Simplified Seawater Alkalinity Analysis: Use of Linear Array Spectrometers

Wensheng Yao; Robert H Byrne

doi:10.1016/S0967-0637(98)00018-1

Simplified Seawater Alkalinity Analysis: Use of Linear Array Spectrometers

Wensheng Yao, Robert H Byrne

College of Marine Science

Research output: Contribution to journal › Article › peer-review

Abstract

Modified spectrophotometric procedures are presented for the determination of seawater total alkalinity using rapid scan linear array spectrometers. Continuous monitoring of solution pH allows titrations to be terminated at relatively high pH, whereby excess acid terms are very small. Excess acid concentrations are quantified using the sulfonephthalein indicators, bromocresol green and bromocresol purple. The outlined spectrophotometric procedures require no thermal equilibration of samples. Using bromocresol green, solution pH T ([H + ] T in moles per kg of solution) is given as:pHT=4.2699+0.002578(35−S)+log((R(25)−0.00131)/(2.3148−0.1299R(25)))">pHT=4.2699+0.002578(35−S)+log((R(25)−0.00131)/(2.3148−0.1299R(25))) −log(1−0.001005S)">−log(1−0.001005S) and R (25)= R ( t ){1+0.00909(25− t )}, where 29&les;S&les;37,13°C&les;t&les;32°C">29&les;S&les;37,13°C&les;t&les;32°C , and R ( t ) is the absorbance ratio ( A 616 / A 444 ) at temperature t and salinity S. Using bromocresol purple, the solution pH T is given as pH T =5.8182+0.00129(35− S )+log(( R (25)−0.00381)/(2.8729−0.05104 R (25))) and R (25)= R ( t ){1+0.01869(25− t )}, where 29&les;S&les;37,13°C&les;t&les;32°C">29&les;S&les;37,13°C&les;t&les;32°C , and R ( t )= A 589 / A 432 . Alkalinity measurements using bromocresol purple had a precision on the order of 0.3 μmol kg -1 and were within 0.3–0.9 μmol kg -1 of the alkalinities of certified seawater reference materials.

Original language	American English
Journal	Deep Sea Research Part I: Oceanographic Research Papers
Volume	45
DOIs	https://doi.org/10.1016/S0967-0637(98)00018-1
State	Published - Jan 1 1998

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@article{64f28fd7c92a49c4b5f29bafa292cb22,

title = "Simplified Seawater Alkalinity Analysis: Use of Linear Array Spectrometers",

abstract = " Modified spectrophotometric procedures are presented for the determination of seawater total alkalinity using rapid scan linear array spectrometers. Continuous monitoring of solution pH allows titrations to be terminated at relatively high pH, whereby excess acid terms are very small. Excess acid concentrations are quantified using the sulfonephthalein indicators, bromocresol green and bromocresol purple. The outlined spectrophotometric procedures require no thermal equilibration of samples. Using bromocresol green, solution pH T ([H + ] T in moles per kg of solution) is given as:pHT=4.2699+0.002578(35−S)+log((R(25)−0.00131)/(2.3148−0.1299R(25))){"}>pHT=4.2699+0.002578(35−S)+log((R(25)−0.00131)/(2.3148−0.1299R(25))) −log(1−0.001005S){"}>−log(1−0.001005S) and R (25)= R ( t ){1+0.00909(25− t )}, where 29&les;S&les;37,13°C&les;t&les;32°C{"}>29&les;S&les;37,13°C&les;t&les;32°C , and R ( t ) is the absorbance ratio ( A 616 / A 444 ) at temperature t and salinity S. Using bromocresol purple, the solution pH T is given as pH T =5.8182+0.00129(35− S )+log(( R (25)−0.00381)/(2.8729−0.05104 R (25))) and R (25)= R ( t ){1+0.01869(25− t )}, where 29&les;S&les;37,13°C&les;t&les;32°C{"}>29&les;S&les;37,13°C&les;t&les;32°C , and R ( t )= A 589 / A 432 . Alkalinity measurements using bromocresol purple had a precision on the order of 0.3 μmol kg -1 and were within 0.3–0.9 μmol kg -1 of the alkalinities of certified seawater reference materials.",

author = "Wensheng Yao and Byrne, {Robert H}",

year = "1998",

month = jan,

day = "1",

doi = "10.1016/S0967-0637(98)00018-1",

language = "American English",

volume = "45",

journal = "Deep Sea Research Part I: Oceanographic Research Papers",

}

TY - JOUR

T1 - Simplified Seawater Alkalinity Analysis: Use of Linear Array Spectrometers

AU - Yao, Wensheng

AU - Byrne, Robert H

PY - 1998/1/1

Y1 - 1998/1/1

N2 - Modified spectrophotometric procedures are presented for the determination of seawater total alkalinity using rapid scan linear array spectrometers. Continuous monitoring of solution pH allows titrations to be terminated at relatively high pH, whereby excess acid terms are very small. Excess acid concentrations are quantified using the sulfonephthalein indicators, bromocresol green and bromocresol purple. The outlined spectrophotometric procedures require no thermal equilibration of samples. Using bromocresol green, solution pH T ([H + ] T in moles per kg of solution) is given as:pHT=4.2699+0.002578(35−S)+log((R(25)−0.00131)/(2.3148−0.1299R(25)))">pHT=4.2699+0.002578(35−S)+log((R(25)−0.00131)/(2.3148−0.1299R(25))) −log(1−0.001005S)">−log(1−0.001005S) and R (25)= R ( t ){1+0.00909(25− t )}, where 29&les;S&les;37,13°C&les;t&les;32°C">29&les;S&les;37,13°C&les;t&les;32°C , and R ( t ) is the absorbance ratio ( A 616 / A 444 ) at temperature t and salinity S. Using bromocresol purple, the solution pH T is given as pH T =5.8182+0.00129(35− S )+log(( R (25)−0.00381)/(2.8729−0.05104 R (25))) and R (25)= R ( t ){1+0.01869(25− t )}, where 29&les;S&les;37,13°C&les;t&les;32°C">29&les;S&les;37,13°C&les;t&les;32°C , and R ( t )= A 589 / A 432 . Alkalinity measurements using bromocresol purple had a precision on the order of 0.3 μmol kg -1 and were within 0.3–0.9 μmol kg -1 of the alkalinities of certified seawater reference materials.

AB - Modified spectrophotometric procedures are presented for the determination of seawater total alkalinity using rapid scan linear array spectrometers. Continuous monitoring of solution pH allows titrations to be terminated at relatively high pH, whereby excess acid terms are very small. Excess acid concentrations are quantified using the sulfonephthalein indicators, bromocresol green and bromocresol purple. The outlined spectrophotometric procedures require no thermal equilibration of samples. Using bromocresol green, solution pH T ([H + ] T in moles per kg of solution) is given as:pHT=4.2699+0.002578(35−S)+log((R(25)−0.00131)/(2.3148−0.1299R(25)))">pHT=4.2699+0.002578(35−S)+log((R(25)−0.00131)/(2.3148−0.1299R(25))) −log(1−0.001005S)">−log(1−0.001005S) and R (25)= R ( t ){1+0.00909(25− t )}, where 29&les;S&les;37,13°C&les;t&les;32°C">29&les;S&les;37,13°C&les;t&les;32°C , and R ( t ) is the absorbance ratio ( A 616 / A 444 ) at temperature t and salinity S. Using bromocresol purple, the solution pH T is given as pH T =5.8182+0.00129(35− S )+log(( R (25)−0.00381)/(2.8729−0.05104 R (25))) and R (25)= R ( t ){1+0.01869(25− t )}, where 29&les;S&les;37,13°C&les;t&les;32°C">29&les;S&les;37,13°C&les;t&les;32°C , and R ( t )= A 589 / A 432 . Alkalinity measurements using bromocresol purple had a precision on the order of 0.3 μmol kg -1 and were within 0.3–0.9 μmol kg -1 of the alkalinities of certified seawater reference materials.

UR - https://digitalcommons.usf.edu/msc_facpub/1619

UR - https://doi.org/10.1016/S0967-0637(98)00018-1

U2 - 10.1016/S0967-0637(98)00018-1

DO - 10.1016/S0967-0637(98)00018-1

M3 - Article

VL - 45

JO - Deep Sea Research Part I: Oceanographic Research Papers

JF - Deep Sea Research Part I: Oceanographic Research Papers

ER -

Simplified Seawater Alkalinity Analysis: Use of Linear Array Spectrometers

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