoning - the once-popular homicide 
• Silver poisoning - the Argyria disease

Compared to Emerging Contaminants (ECs), heavy metal in water is not a new issue. Water filtration system today can easily remove heavy metal from the water. However, heavy metal contamination happens easily due to all kinds of industrial activities going on that discharge wastes loaded with heavy metals. Therefore, the monitoring of water quality in terms of heavy metal contamination should be done from time to time.

The laboratory which is specific for Atomic Absorption Spectrometry (AAS).

Water purification system [Brand: Millipore, Model: Milli-Q Advantage A10]

Unlike distilled water which might still contain some impurities, this water purification system produces ultra pure water which contains no impurity at all. Ultra pure water is used to dilute the standard stock solution to match the concentration of the heavy metal in water sample for analysis using AAS.

Atomic Absorption Spectrometer [Brand: Shimadzu, Model: AA-6800] (top) & 

[Brand: Perkin Elmer, Model: Atomic Absorption Spectrometer 3300] (bottom)

AAS is used to detect concentration of one heavy metal element at a time, at high concentration in the water sample due to its low sensitivity. For each specific heavy metal that we want to analyse, the standard stock solution and also the lamp used for the spectrometer will be different, so before carrying out each analysis, we need to make sure that we use the correct standard stock solution and lamp.

The laboratory which is specific for Inductively Coupled Plasma - Mass Spectrometry (ICP-MS).

ICP-Mass Spectrometer [Brand: Perkin Elmer, Model: ELAN DRC-e] &
Autosampler [Brand: Cetax, Model: ASX-520] (bottom left)

ICP-MS is used to detect a wide range of heavy metal present in water sample in low concentration due to its high sensitivity. Only one multi-element standard is needed for a few types of heavy metals. For both ASS and ICP-MS, the procedure is more or less the same. There should be at least 3 diluted standard stock solutions with different concentrations (the more the better), based on the estimated concentration of the heavy metals in the water sample. The diluted standard stock solutions and water sample placed in respective centrifuge tubes will be placed at the specific sites of the spectrometer. Then a calibration process will be carried out using the spectrometer to obtain a calibration graph. We have to make sure that the deviation of the graph is r = 1, which means it is a perfect straight line to ensure the accuracy of the results. After getting the straight line, the analysis of the concentration of the heavy metal can be carried out.

The Ultra Clean Laboratory which will be in use next semester! What's so special about it? You need to wear a jumpsuit and clean yourself up before entering, that explains the 'ultra clean', hahaha... 

P/S: These heavy metal analyses involve high technology instruments which are quite expensive. Too bad we still don't have the chance to actually use them.