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);
        }