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Fluorescent determination of chloride in nanoliter samples

García, Néstor H ; Plato, Craig F ; Garvin, Jeffrey L ; García, Néstor H

Kidney International, January 1999, Vol.55(1), pp.321-325 [Peer Reviewed Journal]

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  • Title:
    Fluorescent determination of chloride in nanoliter samples
  • Author: García, Néstor H ; Plato, Craig F ; Garvin, Jeffrey L ; García, Néstor H
  • Description: Fluorescent determination of chloride (Cl ) in nanoliter samples. Measurements of Cl in nanoliter samples, such as those collected during isolated, perfused tubule experiments, have been difficult, somewhat insensitive, and/or require custom-made equipment. We developed a technique using a fluorescent Cl indicator, 6-methoxy-N-(3-sulfopropyl) quinolinium (SPQ), to make these measurements simple and reliable. This is a simple procedure that relies on the selectivity of the dye and the fact that Cl quenches its fluorescence. To measure millimolar quantities of Cl in nanoliter samples, we prepared a solution of 0.25 mM SPQ and loaded it into the reservoir of a continuous-flow ultramicrofluorometer, which can be constructed from commercially available components. Samples were injected with a calibrated pipette via an injection port, and the resultant peak fluorescent deflections were recorded. The deflections represent a decrease in fluorescence caused by the quenching effect of the Cl injected. The method yielded a linear response with Cl concentrations from 5 to 200 mM NaCl. The minimum detectable Cl concentration was approximately 5 mM. The coefficient of variation between 5 and 200 mM was 1.7%. Resolution, defined as two times the standard error divided by the slope, between 10 and 50 mM and between 50 and 200 mM was 1 mM and 2.6 mM, respectively. Furosemide, diisothiocyanostilbene-2,2′-disulfonic acid and other nonchloride anions (HEPES, HCO , SO , and PO ) did not interfere with the assay, whereas 150 mM NaBr resulted in a peak height greater than 150 NaCl. In addition, the ability to measure Cl did not vary with pH within the physiological range. We developed an easy, accurate, and sensitive method to measure Cl concentration in small aqueous solution samples.
  • Is Part Of: Kidney International, January 1999, Vol.55(1), pp.321-325
  • Identifier: ISSN: 0085-2538 ; E-ISSN: 1523-1755 ; DOI: 10.1046/j.1523-1755.1999.00239.x
  • Subjects: Cotransport ; Furosemide ; Dids ; Bromide ; Kidney ; Thick Ascending Limb ; Medicine
  • Language: English
  • Source: ScienceDirect Journals (Elsevier)

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