Chloramine-T Concentrations in Serum and Tissue of Tilapia Fish After immersion Therapy in Two Different Concentrations of Chloramine-T

Chloramine-T (Cl-T), a chlorine-liberating organic compound with a biocidal effect, is applied for several purposes such as drinking water disinfection or as an antiseptic for topical infections. The standard treatment regimen is to apply Cl-T at a concentration of 10 or 20 mg/L for 1.0 hours/day for 3-4 consecutive days. The planned goal of the current work was to apply  Cl-T by immersion in a static bath continuously for 3 days, and then evaluate its residual concentrations in serum and edible fish tissues. A total number of 65 tilapia (Oreochromis niloticus) fish were used in the current study: 5 fish samples were used for calibration curve preparation while the other 60 fish individuals were divided into 2 equal groups; the first was exposed to 10 and the second was exposed to 20 mg Cl-T/L; each exposure persisted for 3 consecutive days at 20°C. Chloramine concentrations were assayed in serum and edible tissue (muscles, liver and kidney) of tilapia for 5 days post-treatment with Cl-T using HPTLC (High-performance thin layer chromatography). No signs of toxicity or mortalities were recorded in tilapia exposed to either 10 or 20mg Cl-T/L in such a regimen. Six hours after the end of the low dose (10mg/ L) of Cl-T dipping, muscle tissues retained the highest chloramine residual levels (149.74±17.52 μg/gm) compared to liver and serum (0.84±0.13 μg/g and 1.62±0.06 μg/mL, respectively); meanwhile, kidney samples were under our detection limit (<11.25 ng). Similarly, 6 hours after the end of exposure to 20mg Cl-T/L, muscles recorded the highest concentration of chloramine residues (322.12 ± 34.79 μg/g) compared to liver and serum (2.36 ± 0.30 μg/g and 3.68 ± 0.14 μg/mL, respectively). The  Cl-T residues could be detected in muscles up to 4 days post the end of Cl-T dipping by such practice.  Further studies are needed to calculate the Cl-T withdrawal time after such a long immersion protocol.