This text is focussing on the effectiveness of oxidizing reagents in removal of blood stains. Adjustments, amendments, and concealing of the crime evidence have resulted in an increment in the world’s crime rate. One such recurring hindrance can be seen with the most vital forms of evidence; bloodstains. Bloodstains are considered to be one of the most difficult stains to remove and even after cleaning them off the clothes through the detergents available in the market, there are some colored traces left which do not disappear completely and can be detected.
Forensic scientists use luminol to detect bloodstains which when reacted with iron in blood stains exhibit chemiluminescence. This led to thinking of to what extent were these criminals able to manage the escape by washing the stains and hinder the evidence. After researching about the detergents from journals and websites like "The Science of Stain Removal, Study of Oxyper- H2O2, and Study of sodium perborate" and also studying the effect of various compounds present in them, it was found out that the active oxygen reagents were the sources through which bloodstain removal was possible. This helped in framing a research idea: To what extent does the change in mass of the oxidizing reagent, sodium perborate, sodium percarbonate and hydrogen peroxide found in detergents is effective in removing bloodstains, measured by spectrophotometric analysis of change in chemiluminescence intensity of luminol due to the oxidation of ferrous to ferric ions in stock solution containing oxidizing agents and iron solution imitating blood at room temperature (30°C)? In this essay, the correlation between the removal of the stains and the extent to which it depends on the amount of reagent was measured.
The decrease in chemiluminescence signifies the extent to which the stains are removed. On this basis, the cleansing action of various oxidizing agents like hydrogen peroxide, sodium perborate, and sodium percarbonate was compared. Seeing the competence of the strongest oxidizing reagent, it can be considered that this research will be useful for forensic science departments to detect the extent to which evidence was tried to be concealed as all the oxidizing agents contain H2O2 and even after washing the clothes, some content of H2O2 is left. It will also be valuable for the detergent manufacturers because, through this research, they will opt for a better oxidizing agent to yield a better cleansing action.
Table of Contents
1. Topic
2. Introduction
3. Background information
3.1 Oxidizing reagent
3.2 Mechanism and Detection of Chemiluminescence
4. Research Variables
5. Expectation
6. Chemicals required
7. Apparatus required
8. Cautionary Principles
9. Methodology of Experimentation:
9.1 Preparations of the chemicals
Synthesizing of luminol stock solution
Preparation of Iron stock solution imitating blood
Synthesis of sodium per borate monohydrate
Preparation of 3% H2O2
9.2 Using the spectrophotometer
10. Qualitative analysis
11. Data collection and Graphical analysis
11.1 Absorbance pattern shown by 0.1g of the reagents in visible light region
11.2 Absorbance pattern shown by 0.2g of the reagents in visible light region
11.3 Absorbance pattern shown by 0.3g of the reagents in visible light region
11.4 Absorbance pattern shown by 0.4g of the reagents in visible light region
11.5 Absorbance pattern shown by 0.5g of the reagents in visible light region
12. Explanation of results and discussion
13. Evaluation
14. Conclusion
15. Limitations and improvements
16. Future scope and Extension
Research Objective & Topics
The research investigates the efficacy of varying masses (1–5g) of three common oxidizing agents—sodium perborate, sodium percarbonate, and hydrogen peroxide—in removing simulated bloodstains. The study utilizes spectrophotometric analysis to measure changes in the chemiluminescence intensity of luminol, which serves as an indicator for the oxidation of ferrous ions to ferric ions, thereby quantifying the effectiveness of stain removal.
- Comparison of oxidizing potential among sodium perborate, sodium percarbonate, and hydrogen peroxide.
- Application of spectrophotometry to detect chemiluminescence intensity changes.
- Evaluation of detergent components like sodium silicate and sodium carbonate in cleansing performance.
- Correlation between reagent mass and the oxidative removal of blood-related iron pigments.
Excerpt from the Book
3.2 Mechanism and Detection of Chemiluminescence
H.O. Albrecht discovered Luminol (technically 5-Amino-2, 3-dihydro-1, 4-phthalazinedione) 12. When blood (containing hemoglobin) and luminol mixture (containing H2O2) come in contact, hemoglobin initiates an oxidation reaction between luminol and hydrogen peroxide. 13 During this reaction, luminol undergoes oxidation by gaining oxygen atoms and losing nitrogen atoms and hydrogen atoms forming an energized compound 3-aminophthalate. In it, the electrons of oxygen atoms jumps to higher orbital which when fall back into lower energy state emit photons producing blue light. This exhibits the chemiluminescence property of luminol14.
Summary of Chapters
Topic: Defines the research area focusing on the effectiveness of oxidizing reagents in removing bloodstains.
Introduction: Outlines the problem of residual bloodstains in criminal evidence and the chemical potential of detergents to remove these traces.
Background information: Explains the chemical properties of oxidizing agents like sodium perborate and the chemiluminescence mechanism of luminol.
Research Variables: Defines the independent, dependent, and controlled variables used throughout the experimental procedure.
Expectation: Hypothesizes that increasing the mass of oxidizing reagents will improve stain removal, measurable by decreased chemiluminescence.
Chemicals required: Provides a comprehensive inventory of all materials and reagents used in the laboratory trials.
Apparatus required: Lists the specific laboratory equipment utilized for the synthesis and measurement processes.
Cautionary Principles: Details the safety measures taken to handle reactive chemicals and minimize measurement errors.
Methodology of Experimentation: Describes the step-by-step chemical preparation of luminol, iron solution, and the reagents.
Qualitative analysis: Documents preliminary observations, such as color changes and fizzing, during the mixing of chemicals.
Data collection and Graphical analysis: Presents the raw data and calculated results for absorbance patterns across different mass increments.
Explanation of results and discussion: Analyzes the linear trends observed between reagent mass and absorbance, interpreting the oxidizing effectiveness.
Evaluation: Critically reviews the methodology, noting the role of auxiliary compounds like sodium silicate in yielding credible results.
Conclusion: Summarizes findings, confirming that sodium perborate demonstrates the highest oxidizing strength among the tested agents.
Limitations and improvements: Reflects on potential experimental weaknesses and suggests methods for future optimization.
Future scope and Extension: Proposes wider applications of the research in forensic investigations and the testing of additional compounds.
Keywords
Bloodstains, Oxidizing reagents, Luminol, Chemiluminescence, Spectrophotometry, Sodium perborate, Hydrogen peroxide, Sodium percarbonate, Hemoglobin, Forensic science, Stain removal, Oxidation, Absorbance, Ferrous ions, Detergents.
Frequently Asked Questions
What is the primary focus of this research?
The work investigates how different masses of specific oxidizing agents in detergents affect their ability to remove bloodstains, analyzed through the chemiluminescence of luminol.
What are the central themes explored?
The study centers on chemical oxidation, spectrophotometric analysis of light absorption, and the forensic application of these findings in evidence examination.
What is the core research question?
The study asks to what extent varying the mass (1–5g) of sodium perborate, sodium percarbonate, and hydrogen peroxide affects the removal of iron-containing blood pigments, as measured by luminol chemiluminescence intensity.
Which scientific methodology is employed?
The research uses quantitative experimental trials involving the synthesis of reagents and the measurement of light absorbance using a spectrophotometer set to 428nm.
What is addressed in the main body of the work?
The main body covers the theoretical background, detailed experimental protocols for chemical preparation, data collection across multiple trials, and a thorough comparative discussion of the results.
Which keywords characterize this paper?
Key terms include bloodstains, oxidizing reagents, luminol, chemiluminescence, spectrophotometry, and forensic science.
Why was luminol used in this experiment?
Luminol was chosen because it reacts specifically with the iron in hemoglobin to produce a blue chemiluminescence, allowing the researchers to quantify the remaining iron content after treatment with different detergents.
Which oxidizing reagent was found to be most effective?
The study concluded that sodium perborate exhibited the highest oxidizing strength, followed by hydrogen peroxide, with sodium percarbonate being the least effective.
How did the mass of the reagent influence the results?
The experiment established a positive, linear trend showing that increasing the mass of the oxidizing agent increases the oxidation of ferrous ions, thereby reducing chemiluminescence and increasing light absorbance.
Why are sodium silicate and sodium carbonate included?
These compounds were added as complementary ingredients to prevent mineral sedimentation and avoid bonding issues with hard water, ensuring more credible and consistent experimental results.
- Quote paper
- Ishita Bharadia (Author), 2019, Effectiveness of oxidizing reagents in removal of blood stains, Munich, GRIN Verlag, https://www.grin.com/document/456043
