THE EFFECTIVENESS OF THE FREEZE-FRACTURE CARPET GRINDING TECHNIQUE INTHE 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, t hen digesting acid analyzing the ground material. The freeze fracture technique was performed by two technicians on three sample sets of kno wn lead content. The results indicated that the procedure recovers les s (similar to 67%) than the total lead known to be present within the carpet. Excessive sample handling requirements causing numerous opport unities for material losses during the procedure create the potential for additional reduction in recovery. If this technique is to be attem pted as part of a carpet sampling and testing program, a rigorous samp ling protocol, strict quality control procedures, and a technician pro ficiency testing program should be developed. Data obtained through th e use of this method should be carefully examined prior to basing any quantitative results on their interpretation.