Validation of a method to quantify titanium, vanadium and zirconium in oral mucosa cells by inductively coupled plasma-mass spectrometry (ICP-MS)

• New validated method for Ti, V and Zr determination by ICP/MS in oral mucosa cells.
• The method showed to be sensitive, reproducible, accurate, and robust.
• It is useful for determining in vivo release of metals from orthodontic appliances.

The release of metal ions from fixed orthodontic appliances is a source of major concern. Various studies have evaluated the discharge of metals from these appliances in biological fluids, such as saliva or blood, overlooking the cells with prolonged contact with fixed appliances. The aim of this work is to develop and optimize an analytical procedure to determine Ti, V and Zr in oral mucosa cells in patients with and without orthodontic appliances by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The analytical procedure is based on an extraction and digestion of the samples and quantification of the elements. A suitable and practical procedure for assessing the trueness and precision of the proposed method has been applied by using validation standards. The method has been suitably validated: the regression equation was calculated from standards prepared in the same matrix without oral mucosa cells and the linear range was 0.5–50.0 ng/mL for Zr and 5.0–50.0 ng/mL for Ti and V. Limits of detection were 0.9, 2.8 and 0.4 ng/mL and limits of quantification 1.8, 3.4 and 0.7 ng/mL for Ti, V and Zr, respectively. The recovery percentages (%) obtained oscillated between 101 and 108 for Ti, 98 and 111 for V, and 92 and 104 for Zr. Intermediate precision (RSD%) data obtained were also adequate. The present method showed to be robust for the three factors considered: heating time, volume of the deionized water, and volume of PlasmaPure 65% HNO3 used to dilute the samples, which permits its validation and application to oral mucosa cells from orthodontic patients.