Trichloroacetic acid (TCA) (60 ml of 6%) was used for fish
sample extraction purposes. Nash’s Reagent (Nash, 1953) was
used as an indicator to detect the absorbance of formaldehyde.
Fifteen g ammonium acetate was diluted in a 100 ml
Erlenmeyer flask with an addition of 0.3 ml of acetyl acetone
and 0.2 ml of acetic acid. Nash’s Reagent is light sensitive and
was kept in dark-glass reagent bottle at all time. A 0.1N
potassium hydroxide (KOH) and 0.1N hydrochloric acid (HCl)
was used to adjust the pH of the distillate to be in range of 6.0
to 6.5 by a pH meter.