All solutions are provided with the instrument from Instrumentation Laboratory de Puerto Rico Ltd., Cidra, Puerto Rico 00639.

Lithium diluent (15 mmol l−1)

Dilute 10 ml of 1500 STOCK solution in 1 l of distilled water.

Standard (Na+ = 140, K+ = 5)

Take 0.1 ml and add 20 ml of lithium diluent. Also set up a standard curve with 50, 100, 150 and 200 mmol l-1 NaCl standards and run these samples at the beginning and at the end of the run. Set up a similar series of KCl standards ranging from 1 to 10 mmol l-1 for plasma and 50 to 200 mmol l-1 with urine. Calculate a regression between the readings and the true concentrations for each ion and use these regressions to calculate the values for your samples.

Samples

Add 10 μl of sample to 2.0 ml of the lithium diluent.

Operation

• Turn on gas tap (value set at 35 lb in-2, high-purity propane).

• Turn on IL 143 electrical switch.

• Turn on air (set at 27 lb in-2).

• Machine should ignite – if not, ensure that syphon tube is filled with water.

• Check that aspiration rate is between 30 and 50 s ml-1.

• Set zero with lithium diluent and 140/5 standard using balance control.

• Adjust lithium control if necessary.

• If cannot set the 140, reduce the aspiration rate.

• After running samples, aspirate cleaning solution for 30 s followed by distilled water.