False-positive result when a diphenylcarbazide spot test is used on trivalent chromium-passivated zinc surfaces
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False-positive result when a diphenylcarbazide spot test is used on trivalent chromium-passivated zinc surfaces. / Reveko, Valeriia; Lampert, Felix; Din, Rameez U.; Thyssen, Jacob P.; Møller, Per.
I: Contact Dermatitis, Bind 78, Nr. 5, 2018, s. 315-320.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - False-positive result when a diphenylcarbazide spot test is used on trivalent chromium-passivated zinc surfaces
AU - Reveko, Valeriia
AU - Lampert, Felix
AU - Din, Rameez U.
AU - Thyssen, Jacob P.
AU - Møller, Per
PY - 2018
Y1 - 2018
N2 - Background: A colorimetric 1,5-diphenylcarbazide (DPC)-based spot test can be used to identify hexavalent chromium on various metallic and leather surfaces. DPC testing on trivalent chromium-passivated zinc surfaces has unexpectedly given positive results in some cases, apparently indicating the presence of hexavalent chromium; however, the presence of hexavalent chromium has never been confirmed with more sensitive and accurate test methods. Objectives: To examine the presence of hexavalent chromium on trivalent chromium-passivated zinc surfaces with a DPC-based spot test. Methods: A colorimetric DPC spot test was used for the initial detection of hexavalent chromium on new and 1-year-aged trivalent chromium-passivated zinc surfaces. Then, X-ray photoelectron spectroscopy (XPS) was performed for all samples. Results: The DPC spot test indicated the presence of hexavalent chromium in aged, but not new, trivalent chromium passivation on zinc; however, subsequent analysis by XPS could not confirm the presence of chromium in a hexavalent state. Conclusions: Unintended oxidation of DPC induced by atmospheric corrosion is suggested as a possible reason for the false-positive reaction of the DPC test on a trivalent chromium-passivated zinc surface. Further validation of the use of the DPC test for chromium-containing metallic surfaces is required.
AB - Background: A colorimetric 1,5-diphenylcarbazide (DPC)-based spot test can be used to identify hexavalent chromium on various metallic and leather surfaces. DPC testing on trivalent chromium-passivated zinc surfaces has unexpectedly given positive results in some cases, apparently indicating the presence of hexavalent chromium; however, the presence of hexavalent chromium has never been confirmed with more sensitive and accurate test methods. Objectives: To examine the presence of hexavalent chromium on trivalent chromium-passivated zinc surfaces with a DPC-based spot test. Methods: A colorimetric DPC spot test was used for the initial detection of hexavalent chromium on new and 1-year-aged trivalent chromium-passivated zinc surfaces. Then, X-ray photoelectron spectroscopy (XPS) was performed for all samples. Results: The DPC spot test indicated the presence of hexavalent chromium in aged, but not new, trivalent chromium passivation on zinc; however, subsequent analysis by XPS could not confirm the presence of chromium in a hexavalent state. Conclusions: Unintended oxidation of DPC induced by atmospheric corrosion is suggested as a possible reason for the false-positive reaction of the DPC test on a trivalent chromium-passivated zinc surface. Further validation of the use of the DPC test for chromium-containing metallic surfaces is required.
KW - contact allergy
KW - DPC spot test
KW - EU regulation
KW - false-positive result
KW - hexavalent chromium
KW - trivalent chromium passivation of zinc
U2 - 10.1111/cod.12955
DO - 10.1111/cod.12955
M3 - Journal article
C2 - 29341169
AN - SCOPUS:85040708481
VL - 78
SP - 315
EP - 320
JO - Contact Dermatitis
JF - Contact Dermatitis
SN - 0105-1873
IS - 5
ER -
ID: 217393694