Abstract: Trace amount of cobalt in water samples was pre-concentrated continuously with an organic precipitant and determined by flame atomic absorption spectrometry. The flow injection technique was used to pre-concentrate cobalt by on-line direct precipitation with 1-nitroso-2-naphthol. The precipitation was dissolved with methyl isobutyl ketone (MlBK) and was sent to the flame. The optimum conditions for cobalt determination were determined and used to analyze Co samples. For 1.0 mL of sample, the enrichment factor was 13 and the sample throughput was about lO per hour for 0.5 ppm Co solution. The enrichment factor was increased to 68 fold for 10.0 mL. A semi-reference biologicaI sample was prepared and analyzed. The result was in good agreement with the expected value with RSD of 4%.

Abstract: An inexpensive ultrasonic nebulizer (USN) was developed utilizing a home humidifier. The ultrasonic transducer was taken from a commercial USN and the power supply was from a humidifier. Sample was continuously fed into the nebulizer and the detection limit was improved 3-20 times over a pneumatic nebulizer. Undesirably, noise in signal was also increased several times. 0.5 ppm of Mn was used as an internal reference and the 'long-term' drift could be successfully corrected. Since the noise contained high and low frequency components, both could be effectively removed only by the real-time correction method such as the Myer-Tracy method, where the reference line was simultaneously monitored with the analytical lines. The performance of USN was tested with NIST SRMs and showed good agreement with the certified values.