Correction to: Development of a linear dual column HPLC-MS/MS method and clinical genetic evaluation for tramadol and its phase I and II metabolites in oral fluid.

In the original version of the article titled "Development of a linear dual column HPLC-MS/MS method and clinical genetic evaluation for tramadol and its phase I and II metabolites in oral fluid", published in 41(3):288-298 ( https://doi.org/10.1007/s12272-017-0993-z ), unfortunately an important statement was missing in the Clinical study section by the author. The following statement: "The clinical study was approved by the Institutional Review Board of Keimyung University (Deagu, Republic of Korea, approval number: 40525-201509-BR-70-02) and Kyungpook National University Hospital (Daegu, Republic of Korea, approval number of clinical trial: 2016-08-005) and carried out at the Kyungpook National University Hospital Clinical Trial Center (Daegu, Republic of Korea)." Should read: "Written informed consent was obtained from all subjects. The study was performed in accordance with the guidelines of the Declaration of Helsinki on biomedical research involving human subjects and was approved by the Institutional Review Board of Keimyung University (Deagu, Republic of Korea, approval number: 40525-201509-BR-70-02) and Kyungpook National University Hospital (Daegu, Republic of Korea, approval number of clinical trial: 2016-08-005) and carried out at the Kyungpook National University Hospital Clinical Trial Center (Daegu, Republic of Korea)."