Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_222448_1 (percentage_yield VARCHAR, dpmo VARCHAR)

### Question ###
What is the percentage yield for a DPMO of 3.4?

### Accurate SQL ###

SELECT percentage_yield FROM table_222448_1 WHERE dpmo = "3.4"