R. Vivek*, Dr. T. Rama Mohan Reddy, Dr. V. Uma Maheswara Rao
Department of Pharmaceutical Analysis and Quality Assurance, CMR College of Pharmacy, Medchal, Hyderabad, Rangareddy, India
The role of the aerosol in atomic absorption spectroscopy is considered and theories of the production of aerosols by pneumatic and ultrasonic devices are outlined. The predicted droplet size is related to sensitivity and interference by Al and Si in the estimation of Mg. Experiments using pneumatic and ultrasonic (70-kHz and 115-kHz) nebulizers at sample flow rates from 0.05 ml/min to 3.5 ml/min and with spray chambers of 100-cm3 to 500-cm3 capacity are reported. The results obtained indicate that ultrasonic nebulizers must be operated at high frequency (>500 kHz) and high power to generate fine aerosols (~5-μ dam) at sample flow rates of 1–5 ml/min if they are to be an improvement in sensitivity and interference on the pneumatic nebulizer.
Keywords: flame atomic absorption spectroscopy, sensitivity, nebulizer, flow rate.