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Drinking Water Holding Times

Sample Containers, Preservation and Holding Times for Regulated Parameters

PARAMETER/METHOD	PRESERVATIVE	SAMPLE HOLDING TIME	EXTRACT HOLDING TIME AND STORAGE CONDITIONS	SUGGESTED SAMPLE SIZE	TYPE OF CONTAINER
Metals (except HG)	HNO3 pH<2	6 months		1 L	Plastic or Glass
Mercury	HNO3 pH<2	28 days		100 mL	Plastic or Glass
Alkalinity	Cool, 4C	14 days		100 mL	Plastic or Glass
Asbestos	Cool, 4C	48 hours		1 L	Plastic or Glass
Chloride	none	28 days		100 mL	Plastic or Glass
Residual Disinfectant	none	immediately		200 mL	Plastic or Glass
Color	Cool, 4C	48 hours		100 mL	Plastic or Glass
Conductivity	Cool, 4C	28 days		100 mL	Plastic or Glass
Cyanide	Cool, 4C, Sodium Thiosulfate, NaOH pH>12	14 days		1 L	Plastic or Glass
Fluoride	none	28 days		100 mL	Plastic or Glass
Foaming Agents	Cool, 4C	48 hours
Nitrate (chlorinated)	Cool, 4C non-acidified	14 days		100 mL	Plastic or Glass
Nitrate (non chlorinated)	Cool, 4C, non-acidified	48 hours		100 mL	Plastic or Glass
Nitrite	Cool, 4C	48 hours		100 mL	Plastic or Glass
Nitrate + Nitrite	H2SO4 pH<2	28 days		100 mL	Plastic or Glass
pH	none	immediately		25 mL	Plastic or Glass
o-Phosphate	Cool, 4C	48 hours		100 mL	Plastic or Glass
Silica	Cool, 4C	28 days		100 mL	Plastic
Solids (TDS)	Cool, 4C	7 days		100 mL	Plastic or Glass
Sulfate	Cool, 4C	28 days		100 mL	Plastic or Glass
Temperature	none	immediately		1 L	Plastic or Glass
Turbidity	Cool, 4C	48 hours		100 mL	Plastic or Glass
TTHM or VOC	Ascorbic Acid, 4C, HCL pH<2	14 days		40-120 mL	Glass with PTFE Lined Septum
HAA5	Ammonium chloride, Cool, 4C, Dark	14 days	≤4C, dark 7 days, ≤-10C 14 days	50 mL	Amber Glass with PTFE Lined Cap
SOC-504.1	Sodium Thiosulfate, Cool, 4C	14 days	4C, 24 hours	40 mL	Glass with PTFE Lined Septum
SOC-515.4	Sodium Sulfite, dark, cool ≤10C for first 48 hr ≤6C thereafter	14 days	≤0C 21 days	40 mL	Amber Glass with PTFE Lined Septum
SOC-525.2	Sodium Sulfite, Cool, 4C, HCl pH<2	14 days	4C, 30 days	1 L	Amber Glass with PTFE Lined Cap
SOC-531.1	Sodium Thiosulfate, Monochloroacetic acid, pH<3, Cool, 4C	Cool 4C 28 days		60 mL	Glass with PTFE Lined Septum

For metals, please refer to the following certification document: North Carolina Drinking Water Laboratory Certification