Electrothermal atomic absorption spectrometric determination of cadmium and lead in environmental, botanic and biological samples by different permanent modifiersElectronic supplementary information (ESI) available: Temperature program for modifier coating; optimization of mass and mass ratio of permanent modifiers and cadmium peak profiles; pyrolysis temperatures; characteristic masses and detection limits of cadmium and lead; and contents and recoveries of cadmium and lead in various reference materials.