Interesting facts about radiocarbon dating
I am not aware of any authentic research which supports this claim.
This problem, known as the "," is not of very great practical importance for radiocarbon dating since most of the artifacts which are useful for radiocarbon dating purposes and are of interest to archaeology derive from terrestrial organisms which ultimately obtain their carbon atoms from air, not the water. Samples of coal have been found with radiocarbon ages of only 20,000 radiocarbon years or less, thus proving the recent origin of fossil fuels, probably in the Flood.Since no reliable historically dated artifacts exist which are older than 5,000 years, it has not been possible to determine the relationship of radiocarbon years to calendar years for objects which yield dates of tens of thousands of radiocarbon years.Thus, it is possible (and, given the Flood, probable) that materials which give radiocarbon dates of tens of thousands of radiocarbon years could have true ages of many fewer calendar years. The shells of live freshwater clams have been radiocarbon dated in excess of 1600 years old, clearly showing that the radiocarbon dating technique is not valid.Some may have mistaken this to mean that the sample had been dated to 20,000 radiocarbon years.The second characteristic of the measurement of radiocarbon is that it is easy to contaminate a sample which contains very little radiocarbon with enough radiocarbon from the research environment to give it an apparent radiocarbon age which is much less than its actual radiocarbon age.
In the early days of radiocarbon analysis this limit was often around 20,000 radiocarbon years.