EPA health advisory level for the sum of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in drinking water is 70 ppt. In an interlaboratory study, 10 laboratories analyzed a sample containing 100 ppt of PFOA using a standard method based on LC/MS/MS and the following results were reported for the individual labs: 286, 27, 134, 77, 45, 199, 152, 59, 11 and 169 ppt. Is there a reason to suspect that the method might not be specified sufficiently well? Why?