The M-Vac forensic DNA collection system is rapidly gaining recognition and notoriety as an efficient and highly sought after tool to collect better forensic DNA profiles and to help solve crime. As a relatively new system there are numerous questions about everything from how the system works to how does the operator avoid cross contaminating samples. Below are a number of the frequently asked questions about the M-Vac and how it is currently being used by both law enforcement agencies and forensic labs. If you have additional questions feel free to contact us here.
1 – Why would I use the M-Vac® instead of swabs or taping?
- Rough or porous surfaces
- Large surfaces
- Insufficient DNA
- Touch DNA, contact DNA or LT-DNA
- Failed or inconclusive results from traditional sampling
- Success starts with a good sample
2 – What about “Touch DNA”? Touch DNA, contact DNA or DNA material (usually epithelial cells) that has been deposited by the perpetrator by grabbing, touching or pressing up against an object, is an area where the M-Vac® System works well. When compared to swabbing, taping and cutting, it consistently collects more DNA material. The M-Vac® System’s ability to collect from the top surface and in the cracks and crevices of the evidence helps retrieve trace amounts of DNA material. A number of investigators are finding success where before there was little hope in generating a DNA profile.
3 – What biological materials can be collected?
The M-Vac® system collects epithelial cells (touch, saliva & urine), blood and seminal fluid (sperm). It simply collects the cells from the collection surface.
4 – What if traditional collection methods have already been used on an item?
The M-Vac® is a valuable tool in those scenarios and can often result in conclusive profiles even after traditional methods have been used and yielded inconclusive or partial profiles. It gives cases a second chance.
5 – Since the M-Vac® is so proficient at collecting DNA material, won’t it collect DNA that is not pertinent to the case?
It simply collects more of what is there. No method only collects the DNA material that is pertinent to the case. The tip of the swab is not sorting out which cells to collect. All of the methods simply collect from the evidence using their collection mechanism. Each method has advantageous and disadvantageous that need to be considered with each piece of evidence.
6 – Will the M-Vac® lead to inconclusive mixtures?
If a piece of evidence has a mixture of low-level DNA on it and a swab were to be used, it would often yield an inconclusive partial mixture. The M-Vac® unit’s advantage is it collects more of what is there. Why does that help? There have been a number cases where traditional methods, like swabbing, have yielded inconclusive mixtures and subsequent M-Vac® collections have resulted in conclusive major/minor profiles that helped move the case forward. It simply collects more DNA material and is a better representation of what is on the evidence.
7 – How is a sample taken?
The wet-vacuum is pulled across the evidence surface. Under the sampling head there is a “mini hurricane” caused by the solution spray and the vacuum forces. The DNA material is dislodged and transported by the solution as the vacuum collects it. The solution along with the DNA material is collected into a sterile bottle.
8 – What is the collection area of the M-Vac or where does it collect?
The M-Vac primarily collects a 1 inch (2.5 cm) wide swath. The picture shown to the right is a single pass down a test plate coated with fluorescent powder. For a little more detail, the entire collection head has a diameter of 1.375 inches (3.5 cm) and some collection occurs on each side of the swath, as seen in the picture.
9 – How small of a collection can I take with an M-Vac?
If the M-Vac is placed on the evidence, turned ON, pulled back a 1/4 inch (0.64 cm) and turned OFF, it will have a primary collection zone that looks like a 3/8 x 1 inch (0.95 x 2.5 cm) rectangle.
10 – How is the collection concentrated?
A 0.45 micron PES filter mounted in a disposable, sterile apparatus is attached to the vacuum of the SEC. The collection bottle is removed from the M-Vac, swirled and poured through the filter. The bottle is rinsed with collection solution or filtrate to ensure that the DNA material is transferred to the filter.
11 – How is the filter processed?
Once the DNA material is concentrated onto the filter material, it is cut into pieces and placed into a microcentrifuge tube, preferably a 2 mL tube. Several different processes can be used to extract the DNA. Qiagen, Chelex and Promega methods have all proven to be successful and popular. To request a full list of latest recommended methods and procedures, click here.
12 – What surfaces can be sampled with the M-vac?
The M-Vac® can be used on almost any surface, including rocks, shirts, pants, cinder blocks, bedding, carpet, gloves, hats, wigs, shorts, panties, sweatshirts, tape, upholstery, ropes, fabric, skin surfaces and many others.
13 – How will the M-Vac sampling system help me find a viable DNA profile?
The M-Vac® “wet-vacuum” collection typically retrieves more DNA material from the surface, it works well on rough and porous surfaces and it can collect from larger surfaces when needed. It simply increases the odds of collecting the DNA material that is available.
14 – What is the solution that is sprayed onto the evidence surface and is it sterile?
The solution consists of lab grade, sterile water with phosphate for stabilization. The solution is produced in a clean room and processed in a way to ensure it is DNA free. It is also gamma sterilized to maintain maximum shelf life.
15 – What prevents cross contamination?
All of the items that come in contact with the evidence are replaced between every collection. It makes a clean break between evidence collections and starts with sterile disposables each time.
16 – How much does the system cost?
A starter package which includes training in the United States costs about $27,500. The specific cost depends on the exact package and the travel associated with the training. If you would like to have a quote, please contact us by clicking here.
17 – What is the maximum sample surface area?
The M-Vac® can sample up to 2 square feet (1860 square cm) per collection bottle. The M-Vac® can sample one larger area or multiple smaller areas. Changing collection bottles is fast and easy, so collecting from a much larger area is possible too.
18 – How far away from the system can I take a sample?
Samples can be collected up to 60 feet away from the main unit (SEC).
19 – Is the system portable?
Yes, the SEC unit comes with a wheeled cart to facilitate movement to multiple sampling locations including evidence sampling in a lab or at the police station as well as at a crime scene. It can operate from a wall outlet or from a generator in a mobile application.