Objectives: The aim of this study was to develop and validate a method for determination of residual monomers (TEGDMA and BisGMA) in resins using high performance liquid chromatography (HPLC).
Methods: Specimens (n=6) made by experimental resin were immersed in acetonitrile (5ml-24h). Monomers were detected by UV absorbance at 210nm, on C18 (NST). The separation was performed using Phase A- Water + triethylamine and Phase B- Acetonitrile, at a flow rate of 1.0mL/min by using a gradient run (17min at 55oC). Resins control samples were analyzed immediately and after two days to evaluate the coefficients of variation (CV%) intra and inter-days. Others parameters were evaluated including: robustness (flow rate and temperature), selectivity, limit of detection and quantification. The concentration of residual monomer in each sample solution was calculated using the respective linear regression equation from the calibration graphs. The determination of the residual monomer (W/W%) of samples (n=3) from the same specimen was performed and hence a mean residual monomer value for that specimen was calculated. Data (table) were analyzed by ANOVA and Tukey-Kramer test (α=0.05).
Results:
| TEGDMA (Mean of W/W% -sd) | BISGMA (Mean of W/W% -sd) |
Precision intra and inter-days |
|
|
Day 1 | 1.689(±0.1) | 3.114(±0.3) |
Day 2 | 1.777(±0.1) | 3.551(±0.3) |
Robustness Flow rate |
|
|
Flow 0.9ml/min | 1.969(±0.2) | 3.970(±0.5) |
Flow 1.0ml/min | 1.879(±0.1) | 3.874(±0.2) |
Flow 1.1ml/min | 1.597(±0.1) | 3.244(±0.3) |
Robustness Temperature |
|
|
53oC | 1.901(±0.2) | 3.938(±0.4) |
55 oC | 1.879(±0.1) | 3.874(±0.2) |
57 oC | 1.817(±0.1) | 3.707(±0.3) |
No significant differences were observed in all parameters. In selectivity test had not any interference in the retention time of the monomers evaluated. The acceptance criterion for the limit of detection and quantification were taken as a signal-to-noise ratio of 5 and 10% respectively.
Conclusion: The method developed was sufficiently accurate and precise to be used for the determination of residual monomer in dental resins.