Analytical methodology for the detection of sulfachloropyridazine (SCP) in samples of feathers\u00a0via LC-MS\/MS was implemented based on techniques previously published by other authors:\u00a01- Hindle R. A validated atmospheric pressure chemical ionization method for analysing sulphonamides in pork muscle. 2013. Available at http:\/\/www.youngin.com\/application\/0411-0045EN-E.pdf. Accessed October 12, 2017.2- Renew JE, Huang CH. Simultaneous determination of fluoroquinolone, sulfonamide, and trimethoprim antibiotics in wastewater using tandem solid phase extraction and liquid chromatography\u2013electrospray mass spectrometry. J Chromatogr A 2004; 1042: 113-21.3- Shao B, Dong D, Wu y, Hu J, Meng J, Tu X, Xu S. Simultaneous determination of 17 Sulfonamide residues in porcine meat, kidney and liver by solid phase extraction and liquid chromatography-tandem mass spectrometry. Anal Chim Acta 2005; 546:174-81.4- Pang G, Cao YZ, Zhang JJ, Jia GQ, Fan CL, Li XM, Liu YM, Li ZY, Shi YQ. Determination of sulfonamides in honey by liquid chromatography- tandem mass spectrometry. J AOAC Int 2005; 88:1304-11.5- Stubbings G, Bigwood T. The development and validation of a multi-class liquid chromatography tandem mass spectrometry (LC\u2013 MS\/MS) procedure for the determination of veterinary drug residues in animal tissue using a QuEChERS (QUick, Easy, CHeap, Effective, Rugged and Safe) approach. Anal Chim Acta 2009; 637:68-78.6- Bedendo GC, Jardim IC, Carasek E. A simple hollow fiber renewal liquid membrane extraction method for analysis of sulphonamides in honey samples with determination by liquid chromatography-tandem mass spectrometry. J Chromatogr A 2010; 1217:6449-54.7- Yu H, Tao Y, Chen D, Wang Y, Huang L, Peng D, et al. Development of a high-performance liquid chromatography method and a liquid chromatography-tandem mass spectrometry method with the pressurized liquid extraction for the quantification and confirmation of sulphonamides in the foods of animal origin. J Chromatogr B 2011; 879:2653-62.The method is based on a solid-liquid extraction with organic solvents. The clean up is carried out\u00a0throught\u00a0aromatic sulfonic acid (Bakerbond spe\u2122) disposable extraction columns of 6 mL. The analyte is concentrated using a water bath at 40-50\u00b0C under a mild nitrogen flow.\u00a0For the instrumental analysis, a Symmetry C8 analytical column of 3.5\u03bcm and 2.1 x 100mm (Waters\u00ae) was fitted in an Agilent 1290 infinity series liquid-chromatograph equipment, coupled to an API 3200 (AB Sciex, Darmstadt, Germany) triple-quadrupole mass-spectrometer. The analytical data was then integrated using the Analyst\u00ae version 1.5 software\u00a0package (SCIEX, Framingham, Massachusetts).