Filter paper contamination: Sn and Ca.
D001463:Barbiturates / Q000032:analysis; D001555:Benzene Derivatives; D001826:Body Fluids / Q000032:analysis; D002118:Calcium / Q000032:analysis; D005374:Filtration; D010209:Paper / Q000032:analysis* / Q000592:standards; D012664:Semicarbazones; D014001:Tin / Q000032:analysis
D001463:Barbiturates; D001555:Benzene Derivatives; D012664:Semicarbazones; D014001:Tin; D002118:Calcium