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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
SOC-504.1 Sodium Thiosulfate, Cool, 4C 14 days 4C, 24 hours 40 mL Glass with PTFE Lined Septum
SOC-505 Sodium Thiosulfate, Cool, 4C 14 days (7 days for Heptachlor) 4C, 24 hours 40 mL Glass with PTFE Lined Septum
SOC-506 Sodium Thiosulfate, Cool, 4C, Dark 14 days 4C, dark 14 days 1 L Amber Glass with PTFE Lined Cap
SOC-507 Sodium Thiosulfate, Cool, 4C, Dark 14 days (see method for exceptions) 4C, dark 14 days 1 L Amber Glass with PTFE Lined Cap
SOC-515.1 Sodium Thiosulfate, Cool, 4C, Dark 14 days 4C, dark 28 days 1 L Amber Glass with PTFE Lined Cap
SOC-515.2 Sodium Thiosulfate or Sodium Sulfite, HCl pH<2, Cool, 4C, Dark 14 days ≤4C, dark 14 days 1 L Amber Glass with PTFE Lined Cap
SOC-515.3 Sodium Thiosulfate, Cool, 4C, Dark 14 days ≤4C, dark 14 days 50 mL Amber Glass with PTFE Lined Cap
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-531.1 Sodium Thiosulfate, Monochloroacetic acid, pH<3, Cool, 4C Cool 4C 28 days   60 mL Glass with PTFE Lined Septum
SOC-550 Sodium Thiosulfate, Cool, 4C, HCl pH<2 7 days 4C, Dark, 550 30 days, 550.1 40 days 1 L Amber Glass with PTFE Lined Cap
HAA5 Ammonium chloride, Cool, 4C, Dark 14 days ≤4C, dark 7 days, ≤-10C 14 days 50 mL Amber Glass with PTFE Lined Cap

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