4. Discussion

Key findings
The results obtained showed that the control and all the cloth that contained iron (II) sulfate in all three solutions that reacted with the luminol glowed. This proves what  Cheyne, M. (2011) mentioned which was that luminol is extremely sensitivity and can encompass blood which has been diluted through clean-up attempts. Bleach and detergent also glowed without iron (II) sulfate. Bleach glowed brightly while detergent glow is very dim. Based on a research done by Creamer et al. (2003), commercial bleach (NaClO), produces a sufficiently intense chemiluminescence with luminol reaction to be easily mistaken as blood, but the detergent he tested on (lemon-scented dishwashing liquid, washing detergent) produced no detectable chemiluminescence. This would mean either not all detergent gives a false result or there was a flaw in our experiment.

The only test that gave a negative result was test 7 which contained only soap.
Nilsson A. (2006) also tested on soap for chemiluminescence and it also gave a negative result..

The soap and the detergent also affected the brightness of the glow in test 2 and test 3. In Fig 3, Table on Brightness of the Glow, it shows that the brightness of the glow in the control was 5, but in test 2 and test 3 the brightness was 3. This result is similar to Cameron’s (2012) experiment where the detergent also lessen the reaction strength.

Explanation of key findings
This means that luminol always gives a positive result when there is “blood” present as it has detected “blood.” When there is no “blood”, the cloth that was soaked in bleach and detergent came out positive and the cloth soaked in soap came out negative. This means that bleach and detergent will react with luminol whether the “blood” is present or not and thus, bleach and detergent give a false result and might affect the results during a real crime scene investigation.

 Bleach and detergent contains an activating oxidant that will have a chemical reaction with luminol. The basic idea of luminol is to reveal these traces with a light-producing chemical reaction between several chemicals and haemoglobin (an oxygen-carrying protein). The molecules break down and the atoms rearrange to form different molecules. In this reaction, the reactants have more energy than the products and the molecules get rid of the extra energy in the form of visible light photons. This reaction or process is known as chemiluminescence  (Harris, T. 2002, June 11).

Evaluation of hypothesis
Our hypothesis is wrong. Our hypothesis was that only bleach, out of the three cleaning solutions, would react to luminol, thus giving a false result. The detergent that was used also reacted with luminol and glowed very dimly thus it might affect what is recorded during a real crime scene investigation. Therefore, the hypothesis is wrong as both bleach and detergent can give false results.

 Areas for improvement
The possible errors made were that the droppers might not have been cleaned properly, thus this could have affected the results. The piece of cloth that was used to test on was not equal in size, it would be better if it was the same size to increase accuracy. The area where the iron (II) sulfate and luminol were ‘dropped’ on was not the same and this might have affected the experiment. These mistakes could have been avoided if the cloth was measured properly (the cloth can be stretched) before it was cut and not assume the measurement given was right.

It is recommended that the equipment that are going to be used is clean and it would be best if the cloth can be measured properly before cutting even though the measurement was given so that it can be exactly the same size. Also, ensure that the amount of luminol used for each drop and experiment is the same. It is also good to take labeled pictures and videos and compile them right away.