Analytical Suite Metadata

Chemex colorimetry (tungsten – d.l.=4ppm; 2.5ml of Kerosene, overnight heating)

Chemex, colorimetry (tungsten); potassium bisulphate fusion –detection limit=4ppm; 2.5ml of Kerosene, overnight heating

General Methodology:

Tungsten was determined as follows:  A 0.2 g sample of sediment was fused with 1g KHSO4 in a rimless test tube at 575oC for 15-20 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 then heated overnight 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 absorbance of the kerosene solution was measured at 630 nm using a spectrophotometer.

Instrument: unstated

Sample material: solid

Sample weight: unstated

Analytical Technique:

Hierarchical classification

Technique >> Photometry >> Colorimetry



Analytical Decomposition:

Hierarchical classification

Decomposition >> Fusion >> Acidic



Analytical Methods:

IndexMethod OrderMethod IDQuantityDetection Limit
1  2150     W_Col  4

Associated Analytical Packages:

IndexPackage IDPackage Name
1  370     Chemex (URP stream sediment) AAS (8+Mo), COL(W)
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