Determination of selenium in sea water using electron capture detection-gas chromatography.
Determination of selenium in sea water using electron capture detection-gas chromatography.
A method has been developed for the determination of selenium IV and total selenium in natural waters. It involves the formation of the derivative of seleriiuic 1V with 4-nit:-o-c-phersylenediamine at pH i, extraction into toluene and dLteraination by gas-liquid chromatography, with electron capt- e detectio_ u-_.,3 a column of intermediate polarity. The method is capable of detecting 0.6 pg of selenium corresponding to2 ng Se/1 when s -i00 ml za pla is use. The coefficient of variation is better than 5p, at ten times the limit of detection. Recovery of selenium added to natural waters is essentially identical with that of stnnrlnrds taken trough the same procedure. The procedure was found to be free of interference from other trace elements at concentrations of ten times their nor:-_l range _n sea water in the absence or presence of hUlA. Photo-oxidation o samples buffered with sodium tetraborate was found to convert. all fractions of selenium in the original sample to a mixture of oxidation states, IV and VI. The partition between these was found to be very reproducible, regardless of the salinity of the sample, giving 71, ! 3% of the element as selenium IV. Total selenium was determined on this basis.A total o 135 shipboard determinations of selenium IV and total selenium were made in water samples collected mainly in the sub-tropical North East Atlantic. Seleniun IV showed distinct vertical variability with levels near or below the limit of detection in surface waters rising sharply at the pycnodine to . 20 n,-/l, and increasing further in deeper waters to 35 - 40 ng/l. The distribution correlated well with those of dissolved silicon and phosphate, indicating a probable dominant control by biological processes. Values for tote selenium were not determined by the optimal procedure. They showed parallel trends, but with significant concentrations in --u- -face waters. The difference between the measured fractions is taken to reflect mainly the existence of selenium VI in ocean waters. Chalk rivers draining into Southampton Voter had relatively high concentrations (250 - 390 ng/i) of total selenium, and selenium IV concentrations of 18 - 31 ng/i. During mixing in Southampton Water both species behaved essentially conservatively. Such marked concentration gradients were not found in the Beaulieu Estuary.
University of Southampton
Measures, Christopher Ian
1977
Measures, Christopher Ian
Measures, Christopher Ian
(1977)
Determination of selenium in sea water using electron capture detection-gas chromatography.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A method has been developed for the determination of selenium IV and total selenium in natural waters. It involves the formation of the derivative of seleriiuic 1V with 4-nit:-o-c-phersylenediamine at pH i, extraction into toluene and dLteraination by gas-liquid chromatography, with electron capt- e detectio_ u-_.,3 a column of intermediate polarity. The method is capable of detecting 0.6 pg of selenium corresponding to2 ng Se/1 when s -i00 ml za pla is use. The coefficient of variation is better than 5p, at ten times the limit of detection. Recovery of selenium added to natural waters is essentially identical with that of stnnrlnrds taken trough the same procedure. The procedure was found to be free of interference from other trace elements at concentrations of ten times their nor:-_l range _n sea water in the absence or presence of hUlA. Photo-oxidation o samples buffered with sodium tetraborate was found to convert. all fractions of selenium in the original sample to a mixture of oxidation states, IV and VI. The partition between these was found to be very reproducible, regardless of the salinity of the sample, giving 71, ! 3% of the element as selenium IV. Total selenium was determined on this basis.A total o 135 shipboard determinations of selenium IV and total selenium were made in water samples collected mainly in the sub-tropical North East Atlantic. Seleniun IV showed distinct vertical variability with levels near or below the limit of detection in surface waters rising sharply at the pycnodine to . 20 n,-/l, and increasing further in deeper waters to 35 - 40 ng/l. The distribution correlated well with those of dissolved silicon and phosphate, indicating a probable dominant control by biological processes. Values for tote selenium were not determined by the optimal procedure. They showed parallel trends, but with significant concentrations in --u- -face waters. The difference between the measured fractions is taken to reflect mainly the existence of selenium VI in ocean waters. Chalk rivers draining into Southampton Voter had relatively high concentrations (250 - 390 ng/i) of total selenium, and selenium IV concentrations of 18 - 31 ng/i. During mixing in Southampton Water both species behaved essentially conservatively. Such marked concentration gradients were not found in the Beaulieu Estuary.
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Published date: 1977
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Local EPrints ID: 458668
URI: http://eprints.soton.ac.uk/id/eprint/458668
PURE UUID: de0ebedb-6ca0-488f-a35e-0fee4cdd845b
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Date deposited: 04 Jul 2022 16:53
Last modified: 04 Jul 2022 16:53
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Author:
Christopher Ian Measures
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