Test if a property is an ICollection in Portable class library

iam trying to test if a property of my object is a collection or not but encounter problem since in portable class library many method are not avaible

this is my method:

public virtual bool Equals(TObject other) // where TObject : class
{
    if (other == null)
        return false;

    Type t = GetType();
    Type otherType = other.GetType();

    TypeInfo typeInfo = t.GetTypeInfo();            

    if (t != otherType)
        return false;

    IEnumerable<FieldInfo> fields = typeInfo.DeclaredFields; 
    foreach (FieldInfo field in fields)
    { ...

now i have to test if field is an Icollection or not but

• ImplementedInterfaces is not avaible
• IsAssignableFrom is not avaible
• GetInterfaces() is not avaible
• GetGenericTypeDefinition() is not avaible

maybe this is because i have FieldInfo and not TypeInfo?

is there something i can do?