Determinação simultânea de níquel e cobalto em amostras de bráquetes de aparelhos ortodônticos fixos e saliva comercial utilizando eletrodo de filme de bismuto por voltametria de redissolução adsortiva

Abstract

Nickel and cobalt are metals present in stainless steel alloys that are used for the manufacture of fixed and movable orthodontic appliance parts, so use of these appliances can put patients in contact with these metals after exposure to allergies, like contact dermatitis. Metal analysis is already well described in the literature using atomic absorption spectrometry and inductively coupled plasma mass spectrometry, which are the most commonly used techniques for this type of analysis. Unlike traditional techniques, as electroanalytical methodologies are faster, show lower detection limits, simultaneous detection rates, and lowcost ones are compared to spectrometric methods. In this context, the aim of this work was to analyze nickel and cobalt in bracket samples of fixed orthodontic appliances and in commercial saliva samples by adsorptive stripping voltammetry (AdSV) using a bismuth film electrode. Two types of digestion were performed on a hotplate for saliva and in a microwave equipment for brackets, and after digestion, the samples were analyzed. Microwave digestion of brackets showed good accuracy, which was evaluated by addition and recovery studies, with results ranging from 99 to 110% for nickel and 99 to 105% for cobalt. Saliva digestion by heating plate also showed good accuracy, with results ranging from 93 to 98% for nickel and cobalt. Microwave-digested bracket samples analyzed by AdSV contained 0.26 to 216.9 mg L-1 nickel and 0.010 to 3.10 mg L-1 cobalt. Detection limits were 1.31 µg L-1 for nickel and 0.3 µg L-1 for cobalt.