Table 1.
Intraday reliability of HPLC and HORIBA analyzers for sweat [Na+] and [K+].
| Sweat [Na+] | Sweat [K+] | |||||||
|---|---|---|---|---|---|---|---|---|
| CENTRIFUGE HPLC | CENTRIFUGE HORIBA | CENTRIFUGE HPLC | CENTRIFUGE HORIBA | |||||
| Replicate 1 vs. 2 | Replicate 2 vs. 3 | Replicate 1 vs. 2 | Replicate 2 vs. 3 | Replicate 1 vs. 2 | Replicate 2 vs. 3 | Replicate 1 vs. 2 | Replicate 2 vs. 3 | |
| n | 205 | 204 | 206 | 167 | 116 | 115 | 113 | 75 |
| Mean Difference ± SD (mEq/L) | −0.20 ± 1.73 | −0.09 ± 1.51 | 0.26 ± 1.41* | 0.10 ± 1.18 | 0.01 ± 0.18 | 0.00 ± 0.15 | −0.00 ± 0.14 | −0.01 ± 0.15 |
| 95% CI of Mean Difference (mEq/L) | −0.44 to 0.04 | −0.30 to 0.12 | 0.07 to 0.45 | −0.08 to 0.28 | −0.03 to 0.04 | −0.03 ± 0.03 | −0.03 to 0.02 | −0.04 to 0.03 |
| ICC | 0.998* | 0.999* | 0.999* | 0.999* | 0.988* | 0.992* | 0.996* | 0.996* |
| SEE (mEq/L) | 1.73 | 1.51 | 1.38 | 1.18 | 0.18 | 0.15 | 0.14 | 0.15 |
| TEM (mEq/L) | 1.22 | 1.07 | 1.00 | 0.83 | 0.13 | 0.11 | 0.10 | 0.11 |
| CV (%) | 1.97 | 1.67 | 1.35 | 1.17 | 3.27 | 2.81 | 2.35 | 2.21 |
To determine intraday reliability samples were measured in triplicate when possible (depending on sample volume; exact n for each replicate comparison is provided). CV, coefficient of variation; HPLC, ion chromatography using the Dionex ICS‐3000; HORIBA, Horiba B‐722 for sweat [Na+] and Horiba B‐731 for sweat [K+]; ICC, intraclass correlation coefficient (based on two‐way mixed ANOVA, absolute agreement, average measures); SEE, standard error of the estimate; TEM, typical error of measurement; *P < 0.001.