Table schema:
CREATE TABLE table_name_12 (samples_taken INTEGER, melamine_content_mg_kg_ VARCHAR, producer VARCHAR)

Question: How many samples taken from producer Qingdao Suncare Nutritional Technology with a melamine content less than 53.4?
SQL: SELECT SUM(samples_taken) FROM table_name_12 WHERE melamine_content_mg_kg_ < 53.4 AND producer = "qingdao suncare nutritional technology"