A training report in partial fulfillment of the requirements for the award of the Degree of Bachelor of Science in Industrial Chemistry with IT of Maseno University
Table of Contents
Cover page. 4
Page of institution………………………………………………………………………………………….2
CHAPTER ONE.. 6
1.0. Introduction. 7
1.1 Brief description of the organization. 7
1.2 Government Chemists’ Organizational Structure. 7
1.3 Location of the organization. 8
CHAPTER TWO.. 9
2.0 Department 9
2.1 Responsibilities. 9
CHAPTER THREE.. 13
Body of the report 13
3.0FOOD AND DRUGS SECTION.. 13
3.0.2 Afflatoxin. 14
3.0.3 Acidity content 14
3.0.4 Petroleum products………………………………………………………………………………………………………
3.0.5 Moisture content………………………………………………………………………………..
3.0.6 Transfer oil…………………………………………………………………………………….
3.1 DNA/FORENSIC SECTION.. 15
3.1.1 Forensic DNA profiling technique……………………………………………………………
3.1.2 Procedure for calculating paternity test……………………………………………………………………………
3.2 TOXICOLOGY SECTION.. 15
3.2.1 Sample preparation……………………………………………………………………
3.2.2 Organochlorides test………………………………………………………………………….
3.2.3 Organophosphates test………………………………………………………………………….
3.2.3 Carbamates test……………………………………………………………………………….
3.2.5 Drug extraction…………………………………………………………………………………………………..
3.3 CRIMINALISTICS SECTION
3.3.2 Bhang(Cannabis sativa)……………………………………………………………………..
3.3.3 Identification of fake money
3.3.4 Identification of morphine and heroin
3.4 WATER SECTION……………………………………………………………………………….
3.4.1 Bacteriological analysis
3.4.2 Effluent analysis
3.4.3 Physico-chemical analysis
3.4.4 Spectrophotometric analysis
CHAPTER FOUR.. 19
4.0 Experience. 19
4.0.1 Interaction with staff
- 4.1 Challenges faced 19
- 4.2Conclusion. 20
- 4.3 Recommendation. 20
CHAPTER FIVE.. 22
- 5.0 Refferences. 22
- 5.1 Appendices. 22
This report entails all the activities carried out in Industrial training in the Government Chemist Department. The department has five main sections which performs different functions.
Water section deals with bacteriological analysis and physico -chemical analysis of water. The clients of this section are mostly members of the public and industries. Industries bring their effluents for analysis to check that the levels of heavy metals in the effluents are in accordance with the requirements of the Kenya Bureau of Standards (KEBS).
DNA section deals with murder and paternity cases. The clients of this section are majorly police officers. The paternity cases are the cases where the father of the child denies that he is the father and a DNA is carried out to confirm if he is the father of the child. In murder cases the DNA is carried out to confirm whether the accused person is indeed the one who murdered the deceased. The blood samples and clothes of both the accused and the deceased are brought together with the weapon the accused used for example knife to help in getting the DNA profile of the accused and the deceased.
Criminalistic section deals with drug abuse detection. The clients of this section are the police officers. Includes bhang and changaa which are illegal; the police bring them for analysis after arresting people in order to ascertain whether they are indeed bhang or changaa before the accused is jailed. Also for other drugs like cocaine, heroin among others.
Toxicology section deals with mainly post mortem to determine whether the ingested substance the deceased consumed contained poison. The clients of this section are the police officers. The samples of the deceased brought are stomach contents, liver, small intestines and kidney. The samples are plotted against the standards after the extraction in a TLC plate to determine the type of poison.
Food and drugs section mainly deals with arson cases, cases of vandalized transformer oil and to confirm whether the food samples brought are fit for human or animal consumption. The main clients of this section are the police officers and public health officers. Arson cases are carried out to find out the type of accelerant that was used to burn building. For vandalized transformer oil, a test is carried out to check whether the wavelength of the transformer oil sample confirms with that of the actual transformer oil.
Most of the experiments were carried out in accordance to Kenya Bureau of Standards(KEBS) and World Health Organization (WHO) and all the results obtained were drafted and recommendations given in form of a report.
This report is a proof that my attachment has been a success. I was able to put into practice what I learnt in class and also learn some new things during my attachment.
The external Industrial attachment is an essential component curriculum of Maseno University, Department of Chemistry for Bachelors’ Degree of Science in Industrial Chemistry with IT.
It entails practical work which exposes the student in various disciplines and equips the student with knowledge and skills in Industrial chemistry through research, industry, consultancy, teaching and community service.
Industrial attachment is an attempt to expose students to workings of the industry and thus enable them to;
- Familiarize them with industrial organization.
- Practice and enrich their technical skills in the field of industrial Chemistry.
- Appreciate the linkage between theory and practice
- Develop desirable attitudes and work habits in the field of industrial chemistry
The attachment involves supervision by course coordinator to ascertain success of student in the field.
1.1 Description of the organization
The Government Chemist was established in 1923.It was started by British army unit lab which was used as medical research lab.
It is an institution under government which involves biochemical analysis on toxic products that are taken into human body and abnormalities generated by toxic chemicals.
The Government Chemist is managed by ministry of health.It acts as legal referral laboratory.It offers forensic and analytical laboratory services in field of public and environment health in administration of justice.
The Government Chemist takes a huge role in advising to the regulations in various industries and stakeholders who engage in carrying out of research.
To provide quality analytical laboratory services in timely manner
To be the leading provider of laboratory services in western Kenya region
In pursuit of quality services
- To provide a comprehensive analytical and forensic division
- To provide scientific advice based on analytical or forensic and other chemical considerations.
- To provide a timely production of scientific reports in order to enhance speedy dispensation of justice.
|CABINET SECRETARY MINISTRY OF HEALTH|
1.2 Organizational structure
|PARMENENT SECRETARY MINISTRY OF HEALTH|
|DIRECTOR OF MEDICAL SERVICES|
|GOVERNMENT CHEMIST (NAIROBI)|
|GOVERNMENT CHEMIST MOMBASA|
|GOVERNMENT CHEMIST KISUMU|
|OFFICER IN CHARGE|
|HEAD OF SECTION|
|FOOD AND DRUGS|
1.3 Location of the organization
Government Chemists Department is located in Kisumu along Jomo Kenyatta highway, next to Red Cross Office Kisumu
P.O BOX 2006-40100
- Bacteriological water analysis
- Physiochemical analysis of water
- Effluent analysis
- Test alcohol content.
- Identifying different types of drugs.
- Identifying fake money.
Food and drugs section
- To ascertain for poison in food, drinks and other consumable products.
- To check for accelerants in fire incidents i.e. petrol, diesel.
- To ascertain the quality of food, drugs and other consumable products.
DNA/Serology section (forensic)
Extraction and analysis of DNA for various studies;
- Murder cases
- Paternity cases
- Rape cases
Biochemical analysis of toxic products that are taken into human body.
- Receiving samples.
- Ensuring that I observe the laboratory safety and precautions.
- Ensuring cleanliness of lab equipment and lab benches.
- Following the analytical procedures done by the supervisors keenly and working close with them.
- Carrying out analysis of samples and taking the results to the supervisors.
- Help in carrying out calculations for example paternity index.
- Ensuring that working area is clean after analysis
Body of the report.
FOOD AND DRUGS SECTION
The section analyses food, drugs and other industrial substances for either industrial substances for their chemical composition, safety for human consumption and compliance with Kenya Bureau of Standards (KEBS) and other international specifications. Type of samples include: alcoholic and non-alcoholic beverages, cereals and cereal products, cosmetics, and dairy products.
The tests include: Arson case, Aflatoxin test, Acidity content, Petroleum products, Moisture content, Transformer oil, Alcohol.
Arson is a crime of intentionally, deliberately and maliciously setting fire to building and other property. The arsonist is the person who commits this crime uses accelerant such as gasoline, kerosene or diesel, to ignite, propel and directionalize fire.
The samples include; debris, ash, broken windows, left unburnt items which are collected and used as evidence.
Requirements; Erlenmeyer flask, filter paper, ethanol, sample.
Filter paper was folded into an appropriate shape and placed in a filter funnel. A few activated charcoal was added into the filter and the sample added. Ethanol was poured into the sample-extracting the solvent of the accelerant if present. The filtrate was taken to UV-VIS spectrophotometer.
NB: The samples from fire case should be packed in air tight bag, since most accelerants are volatile and thus vaporize upon placing them in khaki bags.
Aflatoxins are poisonous carcinogens that are produced by certain molds Aspergillus flaus and Aspergillus parasiticus which grow in soil, decaying vegetable and grains.
Improperly stored staple commodities, aflatoxin is common. The health hazard as a result of consuming aflatoxin food include; liver damage, liver cancer, stunted growth among others.
Requirements:weighing balance,measuring cylinder100ml,sample,beakers,CHCl3,Na2SO4,silica gel, MeOH, TLC plate, watman paper, deionized water.
The structure of aflatoxin
50g of the sample was measured and placed in a clean dry beaker.250ml of chloroform(CHCl3) ,250ml of water and finally 25g of Celine 545 was added. The contents were wrist shaken for 30minutes.Into the column ,150ml of n-hexane was added ,then 150ml of diethyl ether and 150ml of methanol: chloroform(MeOH:CHCL3).The contents were heated in water bath to dryness and plotted on TLC plate.
The column was prepared by first adding 5g of Na2SO4 followed by chloroform to ¾ of the column.10g of silica gel was added and left to settle for 7minutes.15g of Na2SO4 was added
|50g of the sample|
|250ml CHCl3;25ml H2O;25g Celine powder (wrist shaken for 30min) mmim)|
|1st 50ml fitrate filtrafiltrate|
|20 300mm column;silica gel 0.056-0.2mm10g containing 1g H2O
|N-hexane(150ml) remove fats
Diethyl ether(150ml) pigments
MeOH: CHCl3(3:97 v/v)150ml
Diethylether discard (3:97v/v 150ml)
Concentrate to Dryness for TLC
3.0.3 Acidity content
Most flour comes from milled; millet, wheat grains, rye, barley, rice nuts, pulses. Wheat flour usually has Ph between 6.0 and 6.8. According to Pearson’s chemical analysis of foods, most flour are slightly acidic but close to neutral in terms of Ph. White flour is often bleached using chlorine .Bleached flour has higher pH compared to unbleached ones which has bitter taste.
Requirements; sample(flour), warm water bath, NaOH, filter funnel, filter paper.
200ml of water was heated in heating mantle and then allowed to cool.18g of the sample (flour)was added and placed in water bath at 40oC.The sample was removed and cooled and then filtered.100ml of the filtrate was titrated with 0.05M NaOH.
3.0.4 Petroleum products
Petrochemicals mainly consist of organic compounds obtained by fractional distillation of petroleum. Fuel is majorly used for internal combustion engines used in transport and industry. Gasoline contains benzene and other organics. Spark ignition engines are designed to burn gasoline in controlled process called deflagration.
Requirements; sample, beakers, cuvette, uv-vis spectrophotometer ,ethanol
2C8H18 + 25O2 16CO2 + 18H2O
10ml of the sample was placed in a cuvette. The DR-6000 UV-VIS spectrophotometer was zeroed with ethanol. The sample was then run in the UV-VIS spectrophotometer.
The peaks obtained was compared with ones on the literature to establish its identity.
3.0.5 Moisture content
Moisture content influences the taste, texture, weight and shelf life of foodstuffs. Even slight deviation from a defined standard can adversely impact physical properties of food materials. Materials which are too dry could affect the consistency of the end product.
Requirements; maize floor, analytical balance, petri dish, moisture meter.
Moisture content = (weight of the sample before drying) – (weight of the sample after drying) ×100%
weight of the sample
5g of the sample was accurately weighed and placed in a metallic plate. The sample was heated for an hour in moisture meter. The results were obtained and recorded.
3.0.6 Transformer oil
Transformer oil is an insulating oil that is stable at high temperature and has excellent electrical insulating properties.
Requirements: sample, two beakers, cuvette, ethanol, uv-vis spectrophotometer.
The sample was first placed in a beaker. The cuvette was filled with ethanol and zeroed the UV-VIS spectrophotometer. The cuvette was later filled with the sample dissolved in ethanol to reduce it concentration. The readings were taken at 211nm and 232nm.
Alcohol is a drink that contains substantial amount of ethanol, a depressant which in low doses causes euphoria, reduced anxiety and at higher concentrations causes intoxication, stupor and unconsciousness. Drinking alcohol is meant for recreational purposes but in most cases, countries have laws regulating production and consumption of alcohol.
Requirements: volumetric flask, fractional column, alcohol meter, sample.
20ml of the sample (summit brand) was measured and placed in a volumetric flask. The content in the flask was placed in fractional column for distillation. The distillate was placed in a measuring cylinder and alcohol meter was used to determine the alcohol content i.e. percentage. The alcohol content obtained in the experiment coincided with the one written on the summit bottle brand bottle.
The section provides scientific investigation for:
Criminal justice section
- Murder investigation.
- Rape case.
- Species identification.
- Paternity test.
- Maternity test.
3.1.1Forensic DNA profiling technique
In human beings, nucleus contains chromosomes composed of DNA that encode all the information necessary to produce a complete human body. Chromosomes store information in the chemical structure of DNA like a compact disk.
Nucleus contains 46 chromosomes two copies of each of 23 different human chromosomes. One copy of each chromosome is inherited from an individual’s mother and one copy is inherited from the individual’s father, giving a child DNA characteristic of both its mother and father.
DNA Extraction Procedure (CHELEX)
- Set the water bath at 56°C.
- Note down all the samples in extraction notebook.
- Label the Eppendorf tubes according to the number of samples.
- Prepare 20% chelex by weighing 0.2 grams into epperndorf tube in 800µl water.
- Add 1000µl deionized water to blood samples and 150µl to buccal swabs.
- Vortex samples for at least 5seconds for blood samples.
- Let stand for 50 minutes and centrifuge 1500PRM for 5 minutes.
- Remove the supernatant (950µl from the blood sample).
- Add 50µl chelex suspension to each blood and buccal swab.
- Add 100µl deionized water to the sample to make 200µl.
- Let it stand in water bath at 56°c for 1 hour.
- Boil for 8 minutes.
- Centrifuge at 1500PRM for 5 minutes.
- Dilute the samples as follows:
- Blood sample 1:5
- Buccal swab 1:20
The sample is now ready for polymerized chain reactions (PCR) steps
Polymerase chain reaction (PCR) steps
- Prepare PCR products negative control and positive control.
- Prepare master mix (calculate volume of total number of samples plus extra to be on safe side)
- Add 5µl master mix times number of sample plus extra into Epperndorf tube. Repeat step 3 for 2.5µl primer set and vortex the master mix.
- Add 7.5µl of master mix into PCR tubes.
- Add 5µl of the samples to PCR steps.
- Place the PCR tubes into thermal cycler and run for 3 hours.
Process involves in 3500 series DNA Analyzer
- Detection:-fluorescent dyes with extraction and emission traits
- Injection :-electro kinetic injection process (formamide water). Important for sampling stacking
- Separation capillary-50um fused silica, 36cm detector. Buffer taps ph. 8.0 Pop-4 polymer polydimethyl acrylamide. Denaturants- urea
3.1.2Procedure for calculating paternity index
Paternity index(P.I)is obtained by the formula
Example XY, XY/XX, if father’s alleles are 29,29 and the child’s allele are 28,29 at the locus D21 then;
P.I at D21=X/Y where X=1 and Y=0.16
Therefore 1/0.16 giving paternity index of 6.2500 at that locus.
The Y value are obtained from the library book of DNA for the specific locus.
Toxicology from “poisonous” is a branch of biology, chemistry and medicine concerned with the study of adverse effects of chemicals, biological and physical agents in biological systems that establishes extent of damage in living organism
This section deals with all cases of sudden death investigations without any prior history of illness and clinical cases in which chemical poisons are suspected to have been administered.
The samples include; blood,ligatured stomach ,kidney,liver,interstines,brain
The main activities include; preparation of the samples, organophosphates, organochlorides and carbamates test.
Ligatured stomach was cut open and the contents emptied into a wide metallic tray. Enough sodium sulphate salt was added to dry the stomach. N-hexane was added and the extract collected in a beaker. The beaker with the contents was placed in water bath to evaporate it .Ethanol was added to re-extract the poison and was spotted on TLC plates alongside the standards.
3.2.2 Organochlorides test
The extract is placed in copper foil and then is heated on top a flame. The production of green flame confirms the presence of organochlorides.
Organochlorides TLC plates
The extract was spotted on a plotted TLC plate alongside standards and the TLC plate placed in the developing tank that contains a mixture of acetone and n-hexane in the ratio (1:9, acetone: n-hexane, v/v)i.e. the mobile phase. Waited till the mobile phase traversed ¾ of the stationery phase. Removed and dried the plate. Viewed using UV-light lamp and recorded results.
3.2.3 Organophosphates test
The extract was spotted on a plotted TLC plate alongside standards and the TLC plates placed in developing tank containing a mixture of acetone and n-hexane in ratio(1:9,acetone:n-hexane,v/v).The mobile phase was allowed to traverse the stationery phase to ¾ of the TLC plate. It was dried and spray with N.B.P reagent.
Preparation of N.B.P spray
Dissolved 5g of 2,6-Dichloro-P-benzoquenone-4-chloroamine in 20ml glacial/acetic acid. Made to one litre in cyclohexane.
3.2.4 Carbamates test
The extract was spotted on plotted TLC plate alongside standards. The plate was placed in a developing tank containing acetone and n-hexane in ratio(3:9 ,acetone :n-hexane, v/v)i.e. mobile phase. The mobile phase was allowed to traverse the stationery phase to ¾ of the TLC plate. The plate was removed, dried and was sprayed with vanillin spray.
Preparation of vanillin spray
0.5g of vanillin (4-hydroxy-3-methoxybenzaldehyde) was dissolved in 100ml of 50% sulphuric acid freshly prepared i.e.(50ml conc H2SO4 + 50ml H2O)
3.2.5 Drug extraction
Drug extraction involves, extraction of drugs in terms of their acidity, basicity and if it is neutral. The drug mainly contains basic, acidic or neutral contents. It is necessary to use reagents such as NaCl, CHCL3, H2SO4, ethanol,50% HCL .The apparatus include UV-VIS spectrophotometer, separating funnel. This experiment is carried out if the drug caused death of animal or human being.
5-10mg of the sample was taken and 50ml of 50% hydrochloric acid was added, then digested for an hour over a hot water bath . It was allowed to cool and acidic drugs were extracted using CHCL3(chloroform)3*100four times. Recombined the organic fractions from above and reduced volume to about 100mls.The acidic drugs was transferred into 5ml 0.1N NaOH (preserve the organic layer).The aqueous layer from the first step(extraction of acidic drugs)was basified with 50% NaOH and allowed to cool then extracted basic drugs using CHCL3 3*100 four times. The organic fractions was recombined and reduced to 100mls.The basic drugs was transferred into N/10(0.1N) H2SO4(preserved organic layer). Recombined the organic layers and evaporated to almost dryness on hot water bath. Reconstituted dissolved extract in ethanol and run in UV-VIS spectrophotometer for neutral drugs.
Digestion of sample in 50%HCL
Cool organic solvent
Aqueous layer Organic layer
Contain basic drugs 20ml NaHCO3
Basify using 60%NaOH
Organic layer Aqueous layer
In this section it mainly deals with illegal use of drugs and alcohol. The samples are usually brought by the police officers. The samples mainly include: bhang,’changaa’,’busaa’,cocaine ,heroine
Recreational liquid used in important occasions. Changaa traditionally brewed spirit, popular in Kenya .Legalized by Government in 2010.Its effects include impairing one’s ability to make rational judgment, leading to irresponsible behavior in sex and abuse of drugs. Other adverse effects include liver cirrhosis.
- Spot test
5mls of the liquid (sample)was taken. Acidified K2Cr2O4 was added. The green color shows positive test for OH.
- Alcohol level using alcohol meter
100ml of the sample was measured using a measuring cylinder. Alcohol meter was inserted and readings taken. The result was compared with limits set by KEBS.
Affects mood and perception of making one see things that are not real/do not exist, leading to confusion, causing suicide.
- UV scan.
The sample extract was scanned under ethanol in UV-VIS spectrophotometer. The peak at 297nm shows positive result for bhang.
- Fast blue reagent.
The substance was crushed using pestle and motar. Fast Blue salt was added, then n-hexane and finally distilled water and left for some time.
Pink color indicates the presence of bhang.
3.3.3 Identification of fake money
Fake money identification involves various activities that consider the money (notes) fake. The following are checked;
- Paper texture.
- Security line which must be continuous.
- Water mark and lions head should show some brightness when viewed with UV-light.
3.3.4 Identification of morphine and heroine
Depressant, painkiller. The drug is either swallowed or dissolved in water and then injected using a syringe which causes allergy, loss of self-control and judgment.
- Uv scan
Extracted the drug using 0.1N H2SO4. UV scan in 0.1N H2SO4 give peaks at 275nm and 305nm
- Marquis test
Little powder was put in white tile. Marquis was added on it.
Purple color is seen-positive for Heroin.
It is a stimulant that affect nervous system and also lead to confusion, depression, hallucinations and physical dependence.
- UV scan
Scan the sample extract in UV-VIS spectrophotometer in 0.1N H2SO4.The peaks were obtained at 233nm and 275nm.
- Scott’s reagent
Little powder of the sample was placed on a white tile. Scott’s reagent was added on it.
Blue color shows positive for cocaine.
3.4 WATER SECTION
The section analyses water for fitness for human consumption, animal and other uses like irrigation and waste water (effluents) for suitability for discharge into environmental or public sewers. It also carries out surveys of various water bodies from time to time to examine the quality for environmental surveillance. The various parameters that are measured in the water section are ph., conductivity, total hardness, chlorides, total alkalinity, total dissolved solids, total suspended solids, analysis of heavy metals in effluents, chemical oxygen demand, biochemical oxygen demand, total nitrogen, nitrates, nitrites, fluorides, iron and sulphates.
3.4.1 Bacteriological analysis
Bacteriological water analysis is a method of analyzing water to estimate the numbers of bacteria present and if needed; to find out what sort of bacteria are they. This procedure is used to routinely confirm that water sample is safe for human consumption, bathing or recreational activities. Indicator organism are bacteria such as non-specific coliform, Escheridia coli and Pseudomonas aeruginesa that are found in animal and human gut. The plate count method.
Working area was first sterilized using methanol. The plates were also sterilized using methanol. The plates were placed in the working area with pads on them and then flooded with M.coli blue reagent using micropipette. Vacuum filter pump was sterilized using methanol and whatman filter paper was placed on it. The sample was poured up to 100ml mark and switched on the pump. The watman filter paper was picked using sterilized forceps and placed on top of flooded pad.
3.4.2 Analysis of heavy metals in effluents using atomic absorption spectrophotometer (AAS)
Industries bring sample of their effluents to government chemist laboratory for analysis before they release it to the rivers. The effluents should not contain high concentration of metals such as mercury which are harmful to the human body when consumed.
The government chemist water laboratory analyses for heavy metals in the effluents in the standards and check if it confirms with the standards that are set by KEBS. Zinc, lead, copper, mercury, nickel, sodium and potassium are example of some heavy metals that are analyzed in effluents. The analysis of metals is usually done in request of the client.
Rinse the tubes with 1:1 HCl and then rinse with distilled water. Measure 50ml of the sample. Add 3ml of hydrochloric acid and 1 ml of nitric acid. Place it in a heating mantle to reduce the volume to 20ml.allow it to cool and then cover the volumetric flask with Para film and allow it to stand overnight for cold digestion.
Filter the sample using the vacuum filter pump and top up to 50ml in a conical flask
Measure 50ml of the sample. Add 2 ml of HNO₃.
Note: blank should be freshly prepared
The standards are prepared in three different concentrations, for example in analysis of nickel metal; the standards are prepared in the concentration of 0.5000, 1.0000, and 2.0000. To make 10ml of the standard of concentration 0.5000, calculate from volume that will be taken from the stock solution of nickel standard which is 100.00
use the formula: C₁V₁=C₂V₂
Where C₁ is the concentration of the standard(0.5000ppm)
Where V₂ is the volume of the standard(10ml)
Where C₂ is the concentration of the stock solution of the standard(100ppm)
Where V₂ is the unknown volume that we are to take from the stock solution of the standard.
After getting the volume that will be taken from the 100ppm, using a micropipette measure the volume for example 0.2µl into a 10ml measuring cylinder and top up with distilled water. Repeat the same procedure for 1.000ppm and 2.000ppm respectively and place them in different vial tubes.
Operation of the AAS
Turn on the personal computer to start windows. Double click on the wiz-AArd icon. The AA-6300 software allows you to complete necessary settings for measurement by following the instructions displayed on the screen after starting the software.
It allows the selection of element to be measured, determine the measuring order and edit the measurement parameters. Select the flame method for measurement. Click on select elements. Select normal lamp for normal hollow cathode lamp. Click on ASC since when using the auto sampler. After finishing the settings, click on the okay button. The message on the lamp setup will appear and click on yes button. The optic parameters sheet will appear and select on lamp position set up. Enter the element symbol from the drop down list and select normal lamp. In the edit parameters page, enter socket number and click on okay button.
This is where calibration curve settings are done. Select 1st since the calibration curve is linear. Select on the concentration of the prepared standard (ppm). In the blank preparation set up the automatic periodic blank measurement. In the measurement sequence for calibration set up, enter the number of standards samples and their concentrations. Enter the number of standard samples In the no field and click on update button. Since the auto sampler is being used, the position field will be displayed, enter the positions in turntables.
Connect to instrument
This section describes how to connect to the instrument and send parameters. When the connection is made to the instrument, the instrument is initialized automatically. Check that the AA main unit and the related units are on and click next button. Click on yes button for the connection to the instrument to start with the “initialize” screen displayed.
It is used to set the parameters for the monochromator and the lamps in the instrument. It displays the wavelength, slit width, socket number, lamp mode. First the line search is carried out and then beam balance is performed. In the line search, the highest peak near the specified wavelength is detected. Upon completion of the process click on close button.
Using the ASC
First check on the position of each actual sample on the ASC turntable accords with the setting on the MRT work sheet
Igniting the flame
Press ignite button and the purge button to ignite the flame
Starting the ASC
Click on start button at the bottom of the main window according to the set order
Extinguishing the flame
After finishing the measurement, press extinguish button on the front of the AAS main unit to extinguish the flame
3.4.3 Physico-chemical analysis of water
Ph is the test of alkalinity or basicity of concentration of hydrogen ions. It is done using a ph meter which measures both temperature and ph of the water.
Requirements: sample, beaker, ph meter.
The sample was placed in a beaker. The two electrodes are dipped into the water (one electrode measures temperature while the other one measures the ph).The reading is taken and recorded.
Chlorides are commonly present in water especially the domestic water due to treatment using chlorine or naturally occurring chlorides .Determined by titration of sample with silver nitrate using an indicator potassium chromate (K2CrO7).Chlorides concentration in excess of 250mg/l gives a salty taste. If chloride is present as calcium or magnesium salt, the detection limit may be as high as 1000mg/l chloride. Maximum allowable level is 250ml/l.
Requirements: water sample, conical flask, K2Cr2O5, silver nitrate, burette, pipette.
Chloride content is calculated as follows;
Where; X→ burette reading
20ml of the sample was measured and placed in erlymeyerflask.2ml of the indicator was added then titrated with AgNO3 until a permanent brown color if formed. Recorded results.
It describes the point at which CO2 ceases to prevail and carbonate alkalinity begins to be present, this change occurs at ph 8.3.In other words the acid range with this indicator is below 8.4 and the alkaline range is above this value.
Alkalinity is determined using phenolphthalein or methyl orange indicator in order to disclose the chemical nature of alkaline compounds and their reaction to hardness producing compounds.
Requirements: Erlenmeyer flask, water sample, methyl orange indicator, phenolphthalein indicator,H2SO4
a) Using methyl orange indicator
20ml of the sample was measured and placed in an Erlenmeyer flask.3 drops of methyl orange indicator was added. The burette was then filled with 0.002N H2SO4.The acid was titrated against the sample and the reading taken at the end point, the color changed from orange to pink.
b) Using phenolphthalein indicator
Where; X→ volume of acid used(H2SO4)
Phenolphthalein alkalinity is also recorded as calcium carbonate (CaCO3) since the strength of H2SO4 used is such that each ml used represents 10ppm of calcium carbonate.
Recommended that drinking water shall not have a Ph greater than 10.6 or a normal carbonate alkalinity greater than 120ppm.
20ml of the sample was measured and placed in an erlenmeyer flask.3 drops of the phenolphthalein indicator was added. The burette was filled with 0.02N H2SO4.The acid was titrated against the sample and the reading was noted at the endpoint. The color changed from pink to colorless.
Total hardness consists of;
- Carbonate or temporary hardness.
Caused by carbonates, bicarbonates and hydroxide are easily precipitated by boiling and scales indicate.
- b) Non-Carbonate or permanganate hardness
Caused by calcium and magnesium sulphates, chlorides and to some extend nitrate .Problems caused by excessive hardness is economical in terms of scale formation in boilers scale and hot water systems. Below 30-50mg/L tend to be corrosive and so should be examined for plumb solvency (liability to take lead).
|< 15||Very soft|
|> 200||Very hard|
There are several methods used for measuring hardness. We titrated using Ethylenediamine-N,N,N’,N’-tetra acetic acid(EDTA) .EDTA is a chelating agent that can donate electrons (Lewis base) there by forming a complex with metal ions (Lewis acid). The EDTA will complex first with the Ca2+ and then with the Mg2+.
As with any titration we will need an indicator to determine when all of the Ca2+ and Mg2+have complexes with the EDTA (i.e. the endpoint).The indicator used in this experiment Is total hardness indicator. The general procedure for this experiment starts with a sample of hard water that contains calcium and magnesium .To ensure that all cations stay in solution and that the indicator works properly ,a buffer is used to adjust the pH to 9.9-10.1.After the pH is adjusted and the indicator is added ,the EDTA titrant is added via a burette. At the endpoint the solution changes from wine-red to blue.
Total hardness in fresh water is usually in the range of 15 to 375mg/L as CaCO3.Calcium hardness in fresh water is in the range of 10 to 250mg/L, often double that of magnesium hardness(5to125mg/L).
Typical sea water has calcium hardness of 1000mg/L, magnesium hardness of 5630mg/L, and total hardness of 6630mg/L as CaCO3.
20ml of the sample was measured and placed in a volumetric flask.3drops of buffer solution was added then small amount of erichromeshwatz-T indicator was also added. The burette was filled with EDTA then titrated against the sample. At the endpoint the color changes from wine-red to colorless. The result was recorded.
Total dissolved solids
Refers to any minerals, salts, metals, cations or anions dissolved in water. TDS comprise of inorganic salts (principally calcium, magnesium, potassium, sodium, bicarbonate and sulphates). TDS are normally described only for fresh water systems although is considered pollutant.
Requirements: water sample, oven, beakers, conductivity meter.
A given mass of water sample was weighed and placed in a preweighed beaker. The contents in the beaker were allowed to boil to evaporation on an oven maintained at 100oC overnight to dryness. The beaker was reweighed and the difference in weight was recorded.
Alternatively, TDS was determined using conductivity meter which also measures other two parameters: salinity and conductivity.
Total suspended solids
TSS is the dry weight of particles trapped by filter. It is a water quality parameter used to access the quality of water waste .It is listed as a conventional pollutant. TSS interferes with water disinfection with chlorine because water particles act as shields for the viruses and bacteria. Similarly, TSS protects bacteria from uv sterilization of water.
Requirements: water sample, filter paper, oven.
A filter paper of porosity 4 was pre- weighed then used to filter the sample of a known quantity. The filter paper was then dried for one hour in an oven maintained at 110°C before it was weighed. The difference in weight is the total weight of the suspended solids.
Oil and grease
Concentration of dispersed oil and grease is an important water parameter for water quality and safety. Oil and grease can cause surface films and shoreline deposits leading to environmental degradation. Oil and grease include fats, oils, waxes, generally waste water. If not removed before discharge of treated wastewater, it can interfere with biological life in both surface and in water. The limits set is 100mg/l.
Requirements: oven, plates, separating funnel, analytical balance,H2SO4, N-hexane,sample.
A metallic plate was placed in an oven at 110oC for four hours. The plates were then cooled and weighed in analytical balance.100ml of the water sample was measured, poured into a separating funnel and 2ml of concentrated H2SO4 was added.5ml of n-hexane was added and shaken for two minutes. The organic layer was separated into the plate. The plate was then dried for 3 hours at 25oC.It was later placed in an oven at 60oC.The plate was cooled and reweighed and the weight of oil and grease was determined by subtraction.
Water turbidity is caused by suspended matter and sometimes may be so fine as to impact paleness (milk whites) or yellow reflection in water. An optical turbidity meter measures water turbidity with Nephelometric Turbidity Units(NTU) or Jackson Turbidity Units (JTU). Fluid contain suspended solids which might be large enough to settle rapidly at the bottom of the container, if left to stand (setleable solids or small particles will settle only very slowly or not at all if the sample is regularly agitated or the particles are colloidal.
The risk of drinking high turbidity level is development of gastrointestinal disease.
Requirements: cuvette, sample, turbidity meter.
Measured a sample and placed in a round cuvette. The sample in cuvette was placed in a turbidity meter. The reading was recorded.
It is the measure of waters capability to pass electrical flow. This ability is directly related to concentration of ions in water. These conductive ions come from dissolved salts and inorganic materials such as alkalis, chlorides, sulfides and carbonate compounds. The limits set by KEBS is 2500 MS/cm.
Requirements: Sample, turbidity meter, cuvette.
Measured a sample and placed in a round cuvette. The sample in cuvette was placed in a conductivity meter. The reading was recorded.
The sum of nitrate-nitrogen, nitrite-nitrogen, ammonia-nitrogen and organically bonded nitrogen. Because nitrogen in waste water can be found in four major forms, each parameter is generally analyzed as a separate component, with total nitrogen calculated from the sum of the four forms. The total nitrogen load on the process is the sum of the soluble organic nitrogen and ammonia contributed by incoming waste water plus any nitrogen contributed by the return activated sludge plus the nitrogen from any recirculation flow back from nitrification stages of treatment process. The limits set is 0.5mg/l.
Requirements: Vial tubes, HCL, distilled water, digestion buffer, borate buffer, DR-6000 spectrophotometer, sample.
Vial tubes were washed with 1:1 HCL acid and then rinsed with distilled water.10ml of the sample was placed in one tube and 10ml of distilled water in another tube.5ml of digestion buffer was added to each tube and taken to the autoclave for 30 minutes at 110oC.1ml of borate buffer solution was added to each tube. The sample was then taken for scanning in DR-6000 spectrophotometer. Stored programs was pressed and selected test for nitrates. The machine was zeroed using the blank. The sample was placed in the spectrophotometer and reading taken.
Permanganate value (PV)
In acid oxidation KMnO4 results in reduction of permanganate ion to manga nous ions.
The remaining unreduced permanganate is determined by titration of iodine liberated from KI with standard Na2S2O4.
Requirements: distilled water, H2SO4, KMnO4, KI, Na2S2O4, starch indicator, sample.
100ml of distilled water was placed in one bottle and 100ml of the sample was placed in another bottle.10ml of H2SO4 was added to acidify the contents in the bottle.20ml of KMnO4 was added to each and left standing for four hours followed by 2ml of KI to each bottle. The contents were titrated with standard Na2S2O4 to colorless .Starch indicator was added near the endpoint to give a sharp endpoint.
NB: Starch indicator should be freshly prepared
Starch indicator preparation
5g starch and 800ml boiling distilled water were mixed, then diluted to a litre followed by boiling for few minutes and let to settle overnight. Preserved with few drops of toluene.
Chemical Oxygen Demand (COD)
Chemical oxygen demand is a measure of the capacity of water to consume oxygen during decomposition of organic matter and the oxidation of inorganic chemicals such as ammonia and nitrite. COD is a measure of water quality. It is expressed in milligrams per liter (Mg/L) which indicates the mass of oxygen consumed per liter of solution. Where wastewater contains only readily available organic bacterial food and no toxic matter, the COD test results provide a good estimation of BOD (Biochemical Oxygen Demand. Mercuric sulphate is a COD catalyst powder that complexes any chloride present.
Requirements: Effluent sample, Vials (2) – containing readily prepared sulfuric acid, mercuric sulphate, silver sulphate and chromic acid mixture, COD reactor, UV-VIS
spectrophotometer, Distilled water.
Procedure for COD determination
Vial tubes were washed and rinsed with distilled water.2.5ml of water sample was placed in one vial tube and on the other vial tube distilled water as blank.1.5ml of 1N potassium dichromate (K2Cr2O7) was added into both vial tubes.3.5ml of concentrated sulphuric acid(H2SO4) was added to both vial tubes. The vials were closed and taken to the spectrophotometer and reading noted.
Biochemical Oxygen Demand
Biochemical Oxygen Demand (BOD) is an empirical measurement of the oxygen requirement by municipal or industrial wastewaters and sewage. The test results are used to calculate the effect of waste discharges on the oxygen resources of the receiving waters. The BOD test is of limited value in measuring the actual oxygen demand since temperature changes, biological population, water movement, sunlight, oxygen concentration and other environmental factors cannot be accurately reproduced in a laboratory. The BOD test is of greatest value after patterns of oxygen uptake for a specific effluent and receiving water have established.
Requirements: Effluent sample,
BOD (mg/L) = [(Initial DO – Final DO) ÷ P]
Where; Initial DO → the prepared sample immediately after preparation (i.e. Day 1)
Final DO → the prepared sample immediately after incubation (i.e. Day 5)
P → volume of sample i.e. 3mL
Volume after dilution 100mL
Sample dilution was prepared by taking 3mL of a well-mixed effluent sample into a 100mL glass-stoppered BOD bottle and toped up with distilled water.
The BOD meter was then calibrated using another BOD bottle half filled with distilled water as a blank. The BOD of the diluted sample was measured in the first day and recorded as the “initial BOD reading”. This BOD bottled was stoppered and incubated for 5 days at 20-250C in a dark place.
After the 5 days, the BOD meter was calibrated again and the BOD of the incubated dilute sample was measured and recorded as the “final BOD reading
3.4.4 Spectrophotometric analysis
Test for iron
. Iron can enter the water system by leaching natural deposits, from iron bearing industrial wastes, effluents from pickling operations, or acidic mine drainage. Iron in domestic water supplies systems stains laundry and porcelain, causing more of a nuisance than a potential health hazard.
In calorimetric iron analysis the 1-10-phenathrolin reagent gives an orange color with ferrous iron and is free from common interference. The indicator is combined with reducing agent for total iron analysis in a single powder formulation ferrous -iron reagent. Domestic water supplies containing more than 0.3mg/L total iron should be rejected due to staining and taste considerations.
Requirements: Iron reagent; ferrous iron powder (contents; 1,10-phenanthrolin-p-toluenesulfonic acid salt, Sodium sulfite & Sodium metabisulfite), UV-Vis spectrophotometer, cuvettes, water sample
The cuvette was filled with 25ml of water sample. One ferrous iron reagent powder pillow was added then swirled .It was left to stand for 3 minutes. Another cuvette was filled with the sample and stored programs was pressed ,then selected the wavelength for the iron at 570nm and zeroed the spectrophotometer. The prepared sample was then placed in the spectrophotometer and reading taken.
Test for nitrate
They indicate water polluted with sewage effluent .High concentration is bad to infants; nitrates from water are converted in body to nitrites which are absorbed into blood stream and converts the oxygen carrying hemoglobin to metaemoglobin-not harmful but the effect is the reduction of water in the hemoglobin , a level of 45mg/L nitrate nitrogen has been established as a maximum allowable concentration of nitrates in public drinking water supplies .High levels of nitrates in water indicate biological waste in the final stages of stabilization or run-off from heavily fertilized fields. Nitrates-rich effluents discharged into receiving waters can degrade water quality by encouraging excessive growth of algae.
Requirements: Nitrate reagent (contents; Benzene Sulfonic acid, 4-amino-benzoic acid, 2,5-dihydroxycopper potassium salt & [Propanedioato (2-)-0,0]-Cadmium phosphoric acid),UV-Vis spectrophotometer, cuvettes, water sample
Pressed stored programs and selected test for nitrate. Square cuvette was filled with 10ml sample. DR6000 was zeroed using the sample. Nitrate pillow was added to the cuvette and swirled. Pressed the timer and a 6 minute reaction time begun. The sample was placed in the cuvette and recorded the reading.
Test for nitrite
Pressed stored programs and selected test for nitrite. The square cuvette was filled with 10ml of the sample. Zeroed the machine using the sample. Added the nitrite pillow to the cuvette and swirled. Pressed the timer and a 20 minute reaction time begun. Placed the sample in the cuvette to the machine and record the reading
Test for sulphate
The water sample is reacted with BaCl2 with the help of conditioning reagent
Pressed stored programs, selected test for sulphate. Square cuvette was filled with 10ml of the sample. Zeroed the DR6000 spectrophotometer with the sample. Add the contents of one sulphate pillow to the cuvette and swirled. Pressed timer for a reaction time of 5minutes begun. Placed the sample in the cuvette to the machine and recorded the reading.
Test for manganese
Waterborne manganese has greater bioavailability than dietary manganese. Higher levels of exposure to manganese in drinking water are associated both increased intellectual impairment and reduced intelligence quotient in school aged children .Human body contains 12mg of manganese in bones. On the other hand correct limits are important in development of metabolism and antioxidant system.
Requirements: water sample, cuvettes, deionized water, ascorbic acid powder pillows
Prepared the blank sample by addition of 10ml of deionized water in a cuvette. Placed 10ml of the sample in another cuvette, added ascorbic acid powder pillows and shaken to allow it dissolve also with the blank.12drops of PAN indicator was added and swirled further. Appearance of orange color indicated presence of manganese ions. The DR-6000 spectrophotometer was zeroed using the blank then reading was taken using the sample.
Test for fluoride
Fluorides occur naturally in natural water and normally maintained in public drinking water for prevention of dental carries (fluorosis).Though if the level is beyond the set limits it leads to skeletal fluorosis and non-skeletal manifestations also browning of teeth. The structure of SPANDS reagent.
Requirements: water sample, SPANDS reagent, cuvettes, pipette, distilled water.
10ml of deionized water was pipetted and placed in one cuvette on the other one is 10ml sample.2ml of SPANDS reagent was carefully pipetted into each cuvette. Selected the timer and 1 minute reaction period begun. The DR-6000 spectrophotometer was zeroed using distilled water containing 2ml SPANDS reagent. The readings was noted in the DR-6000 spectrophotometer.
Test for aluminium
Hypothesis of a link between aluminium in drinking water and Alzheimer’s disease has been supported. Transferrin is a major transport protein for both iron and aluminium to the transferring variant that is present in Alzheimer’s disease. Excess exposure is related to nerve damage, allergies and is also believed to be carcinogenic. The limit is 0.05-0.2mg/l.
Requirements: water sample, aluminum reagent pillow, cuvettes, uv-vis spectrophotometer
50ml of the sample was measured using a measuring cylinder .Ascorbic acid pillow was added into the measuring cylinder containing the sample and the timer was set for0.3seconds. Alluminium pillows was added in the measuring cylinder and the timer was set for 1 minute. Color change appears. The contents are later transferred into two cuvettes and added aluminum bleaching reagent pillow to one cuvette and set the timer for 15 minutes. Zeroed the DR-6000 and the reading was taken
During my attachment period at Government chemist department I learnt how to receive different samples for different sections. For example samples in the DNA section are categorized into two; A cases and B cases. A cases are for murder cases while B cases are cases for paternity. They are recorded in the book of A and B cases and the samples brought are then confirmed
I also learnt about different machines at government chemist; atomic absorption spectrophotometer, single and double beam DR 6000 UV-VIS spectrophotometer, turbidity meter, distiller, pH meter, digester and polymerase chain reaction machine.
I got the chance of learning analysis techniques in different sections like water, food and drugs, toxicology, DNA,
4.0.1 Interaction with staff
I had a very wonderful relationship with the staff at government chemist department. The staff were very supportive during my attachment period at the government chemist. They shared the knowledge they had with me and created a good environment for me during the period I was at the government chemist. My interaction with staff like Mr. Sheundah Ndakalu, Mr. Dalmas Kibet, Mr. Daniel Odhiambo and Mr. Laban Mogere had been a critical factor in my development in the field of chemistry and related fields.
4.1 Challenges faced during attachment
There were some machines that were completely non-operational in the department, hence limiting the number of parameters that are analyzed in the department. In the food and drugs department, the police officers did wrong sampling of debris hence when test for the accelerant was carried out we got no results.
There are some machines that are not available in the department for example gas chromatography mass spectroscopy (GC-MS) and HPLC which is more accurate than the thin layer chromatography.
My attachment at government chemist was a great success. I was able to put into practice what I learnt in industrial chemistry classes. I was equipped with knowledge and scientific skills in areas of analytical and forensic analysis. I gained knowledge in operation of machines like AAS, UV-Vis spectrophotometers
I would recommend someone who is looking for attachment to come to government chemist department since he/she will be able to gain a lot.
The ministry of health should install the technology like CCTV cameras to ensure security of the department.
The ministry should teach the police about proper sampling of exhibits to ensure that the results obtained are accurate
The ministry of health should install a powerful generator in the department, so that in cases that there is no power work can continue without any interruption.
- Quality criteria for water, U.S. Environmental protection agency, EPA#440/5-86-001, 1986. . Water pollution microbiology, Ralph Mitchell ED., Wiley-interscience, 1972.
- Pearson’s Chemical Analysis of Food,by Harold Egan,Ronald Sawyer,Ronald S.Kirk,1981
- Alpha –Awwa-Wpcf, 1975 “standard methods of the examination of water and waste water
AOAC Manual on analytical Methods, 1973.
- Oceans of Life off Southern Africa…..A Payne and R Crawford (Eds) Vlaeberg Cape Town 1989
- De la Rocha, C.L. (2006). “Opal based proxies of paleo environmental conditions.” global biogeochemical cycles 20. Doi:10.1029/2005gb002664.
- Draft for review and comment 1998 towards integrated management and béné c. Public health nutr. 2011 Nov; 14(11):1927-38. Epub 2011 May 20stainable development of Kenya’s coast by coast development author