Enzymatic determination of sodium and chloride in sweat

✍ Scribed by Richard P. Taylor; Timothy J. James

• Book ID: 103041328
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 533 KB
• Volume: 29
• Category: Article
• ISSN: 0009-9120
• DOI: 10.1016/0009-9120(95)02003-9

✦ Synopsis

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.