@md abdus sabur...i want colorimetric method...

i want some protocol, by which we can estimate Arsenic concentration in liquid sample by spectrophotometer.

Hello, try generate arsenic in a flask:  sample containing from 0 to 2.0 µg arsenic into a flask, containing 25 ml of 1:1 hydrochloric acid and 75 ml of water, 2 ml of a 15.00 % potassium iodide solution, for As (V)-As (III) reduction. Ice bath for 15 min,  add 6 mL of NaBH4 solution, by using a peristaltic pump and capillary tubes. Arsine generated from NaBH4 reduction will bubble into the absorption tube containing 2 ml of an absorbing reagent. After next 15 minutes, 2 ml of a developing solution was added. This solution was diluted to 10 ml in water, mixed, and centrifuged. After 5 minutes, the formed complex was read at 560 nm in UV-Vis spectrophotometer.  

@ Alica what is the concentration of NaBH4? which type of developer used in this case...either variamine blue or rhodamine?

Some variation or other of the Gtzeit test is always going to be the best bet.  In its classical form, arsine AsH3 is generated using activated zinc and hydrochloric acid reduction and the gas detected on paper impregnated with mercuric bromide.  Lead acetate or silver nitrate have been used as well for the detection.  LOD of 1 microgram is easily attainable.  Dithizone or kairine give coloured products with As(V) and As(III) respectively and may be adaptable to a spectrophotometric method.  The beauty of the Gutzeit approach though is that the arsenic is removed from the matrix as part of the test.  It is widely believed to be responsible for the massive reduction in the use of arsenic in spousal poisonings.

10.00 % (m/v) NaBH4  solution can prepare in a 2.00 % (m/v) NaOH solution, just before use. As a developer can be use 0.05% variamine blue (in ethanol), but I suppose  rhodamine will be fine, too.

You dont get good results with spectrometric analyses, you should try to get the analyses by atomic absorption or better with ICP

Thanks for good suggestions.

we tried several methods based in morels etc, But always we finish in atomic absortion or ICP. Is the only interference free method specially for biological samples

thanks David

You wont get good analyses for arsenic in biological materials, to get good results you have to use atomic absorption or ICP

After preparation of sample solution in biological materials, you can try a method published in :Anal. Methods, 2015, 7, 279

AAS-hydride generation and other methods are available in my attached file: methods-As.pdf.

If you don't have a ICP-MS you can try this colorimetric method by Silver Diethyldithiocarbamate.

I have used it in the past and it work quit well.

 thanks rathore sir and pier..