4. Add one DPD free-chlorine powder pillow to each of the six labeled beakers.
CAUTION: Handle the powder pillows with care. Mix the powder thoroughly into the sample using a stirring rod. Note: It is not important if a few small bits of powder do not dissolve.
4.ใส่ DPD free-chlorine powder pillow ลงในแต่ละบีกเกอร์ทั้ง6ใบที่ label ไว้แล้ว
ข้อควรระวัง: