Elemental sulfur analysis

Lesley Robertson l.a.robertson at stm.tudelft.nl.removethis
Mon Oct 26 13:05:42 EST 1998

Charles McComas wrote:

> I'm doing research on a sulfide oxidizing bacterial enrichment culture. I
> need a reliable, specific assay to quantitate elemental sulfur. I have tried
> a method that converts to thiocyanate which complexes with iron, but this
> gave readings that seemed implausible. Any suggestions will be appreciated.

  I don't know if this is the method you mean, but we've had pretty reliable
results with it:

Two solutions:
A: 125 mM KCN
B: 12.5 g Fe(NO3)3 dissolved in 20 ml 65% HNO3, then topped up to 100 ml with

Dilute sample to an estimated So concentration below 20 mM. Centrufuge as 13000
rpm for 5 mins. Remove supt. Add 1 ml acetone, extract overnight at room temp.
Dilute with acetone to give an estimated So concentration between 10-200 uM. Add
to 1 ml aliquot 100 ul solution A and 100 ul solution B. Read at 460 nm.
Standard solutions of KSCN (in water) or So (in acetone) are used for the

This is an adaption of the Bartlet & Skoog (1954) method that has been a
standard technique in Delft for about 10 years.
Lesley Robertson
(beware of spam filter on reply address: l.a.robertson at stm.tudelft.nl)

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