MATLAB: Help reading from matrix and find the first corresponding value of time

 x0 = [0.1,0,0.3,0.4];
 y = [0.1,0.2];
 tt = 20;
 
 [t,x] = ode15s(@(t,x) Function(x,y),[0,tt],x0);
 result = [t,x];

Hi,

I have a matrix of time and concentrations (The results are shown below). I want to find the first value of time when the concentration in the third column (defined in red) >= 0.001 which is in this case = 0.6215.

First column shows the time while the other 4 columns show the concentration

Thnak you,

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