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Volatile Organic Compound (VOC's) Sample Collection, Preservation and Storage Guidelines

Please take the time to read the entire instruction sheet once before beginning sampling.  Sample containers and preservation materials are available at the laboratory office.  Check for office hours so your sample collections and/or drop-offs at the laboratory are properly coordinated.

Sample Collection, Dechlorination and Preservation
1. Collect all samples in duplicate using properly prepared 40 to 120 ml borosilicate glass containers with a teflon faced silicone septa.  Vials should be treated as directed to be free of organic chemical contamination.

2. If samples contain residual chlorine and measurements of the concentrations of disinfection by-products (trihalomethanes etc.) are to be made, add approx. 25 mg of ascorbic acid to the bottle before filling.  If you obtained your containers from Cedar Grove, this has already been placed in the container.  The dried deposit you may note in the vial is the ascorbic acid.

3. Fill the sample container to overflowing, but take care not to flush out the rapidly dissolving ascorbic acid.  No air bubbles should pass through the sample as the bottle is filled, or be trapped in the sample when the container is sealed (no headspace).  Prior to sealing the vial, adjust the pH to a value less than 2 by carefully adding one drop of 1:1 hydrochloric acid for each 20 ml of sample volume (2 drops for containers normally supplied by Cedar Grove).  This material is available from the laboratory office.  When any addition is made to a sample, extreme care must be taken not to contaminate the material being added as it is being used.  Avoid allowing the material being added to come in contact with the dropper bulb and discard any unused portion in the dropper rather than returning it to the original container.

4. When sampling from a water tap, open the tap and allow the water to flush until the water temperature has stabilized.  This usually will take 10 minutes.  If this is not feasible for some reason, at least allow a complete flushing of the lines leading to the tap.  Adjust the flow to about 500 ml per minute (1 pint per minute) and collect duplicate samples from the flowing stream. 

5. When sampling from an open body of water, fill a 1 liter (1 quart) wide mouth bottle or beaker (glass if possible) with sample from a representative area and carefully fill duplicate sample vials from this larger container.

6. The samples must be chilled to 40C. after collection and maintained at that temperature until analysis.  Field samples that will not be received at the laboratory on the day of collection must be packaged for shipment or transport with sufficient ice to ensure they will be at 40C. on arrival at the laboratory.

Sample Storage
1. Store samples at 40C. until analysis.  The sample storage area MUST be free of any organic solvent vapors.

2. Analysis must be made within 14 days of sample collection.  Samples not analyzed within this period should be discarded and replaced.  It is important that you bring your samples to the laboratory as soon as possible.  This will avoid storage problems such as improper temperature and contamination.  It will also allow proper scheduling of your analytical work.  Samples without sufficient time for scheduling will be run ONLY on a rush basis and only if this option is viable.

Field Reagent Blanks ("Trip Blanks")
 Duplicate field reagent blanks should be handled along with each sample set.  These "trip" blanks as requested by D.E.R. should accompany the sample collector on a given day and be stored and shipped with the associated sample set.  In some cases sample specific field reagent blanks may be necessary to isolate contamination problems.  These may be requested at the sampler's option when obtaining containers.