Lithium is atomised in an air–acetylene flame within a longitudinal magnetic field. Birefringent and dichroic signals are separately measured using a pulsed hollow cathode source. The arrangement is found to give isotopic selectivity and is useable down to concentrations of about 10 μg/mL. The signal ratio of birefringence: dichroism is found to be approximately independent of sample concentration at the high and low extremes of the calibration curve. However, severe distortions occur at intermediate concentrations. In addition, a reversal of signal magnitudes is observed between6Li and7Li. This effect is attributed primarily to a distortion of the source profile as a result of self-absorption.