AIM: To demonstrate the potential of using 2-aminothiazoline-4-carboxylic acid(ATCA) as a novel biomarker/forensic biomarker for cyanide poisoning. METHODS: A sensitive method was developed and employed for the identification and quantification of ATCA in biological samples, where the sample extraction and clean up were achieved by solid phase extraction(SPE). After optimization of SPE procedures, ATCA was analyzed by high performance liquid chromatographytandem mass spectrometry. ATCA levels following the administration of different doses of potassium cyanide(KCN) to mice were measured and compared to endogenous ATCA levels in order to study the significance of using ATCA as a biomarker for cyanide poisoning.RESULTS: A custom made analytical method was established for a new(mice) model when animals were exposed to increasing KCN doses. The application of this method provided important new information on ATCA as a potential cyanide biomarker. ATCA concentration in mice plasma samples were increased from 189 ± 28 ng/mL(n = 3) to 413 ± 66 ng/mL(n = 3) following a 10 mg/kg body weight dose of KCN introduced subcutaneously. The sensitivity of this analytical method proved to be a tool for measuring endogenous level of ATCA in mice organs as follows: 1.2 ± 0.1 μg/g for kidney samples, 1.6 ± 0.1 μg/g for brain samples, 1.8 ± 0.2 μg/g for lung samples, 2.9 ± 0.1 μg/g for heart samples, and 3.6 ± 0.9 μg/g for liver samples. CONCLUSION: This finding suggests that ATCA has the potential to serve as a plasma biomarker / forensic biomarker for cyanide poisoning. AIM: To demonstrate the potential of using 2-aminothiazoline-4-carboxylic acid (ATCA) as a novel biomarker / forensic biomarker for cyanide poisoning. METHODS: A sensitive method was developed and employed for the identification and quantification of ATCA in biological samples, After the optimization of SPE procedures, the ATCA was analyzed by high performance liquid chromatography tandem mass spectrometry. ATCA levels following the administration of different doses of potassium cyanide (KCN) to mice were measured and compared to endogenous ATCA levels in order to study the significance of using ATCA as a biomarker for cyanide poisoning. application of this method provided important new information on ATCA as a potential cyanide biomarker. ATCA concentration in mice plasma samples w The sensitivity of this analytical method proved to be a (n = 3) to 413 ± 66 ng / mL (n = 3) following a 10 mg / kg body weight dose of KCN introduced subcutaneously tool for measuring endogenous level of ATCA in mice organs as follows: 1.2 ± 0.1 μg / g for kidney samples, 1.6 ± 0.1 μg / g for brain samples, 1.8 ± 0.2 μg / g for lung samples, 2.9 ± 0.1 μg / g for heart samples, and 3.6 ± 0.9 μg / g for liver samples. CONCLUSION: This finding suggests that ATCA has the potential to serve as a plasma biomarker / forensic biomarker for cyanide poisoning.