diff --git a/pk_optimizer/pk2Comp.py b/pk_optimizer/pk2Comp.py
index 2c2052540715e21bf61b8f2b0f59d6f68ed3b7a7..23ee65dfd8771e9d81f80409e57b2ea08b0a07b0 100644
--- a/pk_optimizer/pk2Comp.py
+++ b/pk_optimizer/pk2Comp.py
@@ -37,7 +37,9 @@ class pk2Comp:
         PS : double
             PS is the permeability-surface area constant in mL/(g*min). Defaults to 1/60.      
         """
-        
+        if numParam <= 0 or Flow <= 0 or Vp < 0 or Visf < 0 or PS<0 or PS>10 or Vp>10 or Visf>10:
+            raise ValueError("Input values are incorrect.")
+            
         # Declare Variables for initial conditions
         self.numParam = numParam
         self.flow = Flow
@@ -48,7 +50,7 @@ class pk2Comp:
         self.Cp0 = 0 # Initial concentration of tracer in plasma
         self.Cisf0 = 0 # Initial concentration of tracer in interstitial space
         self.tmax = 10 #Time in seconds
-        self.dt = 0.1 #Time step
+        self.dt = 1 #Time step
         self.a = 2. # Alpha for gamma distribution
         self.rv = gamma(self.a, loc = 2, scale = 0.55) #input function
         self.sol = []
@@ -145,18 +147,3 @@ class pk2Comp:
 
         print('Cp at 10 sec is ' + str(self.sol[100,0]))
         print('Cisf at 10 sec is ' + str(self.sol[100,1]))
-
-
-# In[52]:
-
-
-test = pk2Comp(4,.2,.2,.7,1/60)
-test.main()
-test.getPlot()
-
-
-# In[ ]:
-
-
-
-