Ramanujan Periodic Transform (RPT) is the newly emerging transform to identify periodicities in the given data. RPT represents the given finite length sequence into a weighted linear combination of signals from Ramanujan subspaces. RPT has the inability of handling the frequency components with in the Ramanujan subspace. This is due to the basis function (Ramanujan sum) used in RPT. To overcome this, a new mixed basis representation is proposed which uses both the sequences from Ramanujan subspace and complex exponentials as basis and both the basis are orthogonal to each other. Using this mixed basis representation, the problem of removing Power Line Interference (PLI) in ECG data is addressed. The methodology is tested on the MIT-BIH Arrhythmia database and the obtained results are competitive when compared with other techniques. © 2017 IEEE.