Nile Red Staining for Oil Determination in Microalgal Cells: A New Insight through Statistical Modelling

Table 3

Polynomial modelling of fluorescence intensity as a composite function of the four independent variables. Results (observed fluorescence intensities) of factorial experimental design as displayed in Table 2 were used for the modelling. Fluorescence intensity was recorded at excitation wavelength of 530 nm and emission wavelength of 607 nm. The regression coefficients and values of the linear main effects, the quadratic main effects, and the interaction effects of the four independent variables are reported.  = coded value of cell concentration,  = coded value of ultrasonication power,  = coded value of incubation temperature, and  = coded value of Nile red dye concentration.

Model term	Regression coefficient	Standard error	value
Intercept	55.52	10.57	n/a
	65.95	11.25
	1.15	8.74	0.896
	5.80	7.95	0.472
	14.71	8.74	0.104
	7.36	7.95	0.363
	89.97	12.21
	−42.62	6.44
	−14.35	9.86	0.158
	−7.56	9.86	0.450
	−19.76	10.45	0.070
	5.69	7.50	0.455
	−0.72	4.98	0.887
	8.37	4.98	0.105