Use of ferric chloride to identify salicylate-containing poisons.
OBJECTIVE
Ferric chloride (FeCl3) is used to qualitatively test the urine of patients with presumed salicylate exposure. FeCl3 testing of an unidentified poison might provide evidence of salicylate exposure in situations where FeCl3 urine testing cannot be used. Such situations include the absence of a urine sample, immediately after ingestion before urine contains a detectable quantity of salicylate, or for patients chronically using salicylatesfor which FeCl3 testing is unhelpful. This study seeks to determine if FeCl3 can be used to identify salicylate-containing products.


METHODS
We assessed the reactivity of FeCl3 with commercially available salicylate-containing products. We applied 0.1 mL of 10% FeCl3 solution to each of 15 various salicylate-containing products including: regular and buffered acetylsalicylic acid, bismuth subsalicylate, methylsalicylate, physostigmine salicylate, salicylic acid, trolamine salicylate, and herbal tablets with salicin-containing white willow bark (Salix sp.). These products tested were: regular and enteric-coatedpills (n = 4), powder (n = 1), topical creams (n = 5), topical liquids (n = 4), and intravenous solution (n = 1). FeCl3 was applied to crushed tablets and added directly to liquids and creams. Fifteen salicylate-free controls including liquids, pills, and creams similar in appearance to experimental samples were also tested. Three blinded physiciansfamiliar with FeCl3 testing independently observed the addition of FeCl3 to each sample and rated a positive or negative result.


RESULTS
All salicylate-containing products were interpreted to be clearly FeCl3 positive and all control samples were interpreted to be clearly FeCl3 negative.


CONCLUSIONS
Salicylate-containing products may be identified using FeCl33. When using FeCl3
Hoffman
Robert J
RJ
Maimonides Medical Center, Brooklyn, New York, USA. rjhoffman@pol.net
Nelson
Lewis S
LS
Hoffman
Robert S
RS
D002626:Chemistry, Pharmaceutical; D002712:Chlorides; D004340:Drug Contamination; D005290:Ferric Compounds / Q000737:chemistry*; D006801:Humans; D012459:Salicylates / Q000032:analysis* / Q000506:poisoning
D002712:Chlorides; D005290:Ferric Compounds; D012459:Salicylates; C024555:ferric chloride