Standard curve establishment
The standard curve was obtained by plotting absorbance of
known formaldehyde concentration (viz. 0.838, 1.68, 2.51,
3.35 and 5.03 ppm) from a stock solution of formaldehyde
having 6.2% concentration (Fig. 1). The different
concentration of formaldehyde solution was added with Nash
reagent to get the respective absorbance on spectrophotometer
(using 415 nm). The molar concentration of the formaldehyde
sample ranged “between” 0.26 × 10-4 to 1.56 × 10-4 using
following formula,
A = €Cl
Where, A = Absorbance
€ = molar absorption co-efficient
C = Molar concentration
l = length of the cell
A= €l × C
A= Const. × C
The model used for the equation was, Y = mx equation, the
straight line passing through the origin