public override int GetSpectrumNumber(double retentionTime) { IBDAChromData tic = _msdr.GetTIC(); int index = -1; for (int i = 0; i < tic.TotalDataPoints; i++) { if (index < 0 || Math.Abs(tic.XArray[i] - retentionTime) < Math.Abs(tic.XArray[index] - retentionTime)) { index = i; } } return(index + 1); }