You are asking the right questions. Best to discuss with analytical lab, and they may supply sample bottles with preservative for pesticide analysis. My experience on this is several decades old now, so consult also with updated Standard Methods for Analysis of Water and Wastewater (may be available at lab or library or analytical chemist). If you are analyzing yourself or University lab, make sure you have been certified as a capsble lab, especially if possible legal intent, keep chain of command for handling, proper labeling of sample details, etc. Years ago, we used new opaque plastic milk bottles with preservative from lab, put on ice and/or refrigerated, and transported to lab for analysis within Std Methods limit. Preservative type and storage methods may depend on pesticide. I dont remember freezing samples or storing for extended periods, and many if the samples taken were not sent in for analysis, some were composited during period of flow timing from treatment area to sampling location downstream .

You might be interested in our Spruce Budworm report (1983) on researchgate. It is an example of many instances of using fluorescent dye in spray mix, and other methods like spray drift cards, to help identify possible contaminated samples to send to lab for analysis. Identifying all flowing streams and open waters and buffering helped reduce water contamination. Several spills were also monitored including the Willow Creek spill. Aquatic insect drift rates and benthic sampling another approach used to check for contamination from aerial spraying.

Hello,

Use amber color sterilized (Heat upto 300 celsius temperature) glass bottles for the collection of water samples and better if you can collect around 2L water sample. Preserve your samples with 10ml of chloroform/1L of water sample. Transport samples in cold room condition and store samples in the cold room until start analysis. You can use both solid phase extraction or liquid liquid extraction for the extraction of pesticides from collected water samples. After concentrating, pesticides samples can inject to HPLC, LCMS or GCMS machines. Use EPA methods for the protocols.

Hi, Deepak

I agree with William and Yohan

Amber glass bottles are to be preferred because pesticides may stick to the walls of plastic vials, so the results of quantitative analysis may be dramatically lowered, which is probably not the intended purpose. Amber glass also limits photodegradation of some pesticides which could also lead to biased results.

Thank you all for your precious comments and replies.

thank you

Glass bottles with well sealed cap. if want to preserve the sample add sodium thiosulphate. quantity depend upon sample volume. 5.0 gm in 100 ml bottle. it is better to keep bottle in cool dark place and complete the analysis within 1 months.