Transcript
Page 1: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

A Comparative Study of

4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solutions

Dagmar Sweeney, Rodney Anderson

Forensic Science Program

Department of Biopharmaceutical Sciences

University of Illinois at Chicago

Page 2: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Independent Study Continuation Cotton Swabs vs. 4N6FLOQSwabs™: A Comparative Study for

Optimal DNA Recovery FROM Crime Scene Samples given by Dr. Daniele Podini and Anna Dadhania, Department of Forensic Sciences, The George Washington University

Compared:

2 swab types

2 extraction kits: PrepFiler® Forensic DNA Extraction Kit (Life Technologies, Carlsbad, CA) and DNA IQ™ System (Promega, Madison, WI)

NAO™ (Nucleic Acid Optimizer) Basket

Page 3: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Independent Study Continuation Cotton Swabs vs. 4N6FLOQSwabs™: A Comparative Study for

Optimal DNA Recovery FROM Crime Scene Samples given by Dr. Daniele Podini and Anna Dadhania, Department of Forensic Sciences, The George Washington University

Results:

980% increase with 4N6FLOQSwabs™ swab when extracted with PrepFiler® Forensic DNA Extraction Kit (Life Technologies, Carlsbad, CA)

Page 4: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Presentation Outline Introduction

1. DNA Recovery Comparison

2. The Influence of Swabbing Solution on DNA Recovery from a Nonporous Surface

3. Double Swab Technique

4. Sodium Dodecyl Sulfate Volume Optimization

5. Sample Collection from a Porous Surface

6. Effects of Time and Storing Conditions on DNA Recovery

Discussion

Page 5: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Workflow for Casework Samples

Collect Extract Quantify Amplify Detect & Analyze

Page 6: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Workflow for Casework Samples

Collect Extract Quantify Amplify Detect & Analyze

High Quantity DNA High Quality DNA

Page 7: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solutions

COPAN 4N6FLOQSWABS™ COTTON SWABS Vs.

4N6FLOQSwabs™ and Cotton Swab, Dagmar Sweeney, McCrone Research Institute

Page 8: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Cotton Swabs Cotton fiber wrapped around

wooden applicator 2 km of microfiber

Inhibition of material release

Hydrophilic

Absorbs 25x its weight in water

Sterile

Widely used

Cotton Swab, Dagmar Sweeney, McCrone Research Institute

Page 9: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Copan 4N6FLOQSwabs™ Sprayed-on nylon fibers on a

solid molded plastic applicator 6 m microfiber Sample stays close to the

surface

Hydrophilic Capillary Action ETO-treated

(Ethylene Oxide) Human DNA, DNase and

RNase-free 4N6FLOQSwabs™, Dagmar Sweeney, McCrone Research Institute

Page 10: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

1. DNA Recovery Comparison

Questions asked:

How high is DNA recovery from Nylon swabs?

By how much is the DNA yield better or worse in comparison to cotton swabs?

4N6FLOQSwabs™, Dagmar Sweeney, McCrone Research Institute

Page 11: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

1. DNA Recovery Comparison: Materials

Fresh saliva collected and mixed with Tris – EDTA buffer (TE buffer)

Ratios of saliva to TE buffer tested

1:10

1:100

1:200

Applicators Copan Nylon Swabs

Pur-Wraps® Sterile Cotton Tipped Applicators

Page 12: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

1. DNA Recovery Comparison: Methods

75 µL of each saliva solution applied directly on Nylon Swab (N=4)

75 µL of each saliva solution applied directly on Cotton Swab (N=4)

75 µL of TE buffer applied directly on Nylon Swab (N=1)

75 µL of TE buffer applied directly on Cotton Swab (N=1)

Page 13: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

1. DNA Recovery Comparison: Methods

All swabs allowed to air dry and stored at room temperature (RT)

Swabs extracted after 1 week

PrepFiler® Forensic DNA Extraction Kit (Applied Biosystems)

Automate Express™ DNA Extraction System (Applied Biosystems)

Quantitation

Quantifiler® Trio DNA Quantification Kit (Applied Biosystems)

7500 Real Time PCR System (Applied Biosystems)

Page 14: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

1. DNA Recovery Comparison: Results

05

10152025303540455055

1:10 1:100 1:200

Tota

l DN

A Yi

eld

(ng)

Saliva to TE Ratio

Nylon SwabsCotton Swabs

* *

2 x more DNA recovered from nylon swabs

Data presented as mean ± SE, N = 4. An unpaired, 2-tailed t-test was performed to compare average total DNA recovery from 4N6FLOQSwabsTM and cotton swabs. As indicated, * represents a P value of less than 0.01.

*

Page 15: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

1. DNA Recovery Comparison: Hypothesis

Nylon swabs:

Sample stays close to the surface

More surface area readily available for sample adhesion and release

More sample released for analysis

Nylon fiber from 4N6FLOQSwabs™ (20x magnification) Dagmar Sweeney, McCrone Research Institute

Page 16: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

2. The Influence of Swabbing Solution on DNA Recovery from Nonporous Surface

Questions asked: How well nylon swabs

perform when they are used to collect samples from a surface?

Is there any interference with different swabbing solutions? 4N6FLOQSwabs™ with water, Dagmar Sweeney, McCrone Research Institute

Page 17: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

2. The Influence of Swabbing Solution on DNA Recovery from Nonporous Surface

“The Influence of Swabbing Solutions on DNA Recovery from Touch

Samples” Sarah M. Thomasma, M.S. and David R. Foran, Ph.D.

2% sodium dodecyl sulfate (SDS) increased DNA yield

Page 18: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

2. The Influence of Swabbing Solution on DNA Recovery from Nonporous Surface: Materials

Ceramic tile soaked in 10% bleach for 30 min, rinsed with water, autoclaved, air dried, and UV irradiated for 20 min on each side

Fresh saliva collected and mixed with TE buffer in 1:200 ratio

Swabbing Solutions

2% Sodium Dodecyl Sulfate (SDS)

Deionized water (dH2O)

Applicators

Copan Nylon Swabs

Pur-Wraps® Sterile Cotton Tipped Applicators

Page 19: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

2. The Influence of Swabbing Solution on DNA Recovery from Nonporous Surface: Methods

50 µL of the saliva/TE solution applied on the marked ceramic tile

50 µL of the saliva/TE solution applied directly on nylon swabs and

cotton swabs (N=3)

Saliva deposits allowed to dry overnight

Swabs moistened with 50 µL of swabbing solution and passed 50x

over dried saliva deposits (N=3)

Page 20: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

2. The Influence of Swabbing Solution on DNA Recovery from Nonporous Surface: Methods

Swabs extracted immediately

PrepFiler® Forensic DNA Extraction Kit (Applied Biosystems)

Automate Express™ DNA Extraction System (Applied Biosystems)

Quantitation

Quantifiler® Trio DNA Quantification Kit (Applied Biosystems)

7500 Real Time PCR System (Applied Biosystems)

Page 21: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

2. The Influence of Swabbing Solution on DNA Recovery from Nonporous Surface: Results

0

0.5

1

1.5

2

2.5

Control Water 2% SDS

Tota

l DN

A Yi

eld

(ng)

Swabbing Solutions

Nylon Swab

Cotton Swab

No significant difference in DNA yield with different swabbing solutions

*

Data presented as mean ± SE, N = 3. * denotes significantly higher DNA yields from 4N6FLOQSwabsTM than from cotton swabs and different swabbing solutions, based on ANOVA test. P value of less than 0.01.

Page 22: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

2. The Influence of Swabbing Solution on DNA Recovery from Nonporous Surface: Hypothesis

SDS solution wet the swabbed surface more readily and thoroughly than did water alone

Detergent seems to help to increase collected sample size but: Cotton swabs – sample stays in

cotton fibers Nylon swabs – adhesion/release

to/from nylon fibers and capillary action of the fibers unaffected

4N6FLOQSwabs™ with water (left) and 2% SDS (right), Dagmar Sweeney, McCrone Research Institute

Page 23: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

3. Double Swab Technique

No significant difference in DNA yield with different swabbing solution.

Observed residual liquid mainly when SDS used.

How much DNA left behind?

Cotton Swab with 2% SDS as a wetting agent, Dagmar Sweeney, McCrone Research Institute

Page 24: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

3. Double Swab Technique: Materials

Ceramic tile soaked in 10% bleach for 30 min, rinsed with water, autoclaved, air dried, and UV irradiated for 20 min on each side

Saliva collected and mixed with TE buffer in 1:200 ratio

Swabbing Solutions

2% Sodium Dodecyl Sulfate (SDS)

Deionized water (dH2O)

Applicators

Copan Nylon Swabs

Pur-Wraps® Sterile Cotton Tipped Applicators

Page 25: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

3. Double Swab Technique: Methods

50 µL of saliva/TE solution applied on the marked ceramic tile

50 µL of the saliva/TE solution applied directly on nylon swabs and

cotton swabs (N=3)

Saliva deposits allowed to dry overnight

Swabs moistened with 50 µL of swabbing solution and passed 50x

over dried saliva deposits (N=3)

A dry swab applied to absorb residual liquid

Page 26: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

3. Double Swab Technique: Methods

Swabs extracted immediately and separately PrepFiler® Forensic DNA Extraction Kit (Applied Biosystems) Automate Express™ DNA Extraction System (Applied

Biosystems) Quantitation Quantifiler® Trio DNA Quantification Kit (Applied

Biosystems) 7500 Real Time PCR System (Applied Biosystems)

Page 27: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

3. Double Swab Technique: Results

0

0.5

1

1.5

2

2.5

Control Water 1st Swab Water 2nd Swab SDS 1st Swab SDS 2nd Swab

Tota

l DN

A Yi

eld

(ng)

Nylon Swab

Cotton Swab

0.130 ng of DNA collected with the 2nd nylon swab / SDS

Data presented as mean ± SE, N = 3. * denotes significantly higher DNA yields from 4N6FLOQSwabsTM than from cotton swabs and different swabbing solutions, based on ANOVA test. P value of less than 0.01.

Page 28: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

3. Double Swab Technique: Hypothesis

SDS (detergent) loosens more sample from the surface

Nylon swabs’ design allows for maximum uptake and release

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Water 2nd Swab SDS 2nd Swab

Tota

l DN

A Yi

eld

(ng)

Nylon Swab

Cotton Swab

Data presented as mean ± SE, N = 3. * denotes significantly higher yields than water, based on independent samples t-test. (a P value of less than 0.01).

Page 29: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

4. SDS Volume Optimization

Lots of residual liquid left behind when 50 µL SDS used.

What is the ideal SDS volume that leaves no residual liquid but allows for high sample collection?

Nylon swab with 2% SDS as a swabbing solution, Dagmar Sweeney, McCrone Research Institute

Page 30: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

4. SDS Volume Optimization: Materials

Ceramic tile soaked in 10% bleach for 30 min, rinsed with water, autoclaved, air dried, and UV irradiated for 20 min on each side

Fresh saliva collected and mixed with TE buffer in 1:200 ratio

Swabbing Solution

2% Sodium Dodecyl Sulfate (SDS)

Applicator

Copan Nylon Swabs

Page 31: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

4. SDS Volume Optimization: Methods

50 µL of saliva / TE solution applied on the marked ceramic tile

50 μL of saliva/TE solution directly on the control swab (N=3)

Saliva deposits allowed to dry overnight

Swabs moistened with 5, 10, 25, and 50 µL of 2% SDS and

passed 50x over dried saliva deposits (N=3)

Page 32: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

4. SDS Volume Optimization: Methods

Swabs extracted immediately

PrepFiler® Forensic DNA Extraction Kit (Applied Biosystems)

Automate Express™ DNA Extraction System (Applied Biosystems)

Quantitation

Quantifiler® Trio DNA Quantification Kit (Applied Biosystems)

7500 Real Time PCR System (Applied Biosystems)

Page 33: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

4. SDS Volume Optimization: Results

0

0.5

1

1.5

2

2.5

3

3.5

Control 5 10 25 50

Tota

l DN

A Yi

eld

(ng)

2% SDS Volume (µL)

Less SDS Volume = Higher DNA Yield

Data presented as mean ± SE, N = 3. ANOVA test was performed to compare average total DNA recovery from 4N6FLOQSwabsTM with various SDS volumes. * denotes significantly lower yields than 5 μL, based on independent samples t-test, P value of less than 0.01.

Page 34: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

4. SDS Volume Optimization: Hypothesis Less SDS volume used to

moisten nylon swabs increased DNA yield

5 μL and 10 μL: Only tip of the swab was moistened - enough to wet a sample area – dry fibers collected remaining liquid

25 μL - 50 μL: Nearly the whole swab was wet – no dry fibers to collect remaining liquid

4N6FLOQSwabs™ release samples even with soft pressure

Nylon fibers from 4N6FLOQSwabs™ stored at 24˚C with 2% SDS as a swabbing solution (40 x magnification), Dagmar Sweeney, McCrone Research Institute

Page 35: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

5. Sample Collection from a Porous Surface

Questions:

How does 4N6FLOQSwabs™ compare to cotton swabs on porous surface?

Is there any significant difference between 2% SDS and water on porous surface?

Cotton fibers from a cotton swab stored at 24˚C with 2% SDS as a wetting agent (40 x magnification), Dagmar Sweeney, McCrone Research Institute

Page 36: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

5. Sample Collection from a Porous Surface: Materials

Thin cloth soaked in 10% bleach for 30 min, rinsed with water, autoclaved, air dried, and UV irradiated for 20 min on each side

Fresh saliva collected and mixed with TE buffer in 1:200 ratio

Swabbing Solutions

2% Sodium Dodecyl Sulfate (SDS)

Deionized Water

Applicators

Copan Nylon Swabs

Pur-Wraps® Sterile Cotton Tipped Applicators

Page 37: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

5. Sample Collection from a Porous Surface: Methods

Cloth was elevated from the surface

50 µL of saliva / TE solution applied on the marked cloth

50 μL of saliva/TE solution directly on the control swab (N=3)

Saliva deposits allowed to dry overnight

Swabs moistened with 25 µL of swabbing solution and

passed 50x over dried saliva deposits (N=3)

Page 38: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

5. Sample Collection from a Porous Surface: Methods

Swabs extracted immediately

PrepFiler® Forensic DNA Extraction Kit (Applied Biosystems)

Automate Express™ DNA Extraction System (Applied Biosystems)

Quantitation

Quantifiler® Trio DNA Quantification Kit (Applied Biosystems)

7500 Real Time PCR System (Applied Biosystems)

Page 39: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

5. Sample Collection from a Porous Surface: Results

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Control SDS Water

Tota

l DN

A Yi

eld

(ng)

Nylon Swab

Cotton Swab

Significantly more DNA recovered from cotton swabs

Data presented as mean ± SE, N = 3. ANOVA test was performed to compare average total DNA recovery from 4N6FLOQSwabsTM to cotton swabs with different swabbing solutions.

Page 40: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

5. Sample Collection from a Cloth: Hypothesis

Nylon swabs released lots of liquid upon a touch with the cloth surface

Competitive behavior between nylon fibers and cloth porous fibers

0

0.005

0.01

0.015

0.02

0.025

SDS Water

Tota

l DN

A Yi

eld

(ng)

Nylon SwabCotton Swab

Data presented as mean ± SE, N = 3. An unpaired, 2-tailed t-test was performed to compare average total DNA recovery from 4N6FLOQSwabsTM and cotton swabs. * denotes significantly higher yields than nylon swabs based on independent samples t-test (P value of less than 0.05).

Page 41: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

6. Effects of Time and Storing Conditions on DNA Recovery

Questions asked:

DNA degradation?

Bacterial contamination?

4N6FLOQSwabs™ stored at -20˚C with 2% SDS as wetting agent, Dagmar Sweeney, McCrone Research Institute

Page 42: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

6. Effects of Time and Storing Conditions on DNA Recovery: Materials

Saliva collected and mixed with TE buffer in 1:10 ratio

Applicators

Copan Nylon Swabs

Pur-Wraps® Sterile Cotton Tipped Applicators

Page 43: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

6. Effects of Time and Storing Conditions on DNA Recovery: Methods

Swabs moistened with 75 µL of saliva / TE solution

All swabs allowed to air dry

Swabs stored at room temperature (RT) and

freezing temperature (FT) (N=3)

RT - app. 20˚C - 23˚C

FT - app. - 20˚C

Page 44: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

6. Effects of Time and Storing Conditions on DNA Recovery: Methods

Swabs extracted when air dried and after 3 months

PrepFiler® Forensic DNA Extraction Kit (Applied Biosystems)

Automate Express™ DNA Extraction System (Applied Biosystems)

Quantitation

Quantifiler® Trio DNA Quantification Kit (Applied Biosystems)

7500 Real Time PCR System (Applied Biosystems)

Page 45: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

6. Effects of Time and Storing Conditions on DNA Recovery: Results

0

10

20

30

40

50

60

Tota

l DN

A Yi

eld

(ng)

DNA lost after 3 months at RT but not FT

Data presented as mean ± SE, N = 3. ANOVA test was performed to compare average total DNA recovery from 4N6FLOQSwabsTM to cotton swabs under different storing conditions. * denotes significantly lower yields than FT environment, based on ANOVA and independent samples t-test.

Page 46: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

6. Effects of Time and Storing Conditions on DNA Recovery: Hypothesis

Nylon swabs:

Sample embedded close to the surface leads to better DNA recovery but also faster DNA degradation

More sample is lost through handling

Nylon fibers from 4N6FLOQSwabs™ stored at 24˚C with 2% SDS as a swabbing solution (40 x magnification) Dagmar Sweeney, McCrone Research Institute

Page 47: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

STR Profiles

Globalfiler® PCR Amplification Kit (Life Technologies)

Full STR profiles generated using GeneMapper® ID-X 1.4

All tested samples provided full STR profiles

Page 48: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

STR Profiles

Page 49: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Project Continuation

Continue to observe effects of time and storing conditions on DNA recovery

Effects of time and storing conditions on DNA recovery when detergent is used

Examine other surfaces (jeans, leather, brick, wood, etc.)

Set up ideal conditions for sample collection (swabbing solutions, swabbing solution volume)

Page 50: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Conclusion Pros:

4N6FLOQSwabs™ easy to handle

No razor or scissors needed

Low volume of a wetting agent needed to moisten swabs

Outperforms cotton swabs when low count number DNA samples are collected from a nonporous surface.

Page 51: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Conclusion Cons:

Sample easily released by minor pressure

Transfer or storage containers should be rinsed with lysis buffer before extraction

Competitive behavior between nylon and porous fibers of a porous surface

Nylon fibers from 4N6FLOQSwabs™ (40 x magnification) Dagmar Sweeney, McCrone Research Institute

Page 52: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

Acknowledgments

Forensic Science Program, University of Illinois at Chicago

Thermo Fisher Scientific / Life Technologies

McCrone Research Institute, Chicago

Page 53: A Comparative Study of 4N6FLOQSwabs™, Cotton Swabs, and Swabbing Solution

References Anna Dadhania, Daniele Podini. Cotton Swabs vs. 4N6FLOQSwabs™: A Comparative Study

for Optimal DNA Recovery FROM Crime Scene Samples. Life Technologies 2013.

B.C.M. Pang *, B.K.K. Cheung. Double swab technique for collecting touched evidence. Legal Medicine 2007; 9: 181-4.

C. Lenz *, L.R. Flodgaard, B. Eriksen, N. Morling. Retrieval of DNA and genetic profiles from swabs taken inside cars. International Congress Series 2006; 1288: 595–7.

Graham Williams*, Manohar Pandre, Waseeh Ahmed, Emma Beasley, Emma Omelia, Damian World and Holly Yu. Evaluation of Low Trace DNA Recovery Techniques from Ridged Surfaces. J Forensic Res 2013, 4:4.

Sarah M. Thomasma,1 M.S. and David R. Foran,2 Ph.D. The Influence of Swabbing Solutions on DNA Recovery from Touch Samples. J Forensic Sci, 2013, 58, 10.1111/1556-4029.12036.

Robert O’Brien, Debra Figarell. Swab Collection Study. National Institute of Justice 2012.


Top Related