I need a chemical method with less chemical use for determination of Arsenic in drinking water. The work is focused on developing low cost and field portable sensor for detection of Arsenic in drinking water resources, which may be used by the people from rural areas.
Dear Iftak,
The following two links contain colorometric methods for arsenic determination in drinking water.
The method below is the popular one use to determine arsenic by colorometric method:
Colorimetric/spectrometric methods
These methods take advantage of the formation of volatile arsine (AsH3) gas to separate arsenic from other possible interference with the sample matrix. The colorimetric methods are easy to use and inexpensive in terms of equipment and operator cost. They are useful for the semi-quantitative determination of high concentrations of arsenic in water. The silver diethylthiocarbamate (AgDDTC) method is the most popular spectrophotometric method for the determination of arsenic in water. The method is based on the generation of arsine either with zinc and hydrochloric acid or sodium borohydride in acidic solutions. The arsine gas is then flushed through a solution of diethylthiocarbamate in pyridine or pyridine/chloroform. The red-coloured complex can be measured at 520
nm. Using a modification of this method, Dhar et al. (1997) reported a detection limit of 40 µg/L for arsenic in water samples, with a 95% confidence. Pillai et al. (2000) reported a new simple and reliable spectrophotometric method to determine total arsenic in environmental and biological samples. It involves bleaching the
pinkish-red dye Rhodamine-B (measured at 553 nm) by the action of iodine released from the reaction between potassium iodate and arsenic in a slightly acidic medium. The classic Gutzeit test (Vogel, 1954) is derived from the historical Marsh test. It is based on the generation of arsine (AsH3) from arsenic compounds by the addition of zinc granules to concentrated sulfuric acid. The arsine can be detected by its reaction on a strip of filter moistened with silver nitrate or mercuric chloride, which produces a grey or a yellow to reddish-brown spot, respectively
https://monographs.iarc.fr/ENG/Monographs/vol84/mono84-6.pdf
http://www.ncbi.nlm.nih.gov/books/NBK230885/
Hoping this will be helpful,
Rafik
Arsenic ingeneral present in very low concentration in water, mostly in ppb level. However, calibration and standardisation may be difficult by colorimetric process. Furthermore, Results may not be so accurate as well as time consuming and expensive also. Present time AAS and ICP-MS facilities are widely available on payment basis and that can be cast effective and give better result.
Sir, Besides AAS and ICP-MS is there any other reliable method which can be used for in-field detection and analysis. There are many Arsenic affected regions in Assam and presence of As in drinking water in these regions causes a serious health issues again before implementing any removal facility, detection of As concentration becomes challenging due to unavailability of such laboratory facility in these remote locations.
Hi Iftak, While doing research on arsenic in well and stream water in Chile & Argentina I used the Hach system. The arsenic problem is as bad in South & Central America as Assam, and Bangladesh.
http://www.hach.com/arsenic-low-range-test-kit/product%3Fid=7640217303
The best results were managed by using a temperature controlled box. 18 degrees C was the optimal for carrying the samples from the point of extraction to the test center. As a lot of this was in the Atacama then in Patagonia, I only managed three test site extractions per day. And got a good repeat accuracy as I learned about the test equipment. I would not recommend this to untrained persons as the results can be changed with temperature changes over time from extraction to test.
I understand that Cambridge are working on a new test kit that will be more accurate. But it's still in the planning stage.
Hi all
In your opinion what safety measurements are needed if students work with environmental water with arsenic levels
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