Philippine National Standards for Drinking Water - LWUA
Philippine National Standards for Drinking Water - LWUA
Philippine National Standards for Drinking Water - LWUA
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Table 3. Sampling and Preservation methods according to parameters †<br />
Determination Container<br />
Material<br />
Minimum<br />
Sample<br />
(mL)<br />
Mode of Preservation Holding Time<br />
Recommended<br />
/Regulatory ‡<br />
Acidity P, G(B) 100 Refrigerate 24 h / 14 d<br />
Alkalinity P, G 200 Refrigerate 24 h / 14 d<br />
Boron<br />
P (PTFE) 1000 HNO 3 to pH 12,<br />
refrigerate in the dark<br />
24 h / 14 d; 24 h<br />
if sulfide present<br />
Fluoride P 100 None required 28 d / 28 d<br />
Hardness P, G 100 Add HNO 3 or H 2 SO 4 to 6 mo / 6 mo<br />
pH
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