Long-term storage of Oragene®/saliva samples†
Unpurified Oragene/saliva samples

Purified DNA from Oragene/saliva samples

1. Unpurified samples may be stored at room
temperature for up to 5 years.

1. Store purified DNA in 1× TE buffer (10 mM
Tris-HCl, 1 mM EDTA, pH 8.0 or greater).

2. Freezing samples at -20°C is best for indefinite
long-term storage because it minimizes
evaporation of the liquid sample.

2. Store DNA frozen at -20°C.

3. To reduce storage space, samples may be split
into aliquots and stored in microcentrifuge tubes.
To ensure sample homogeneity, heat the entire
sample for 2 hours at 50°C before aliquoting1.

3. Minimize the number of freeze-thaw cycles
by splitting the DNA into multiple aliquots.

Table 1: Oragene/saliva sample long-term storage recommendations.

Introduction

Aliquots in microcentrifuge tubes

The preservation and storage of DNA samples is an
important consideration for molecular epidemiology
and population studies. Table 1 summarizes
recommendations for the long-term storage ofpurified and unpurified saliva samples collected with
the Oragene self-collection kit. This bulletin also
discusses the rationale for these recommendations.

The Oragene kit is designed for user-friendly saliva
collection from donors. However, in the lab, storage
in more compact tubes may be preferable. To reduce
storage space, the Oragene/saliva sample may be split
into 4 aliquots of 1 mL each and stored in 1.5 mLscrew-top microcentrifuge tubes. It is advisable
to use tubes with O-rings to ensure a tight seal
and minimize long-term evaporative loss.

Storage of unpurified Oragene/saliva samples
Storage at room temperature
DNA from saliva is stable in the Oragene self-collection
kit for up to 5 years2. This stability is achieved with
proprietary reagents that inactivate bacteria andnucleases in saliva and minimize chemical hydrolysisof DNA.

Frozen storage
Oragene/saliva samples may also be stored at -20°C or-80°C. Samples may undergo at least three freeze-thaw
cycles with no evidence of DNA degradation. Although
the Oragene kit is designed to ensure a tight seal, frozen
storage may further reduce evaporation of the liquidmedium during long-term storage.

†Storage of purified DNA from Oragene/saliva samples
Preventing DNA degradation
There are three major causes of DNA degradation
in a purified sample3. Samples may be accidentallycontaminated by bacteria, but storage at -20°C or
lower will minimize bacterial metabolism and therelease of nucleases. DNases may be inadvertently
introduced from the skin, but this can be minimized
by wearing gloves when handling samples. Repeatedcycles of freezing and thawing may also contribute to
DNA degradation. This may be minimized by splitting
the purified DNA into multiple aliquots and thawingone at a time.

Saliva samples were collected with Oragene®•DNA or Oragene®•DISCOVER.

(outside the USA)(in the USA)

Some DNA Genotek products may not be available in all geographic regions, contact your sales representative for details.

www.dnagenotek.com • support@dnagenotek.com

Comparison of TE and water

Biobank recommendations

Kasper and Lenz4 (2004) performed an 8-year study

An EU workshop on biobanks5 recommends freezing
DNA samples to prevent bacterial contamination andto minimize evaporation of the sample. Tris-EDTA(TE) buffer contains sufficient buffering capacity toprevent acid hydrolysis of DNA. Similarly, the UK
Biobank6 recommends the storage of DNA in a
nuclease-inhibiting environment at a temperatureof -20°C, since no significant increase in stability isobserved at temperatures below -20°C.

of DNA stored in water or Buffer AE (10 mM TrisHCl;
0.5 mM EDTA, pH 9.0). DNA stored in Buffer AE
at -20°C or 2°C to 8°C showed no degradation by gelelectrophoresis and amplified well in a PCR assay.
DNA in water remained intact when stored at -20°C
but samples were degraded when stored at 2°C to 8°Cand performed poorly in a PCR assay. Pure waterlacks buffering capacity and an acidic pH may leadto DNA hydrolysis.

References
123456Laboratory protocol for manual purification of DNA from 0.5 mL of sample. DNA Genotek. PD-PR-006.
Birnboim, H.C. Long-term stability of DNA from saliva samples stored in Oragene kit. DNA Genotek. PD-WP-005.
O’Brien, D. (2002). High-throughput DNA purification. Modern Drug Discovery. 5(3), 25–26.
Kasper, Y. and Lenz, C. (2004). Stable 8-year storage of DNA purified with the QIAamp DNA blood mini kit. QIAGEN News. 2004 e10.
January 28-31, 2003. Biobanks for health: Optimising the use of European biobanks and health registries for research relevant to publichealth and combating disease. Report and recommendations from an EU workshop held at Voksenåsen Hotel, Oslo.
July 7, 2004. Sample handling and storage: Subgroup protocol and recommendations. UK Biobank, Version 1.0.

Technical support is available Monday to Friday (9h00 to 17h00 EST):•••

Toll-free (North America): 1.866.813.6354, option 6
All other countries: 613.723.5757, option 6
Email: support@dnagenotek.com

Oragene®•DNA is not available for sale in the United States.
Oragene®•DISCOVER is for research use only, not for use in diagnostic procedures.
®Oragene is a registered trademark of DNA Genotek Inc. All other brands and names contained herein are the property of their respective owners.
All DNA Genotek protocols, white papers and application notes, are available in the support section of our website at www.dnagenotek.com.

PD-PR-012 Issue 4/2011-11© 2011 DNA Genotek Inc., a subsidiary of OraSure Technologies, Inc., all rights reserved.

www.dnagenotek.com • support@dnagenotek.com

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