Evaluation of successive DNA extractions from different types of swabs Ella Pickell1, Charlotte Arsenault2, Georgiana Gibson-Daw2, Deborah S.B.S. Silva1 1
2
Chemistry Department, Hofstra University, Hempstead-NY, 11549, USA Department of Arts and Sciences, Western New England University, Springfield-MA, 01119, USA
INTRODUCTION Once a sample is collected, the DNA is extracted and it can often yield low DNA amounts, which may not be enough for use in different DNA tests. In order to increase the DNA yield, the swab should go through the extraction process multiple times. The goal of this study was to investigate the success rate of obtaining good DNA yields from previously extracted swabs.
RESULTS Table 1. Percent Recovery of DNA from Swabs Swab Information Sample Type
Swab Type
Percent Recovery Spin Basket Use
1st Extraction
2nd Extraction
3rd Extraction
4th Extraction
Extractions 2-4
82.934
16.976
0.080
0.059
Each Extraction
93.505
6.184
0.225
0.086
Extractions 2-4
67.955
26.607
4.046
1.393
Each Extraction
73.594
18.126
4.721
3.559
Extractions 2-4
75.992
19.656
3.033
1.319
Each Extraction
96.817
2.751
0.256
0.177
Extractions 2-4
74.370
23.510
1.965
0.156
Each Extraction
89.371
7.473
2.815
0.340
Flocked
METHODOLOGY Reference
Reference sample
Cotton
Flocked swab
Spin basket each
Cotton swab
Spin basket 2-4
Spin basket each
Flocked Case
Spin basket 2-4
Cotton
Case-type sample
Flocked swab
Table 2. Profile recovery of 144 total extractions Swab Type
Cotton swab
Spin Basket Use
46/48 complete profile Flocked
with & without
Cotton
with & without
Flocked
with & without
Reference Spin basket each
Spin basket 2-4
Spin basket each
Profile Information
Spin basket 2-4
2 - 4th extraction: drop-outs 24/24 complete profile 20/24 complete profile
Sample collection
DNA extraction
Quantification
PCR
CE
4 - 4th extraction: drop-outs & drop-ins 10/12 complete profile
with out
Case Cotton
2 - 4th extraction: drop-outs 6/12 complete profiles
with
6 – 2nd, 3rd, 4th extraction: drop-outs & drop-ins