Sonoelectroanalytical detection of ultra-trace arsenic

The electroanalytical detection of arsenic on a gold electrode is investigated in the presence and absence of ultrasound. It is found that under quiescent conditions a detection limit of 1.8 x 10(-7) M is achievable using a 120 seconds accumulation period. Applying optimised ultrasound during the accumulation period was found to reduce the limit of detection to 1 x 10(-8) M from using a deposition period of 60 s at -0.5 V, while increasing the sensitivity by a factor of 15. The methodology was tested on a river sample containing significant copper contamination and electrode passivating organic materials. This technique provides promise for 'in the field' measurements due to the electrode-depassivating effects of ultrasound.