Forensic Chemistry and Toxicology PDF

**FORENSIC3: INTRODUCTION OF FORENSIC CHEMISTRY AND TOXICOLOGY** **Forensic** denoting the application of scientific methods and techniques to the investigation of crime. **Chemistry** is a branch of science that deals with the study of matter, phases it undergoes, and energy that accompanies in e...

**FORENSIC3: INTRODUCTION OF FORENSIC CHEMISTRY AND TOXICOLOGY** **Forensic** denoting the application of scientific methods and techniques to the investigation of crime. **Chemistry** is a branch of science that deals with the study of matter, phases it undergoes, and energy that accompanies in every changes. **Forensic chemistry** is the analytic study of substances that could easily be misidentified or confused, and finding their identity. **Forensic chemists** analyze the physical and chemical properties of different materials in order to identify them correctly where one or more materials may have similar properties.(who practices forensic) **Explosives** - any substance that may cause an explosion by its sudden decomposition or combustion. **CLASSIFICATION OF EXPLOSIVES** 1.View point of chemical composition 2\. With respect to functioning characteristics **[HAIR AND TEXTILE FIBERS]** Hair examination is one of the oldest forms of physical evidence. It is used older that of fingerprints. It is valuable because the hair of each kind of animal is different and distinct from all others. Like fibers, it is most likely to be involved in contact between the victim and suspect. Most crimes causes contact between one person and another. As such, it results in the transfer of fibers and hairs from the victim to the criminal and vice versa. The successful investigation of crimes of violence such as rape, murder, assault, kidnapping, as well as hit and run, among others, are frequently materially assisted by the result of examination of hair and fibers. **Hair is very resistant in decomposition and purification**, thus they often remain as a means of identification long after others such as facial and fingerprints have been destroyed. **Hair** - a specialized epithelial outgrowth of the skin which occurs everywhere on human body except on the palm of the hand and sole of the feet. It is an appendage of the skin. Hair is not completely round but may be oval or flattened. Its width is not always the same along its length. It strays out pointed and narrow and then strays more or less the same. **Kinds of Hair** (Among mammals including human beings) 1\. **Real Hair** - generally long and stiff 2\. **Fuzz Hair** - generally short, fine at all times curly and woody **Parts of Hair** 1\. **Root**-portion embedded in the skin 2\. **Shaft** - portion above the surface of the skin, the most distinctive part of the hair. 3.**Tip**-sometimes termed point, the distal end of an uncut hair. **Microscopic Examination of Human Hair** 1\. Color **Melanin** - the brownish black pigment in the hair and skin, among others, the chemical responsible for the color of hair. 2\. Length by actual measurement 3\. Characteristics of hair 4\. Width 5\. Characteristics of hair tip if present 6\. Manner by which hair had been cut 7\. Condition of root or base or bulb of the hair 8\. **Characteristics of cuticle**- the size, general shape and the irregularity of the scale are observed. 9\. **Characteristics if cortex** - it is embedded with pigment granules that impart hair with color. It is the color, shape and distribution of these granules that provide chemist with important points of comparison between hairs of different individuals. 10.**Presence of Dye in Hair** Dye hair can be distinguished from natural hair. Under microscope, dyed hair has dull appearance and the color tone is constant, whereas natural hair is not and the individual pigment granules stand more sharply. 11.Determination of whether naturally or artificially curled 12.Character of medulla **Medullary Index** - is the relationship between the diameter of the medulla and the diameter of the whole hair. Its determination is performed under microscope provided with micrometer eyepiece. Hair with narrow medulla less than 0.5 belongs to human, hair with medium medulla approximately 0.5 belongs to cows, horses, and others, and hair with thick medulla greater than0.5 belongs to other animals not indicated above. **Comparison between Human Hair and Animal Hair** ------------------------------------------------------------------------- -------------------------------------------- **Human Hair** **Animal Hair** 1\. M.I. is less than 0.5 M.I. more than 0.5 2\. Medulla may not be present Medulla is always present 3\. The scale pattern is fine and each one Overlaps the other more than Scale is coarse and overlaps less than 1/2 4/3 4\. Pigment granules are fine Pigment granules are coarse **Region of the Body from which Human Hair has been removed** 1\. **Scalp Hair**-they are more mature than any kind of human hair 2\. **Beard Hair**-coarse, curved, very stiff, and often in triangular in cross section 3. Hair from eyebrows, eyelid, nose, and ear - short, stubby and have wide medulla, eyebrow and eyelashes are usually very short and has a sharp tip 4\. **Trunk hair** - vary in thickness along the shaft and are immature but are somewhat similar to head hairs, they have fine, and long tip ends. 5\. **Limb Hair** - similar o trunk hair but usually are not so long or so coarse and usually contains less pigment. 6\. **Auxiliary Hair** - is fairly long with unevenly distributed pigment. They vary considerably in diameter along the shaft and have frequently a bleached appearance. It has an irregular shape and structure. Looks like pubic hair but the ends are sharper and the hair is not so curly. 7\. **Pubic Hair** - similar to axillary hair but are coarse, and do not appear bleach; more wiry, have more constriction and twist and usually have continuous broad medulla, has many broken ends because the clothing rubs. **Approximate Age of an Individual through Hair Examination** **Infant hairs** - are *fine, short in length, have fine pigment and are rudimentary in character, children\'s hair through adolescence is generally finer and more immature than adult hair but cannot be definitely differentiated with certainty*. It is noted that the pigment is missing or starting to disappear in the hair, it can be stated that the hair is from an adult. It is common for a relatively young person to have prematurely grey or white hair but not body hairs. **Textile Fibers** - fibers that can be converted into yarn **Yarn** - made of fibers which have been twisted together like a thread. **Classification of Textile Fibers** 1\. Natural Fiber 2\. Synthetic or Artificial Fiber **Test for fibers** 1\. **Burning test or ignition test** - is a simple preliminary, microscopic examination, it determines whether fiber is mineral, animal or vegetables. 2\. **Fluorescence test** - used to determine general group to which a fiber belong. It is not reliable for positive identification of fiber. 3\. **Microscopic test** - it is the most reliable and best means of identifying fibers 4\. **Chemical test** **Chemical Test for Fibers** 1\. **Staining Test** - fiber is stained with picric acid, million reagent stannic chloride or iodine solution. 2\. **Dissolution Test** - if fiber is white or light colored it is treated with the following chemicals 10% NaOH, 5 % oxalic acid, half saturates oxalic acid, concentrated oxalic acid, concentrated and diluted ammonium hydroxide and concentrated nitric acid. **Characteristics of Common Textile Fiber** 1\. **Cotton** - unicellular filament, flat, ribbon like twisted spirally to right or left on its axes, central canal is uniform in diameter. 2\. **Mercerized Cotton** - straight, cylindrical with occasional twist; unevenly lustrous, smooth except for occasional transverse folds or wrinkles and cuticle are mostly lacking. 3\. **Linen** - multicellular filament, (straight and cylindrical not twisted and flattened, tapering to a sharp point. The cell wall are thick, the lumen appearing is narrow and dark line in the center of the fibers to appear jointed resembling bamboo. 4\. **Cultivated silk**-smooth cylindrical lustrous thread, usually single but often double, the twin filament held together by an envelope of gum. They are more or less transparent, and without definite structure. 5\. **Wild silk** - similar to cultivated silk but broader and less regular in outline. Mark by very fine longitudinal striation with infrequent diagonal crpss markings. 6\. **Artificial silk**-cylindrical, lustrous, appearing like a glass rod. 7.**Wool** - easily distinguished by the presence of flattened, overlapping epidermal scales not found in silk or any of the vegetables fibers. **[QUESTIONED DOCUMENT]** **Chemical Aspects of Document Examination** **Document** - an original or official written or printed paper furnishing information or used as a proof of something else, it may refer to any object that contains handwritten or type written markings whose source or authenticity is in doubt. **Examination and Comparison of Paper** The essential materials in a document examination of any kind are the paper and ink or pencil or writings. The examination of paper may be necessary if we want to know the age of the document, presence of alterations, erasures, and other forms of forgery. **Problems Encountered in Document Examination** 1.Determination of whether two pieces of paper originated from the same source; 2.Determination the probable age of the paper; 3.Determination of the composition of paper. **Egyptian Papyrus** one of the earliest substance used for writing, derived from the name papyrus from which the paper word derived. **Composition of Paper** 1\. **Fiber Composition** - practically all papers may be classified from the stand point of their basic fiber composition into sets of fiber mixtures namely mechanical pulp, soda-sulfate mixture, and rag sulfate 2.**Sizing Material**- improve the quality of paper (texture) such as rosin, casein, gelatin, and starch.. 3.**Loading Material**- add weight to the paper it partially fill the pores between the fibers of the papers such as calcium sulphate and barium sulphate. **Four Test of Paper** 1\. **Preliminary Examination** deals with the appearance of the document as observed the folds and creases, odor, impression caused by transmitted light and presence of discoloration in daylight and under ultra violet light. **Water Marks** - distinctive marks or designs placed in the paper at a time of its manufacture by a roll usually a dandy roll. **Wire Marks,** marks produced on paper by a flexible wire soldered on the surface of the dandy roll that carries the water marks. 2\. **Physical Test Causing No Perceptible Change** *Test applied on the paper without perceptibly changing or altering the original appearance of the document* (measurement of length and width, measurement of thickness, measurement of weight/unit area, color of paper, texture, gloss, microscopic examination and opacity (the quality of paper that does not allow light to pass through in an object. 3\. **Physical Examination Causing a Perceptible Change** *This is done only when sufficient samples are available and if proper authorization from the court is acquired.* (a.) **Bursting strength test or POP test** apparently pressure necessary to burst a hole in a sheet when properly inserted in suitable instrument (b.) **Folding endurance test** it is obtained on an instrument which registers the number of alternate folds the paper will stand before breaking. (c.) **Accelerated aging test** there are some methods of artificially aging document. Soaking in coffee solution, soaking in tea solution, exposure to charcoal, ironing, heating in an oven, exposure to ultraviolet. (d.) **Absorption test** made to determine either the rate of absorption of the paper. 4\. **Chemical Test** determines the fiber composition, loading material, and sizing material used in the paper **INK** - Some of the most important question arises in the analysis of inks are whether the ink is of the same or alike or different in kind from ink on other parts of the same document or in other document, whether the two writings made with the same kind of ink were made with the identical ink, or inks of different qualities or in different condition, whether an ink is also as old as it is supposed to be and, whether documents of different dates or a succession of differently dated book entries shows the natural variation in ink writing or whether the conditions point to one continuous writing at one time under identical condition. **Types of ink** 1.**Gallotannic ink or iron ink** - the most frequently used ink for making entries in the record of book and for business today, it is made up of iron salt and nutgall this ink penetrate into interstices of the fiber and not merely on the surface 2\. **Loll logwood ink** - made up of saturated solution of logwood and very small amount of potassium dichromate, this ink is inexpensive, does not corrode steel pen. 3\. **Negrosine ink or aniline ink** - made up of coal tar product called nigrosine dissolve in water, it easily smudges, affected by moisture may be wash off from the paper with little difficulty. 4.**Carbon ink or Chinese ink or India ink** - the oldest ink material known, made of carbon in form of lampblack it does not penetrate deeply on the paper so that it may be easily washed off 5\. **Colored writing ink** - composed of synthetic aniline dyestuffs dissolved in water, ammonium vanadate is added to render writing more permanent. 6\. **Ball point ink** - made up of light fast dyes soluble in glycol type of solvent as carbitol, glycol or oleic acid.