Analytical Suite Metadata

Chemex (lake and stream sediment) COL(W)



Chemex, lake and stream sediment; colourimetry (tungsten)

General Methodology:

Tungsten was determined as follows:  A 0.2 g sample of sediment was fused with 1g K2S2O7 in a rimless test tube at 575oC for 15 minutes in a furnace.  The cooled melt was then leached with 10 ml concentrated HCl in a water bath heated to 85oC.  After the soluble material had completely dissolved, the insoluble material was allowed to settle and an aliquot of 5 ml was transferred to another test tube.  5 ml of 20% SnCl2 soution were then added to the sample aliquot, mixed and heated for 10 minutes at 85oC in a hot water bath.  A 1 ml aliquot of dithiol solution (1% dithiol in iso-amyl acetate) was added to the test solution and the test solution was heated for 4 - 6 hours at 80 - 85oC in a hot water bath.  The test solution was then removed from the hot water bath, cooled and 2.5 ml of kerosene added to dissolve the globule containing the tungsten-dithiol complex.  The colour intensity of the kerosene solution was measured at 630 nm using a spectrophotometer.  The method is described by Quin and Brooks (1972).

Reference:

Quin, B.F. and Brooks, R.R. (1972).  The rapid determination of tungsten in soils, stream sediments, rocks and vegetation.  Analytica Chimica Acta v58 p301-309.

Instrument: unstated

Sample material: solid

Sample weight: unstated


Analytical Technique:

Hierarchical classification

Technique >> Photometry >> Colorimetry

Children

Dithizone


Analytical Decomposition:

Hierarchical classification

Decomposition >> Fusion >> Acidic

Children

K2S2O7


Analytical Methods:

IndexMethod OrderMethod IDQuantityDetection Limit
1  1018     W_Col  2

Associated Analytical Packages:

IndexPackage IDPackage Name
1  416     Chemex (NGR lake sediment) AAS (8+5), CVAAS (Hg), COL(W), LOI, NADNC (U-5**10)
2  417     Chemex (NGR stream sediment)  AAS (8+5), CVAAS (Hg), COL(W), LOI, NADNC (U-5**10)
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