Chemistry Forensic Study Cards

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|Ensuring accuracy and contamination of samples for analysis – 1a and 1A |Ensuring accuracy and contamination of samples for analysis – 1a and | | |1A (continued) | |Caution must be taken by scene investigators with regard to their tools, | | |clothing and evidence storage facilities, since debris can lead to false |All scientific analyses must be accurate and reproducible, hence all | |positive results if it has been contaminated by dirty tools or gloves. |instruments used to examine samples must be well calibrated and | | |measurements of standards and controls used to ensure accuracy of | |Discuss the following precautions: |sample analysed. | |Wearing overalls, hair covering, masks, shoe covers to prevent contamination. | | |Samples placed in sterile sealable bags/containers using sterile forceps. |Example: Urine analysis in drug testing: | |Laboratories used for forensic examination must be sterile, with absolutely | | |minimal chance of contamination. |Analytical tools/techniques used must demonstrate excellence. | |A lack of sample security and poor laboratory practices can reduce reliable |All instrumentation must be calibrated and monitored consistently to | |evidence to “reasonable doubt” |ensure reliability. | | |All standards used must be prepared using accurate techniques and | | |controls used and reproduced to ensure consistency. | | | | | |The forensic chemist must verify chain custody for each sample | | |analysis and document the techniques employed and data collected. | | |They must be prepared to defend their work in legal hearings and | | |trials. | |Organic and inorganic compounds – 1b |Different classes and tests for carbon compounds – 1c and 1E | |Organic (carbon) compounds are compounds, which contain mainly carbon and | | |hydrogen, but may also contain smaller quantities of oxygen, nitrogen, sulfur, |Carbon compound class | |phosphorus and other elements. |Functional group | |Commonly found or derived from living things: glucose, amino acids, starch and |Distinguishing test | |ethanol. Chemists can also synthesise many organic substances in the |...
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