Table 1.
Performance characteristics of microcalorimetric instrumentation at 25 °C.
| Characteristic | |
|---|---|
| calibration constant (F) | 16 to 22 W V−1 |
| sensitivity (1/F) | 0.045 to 0.059 V W−1 |
| noise level of baseline | 20 nV peak-to-peak |
| detectability (1/3 × noise level/sensitivity) | 0.15 μW |
| stability of baseline | 100 nV over 24 hours |
| linearity of calibration constant | 0.1 percent from 0.01 mW to 2 mW |
| time constanta | 63 s |
| stability of calibration constant | 0.2 percent over 2 years |
| imprecisionb: | |
| q ≈ 10 mJ | 0.3% |
| q ≈ 100 mJ | 0.1% |
| q ≈ 500 mJ | 0.05% |
| q ≈ 300 mJ (chemical heat) | 0.2% |
| “blank” heat effects: | |
| no reaction vessel in place | 0.023±0.03 mJ |
| empty vessel in calorimeter | −0.065±0.06 mJ |
| H2O | 0.67±0.22 mJ |
| human serum | -0.75±1.0 mJ |
| glucose isomerase (T = 25 °C) | −101±4 mJ |
| inaccuracyc | <0.2% |
a
A reaction vessel containing 1.0 mL of water was in the copper container.
b
Based upon experiments in which electrical heat was introduced for periods of 10 to 100 seconds. All uncertainties are standard deviations.
c
The inaccuracy was assessed by the performance of both heater placement tests [1] and by measurements of heats of neutralization of HCl with excess NaOH.