The problem of estimating bounds for time-varying parameter perturbations using measurement data is addressed. In particular, time-varying time-delay is considered. An estimate of the perturbation is produced based on a quantized approximation of the uncertainty and the sparse structure of its derivative. The Pade-approximation and orthogonal collocation method are used to approximate the delay. A first-order system with time-delay is used as an illustrative example. The gain, time-constant and time-delay are considered as uncertainties here.