A Hsl-600 CTA Ultrasonic Systems ultrasonic bath operating at
40 kHz and 200 W was applied for the mercury extractions from the
samples ofmineral fertilizers. A Fanem (model 211) centrifuge with capacity
for 4 tubes of 15 mL was used for centrifugation of the extracts.
Mercury determination in the extractswas performed by two analytical
methods using a Varian atomic absorption spectrometer (model
SpectrAA 220 FS) coupled to a Varian hydride generator (model VGA
77), and an Agilent (4100MP-AES) microwave-induced plasma atomic
emission spectrometer integrated to a 3-channel peristaltic pump. This
equipment offers versions with a 5-channel peristaltic pump for determinations
of Hg, As, and Se that requires a cold vapor or hydride