An inductively coupled plasma optical emission spectrometer
(ICP OES) with radially viewed configuration, model VISTA PROCCD
(Varian), was used for Ca determinations. The ICP sample
introduction system used was composed of a V-groove nebulizer
and a Sturman–Masters spray chamber. The fixed ICP operational
parameters were: 40 MHz generator frequency; 1.2 kW radio frequency
power; 15 L min1 plasma argon-flow rate; 1.5 L min1
auxiliary argon-flow rate; 0.9 L min1 nebulizer argon-flow rate;
and 0.8 mL min1 sample flow rate. A 2.4 mm central tube internal
diameter torch was used. The measurements were performed at
393.366 nm, which corresponds to the Ca (II) emission line.
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