Dear Authors:

Both referees reviewed your manuscript very favourably, and asked only for a set of minor revisions to be made. Most notably both picked up the issue of the CHBrCl2 - CH2Br2 interference, which would likely benefit from a further bolstering of the discussion already included on the implications of a possibly varying amount of interference. This for the sake of complete clarity.

Otherwise I am delighted to accept the manuscript for publication, pending completion of these few requested corrections.

Best wishes,

Bill Sturges