“…Analytical standards for TTX and its analogues are important because they are required for most analysis types. Certified reference materials for TTX are available from many sources: Funakoshi (purity = 96%, Tokyo, Japan), Nacalai tesque (purity ≥94%, Kyoto, Japan), Wako pure chemical industries (purity >99%, Osaka, Japan), Affixscientific Corporation (purity ≥98%, Fremont, CA, USA), Sigma-Aldrich (St. Louis, MO, USA), Cifga (Lugo, Spain), ,,, Tocris Bioscience (purity ≥98.8%, Bristol, UK), ,, Biorbyt Ltd. (Cambridge, UK), Abcam plc (Cambridge, UK), Latoxan (Valence, France), , J&K Scientific Ltd. (Beijing, China), Must Bio-Tech Co., Ltd. (Chengdu, China), , among others. Sometimes, TTX standards contain its analogues, for example, a TTX standard solution from CIFGA (Lugo, Spain) contains TTX, 4,9-anhydroTTX, 11-deoxyTTX, 4-epiTTX, and trace levels of 5,6,11-trideoxyTTX and 11-norTTX-6-ol .…”