MySql – Get comma separated values from a table, should not exist in another table

I have two tables, table structures as below.

Table: items
Id   item_name     item_ids
1    pens          10,11,12,13
2    books         20, 30
3    computer      50, 60, 80

Another table : activities

Id  activity_id
1   10
2   11
3   20
4   60

So Now I want to get item_ids from items table which are not present in activities table using JOINS NO SUBQUERY. Lets say I want to retrieve item_ids of pens those are not in activities table. Ex For pens, item_ids are 10, 11,12,13. My result should be 12 and 13.