Enzymatic determination of sodium and chloride in sweat.

Abstract

OBJECTIVE:

To develop methods based on enzyme activation for the analysis of sweat sodium and chloride using beta-galactosidase and alpha-amylase, respectively.

METHODS:

Both were monitored kinetically on the Cobas Fara centrifugal analyzer. The sweat, collected with the Macroduct system, was diluted no more than five-fold for the volumes obtained of 16 to 80 mu L, median 32.5 mu L. The sodium assay utilized a sodium-binding cryptand to maximize linearity.

RESULTS:

Between-run coefficients of variation (%) at 10, 20, and 50 mmol/L were 3.6, 4.5, and 1.3 for sodium and 7.1, 6.1, and 6.0 for chloride, respectively. The sodium method showed excellent agreement with flame photometry (y = 0.997x + 0.742; r = 0.998), and chloride with a mercuric thiocyanate method (y = 0.995x + 0.485; r = 0.996), giving equivalent discrimination between patients with and without cystic fibrosis.

CONCLUSIONS:

The methods enable the rapid analysis on the same analyzer of both sodium and chloride in a single dilution of sweat collections of low volume.

• Authors: R P Taylor, T J James
• Journal: Clinical biochemistry (Clin Biochem) Vol. 29 Issue 1 Pg. 33-7 (Feb 1996) ISSN: 0009-9120 [Print] United States
• PMID: 8929821 (Publication Type: Journal Article)

Chemical References

• Bridged Bicyclo Compounds, Heterocyclic
• Chelating Agents
• Chlorides
• 2-nitrophenylgalactoside
• Nitrophenylgalactosides
• cryptating agent 221
• Sodium
• alpha-Amylases
• beta-Galactosidase

Topics

• Bridged Bicyclo Compounds, Heterocyclic
• Chelating Agents
• Chlorides (analysis)
• Cystic Fibrosis (diagnosis)
• Enzyme Activation
• Humans
• Hydrogen-Ion Concentration
• Kinetics
• Linear Models
• Nitrophenylgalactosides (metabolism)
• Photometry (methods)
• Reproducibility of Results
• Sensitivity and Specificity
• Sodium (analysis)
• Sweat (chemistry)
• alpha-Amylases (metabolism)
• beta-Galactosidase (metabolism)