Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements
Ocean acidification, a phenomenon of seawater pH decrease due to increasing atmospheric CO2, has a global effect on seawater chemistry, marine biology, and ecosystems. Ocean acidification is a gradual and global long-term process, the study of which demands high-quality pH data. The spectrophotometr...
Published in: | Marine Chemistry |
---|---|
Main Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
2020
|
Subjects: | |
Online Access: | https://ueaeprints.uea.ac.uk/id/eprint/77116/ https://doi.org/10.1016/j.marchem.2020.103849 |
id |
ftuniveastangl:oai:ueaeprints.uea.ac.uk:77116 |
---|---|
record_format |
openpolar |
spelling |
ftuniveastangl:oai:ueaeprints.uea.ac.uk:77116 2023-05-15T17:51:00+02:00 Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements Li, Xinyu García-Ibáñez, Maribel I. Carter, Brendan R. Chen, Baoshan Li, Qian Easley, Regina A. Cai, Wei Jun 2020-09-10 https://ueaeprints.uea.ac.uk/id/eprint/77116/ https://doi.org/10.1016/j.marchem.2020.103849 unknown Li, Xinyu, García-Ibáñez, Maribel I., Carter, Brendan R., Chen, Baoshan, Li, Qian, Easley, Regina A. and Cai, Wei Jun (2020) Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements. Marine Chemistry, 225. ISSN 0304-4203 doi:10.1016/j.marchem.2020.103849 Article PeerReviewed 2020 ftuniveastangl https://doi.org/10.1016/j.marchem.2020.103849 2023-01-30T21:53:34Z Ocean acidification, a phenomenon of seawater pH decrease due to increasing atmospheric CO2, has a global effect on seawater chemistry, marine biology, and ecosystems. Ocean acidification is a gradual and global long-term process, the study of which demands high-quality pH data. The spectrophotometric technique is capable of generating accurate and precise pH measurements but requires adding an indicator dye that perturbs the sample original pH. While the perturbation is modest in well-buffered seawater, applications of the method in environments with lower buffer capacity such as riverine, estuarine, sea-ice meltwater and lacustrine environments are increasingly common, and uncertainties related to larger potential dye perturbations need further evaluation. In this paper, we assess the effect of purified meta-Cresol Purple (mCP) dye addition on the sample pH and how to correct for this dye perturbation. We conducted numerical simulations by incorporating mCP speciation into the MATLAB CO2SYS program to examine the changes in water sample pH caused by the dye addition and to reveal the dye perturbation mechanisms. Then, laboratory experiments were carried out to verify the simulation results. The simulations suggest that the dye perturbation on sample pH is a result of total alkalinity (TA) contributions from the indicator dye and chemical equilibrium shifts that are related to both the water sample properties (pH, TA, and salinity) and the indicator dye solution properties (pH and solvent matrix). The laboratory experiments supported the simulation results; the same dye solution can lead to different dye perturbations in water samples with different pH, TA, and salinity values. The modeled adjustments agreed well with the empirically determined adjustments for salinities >5, but it showed greater errors for lower salinities with disagreements as large as 0.005 pH units. Adjustments are minimized when the pH and salinity of the dye are matched to the sample. When the dye is used over a wide range of salinity, ... Article in Journal/Newspaper Ocean acidification Sea ice University of East Anglia: UEA Digital Repository Marine Chemistry 225 103849 |
institution |
Open Polar |
collection |
University of East Anglia: UEA Digital Repository |
op_collection_id |
ftuniveastangl |
language |
unknown |
description |
Ocean acidification, a phenomenon of seawater pH decrease due to increasing atmospheric CO2, has a global effect on seawater chemistry, marine biology, and ecosystems. Ocean acidification is a gradual and global long-term process, the study of which demands high-quality pH data. The spectrophotometric technique is capable of generating accurate and precise pH measurements but requires adding an indicator dye that perturbs the sample original pH. While the perturbation is modest in well-buffered seawater, applications of the method in environments with lower buffer capacity such as riverine, estuarine, sea-ice meltwater and lacustrine environments are increasingly common, and uncertainties related to larger potential dye perturbations need further evaluation. In this paper, we assess the effect of purified meta-Cresol Purple (mCP) dye addition on the sample pH and how to correct for this dye perturbation. We conducted numerical simulations by incorporating mCP speciation into the MATLAB CO2SYS program to examine the changes in water sample pH caused by the dye addition and to reveal the dye perturbation mechanisms. Then, laboratory experiments were carried out to verify the simulation results. The simulations suggest that the dye perturbation on sample pH is a result of total alkalinity (TA) contributions from the indicator dye and chemical equilibrium shifts that are related to both the water sample properties (pH, TA, and salinity) and the indicator dye solution properties (pH and solvent matrix). The laboratory experiments supported the simulation results; the same dye solution can lead to different dye perturbations in water samples with different pH, TA, and salinity values. The modeled adjustments agreed well with the empirically determined adjustments for salinities >5, but it showed greater errors for lower salinities with disagreements as large as 0.005 pH units. Adjustments are minimized when the pH and salinity of the dye are matched to the sample. When the dye is used over a wide range of salinity, ... |
format |
Article in Journal/Newspaper |
author |
Li, Xinyu García-Ibáñez, Maribel I. Carter, Brendan R. Chen, Baoshan Li, Qian Easley, Regina A. Cai, Wei Jun |
spellingShingle |
Li, Xinyu García-Ibáñez, Maribel I. Carter, Brendan R. Chen, Baoshan Li, Qian Easley, Regina A. Cai, Wei Jun Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements |
author_facet |
Li, Xinyu García-Ibáñez, Maribel I. Carter, Brendan R. Chen, Baoshan Li, Qian Easley, Regina A. Cai, Wei Jun |
author_sort |
Li, Xinyu |
title |
Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements |
title_short |
Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements |
title_full |
Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements |
title_fullStr |
Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements |
title_full_unstemmed |
Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements |
title_sort |
purified meta-cresol purple dye perturbation:how it influences spectrophotometric ph measurements |
publishDate |
2020 |
url |
https://ueaeprints.uea.ac.uk/id/eprint/77116/ https://doi.org/10.1016/j.marchem.2020.103849 |
genre |
Ocean acidification Sea ice |
genre_facet |
Ocean acidification Sea ice |
op_relation |
Li, Xinyu, García-Ibáñez, Maribel I., Carter, Brendan R., Chen, Baoshan, Li, Qian, Easley, Regina A. and Cai, Wei Jun (2020) Purified meta-Cresol Purple dye perturbation:How it influences spectrophotometric pH measurements. Marine Chemistry, 225. ISSN 0304-4203 doi:10.1016/j.marchem.2020.103849 |
op_doi |
https://doi.org/10.1016/j.marchem.2020.103849 |
container_title |
Marine Chemistry |
container_volume |
225 |
container_start_page |
103849 |
_version_ |
1766157970101501952 |