Sample Handling Makes a Difference

Broken charcoal tubes… asbestos samples stuck to duct tape…frozen impinger solutions…baked DNPH tubes. Unfortunately, these are all examples of some actual shipments that have been received by our labouratory. (Obviously, analyses of such samples cannot yield reliable results.) We would like to offer some suggestions on how you can help preserve the integrity of your media and, ultimately, the reliability of your analyses.

Proper sample preparation and shipping procedures vary with the compound being analyzed as well as with the sampling medium. That’s why it’s so important to carefully read and follow any instructions on the sample preparation forms sent with the sampling media. We’ve also provided packaging and shipping information on our new fee schedule, and sample storage instructions are specified within the NIOSH and OSHA methods. When in doubt call us!

Some samples are easily degraded by heat. Any media you receive in a cooler should be sent back in that same cooler via an overnight delivery service. Media for some samples, such as the treated filters used for isocyanates or the DNPH-treated silica gel tubes for formaldehyde, must be kept in a freezer before and after sampling. If you’re using ice, be sure to place the samples in a waterproof bag to protect them from moisture. In some instances, (methanol and isopropanol are common examples), the samples must be frozen after completion of sampling and shipped overnight in a cooler with ice packs. Refrigeration of the sample medium prior to sample collection is not necessary.

Wrap all glass tubes and other delicate items in bubble wrap. Don’t use duct tape – strong adhesives can tear off labels and make sample separation difficult for our analysts.

Special Requirements

Filters used for hexavalent chromium sampling when using NIOSH 7600 only should be removed from the cassette and placed into an empty glass vial as soon as possible after sampling. If the filters aren’t removed, the backup pad may reduce some of the CrVI, and your results will be biased low.

Asbestos air sampling cassettes should be shipped using bubble wrap or newspaper. Avoid regular Styrofoam peanuts – they can generate static charges that may pull asbestos fibres off the filter onto the walls of the cassette. (Cellulose peanuts do not form this static charge and can be used for packing asbestos samples.)

Any filters coated with DNPH, such as those used for glutaraldehyde, should be kept covered with foil during sampling. Foil protects the media from light, which can break down the DNPH derivative and give low results.