Table 4.
Direct analysis of substances in nanoliter samples of tubular fluid.
| Measured substance | Method |
|---|---|
| Na+ | MFP (68); FTF (91); FTC (53); EAAS (48) |
| K+ | MFP (68); FTC (53); EAAS (48) |
| Li+ | EAAS (48) |
| Ca2+ | FTC (75) or FTF (91) |
| Mg2+ | FTC (76); EAAS (32) |
| NH4+ | FTF (21) |
| multiple cations * | capillary zone electrophoresis (52) |
| Cl- | electrometric titration (45); FTC (51) or FTF (18; 91) |
| Bicarbonate | calorimetry (78; 82) |
| Phosphate | FTC (76; 89) |
| multiple anions ** | capillary zone electrophoresis (15) |
| CO2 | calorimetry (78); FTF (50); |
| pH | antimony microelectrode (41) |
| Osmolality | freezing point depression (44) |
| Glucose | FTC (19); FTF (66) |
| Urea | FTC (77) |
| angiotensin II | radio-immuno assay (6; 58) |
| ATP | luciferin/luciferase enzyme reaction (74) |
EAAS, electrothermal atomic absorption spectrophotometry; FTC, flow-through colorimetry; FTF, flow-through fluorometry; MFP, microflame photometer;
*
NH4, Na, K, Ca, Li, Mg, Ba;
**
Cl-, nitrate, citrate, phosphate, bicarbonate, iothalamate. To the author’s knowledge, instruments for MFP, FTC, FTF, and freezing point depression analysis in nanoliter volumes are currently not or no longer commercially available.