Thermal degradation of partially purified paralytic shellfish poison toxins at different times, temperatures, and pH

Mixtures of purified and partially purified paralytic shellfish poisoning ( PSP) toxins including C1/2 and B1 toxins, gonyautoxins 1-4 (GTX), neosaxito xin (NEO), and saxitoxin SIM were heated at different temperatures (90 to 1 30 degreesC), heating times (10 to 120 min), and pH (3 to 7) and analyzed b y HPLC. C toxins declined rapidly at low pH, and GTX 1/4 toxins decreased a t high temperatures and at high pH. GTX 2/3 increased initially at low pH a nd then declined with subsequent heating, whereas STX increased consistentl y at pH 3 to 4. The integrated total specific toxicity declined at high pH (6 to 7).The kinetics of thermal destruction were 1(st) order, and the effi cacy of thermal destruction was highly dependent on pH, with rapid thermal destruction of carbamate compounds at higher pH. D values of carbamate toxi ns decreased with increasing temperature at high pH. Heating at low pH resu lted in conversion of least toxic compounds to highly toxic compounds.