Table 3.
Repeatability and intermediate precision of absorbance measurements for selected concentrations of citric acid and trisodium citrate: mean values from six repetitions (n = 6).
| Measured concentration (mmol/L) | Repeatability (intra-day precision) | Intermediate precision (inter-day precision) | ||
|---|---|---|---|---|
|
|
|
|||
| Absorbance (mean ± SD) | RSD (%) | Absorbance (mean ± SD) | RSD (%) | |
| Citric acid | ||||
| 1.0 | 0.2047 ± 0.0008 | 0.399 | 0.2046 ± 0.0006 | 0.297 |
| 2.5 | 0.5073 ± 0.0008 | 0.161 | 0.5073 ± 0.0008 | 0.148 |
| 4.5 | 0.9035 ± 0.0005 | 0.061 | 0.9037 ± 0.0007 | 0.074 |
| Trisodium citrate | ||||
| 1.0 | 0.2007 ± 0.0005 | 0.257 | 0.2005 ± 0.0005 | 0.257 |
| 2.5 | 0.5008 ± 0.0008 | 0.150 | 0.5006 ± 0.0006 | 0.121 |
| 4.5 | 0.9033 ± 0.0005 | 0.057 | 0.9036 ± 0.0005 | 0.057 |