The effectiveness of the freeze fracture carpet grinding technique in the determination of total lead

This article describes a study using carpets of known lead content to determine whether a grinding technique is useful in preparing carpeted surfaces for chemical analysis for total lead. This technique, termed 'freeze fracture,' involves freezing and grinding carpet samples, then digesting and analyzing the ground material. The freeze fracture technique was performed by two technicians on three sample sets of known lead content. The results indicated that the procedure recovers less (~67%) than the total lead known to be present within the carpet. Excessive sample handling requirements causing numerous opportunities for material losses during the procedure create the potential for additional reduction in recovery. If this technique is to be attempted as part of a carpet sampling and testing program, a rigorous sampling protocol, strict quality control procedures, and a technician proficiency testing program should be developed. Data obtained through the use of this method should be carefully examined prior to basing any quantitative results on their interpretation.