An improved test for cocaine, methaqualone and methadone with a modified cobalt(II) thiocyanate reagent

Alliston, Geraldine V.; Bartlett, A.F.; Maunder, Mike; Phillips, G. F.

doi:10.1039/an9729700263

Cited by 10 publications

(3 citation statements)

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“…In contrast, the cocaine reference material dissolved quickly in the liquid. A similar creation of blue flecks with aqueous cobalt thiocyanate and methaqualone was attributed to the high surface tension of the aqueous solution preventing the sample being “wetted” by the reagent [26]. Cocaine, an alkaloid with unshared electrons on its nitrogen atom, forms a coordination compound with the cobalt thiocyanate resulting in the formation of the blue color when cocaine is added to cobalt thiocyanate [27].…”

Section: Resultsmentioning

confidence: 99%

Fentanyl as a potential false positive with color tests commonly used for presumptive cocaine identification

Kosecki

Brooke

Canonico

2022

Journal of Forensic Sciences

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Chemical color tests are widely utilized as part of the analytical scheme approved to identify drugs in forensic laboratories and in the field by law enforcement officers.Although these test results are considered preliminary indications of the presence of a drug, forensic scientists sometimes use these test results to direct their confirmatory testing and law enforcement officers use these test results when making arrest decisions and decisions on how to impound evidence. The color tests commonly used to identify cocaine are aqueous cobalt thiocyanate, the Young's test, the Scott's test, and the modified Scott's test. Field testing of a white powder was reported by a law enforcement officer to be positive for cocaine hydrochloride using a commercially available test kit based on the modified Scott's test. The forensic laboratory determined that the powder contained fentanyl and mannitol; cocaine was not detected. Subsequently, the case material, fentanyl and cocaine reference materials, and cocaine cut with mannitol were tested using aqueous cobalt thiocyanate, the Young's test, the Scott's test, and the modified Scott's test. The fentanyl standard and case material produced the colors that would be interpreted as cocaine using the aqueous cobalt thiocyanate and Young's tests. The misidentification of fentanyl as cocaine with these tests could create a potentially hazardous situation. The cocaine containing samples were distinguishable from the fentanyl containing samples with the Scott's and modified Scott's test when 1 mg of cocaine material was tested, whereas a 3-mg cocaine sample produced the same color sequence as fentanyl.

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Section: Resultsmentioning

confidence: 99%

Fentanyl as a potential false positive with color tests commonly used for presumptive cocaine identification

Kosecki

Brooke

Canonico

2022

Journal of Forensic Sciences

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“…A blue compound of the general form [CoL 2 (SCN) 2 ] is likely the result of the coordination of nitrogenous bases with aromatic amine sites with cobalt(II). The difference noted for the coordinating ability of aliphatic and aromatic amines is significant, as many controlled substances are aliphatic amines, with only a few being aromatic amines [39][40][41], such as methaqualone [42]. Careful analysis of the CSD data provided additional evidence that the aromatic amines bind more strongly to Co(II) than aliphatic amines, with the most probable Co-N distances shorter by 0.02 Å.…”

Section: Discussionmentioning

confidence: 99%

Polymorphism of Bis(benzimidazole)bis(thiocyanato-N)cobalt(II) and Its Relevance to Studies of the Chief Color Test for Cocaine

Burks,

Noa,

Öhrström

2024

Inorganics

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Cobalt(II) thiocyanate-based tests are routinely used to screen cocaine products, with the formation of a blue species interpreted as a positive response. Two popular candidates for the origin of the blue color are an ionic coordination compound, frequently referred to as an ion pair, of the general form (HL)2[Co(SCN)4] or the coordination compound [CoL2(SCN)2], where L represents select nitrogenous bases. Given the high number of nitrogenous bases documented to yield false positives for cobalt(II) thiocyanate-based tests, a reasonable hypothesis is that both candidates are possible but their preferential formation depends on the specific nitrogenous bases screened. This hypothesis was tested through the crystallographic and spectroscopic analysis of reaction products of cocaine hydrochloride, lidocaine monohydrate hydrochloride, and benzimidazole exposed to a classic cobalt(II) thiocyanate reagent. Single-crystal X-ray diffraction revealed that the blue product isolated from benzimidazole test vessels is a coordination compound, with comparative ultraviolet–visible and Raman spectroscopy validating that blue precipitates collected from cocaine hydrochloride and lidocaine monohydrate hydrochloride reaction containers are ionic coordination compounds. Peaks corresponding to π-π* transitions in UV-vis at around 320 nm (cocaine hydrochloride: 320 nm, lidocaine hydrochloride: 323 nm) shift to a higher wavelength of 332 nm for the coordinated benzimidazole, and the broader d-d transitions at 550–630 nm show both a shift and change in envelope for benzimidazole coordinated with cobalt(II). The compound is a new polymorph of bis(benzimidazole)bis(thiocyanato-N)Cobalt(II), γ-[Co(Hbzim)2(SCN)2] (Hbzim = benzimidazole), and the differences in the intermolecular interactions to the two previous polymorphs were clarified by graph set analysis and Hirshfeld surface analysis. Furthermore, the coordination of aromatic nitrogen bases (such as benzimidazole) with Co(II) and aliphatic bases was compared by analyzing the Cambridge Structural Database, and the aromatic bases were found to have a shorter Co-N bond length compared to the aliphatic bases by around 0.02 Å.

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“…Challengingly, numerous organic bases produce blue reaction species when exposed to cobalt(II) thiocyanate solutions such as lidocaine, procaine, diphenhydramine, ephedrine, phencyclidine, fentanyl, α-pyrrolidinopentiophenone, and/or their salts [11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Clarifying the complex chemistry of cobalt(II) thiocyanate‐based tests for cocaine using single‐crystal X‐ray diffraction and spectroscopic techniques

Burks,

Öhrström,

Amombo Noa

2023

Journal of Forensic Sciences

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Cobalt(II) thiocyanate‐based tests are routinely used to screen cocaine products, with the formation of a blue species interpreted as a positive response. An array of other organic bases has been identified as false positives – including well‐documented cocaine product adulterant lidocaine and its salt. False positives prompt continued test development, though improvements are hindered by unresolved product structures and reaction pathways. Toward greater clarity, cobalt(II) thiocyanate reactions with cocaine hydrochloride, along with lidocaine and its salt, were investigated using multiple analytical techniques. Reactions involving cocaine hydrochloride yielded glassy, amorphous blue material while reactions of lidocaine hydrochloride monohydrate produced larger, needle‐like crystals whose structure was determined via single‐crystal X‐ray diffraction to be an ion pair (Hlidocaine+)2([Co(SCN)4]2−)·H2O. While the blue precipitate isolated from reactions involving cocaine hydrochloride was unsuitable for crystallographic structure determination, comparative ultraviolet–visible, attenuated total reflectance infrared, and Raman spectroscopic analysis – along with elemental analysis – supports that this solid is comprised of a comparable ion pair (Hcocaine+)2[Co(SCN)4]2−. Pink crystals isolated from lidocaine reaction vessels were identified as coordination compounds cis‐[CoL2(SCN)2] and trans‐[CoL2(SCN)2] where L = lidocaine, while pink crystals from both cocaine hydrochloride and lidocaine hydrochloride monohydrate reaction vessels were the coordination polymer trans‐[Co(H2O)2(SCN)2]·H2O. The results presented herein enable reaction optimization to favor a desired product, whether ion pair or coordination species.

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An improved test for cocaine, methaqualone and methadone with a modified cobalt(II) thiocyanate reagent

Cited by 10 publications

References 0 publications

Fentanyl as a potential false positive with color tests commonly used for presumptive cocaine identification

Fentanyl as a potential false positive with color tests commonly used for presumptive cocaine identification

Polymorphism of Bis(benzimidazole)bis(thiocyanato-N)cobalt(II) and Its Relevance to Studies of the Chief Color Test for Cocaine

Clarifying the complex chemistry of cobalt(II) thiocyanate‐based tests for cocaine using single‐crystal X‐ray diffraction and spectroscopic techniques

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