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
water.

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
calibration.

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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