ΔA

Time interval (min)

Regression equation

Correlation coefficient (R²)

A4 - A2

2 - 4

y = 3.5089x − 0.0034

0.794

A6 - A2

2 - 6

y = 4.6634x − 0.0041

0.7724

A8 -A2

2 - 8

y = 7.4594x − 0.0067

0.8962

A10 - A2

2 - 10

y = 6.8909x + 0.002

0.8255

A12 - A2

1 - 12

y = 7.9068x + 0.0242

0.7553

A14 - A2

2 - 14

y = 10.104x + 0.0043

0.9131

A16 - A2

2 - 16

y = 11.495x + 0.0173

0.8976

A18 - A2

2 - 18

y = 12.687x + 0.0277

0.8465

A20 - A2

2 - 20

y = 23.097x − 0.0325

0.8131