Ion storage techniques and time-of-flight mass spectrometry in physical forensic science

The article highlights the reasons for growth in forensic science sector, the problems faced by it and the methods which can be implemented to overcome the obstacles.

It talks about need for focusing on the consumer as well as a growing need for training and education.

New developments especially in the field of biometrics and chemistry has enable forensic science to provide more concrete and reliable information to the investigators. 

Advancement in technology is changing the role of forensic science. Earlier it was cast in a supporting role but now it is set to become the play-maker in many types of investigations. 

In all, new insights, technologies and increasing awareness has initiated a transition in the forensic science sector.

Investigation process involves combination of various parameters that will lead the investigation to the accused.

Forensic Science is a key tool in the hands of investigator that decodes the primary evidence. It employs scientific techniques that translates the findings into information that has evidential value.

Investigation process involves combination of various parameters that will lead the investigation to the accused.

Forensic Science is a key tool in the hands of investigator that decodes the primary evidence. It employs scientific techniques that translates the findings into information that has evidential value.

* In what way technology has influenced forensic science?

In the past, the analysis of criminal cases was done mostly with the help different chemical and a few physical methods. But today the forensic scientists use high-tools at their disposal for analyzing evidences. Foe example: today most of the police departments use computerized crime mapping and electronic information systems

Describes an ion storage trap/time-of-flight mass spectrometer (IS/TOE-MS) for performing real-time monitoring of volatile and semivolatile compounds in air. We selected this approach because the IS/TOF-MS combination is capable of providing both fast analysis and sample preconcentration needed for trace-air analysis. Specifically, the IS, which serves as the pulsed extraction source for the TOF-MS, can also be used to preconcentrate target chemicals to lower detection limits. TOE/MS provides for real-time monitoring whereby an entire mass spectrum typically can be produced in less than 100μs. Given the relatively long storage-time capability of the IS (i.e., 10 ms to rather than 1 s), the IS/TOF-MS system achieves a duty cycle that approaches 100%. The transmission efficiency in the IS/TOF-MS is equally as high because the entire ion population accumulated in the IS device can be extracted toward the TOF/MS. The theory and operation of the IS as a pulsed extraction source for TOF-MS analysis of VOCs is discussed and the instrument's performance is evaluated

and also from some google websites

How are spectra used in forensic science?

Author: William J. Tilstone, Kathleen A. Savage, and Leigh A. Clark

Place: National Forensic Science Technology Center in Largo

Year of Publication: 2006

Author: K. Lee Lerner, Brenda Wilmoth Lerner

Place: Harvard University

Year of Publication: 2006

2.

http://www.fsijournal.org/

I then searched for techniques important for forensic science and came across DNA Fingerprinting

Forensic science is a very useful tool in solving crime cases. It does not simply deal with circumstantial evidence. It can help solve a case which is not leading anywhere with a simple test, like the recent Sheena Bora murder case. And new innovations and reforms in forensic science will help in improving security as well as solve domestic, immigration and conservation issues.

Technology in focus: DNA Extraction

Application of the technology: DNA fingerprinting

Alternative: Personal microbiomes as fingerprints

2. Atomic Absorption Spectrometry-

The ability to identify and accurately measure small amounts of a particular chemical element.

3. Forensic Toxicology- It is analysis of blood and tissue samples which is used to detect presence of drugs, alcohol and it is mostly related to pharmacology and pathology.

4. Forensic ballistics fIngerprinting - These are the technique that rely on marks that firearms leave on bullets to match a bullet to the gun it was fired with.

5. Lumicyano- A new product with which  police can highlight fingerprints using fluorescence and do so more quickly, with lower overall costs, than the more tedious and time

2. Forensic Archaeology: In Forensic archaeology we can date items found in grave sites, including bones, using a range of techniques. Carbon dating can determine whether the grave site is recent or ancient. It is closely related to forensic anthropology.

Q.2) Are you aware of the advantages of this technique?

Q.3) Do you think that this technique can have other applications apart from criminal investigation?

Q.4) Are you aware of the procedure of DNA Fingerprinting?

Q.5) Will you volunteer to have your DNA Fingerprinting done?

Q.6) Considering its unique feature, do you feel that state agencies should have this database of every citizen?

Q.7) If it consitutes foolproof evidence are there any chances of its misuse by investigation agencies

1.page 10, line 6: underpinning-a set of ideas, motives, or devices which justify or form the basis for something.

2.page 22, 5th last line: cross jurisdictional

3.page 27, 2nd last line: perpetuate-make (something) continue indefinitely.

I also found some new terms in the DNA Fingerprinting article.

1.Oligonucleotide-a polynucleotide whose molecules contain a relatively small number of nucleotides.

2.Multilocus-Multilocus sequence typing (MLST) is a technique in molecular biology for the typing of multiple loci. 

3.High stringency hybridization- refers to conditions during hybrization procedure

4. Short tandem repeats- A short tandem repeat is a microsatellite, consisting of a unit of two to thirteen nucleotides repeated hundreds of times in a row on the DNA strand. STR analysis measures the exact number of repeating units.

5. Allelic-one of a pair of genes that appear at a particular location on a particular chromosome and control the same characteristic, such as blood type or colorblindness

2. Criminal Identification and Forensics
DNA isolated from blood, hair, skin cells, or other genetic evidence left at the scene of a crime can be compared, through VNTR patterns, with the DNA of a criminal suspect to determine guilt or innocence. VNTR patterns are also useful in establishing the identity of a homicide victim, either from DNA found as evidence or from the body itself.

3. Personal Identification
The notion of using DNA fingerprints as a sort of genetic bar code to identify individuals has been discussed, but this is not likely to happen anytime in the foreseeable future. The technology required to isolate, keep on file, and then analyze millions of very specified VNTR patterns is both expensive and impractical. Social security numbers, picture ID, and other more mundane methods are much more likely to remain the prevalent ways to establish personal identification.

CONCLUSION

Twenty years after the development of DNA fingerprinting, DNA analysis remains the key to linking suspects to biological evidence and to identifying individuals in crimes and disasters. Another important use is the establishment of paternity in custody and child support litigation. DNA profiling is used to diagnose inherited disorders and human diseases.

The list of additional uses for DNA fingerprinting continues to grow. For example, DNA markers have proven to be powerful in the study of population genetics. Molecular markers are used to detect sudden changes in populations, effects of population fragmentation, and interaction of different populations.

6- autoionization

Formation of an ion when an atom or molecule in a discrete state with an internal energy greater than the ionization threshold loses an electron spontaneously without further interaction with an energy source. 7. auxiliary gas Gas used in a spray ion source in addition to the nebulizing gas to aid in solvent removal.

8. average mass Mass of an ion or molecule weighted for its isotopic composition. 9. axial ejection Ejection of an ion from an ion trap in a direction parallel to the longitudinal axis of the trap. 10. axialization Technique used in Fourier-transform ion cyclotron resonance mass spectrometers to limit the translational motion of the trapped ions so that they occupy a small volume near the trap center, thus optimizing performance criteria including resolving power. 11. background mass spectrum Mass spectrum observed when no analyte is introduced into the mass spectrometer. 12. base peak (BP) Peak in a mass spectrum that has the greatest intensity. Note: This term may be applied to the mass spectra of pure substances or mixtures. 13. base peak chromatogram (BPC) base peak ion chromatogram Chromatogram obtained by plotting the signal of the ions represented by the base peak detected in each of a series of mass spectra recorded as a function of retention time.

1. Kuster B. et al. (2005) Scoring proteomes with proteotypic peptide probes. Nat Rev Mol Cell Biol. 6, 577-83.
2. Mallick P. and Kuster B. (2010) Proteomics: A pragmatic perspective. Nat Biotechnol. 28, 695-709.
3. Willard H. H. (1988) Instrumental methods of analysis. Belmont, Calif.: Wadsworth Pub. Co. xxi, 895pp.
4. Finehout E. J. and Lee K. H. (2004) An introduction to mass spectrometry applications in biological research. Biochem Mol Biol Educ. 32, 93-100.
5. Chowdhury S. K. et al. (1990) Electrospray ionization mass spectrometric peptide mapping: A rapid, sensitive technique for protein structure analysis. Biochem Biophys Res Commun. 167, 686-92.
6. Fenn J. B. et al. (1989) Electrospray ionization for mass spectrometry of large biomolecules. Science. 246, 64-71.
7. Barber M. et al. (1981) Fast atom bombardment of solids as an ion source in mass spectroscopy. Nature. 293, 270-5.
8. Bakhtiar R. and Tse F. L. (2000) Biological mass spectrometry: A primer. Mutagenesis. 15, 415-30.
9. Hoffmann E. d. and Stroobant V. (2001) Mass spectrometry : Principles and applications. Chichester ; New York: Wiley. xii, 407pp

7) What is the difference between stable, unstable and 

metastable  ions in mass spectrometry?

11)What is the difference between ionization energy (IE) and 

appearance energy (AE)?