Determination of pH by colorimetry in small tear samples. Simple method for pH measuring in ophthalmological diseases of the anterior ocular surface

Authors

  • Luis Fernando Barba-Gallardo Universidad Autónoma de Aguascalientes
  • Martín Humberto Muñoz-Ortega Universidad Autónoma de Aguascalientes
  • Guillermo Andrés Díaz-Parra Universidad de Guadalajara
  • Pedro Garzón de la Mora Universidad de Guadalajara
  • Sergio Alberto Ramírez-García Universidad de la Sierra Sur
  • José Rafael Villafán-Berna Universidad Autónoma de Aguascalientes

DOI:

https://doi.org/10.33064/iycuaa2019761790

Keywords:

bromothymol blue, anterior ocular surface, tear, pH

Abstract

There are no simple methods in clinical practice to quantify tear pH. Our objective was to standardize a method for the determination of pH in small tear samples of patients. A colorimetric scale was constructed in a pH range of 6 to 8.0 using bromothymol blue as indicator, with 0.1M KH2PO4 (constant) and ascending volumes of 0.1M NaOH. The method was validated in 20 uL of tear of 73 subjects, in whom it was possible to distinguish changes in the pH from 0.2 in 0.2 in a range of 6.0 to 8.0 with a coefficient of intrasubject variation of 0.8 to 4.0%. The method presented here is precise, with low inter-assay variation. This, combined with its simplicity, low cost and small sample volume, make it an alternative for monitoring the pH of the tear either, in the patient's bed or in primary care.

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Author Biographies

Luis Fernando Barba-Gallardo, Universidad Autónoma de Aguascalientes

Departamento de Optometría, Universidad Autónoma de Aguascalientes. Av. Universidad 940, Ciudad Universitaria, C. P. 20131, Aguascalientes, Aguascalientes, México

Martín Humberto Muñoz-Ortega, Universidad Autónoma de Aguascalientes

Departamento de Química, Universidad Autónoma de Aguascalientes. Av. Universidad 940, Ciudad Universitaria, C. P. 20131, Aguascalientes, Aguascalientes, México.

Guillermo Andrés Díaz-Parra, Universidad de Guadalajara

Departamento de Biología Molecular, Universidad de Guadalajara. Sierra Mojada 950, Col. Independencia, C. P. 44340, Guadalajara, Jalisco, México

Pedro Garzón de la Mora, Universidad de Guadalajara

Departamento de Biología Molecular, Universidad de Guadalajara. Sierra Mojada 950, Col. Independencia, C. P. 44340, Guadalajara, Jalisco, México.

Sergio Alberto Ramírez-García, Universidad de la Sierra Sur

Instituto de Investigación sobre la Salud Pública, Universidad de la Sierra Sur, Sistema de Universidades Estatales de Oaxaca (SUNEO). Calle Guillermo Rojas Mijangos s/n, esq. Av. Universidad, Col. Ciudad Universitaria, C. P. 70800, Miahuatlán de Porfirio Díaz, Oaxaca, México.

José Rafael Villafán-Berna, Universidad Autónoma de Aguascalientes

Cátedras CONACYT-Departamento de Cirugía, Universidad Autónoma de Aguascalientes. Av. Universidad 940, Ciudad Universitaria, C. P. 20131, Aguascalientes, Aguascalientes, México

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Published

2019-01-31

How to Cite

Barba-Gallardo, L. F., Muñoz-Ortega, M. H., Díaz-Parra, G. A., Garzón de la Mora, P., Ramírez-García, S. A., & Villafán-Berna, J. R. (2019). Determination of pH by colorimetry in small tear samples. Simple method for pH measuring in ophthalmological diseases of the anterior ocular surface. Investigación Y Ciencia De La Universidad Autónoma De Aguascalientes, (76), 41–48. https://doi.org/10.33064/iycuaa2019761790

Issue

No. 76 (2019)

Section

Artículos de Investigación

Categories

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Las obras publicadas en versión electrónica de la revista están bajo la licencia Creative Commons Atribución-NoComercial-CompartirIgual 4.0 Internacional (CC BY-NC-SA 4.0)

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