Isotachophoretic determination of hydrosulfite and metabisulfite in technical samples
A method for determination of metabisulfite and hydrosulfite in poultice and decolorant by isotachophoresis was developed. Metabisulfite and hydrosulfite are ionizable oxoanions of sulfur of similar character that can easily be oxidized to sulfates. To protect the analytes from oxidation the solid s...
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Published in | Talanta (Oxford) Vol. 74; no. 2; pp. 183 - 189 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Amsterdam
Elsevier B.V
30.11.2007
Oxford Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | A method for determination of metabisulfite and hydrosulfite in poultice and decolorant by isotachophoresis was developed. Metabisulfite and hydrosulfite are ionizable oxoanions of sulfur of similar character that can easily be oxidized to sulfates. To protect the analytes from oxidation the solid samples were dissolved in a 1% (w/v) solution of formaldehyde. Hydrosulfite and metabisulfite present in the samples were transformed by the reaction with formaldehyde to stable compounds, hydroxymethanesulfinate and hydroxymethanesulfonate that were determined isotachophoretically without any pretreatment except for sample filtering and degassing. A capillary of 0.4
mm i.d. and 100
mm effective length made of fluorinated ethylene–propylene copolymer was filled with an electrolyte system consisting of 10
mmol
L
−1 HCl
+
11
mmol
L
−1 imidazole, 0.15% (w/v) hydroxyethylcellulose, pH 6.0 (leading electrolyte) and 5
mmol
L
−1 benzoic acid
+
6
mmol
L
−1 imidazole, pH 6.5 (terminating electrolyte). Separation was performed at a driving current of 80
μA and for detection current was decreased to 30
μA. Using contactless conductivity detection, the calibration curves in the tested concentration range up to 2.5
mmol
L
−1 were linear for both metabisulfite and hydrosulfite complexes. The concentration detection limits for metabisulfite and hydrosulfite were 2.9 and 3.4
μmol
L
−1, respectively. For 1
mmol
L
−1 concentration, values of R.S.D. (
n
=
6) were 2.6% for hydrosulfite and 0.8% for metabisulfite. Isotachophoretic determination took about 20
min. The elaborated isotachophoretic procedure is simple to perform, sufficiently sensitive and accurate. In addition to this, low cost of analyses makes the method an alternative procedure to methods used so far for the determination of oxoanions of sulfur. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0039-9140 1873-3573 |
DOI: | 10.1016/j.talanta.2007.05.045 |