[SOLVED]Destroy gameObject, not OnCollisionEnter but after a while

I need to make my GameObject destroy after tot seconds from the collision. I tried both with OnCollisionEnter() and a Timer and with Invoke("Destroy", Timer) but it simply collides without destroying.

 public void Destroy()
         {
             Destroy(this.gameObject);
         }
     
         public void OnCollisionEnter(Collision collision)
         {
             ContactPoint contact = collision.contacts[0];
             Quaternion rot = Quaternion.FromToRotation(Vector3.up, contact.normal);
             Vector3 pos = contact.point;
             GameObject istanza = (GameObject)Instantiate(particles, pos, rot); //until this point the OnCollisionEnter is taken from docs.unity3d.com, and it works
             if (collision.gameObject.tag.Equals("Item"))
             {
                 if (PlayerPrefs.GetString("ItemKept", null) == bestItem)
                 {
                     float Timer = //expression to define how much should I wait
                     Invoke("Destroy", Timer);
                 } else if (PlayerPrefs.GetString("ItemKept", null) == null)
                 {
                     float Timer = //expression to define how much should I wait
                     Invoke("Destroy", Timer);
                 }
                 else if (PlayerPrefs.GetString("ItemKept", null) != bestItem)
                 {
                     float Timer = //expression to define how much should I wait
                     Invoke("Destroy", Timer);
                 }
             }
         }

P.S. Please forgive Grammatical error, I'm a non-Anglophone student. EDIT: Works perfectly now, I forgot to put the hitting item's tag and I used a float "life"; I make it smaller every hit and, to save the changes to life, I use PlayerPrefs.SetFloat("TempLife", life) and life=PlayerPrefs.GetFloat("TempLife", life)