Sodium (Na+): Perkin Elmer AAnalyst 100 Atomic Absorption Spectrometer

I) Principle

The ground state sodium atom absorbs light energy at 589.0 nm as it enters the excited state. As the number of sodium atoms in the light path increases, the amount of light absorbed also increases. By measuring the amount of light absorbed, a quantitative determination of the amount of sodium present can be made. 0.5 % lanthanum solution is added to each standard, control and sample to prevent chemical and ionization interference.

II) Preparation of Stock Standard

In a 1000 mL volumetric flask, dissolve 2.5420 g sodium chloride (NaCl) to the mark with deionized water. This standard stock solution is 1000 mg Na⁺/L.

III) Preparation of Reagents

0.5 % Lanthanum Solution

In a 1000 mL volumetric flask, dissolve 13.37 g lanthanum chloride (LaCl₃.7H₂O) to the mark with deionized water.

IV) Analysis Procedure

A) Spike each standard, control and sample 9:10 with 0.5 % Lanthanum Solution (1 part 0.5 % Lanthanum Solution and 9 parts standard, control or sample).

B) Install Na-K hollow cathode lamp. Perkin-Elmer part #N305-0204.

C) Ensure that the correct Default Conditions are entered.

1) Recall Method=2

2) Lamp Current=12

3) Slit=0.2

4) Full Height=Y(Yes)

5) Wavelength(nm)=589.0

6) Int. Time=5.0

7) Replicates=5

8) Cal=1(Nonlinear)

9) Cal=1(Hold)

10) STD1-----

11) Read Delay(sec)=3

D) Use an oxidizing (lean, blue) air-acetylene flame.

E) Calibrate with standards that bracket the sample concentration. Check the calibration curve for drift, accuracy and precision with standards and controls every 20 samples. Correlation coefficient should be greater than or equal to 0.990.