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Region 9 Laboratory SOP 140
Trace Metal Labware Cleaning Procedures
Summary
This method describes the procedure for acid-cleaning lab apparatus, sample containers and (mostly polyethylene) sampling equipment used for trace metal analyses in the laboratory or sample collection in the field. Labware is first rinsed in a soapy solution by the analyst to remove dust and organic residues. Next the analyst rinses the labware with metal free water several times. Then labware must be decontaminated by a series of acid baths; again with metal free water rinsing in between. Two separate acid bath sequences are described. High density polyethylene (HDPE) and low density polyethylene (LDPE) are cleaned with nitric and hydrochloric acid and stored with weak hydrochloric acid solution (HCl). Fluoropolymer labware (FEP or PTFE) is cleaned twice with nitric acid (HNO3) and then stored in weak HCl solution. Some acid baths may be heated to activate the process although it is not required. The analyst is requested to use caution at all times with these acid baths and the acidic solutions inside each polyethylene bottle. Finally, the analyst stores the acid-cleaned labware and bottles in double zip-type bags and preferably inside metal-free areas to prevent contamination from dust and metallic surfaces.