ENV460 Course File

4.4 CONCLUSION
To sum up, 16 research papers on the detection of genotoxic PAHs in various food

products published in the past ten years were reviewed. In this study, the extraction and
analysis method, level of PAHs, and health risk assessment associated with the consumption
of food products were analyzed to gather the data. The foodstuffs involved in this study were
grilled meat and fish, edible oils, and bread. Besides, ILCR, MOE, chronic daily intake, and
dietary intake were health risk assessment approaches in the reviewed studies. Therefore,
further review data on different types of PAHs-containing food products and its health risk
assessment are essential to protect public health and increase food safety in our country.

References

Abdul-Gafaru Osumanu. (2017). ​Health Risk Assessment of PAH in Bread [PDF]. Africa:
Department of Food Science and Technology. Retrieved on March 26, 2020, from
http://ir.knust.edu.gh/bitstream/123456789/11409/1/ABDUL-GAFARU%20OSUMAN
U%20THESIS%20%28CORRECTIONS%20DONE%29.pdf

Alomirah, H., Al-Zenki, S., Al-Hooti, A., Zaghloul, S., Sawaya, W., Ahmed. N. & Kannan,
K. (2011). Concentration and dietary exposure to polycyclic aromatic hydrocarbons
(PAHs) from grilled and smoked foods. ​Journal of Food Control. 2​ 2(12), 2028-2035.
https://doi.org /10.1016/j.foodcont.2011.05.024

Al-Rashdan, A., Helaleh, M. I. H., Nisar, A., Ibtisam, A., & Al-Ballam, Z. (2010).
Determination of the Levels of Polycyclic Aromatic Hydrocarbons in Toasted Bread

Using Gas Chromatography Mass Spectrometry. ​International Journal of Analytical
Chemistry,​ ​2010,​ 1–8. h​ ttps://doi.org/10.1155/2010/821216

Ciecierska, M., & Obiedziński, M. W. (2013). Polycyclic aromatic hydrocarbons in the
F​ ood Chemistry,​ 1​ 41(​ 1),
bakery chain. 1–9.

https://doi.org/10.1016/j.foodchem.2013.03.006

Commission Directive (EU). 2015. “COMMISSION DIRECTIVE (EU) 2015/1127 of 10 July
2015 Amending.” (1881):8–11.

Conte, Francesca, Chiara Copat, Sabrina Longo, Gea Oliveri, Giovanni Arena, Angela
Dimartino, Maria Violetta, and Margherita Ferrante. 2016. “Polycyclic Aromatic
Hydrocarbons in Haliotis Tuberculata ( Linnaeus , 1758 ) ( Mollusca , Gastropoda ):
Considerations on Food Safety and Source Investigation .” 94:57–63.

Eslamizad, S., Kobarfard, F., Javidnia, K., Sadeghi, R., & Bayat, M. (2016). ​Determination of
Benzo [ a ] pyrene in Traditional, Industrial, and Semi- industrial Breads Using a
Modified QuEChERS Extraction, Dispersive SPE, and GC-MS and Estimation of its
Dietary Intake.​ ​15(​ March 2015), 165–174.

Farhadian, A., Jinap, S., Abas, F., & Sakar, Z., I. (2010). Determination of polycyclic
aromatic hydrocarbons in grilled meat. ​Journal of Food Control, 2​ 1(5), 606-610.
https://doi.org /10.1016/j.foodcont.2009.09.002

Irnanda, K., Meiftasai, A., & Nagadi, S. (2012). Safety evaluation of chicken satay in

Yogyakarta Indonesia based on benzo(a)pyrene content. I​ ndonesian Journal of Cancer
Chemoprevention, ​3(3).

http://dx.doi.org/10.14499/indonesianjcanchemoprev3iss3pp432-436

Ishizaki, A., K. Saito, N. Hanioka, S. Narimatsu, and H. Kataoka. 2010. “Determination of
Polycyclic Aromatic Hydrocarbons in Food Samples by Automated On-Line in-Tube
Solid-Phase Microextraction Coupled with High-Performance Liquid
Chromatography-Fluorescence Detection.” J​ ournal of Chromatography A
1217(35):5555–63.

Jahurul, M. H. A., Jianp, S., Zaidul, I. S. M., Sahena, F., Farhadian, A., & Hajeb, P.
Determination of fluoranthene, benzo(b)fluoranthene and benzo(a)pyrene in meat and
fish products and their intake by Malaysia. ​Journal of Food Bioscience, ​1, 73-80.
https://doi.org /10.1016/j.fbio.2013.03.006

Jiang, Dafeng, Chenglong Xin, Wei Li, Jindong Chen, Fenghua Li, Zunhua Chu, Peirui Xiao,
and Lijun Shao. 2015. “Quantitative Analysis and Health Risk Assessment of Polycyclic
Aromatic Hydrocarbons in Edible Vegetable Oils Marketed in Shandong of China.”
Food and Chemical Toxicology​ 83:61–67.

Jiang, D., Wang, G., Li, Linlin., Wang, Xiaolin., Li, Wei., Li, Xi., Shao, Lijun., & Li,
Fenghua. (2018). Occurrence, dietary exposure, and health risk estimation of polycyclic
aromatic hydrocarbons in grilled and fried meats in Shandong of China. ​Journal of Food
Science & Nutrition. h​ ttps://doi.org /10.1002/fsn3.843

Krajian, H., and A. Odeh. 2018. “Levels of 15 + 1 EU Priority Polycyclic Aromatic
Hydrocarbons in Different Edible Oils Available in the Syrian Market.” P​ olycyclic
Aromatic Compounds​ 38(4):369–78.

Lee, Joon Goo, Jung Hyuck Suh, and Hae Jung Yoon. 2019. "Occurrence and Risk
Characterization of Polycyclic Aromatic Hydrocarbons of Edible Oils by the Margin of
Exposure (MOE) approach." ​Applied Biological Chemistry​ 62(1).

Liu, Shao-heng, Guang-ming Zeng, Qiu-ya Niu, Yang Liu, Lu Zhou, Lu-hua Jiang, Xiao-fei
Tan, Piao Xu, Chen Zhang, and Min Cheng. 2017. "Bioresource Technology
Bioremediation Mechanisms of Combined Pollution of PAHs and Heavy Metals by
Bacteria and Fungi : A Mini-Review." ​Bioresource Technology​ 224:25–33.

Rozentale, I., Zacs, D., Perkons, I., & Bartkevics, V. (2017). A comparison of gas
chromatography coupled to tandem quadrupole mass spectrometry and high-resolution
sector mass spectrometry for sensitive determination of polycyclic aromatic
hydrocarbons (PAHs) in cereal products. ​Food Chemistry​, 2​ 21​, 1291–1297.
https://doi.org/10.1016/j.foodchem.2016.11.027

Shariatifar, Nabi, Manouchehr Dadgar, Yadolah Fakhri, Saeed Shahsavari, Mojtaba Moazzen,
Mahsa Ahmadloo, Amin Kiani, Saeed Aeenehvand, Shahrokh Nazmara, and Amin
Mousavi Khanegah. 2020. “Levels of Polycyclic Aromatic Hydrocarbons in Milk and
Milk Powder Samples and Their Likely Risk Assessment in Iranian Population.” J​ ournal
of Food Composition and Analysis​ 85(October 2019):103331.

Sultana., M. S., Rana, S., Yamazaki, S., Aono, T., & Yoshida, S. (2017). Health Risk
Assessment for carcinogenic and non-carcinogenic heavy metal exposures from
vegetables and fruits of Bangladesh. ​Cogent Environmental Science, 3(1).
https://doi.org/10.1080/23311843.2017.1291107

Tongo, Isioma, Ozekeke Ogbeide, and Lawrence Ezemonye. 2017. “Human Health Risk
Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Smoked Fish Species from
Markets in Southern Nigeria.” ​Toxicology Reports​ 4:55–61.

Tran-Lam, T. T., Dao, Y. H., Nguyen, L. K. T., Ma, H. K., Tran, H. N., & Le, G. T. (2018).
Simultaneous determination of 18 polycyclic aromatic hydrocarbons in daily foods
(Hanoi metropolitan area) by gas chromatography-tandem mass spectrometry. ​Foods,​
7​(12). https://doi.org/10.3390/foods7120201

Xia, Zhonghuan, Xiaoli Duan, Weixun Qiu, Di Liu, Bin Wang, Shu Tao, Qiujing Jiang, Bin
Lu, Yunxue Song, and Xinxin Hu. 2010. “Health Risk Assessment on Dietary Exposure
to Polycyclic Aromatic Hydrocarbons (PAHs) in Taiyuan, China.” ​Science of the Total
Environment​ 408(22):5331–37.

Yousefi, Mojtaba, Ghazal Shemshadi, Nasim Khorshidian, Vahid Ghasemzadeh-Mohammadi,

Yadolah Fakhri, Hedayat Hosseini, and Amin Mousavi Khaneghah. 2018. “Polycyclic
Aromatic Hydrocarbons (PAHs) Content of Edible Vegetable Oils in Iran: A Risk
Assessment Study.” F​ ood and Chemical Toxicology​ 118(May):480–89.

ENV460:Review Paper

No Group Student ID Student Name
1 HS2436D
2 HS2436C 2018227256 NURUL IZZATY IZLEEN BINTI HASM
3 HS2436C
4 HS2436C 2018249606 NURUL AQILAH BINTI SHARIFF
5 HS2436D
6 HS2436C 2018262688 NURUL RAIHANA BINTI MOHAMM
7 HS2436C
8 HS2436D 2018264734 NUR AFIQAH SYAZWANY BINTI MO
9 HS2436D
2018264956 NUR LIYANA BINTI AZHARI
10 HS2436C
11 HS2436D 2018292198 MAIZATUL RAIHANAH BINTI MOKH
12 HS2436C
2018425214 NORHAZIRAH BINTI MUHAMAD H

2018441266 NURUL SYAZWANI BINTI YUSOF

2018441398 NUR SYAZANA BT SAFFIE

2018657382 NORHAYATI BINTI ABDUL HAMID

2018693604 NUR SA ADA ALYA BINTI AB AZIZ

2018693752 RABI ATUL ADAWIYAH BINTI ABDU

MADY Total Mark (50%)
MAD SALLEH 39.5
OHD ISA 40
HTARUL KUDUS 40.5
HAMLUN 40.5
39
UL WAHAB 38.5
40
37.5
39
40.5
39.5
40

CENTRE OF ENVIRONMENTAL HEALTH
AND SAFETY

FACULTY OF HEALTH SCIENCES

ENV 460
ANALYTICAL TECHNIQUE AND INSTRUMENTATION

TEST 1

TEST 1: MARCH -SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

(Total Mark: 40)

Question 1 - Essay (4.00)

State the purpose of environmental sampling
Answer

Schema

To determine how much pollutant enters into the environment through stack emission, wastewater
discharge, and so forth in order to comply with regulatory requirement
To measure the ambient background concentration and assess the degree of pollution and to identify the
short and long term trends
To detect accidental release and evaluate risk and toxicity to human and biota
To study the fate and transport of contaminants and evaluate the efficiency of remediation systems.

Question 2 - Essay (8.00)

Explain the criteria that need to be considered for selecting a sampling plan?
Answer

Schema
Objectives – Baseline Monitoring, Trend detection, search for hotspot and margin of error allowable
Variability– Spatial and Temporal Variation
Cost factor – Sampling cost, Analytical cost
Non technical factor– Samplig convinience, Accesibility, regulations

Page 1/5

TEST 1: MARCH -SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

Question 3 - Essay (6.00)

Describe a few types of sample preservation and storage
Answer

Schema

Refrigeration
Chemical Addition
Proper container

Page 2/5

TEST 1: MARCH -SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

Question 4 - Essay (6.00)

Explain 2 types of sampling strategies
Answer

Schema

Judgemental Sampling

Selection of sampling locations based on professional judgment using prior information on the sampling
site, visual inspection and/or personal knowledge and experience
Schedule and budget - tight, early stage when objective is just screen the area
Primary representative sampling approach for groundwater assessment – selection of monitoring well
No randomization

Simple Random Sampling

Arbitrary collection of samples by a process that gives each sample unit in the population the same
probability of being chosen
Assumes variability of sampled medium is insignificant – homogenous population
Applies for sites with little background information
Not applicable for heterogeneous population
Ignoring prior information leads to more samples
Statistical analysis of data - simple and straight forward

Stratified Random Sampling

Sampling population is divided into several non overlapping strata (b)
Each strata is more homogenous than whole population
Strata could be temporal or spatial
Sample size can be adjusted

Systematic random - subdivides the area into grids and collects samples using simple random sampling
Systematic Grid - easy to implement, Uniform distribution over the space or time domain Critical part -
choose right grid spacing

Page 3/5

TEST 1: MARCH -SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

Question 5 - Essay (6.00)

State the purpose of sample preparation

Answer

Schema
To homogenize sample or remove moisture
To increase or decrease analyte concentration
To remove interfering chemicals
To change the sample phase
To liberate analyte from sample matrix
To modify chemical structure

Page 4/5

TEST 1: MARCH -SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

Question 6 - Essay (10.00)

Explain the classical hotplate digestion method
Answer

Schema

Page 5/5

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Student ID : 2018227256 Total Mark: 35.00 / 40.00
Student Name : NURUL IZZATY IZLEEN BINTI HASMADY
Code : ANALYTICAL TECHNIQUE AND INSTRUMENTATION
Group : HS2436D
Lecturer Name : DR. AHMAD RAZALI BIN ISHAK

Title : Test 1: ENV460 Analytical Technique and Instrumentation
Taken : 2020-04-21 20:31:20

Question 1 - Essay (4.00 / 4.00)

State the purpose of environmental sampling

Answer

1. To determine the amount of pollutants that enters into environment through stack emission,
waste water discharge and so forth to comply with regulatory requirement

2. To measure the ambient background concentration and assess the degree of pollutants and
to identify the short and long term trends

3. To detect the accidental release and evaluate the risk and toxicity to human and biota
4. To study the fate and tranasport of contaminants and evaluate the efficiency of remediation

systems

Schema

-

To determine how much pollutant enters into the environment through stack emission,
wastewater discharge, and so forth in order to comply with regulatory requirement
To measure the ambient background concentration and assess the degree of pollution and
to identify the short and long term trends
To detect accidental release and evaluate risk and toxicity to human and biota
To study the fate and transport of contaminants and evaluate the efficiency of remediation
systems.

Question 2 - Essay (6.00 / 8.00)

Explain the criteria that need to be considered for selecting a sampling plan?

Answer

A sampling plan is a detailed outline of which measurements will be taken at what times, on which
material, in what manner, and by whom. Sampling plans should be designed in such a way that the
resulting data will contain a representative sample of the parameters of interest and allow for all
questions such as where,when, how many, as stated in the goals, to be answered. Criteria for
selecting sampling plan are as below:

1. Objective : Should have clear objective about the purpose of the study. get information
about the study such as get information using baseline monitoring or past studies. Other
element that can be look up to when determining objective are trend detection, search for
hotspot and margin of error allowable.

2. Variability : Decide the sampling either spatial variation or temporal variation.
3. Cost factors : Need to take into account the cost factors such as sampling cost, analytical

cost and fixed or minimum cost to ensure the method used according to budget so that
procedure of sampling are achievable.
4. Non-technical factor : The accessibility of equipment or instrument that will be used in
sampling and the availability of resources should take into account so that the sampling can
be done in convenience way.

Schema

-

Objectives – Baseline Monitoring, Trend detection, search for hotspot and margin of error
allowable
Variability– Spatial and Temporal Variation
Cost factor – Sampling cost, Analytical cost
Non technical factor– Samplig convinience, Accesibility, regulations

Question 3 - Essay (6.00 / 6.00)

Describe a few types of sample preservation and storage

Answer

Sample preservation and storage purposely to minimize the physical, chemical, biological changes
from sample collection to analysis. Types of sample preservation and storage are:

1. Refrigeration

Place the sample at cold temperature between 2⁰- 6⁰ and in dark. The cold storage can reduce the
metal solubility

2. Chemical addition

Acid, base, biocide can be added to preserve the sample. Chemical addition or pH change can
reduce metal adsorption to glass container wall. For example organic sample will undergo
biodegradation during storage, thus preservation are using low pH and temperature by adding
mercury chloride (hgcl2)to kill bacteria.

3. Proper container

It is important to know the nature of the sample to choose the correct container for storage such as
glass or plastic, cap or septum, and amber bottle. For example, oil tends to adsorption to plastics,
thus proper ways to the preservation is by using the glass bottle.

Schema

-

Refrigeration
Chemical Addition
Proper container

Question 4 - Essay (5.00 / 6.00)

Explain 2 types of sampling strategies

Answer

Judgemental Sampling

The choice of sampling units for inclusion in the study depends exclusively on the professional
judgement using prior information on the sampling site, visual inspection and personal knowledge
and experience. Judgemental sampling is less time consuming than other sampling techniques. It
also does not support any statistical interpretation of sampling result and no randomization. For
example, in a situation where researcher need to conduct convenience sampling to gather feedback
from professor about their university, but the fact that the chance for the result to be skewed are
high, so researcher prefer judgemental sampling to select those professors who will provide 100%
feedback

Stratified Random Sampling

This is a sampling method that involves the division of a population into subgroup (strata).
Importantly, strata used in this technique must not overlap, because if they did, some individuals
would have a higher chance of being selected than others. This strata is more homogenous than
whole population and it can be temporal or spatial. When, using this technique, sample size can be
adjusted. Example of stratified random sampling is, one might divide a sample of adults into
subgroups by age like 18-29, 30-39, 40-49, 50-59, 60-69 and above.

Schema

-

Judgemental Sampling

Selection of sampling locations based on professional judgment using prior information on
the sampling site, visual inspection and/or personal knowledge and experience
Schedule and budget - tight, early stage when objective is just screen the area
Primary representative sampling approach for groundwater assessment – selection of
monitoring well
No randomization

Simple Random Sampling

Arbitrary collection of samples by a process that gives each sample unit in the population
the same probability of being chosen

Assumes variability of sampled medium is insignificant – homogenous population
Applies for sites with little background information
Not applicable for heterogeneous population
Ignoring prior information leads to more samples
Statistical analysis of data - simple and straight forward

Stratified Random Sampling

Sampling population is divided into several non overlapping strata (b)
Each strata is more homogenous than whole population
Strata could be temporal or spatial
Sample size can be adjusted

Systematic random - subdivides the area into grids and collects samples using simple
random sampling
Systematic Grid - easy to implement, Uniform distribution over the space or time domain
Critical part - choose right grid spacing

Question 5 - Essay (6.00 / 6.00)

State the purpose of sample preparation

Answer

To homogenize sample which include blending and mixing of the sample or remove
moisture
To increase or decrease analyte concentration
To remove interfering chemicals that will cause inaccurate analytical result.
To change the sample phase
To liberate analyte from sample matrix
To modify chemical structure

Schema

-To homogenize sample or remove moisture
To increase or decrease analyte concentration
To remove interfering chemicals
To change the sample phase
To liberate analyte from sample matrix
To modify chemical structure

Question 6 - Essay (8.00 / 10.00)

Explain the classical hotplate digestion method

Answer
Classical hot plate digestion is one of the wet digestion for metal analysis from solid sample. This
method use mineral or oxidizing acid as external heat source to decompose the matrix and liberate
the metal in an analysable form.
Hot plate digestion is conducted under ventilation hood so that minimal exposure to metals while
allowing corrosive acids to be washed from hood after digestion is completed. Acid digestion can be
carried out for sediment, sludge and soil. Besides, digestion of food samples also can be done such
as on cereals, meat, fish and vegetables. The methods of classical hot plate digestion for sediment,
sludge and soil as below :

1. Prepare 1g of soil
2. Add 10ml of 1:1 HNO3 and cover with a watch glass. Heat the sample to 15 minutes without

boiling
3. Allow the sample to cool, add 5 ml of concentrated og HNO3. Cover with watch glass. Heat

the sample for 30 minutes without boiling. Add HNO3 until no brown fume given off.
4. Reduce volume to below 5 ml and let it cool. Add 2 ml of water and 30% of H202 and heat

below boiling point. Additional H2O2 until effervescence ceased. Process continue for2
hours at T<BP. Reduce the volume to <5ml
5. Add 10ml HCL and heat for 15 minutes. Filter and transfer to 100 ml VF for FLAAS or ICPMS.
6. Filter if necessary. Quantitatively transfer to 1000ml VF. Abalysis by GFAAS or ICPMS.
Schema

-

CENTRE OF ENVIRONMENTAL HEALTH
AND SAFETY

FACULTY OF HEALTH SCIENCES

ENV 460
ANALYTICAL TECHNIQUE AND INSTRUMENTATION

TEST 2

TEST 2 : MARCH-SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

(Total Mark: 45)

Question 1 - Essay (5.00)

Describe briefly the different type of extraction techniques for organic environmental pollutant from a solid
sample.
Answer

Schema

Page 1/4

TEST 2 : MARCH-SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

Question 2 - Essay (10.00)

Explain the procedure of Soxhlet extraction with an appropriate illustration.
Answer

Schema

A Soxhlet uses a range of organic solvents to remove organic compounds such as methanol, acetone -polar
compound), Chloroform , Petroleum ether, Hexane (Non Polar)Ethyl acetate (Phenolic compound).
The solid sample (10 g) and a similar mass of anhydrous sodium sulfate are placed in the porous thimble
(cellulose) and inserted in the inner tube of the Soxhlet apparatus.
The apparatus is then ﬕtted to a round-bottomed flask of appropriate volume containing the organic solvent of
choice, and to a reflux condenser.
The solvent is then boiled gently using an isomantle – the solvent vapour passes up through the tube marked (A),
is condensed by the reflux condenser, and the condensed solvent falls into the thimble and slowly ﬕlls the
body of the Soxhlet apparatus.
When the solvent reaches the top of the tube (B), it syphons over into the round-bottomed flask the organic
solvent containing the analyte extracted from the sample in the thimble.
The solvent is then said to have completed one cycle.
The whole process is repeated frequently until the pre-set extraction time is reached.As the extracted analyte will
normally have a higher boiling point than the solvent, it is preferentially retained in the flask and fresh solvent
recirculates.
This ensures that only fresh solvent is used to extract the analyte from the sample in the thimble.

Page 2/4

TEST 2 : MARCH-SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

Question 3 - Essay (5.00)

Briefly describe the different type of extraction techniques of organic contaminants from a liquid sample
Answer

Schema

Liquid– liquid extraction
Solid Phase Extraction
Solid Phase Microextraction

Question 4 - Essay (10.00)

Explain FOUR steps of Solid Phase Extraction (SPE) operation
Answer

Schema

Page 3/4

TEST 2 : MARCH-SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE & INSTRUMENTATION ENV460

Question 5 - Essay (5.00)

State FIVE sample introduction techniques for gas chromatography (GC).
Answer

Schema
Liquid injection
SPME
Headspace
Purge and Trap
Thermal Desorption

Question 6 - Essay (10.00)

Describe THREE steps of purge and trap method in gas chromatography (GC)

Answer

Schema
Purge
Analytes are extracted by the purge gas from the sample transferred to the U-shaped glass tube.
Trap
The extracted analytes are collected to the adsorbent contained in the trap tube.
Desorption drain
The collected analytes are desorbed by heating the trap tube.then back-flushed with nitrogen to send the sample
to the GC column.

Page 4/4

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Student ID : 2018264734 Total Mark: 40.00 / 45.00
Student Name : NUR AFIQAH SYAZWANY BINTI MOHD ISA
Code : ANALYTICAL TECHNIQUE AND INSTRUMENTATION
Group : HS2436C
Lecturer Name : DR. AHMAD RAZALI BIN ISHAK

Title : Test 2
Taken : 2020-05-21 13:05:09

Question 1 - Essay (5.00 / 5.00)

State FIVE sample introduction techniques for gas chromatography (GC).

Answer

FIVE sample introduction techniques for gas chromatography (GC) are:

1. liquid injection
2. solid phase micro extraction (SPME)
3. headspace
4. purge and trap
5. thermal desorption

Schema

-Liquid injection
SPME
Headspace
Purge and Trap
Thermal Desorption

Question 2 - Essay (9.00 / 10.00)

Explain the procedure of Soxhlet extraction with an appropriate illustration.

Answer

Soxhlet extraction is apparatus consists of a solvent reservoir, an extraction body, a heat source
and a water-cooled reflux condenser.

1. The solid sample (10g) and a similar mass of anhydrous sodium sulfate are placed in the
porous thimble (cellulose) and inserted in the inner tube of the Soxhlet apparatus

2. Next, the apparatuus is then fitted to a round-bottomed flask of appropriate volume
containing the organic solvent of choice, and to a reflux condenser.

3. Then, the solvent is then boiled gently using an isomantle. The solvent vapour passes up
through the tube marked (A), is condensed by the reflux xondenser, and the condensed
solvent falls into the thimble and slowly fills the body of the Soxhlet apparatus.

4. When the solvent reaches the top of the tube (B), it syphons oven into the round-bottomed
flask the organic solvent containing the anlyte extracted from the sample in the thimble.

5. The solvent is then said to have completed one cycle.
6. The whole process is repeated frequently until the preset extraction time is reached.
7. As the extracted analyte will normally have a higher boiling point than the solvent, it is

preferentially retained in the flask and fresh solvent recirculates. This ensures that only
fresh solvent is used to extract the analyte from the sample in the thimble.

For Soxtex,

Stage 1, a thimble containing the sample is immersed in the boiling solvent for approximately 60
min.

Stage 2, the thimble is elevated above the boiling solvent and the sample extracted as in the
standard Soxhlet extraction approach. This is carried out for up to 60 min.

Stage 3 involves the evaporation of the solvent directly in the Soxtec apparatus for 10 to 15 min.

Schema

-A Soxhlet uses a range of organic solvents to remove organic compounds such as methanol,
acetone -polar compound), Chloroform , Petroleum ether, Hexane (Non Polar)Ethyl acetate
(Phenolic compound).
The solid sample (10 g) and a similar mass of anhydrous sodium sulfate are placed in the porous
thimble (cellulose) and inserted in the inner tube of the Soxhlet apparatus.
The apparatus is then fitted to a round-bottomed flask of appropriate volume containing the organic
solvent of choice, and to a reflux condenser.
The solvent is then boiled gently using an isomantle – the solvent vapour passes up through the
tube marked (A), is condensed by the reflux condenser, and the condensed solvent falls into the
thimble and slowly fills the body of the Soxhlet apparatus.
When the solvent reaches the top of the tube (B), it syphons over into the round-bottomed flask the
organic solvent containing the analyte extracted from the sample in the thimble.
The solvent is then said to have completed one cycle.
The whole process is repeated frequently until the pre-set extraction time is reached.As the
extracted analyte will normally have a higher boiling point than the solvent, it is preferentially
retained in the flask and fresh solvent recirculates.
This ensures that only fresh solvent is used to extract the analyte from the sample in the thimble.

Question 3 - Essay (8.00 / 10.00)

Describe THREE steps of purge and trap method in gas chromatography (GC)

Answer

THREE steps of purge an trap method in gas chromatography (GC) are purge, trap and desorption
drain.

1. For purge, the analytes are extracted by the purge gas from the sample tranferred to the U-
shaped glass tube.

2. The second step is trap, which is the extracted analytes are collected to the adsorbent

contained in the trap tube.
3. Lastly, desorption drain required the collected analytes to desorbed by heating the trap

tube. Then, back-flushed with nitrogen to send the sample to the GC column.

Schema

-Purge
Analytes are extracted by the purge gas from the sample transferred to the U-shaped glass tube.
Trap
The extracted analytes are collected to the adsorbent contained in the trap tube.
Desorption drain
The collected analytes are desorbed by heating the trap tube.then back-flushed with nitrogen to
send the sample to the GC column.

Question 4 - Essay (5.00 / 5.00)

Describe briefly the different type of extraction techniques for organic environmental pollutant from
a solid sample.

Answer

The different type of extraction techniques for organic environmental pollutant from a solid sample
are soxhlet extraction, shake-flask extraction, ultrasonic extraction, supercritical fluid extraction,
microwave-assisted extraction, pressurized fluid extraction and matrix solid-phase dispersion.

Soxhlet extraction required the apparatus consists of a solvent reservoir, an extraction body, a heat
source and a water-cooled reflux condenser. A soxhlet uses a range of organic solvents to remove
organic compounds.

Second extraction techniques are shake-flask extraction which is a conventional liquid-solid
extraction. Shake-flask extraction is carried out by placing a soil sample into a suitable glass
container, adding a suitable organic solvent, and then agitating or shaking.

Next extraction techniques are ultrasonic extraction. Ultrasonic extrcation use sound waves to
agitate a sample immersed in a organic solvent by using a sonic probe or a sonic bath.

Futhermore, supercritical fluid extraction (SFE) also one of the extrcation techniques. SFE relies on
the diversity of properties exhibited by a supercritical fluid (CO2) to selectively extract analytes
from solid, semi-solid or liquid matrices. SFE properties are good solvating power, high diffusivity
and low viscosity and minimal surface tension.

Moreover, the next technique is microwave-assisted extraction (MAE). MAE utilizes organic solvent
and heat to extract organic pollutants from a solid matrices. The major difference between this
approach and others is the use of a microwave oven as the heat source.

In addition, pressurized fluid extraction also known as accelerated solvent extraction (ASE).
Pressurized fluid extraction uses heat and pressure to extract analytes rapidly and efficiently from
solid matrices.

Lastly, matrix solid-phase dispersion. Matrix solid-phase dispersion (MSPD) is analogous to solid-

phase extraction (SPE). The main difference of MSPD is used for solid samples.
Schema
-

Question 5 - Essay (8.00 / 10.00)

Explain FOUR steps of Solid Phase Extraction (SPE) operation
Answer
FOUR steps of Solid Phase Extraction (SPE) operation are:

1. Sorbent wetted and pre-conditioned. The sample is forced by pressure or vacuum through
the sorbent.

2. Sample applied and retained by sorbent, while some extraneous material passed through.
The analyte retained by the sorbent with other extraneous material present in the sample.

3. Remaining extraneous material washed off sorbent. The extraneous material washed from
the sorbent by the passing of an appropriate solvent.

4. Analyte eluted from sorbent and collected for analysis. The analyte of interest then eluted

CENTRE OF ENVIRONMENTAL HEALTH
AND SAFETY

FACULTY OF HEALTH SCIENCES

ENV 460
ANALYTICAL TECHNIQUE AND INSTRUMENTATION

TEST 3

TEST 3 : MARCH-SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE AND INSTRUMENTATION ENV460

(Total Mark: 60)

Question 1 - Essay (10.00)

a. State THREE sample preparation method of liquid samples for organic analysis. (3 marks)
b. Describe ONE of the methods mentioned in (a). (7 marks)

Answer

Schema

Question 2 - Essay (10.00) (4
(6
a. State FOUR introduction technique in gas chromatography
marks)

b. Describe the principle of purge and trap method.
marks)

Answer

Schema

Page 1/3

TEST 3 : MARCH-SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE AND INSTRUMENTATION ENV460

Question 3 - Essay (10.00) (5 marks)

a. State the components of Atomic Absorption Spectroscopy (AAS) (5 marks)
b. Describe several applications of AAS

Answer

Schema

Question 4 - Essay (10.00) (10 marks)

Describe TWO separation modes in High-Performance Liquid Chromatography (HPLC)

Answer

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TEST 3 : MARCH-SEPTEMBER 2020 ENV460 ANALYTICAL TECHNIQUE AND INSTRUMENTATION ENV460

Question 5 - Essay (10.00) (4 marks)
(6 marks)
a. Discuss the components on gas chromatography
b. Compare liquid and gas chromatography
Answer

Schema

Question 6 - Essay (10.00) (5 marks)
(5 marks)
a. Why is method validation is necessary?
b. State FIVE analytical characteristics used in method validation?

Answer

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Page 3/3

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Student ID : 2018262688 Total Mark: 58.00 / 60.00
Student Name : NURUL RAIHANA BINTI MOHAMMAD SALLEH
Code : ANALYTICAL TECHNIQUE AND INSTRUMENTATION
Group : HS2436C
Lecturer Name : DR. AHMAD RAZALI BIN ISHAK

Title : Test 3 : Analytical technique and instrumentation
Taken : 2020-07-06 03:46:47

Question 1 - Essay (10.00 / 10.00)

a. State the components of Atomic Absorption Spectroscopy (AAS) (5 marks)
b. Describe several applications of AAS (5 marks)

Answer

a. The components of Atomic Absorption Spectroscopy (AAS) are:

Light source/lamp. There are two types of light sources. The most used are Hollow-
cathode lamps (HCL) and electrodeless discharge lamp (EDL). The HCL contains a cathode
of the analyte element and an anode and is filled with a noble gas. When a high voltage is
applied across the anode and cathode, the metal atoms in the cathode are excited to
produce light with a particular emission spectrum. Meanwhile, the EDL contains the element
in a small quartz tube filled with a noble gas. A high-frequency field leads to a plasma within
the tube, in which the element is excited and emits specific light.
Atomizer. An atomize, or atomization cell is the site where the sample is introduced. There
are two types of atomizers, which are flame or graphite-furnace. It causes the metal-
containing sample to be dissociated and liberated from a hot environment. So, such an
atmosphere of the atomization cell is sufficient to cause a broadening of the absorption line
of metal.

b. There are several applications of AAS, such as:

Water analysis
In the analysis of foods for metallic elements, if the sample is a beverage it can often aspire
directly and the atomic absorption signal measured. Other food sample types such as
animal tissues, plants, and vegetables must first undergo a sample pre-treatment step. This
means that the sample must be ashed at a temperature no higher than 500°C to prevent
losses of some of the more volatile elements. The sample can also be digested using
mixtures of nitric, sulfuric, and perchloric acids.
Analysis of animal feedstuffs
Analysis of additives in lubricating oils and greases
Analysis of soils
Clinical analysis of heavy metals in the blood samples such as the whole blood, plasma, and
serum.

Schema

Question 2 - Essay (10.00 / 10.00)

a. State FOUR introduction technique in gas chromatography (4 marks)
b. Describe the principle of purge and trap method. (6 marks)

Answer

a. There is four introduction technique in gas chromatography:

Liquid injection
Solid-phase microextraction
Headspace
Purge and trap

b. The principle of purge and trap method is as follow:

This method is widely used for the extraction of volatile organic compounds from aqueous
samples of water, wastewater, or natural effluent. The volatile and semi-volatile analytes
are purged out from the matrix such as water by using an inert gas, usually nitrogen, then
trapped or collected in a solid sorbent material such as Tenax or activated carbon. After
that, the sorbent is heated to release the target compounds into the gas chromatography
for analysis.
There are three methods in the purge and trap method. The first one is sample purging.
Next is the analyte trapping, and the last step is desorption of analyte for analysis. During
the sample purging, the aqueous sample is usually around 5 ml is introduced into the U-
shaped glass purging vessel. Then, the high purity of the nitrogen gas bubble is passing to
the sample to remove and push the volatile analyte into the adsorbent contained in the
trap. So, the nitrogen usually 40-50 ml per minute and around 10-12 minutes. The purge
and trap method is followed by the adsorption method. The trap is heated about 120 to 250
degrees, and then back-flushed with nitrogen to send the sample to the GC column.
Typically, the adsorption time is 2 to 4 minutes, with a nitrogen flow rate of 1-2 ml per
minute.
The thermal desorption is the last component in the purge and trap method. The role of
thermal desorption is in conjunction with gas chromatography is to dissolve the analyte
from the tube or collecting material by application of heat and then analyzed by the
chromatography. So, the volatile analyte in the atmosphere can be absorbed onto the tube
or solid support material. This tube is used to concentrate the volatile compounds such as
air samples in the environment or the workplace. In this manner, the air sample in the
atmosphere can be regularly monitored. By placing the inlet of the tube at the suspected
source of contaminant, a measured volume of air to the tube containing the solid sorbent by
using an air sampling pump or vacuum pump.
After the monitoring is done, the tube brings back to the lab for analysis. The tube is then
inserted into the gas chromatography thermal desorption unit, where the analyte is then
dissolved directly to the gas chromatography by flowing the nitrogen over the samples. The
tube is then heated to release (desorb) the target compounds into the GC injector for
subsequent GC analysis.

Schema

Question 3 - Essay (10.00 / 10.00)

a. Discuss the components on gas chromatography (4 marks)
b. Compare liquid and gas chromatography (6 marks)

Answer

a. The components on the gas chromatography (GC) are as follows:

Carrier gas. The mobile phase is a carrier gas, as the gas flow through the system and
carries the injection sample. The properties of carrier gas are must be dry, which has no
water, free of oxygen, constant flow rate, and chemically inert. For example, the helium gas
has a broad range of flow rates and compatible with many detectors. The instance of carrier
gas to be used are nitrogen, argon, hydrogen, and carbon dioxide.
Injector. In the vaporization chamber, the injector is heated to 50°C and above the lowest
boiling point of the sample. It is then mixed with carrier gas to transport the sample to the
column.
Packed column. A finely divided, inert, solid support material, which is commonly based
on diatomaceous earth, is coated with the liquid stationary phase. The most packed
columns are 1.5 - 10m in length and have an internal diameter of 2 – 4mm. The capillary
columns have an internal diameter of a few tenths of a millimeter. The inner walls are
coated with a thin layer of stationary phase.
Detector. The detector is used as a quantitative measurement of the sample. The
example of the sensor commonly used in GC is mass spectrometry (MS), flame ionization
detector (FID), thermal conductivity detector (TCD), and electron capture detector (ECD).
The function of these detectors is to generate the signal and convert it to a chromatogram.

b. The comparison of liquid and gas chromatography is as follows:

Liquid Chromatography Gas Chromatography

The mobile phase is a liquid The mobile phase is a gas

Separation is based on the interaction of the Separation is primarily based on the boiling

solute with the chromatography medium points of solute molecules

Can be performed in a sheet or a column Can be carried out only in a column

Can be used to separate any soluble compound, Can be applied in the separation of volatile

e.g., amino acids, proteins, drugs, nucleic acids, compounds and gaseous mixtures

lipids, antioxidants, carbohydrates, and natural

and artificial polymers

Usually carried out at room temperature so heat- Performed at higher temperatures so thermally

sensitive compounds can be safely analyzed labile substances might get denatured

using the technique

Solute retention here is based on the interaction Separation is based on the boiling points of the

of solutes with the mobile and stationary phases solute molecules so it is not very flexible in terms

so it is easy to optimize results of optimizing separation

This analysis is a relatively slower technique The analysis is faster and usually measured in

minutes, although it can take as little as a couple

of seconds

Often gives a higher peak or broader band Provides comparatively better resolution

resulting in lower resolution

Uses polar solvents like water or methanol Uses any solvent that vaporizes
Schema

Question 4 - Essay (8.00 / 10.00)

Describe TWO separation modes in High-Performance Liquid Chromatography (HPLC) (10 marks)

Answer

There are two separation modes in High-Performance Liquid Chromatography (HPLC), the normal
phase, and the reversed-phase mode.

In the normal phase mode in HPLC, the mobile phase is nonpolar, while the stationary phase
is polar hydrophilic. The column is filled with silica particles. The silica is polar, so the polar
molecules bind or adsorb to it, and the nonpolar molecules will pass more quickly through
the stationary phase. The normal phase can be used for compounds that are too
hydrophobic or hydrophilic for separation using reversed-phase. It is also used when the
compounds that are not soluble in water or that may decompose in water are candidates for
normal-phase chromatography. One of the primary uses of normal-phase chromatography is
for the separation of isomers.
In the reversed-phase mode in HPLC, the mobile phase is polar, and the stationary phase is
nonpolar hydrophobic. The silica in the column is modified to make it nonpolar. Typically, 8
or 18 carbons are added to the silica (C8-C18). The silica 18 is nonpolar. The nonpolar
molecules bind or adsorb to it, and the polar molecules will pass more quickly through the
stationary phase. Reversed-phase HPLC is the most commonly used form of HPLC, as it is
easier to use than a normal phase. Besides, reversed-phase has a hydrophobic stationary
phase which can be applied to a wide range of molecules, and it works well in retention time
for most of the organic analytes as 70-80% of common analytes can be measured by
reversed-phase HPLC. Reversed-phase also has more options for the chromatographed. It
also allows precise control of variables such as organic solvent type and concentration, and
pH.

Schema

Question 5 - Essay (10.00 / 10.00)

a. State THREE sample preparation method of liquid samples for organic analysis. (3 marks)
b. Describe ONE of the methods mentioned in (a). (7 marks)

Answer
a. There is three sample preparation method of liquid samples for organic analysis as follows:

b. The liquid-liquid extraction method is described as follow:

Liquid-liquid extraction (LLE)

Solid-phase extraction (SPE)

Solid-phase microextraction (SPME)

In the principle of LLE, the sample is distributed or partitioned between two immiscible
solvents due to the analyte and matrix have different solubility. In other words, it is a
method by which a compound is pulled from the water, in the aqueous phase to organic
solvent, where water and organic solvent are not miscible. Then, the appearance of two
layers during the LLE process at the equilibrium can be seen.
So, the main advantage of this approach is the wide availability of pure solvents such as
dichloromethane, acetone nitrite, and methanol, and LLE can be conducted using a low-cost
apparatus such as by only using separating funnels.
The selectivity and efficiency of the LLE process are critically governed by choice of the two
immiscible solvents, an aqueous and organic solution, so the more hydrophobic analyte will
prefer the organic solvent. In contrast, the more hydrophilic compounds prefer the aqueous
phase.
There are two conventional approaches to LLE, which are discontinuous and continuous
methods. In a discontinuous approach, the extraction is carried out discontinuously, where
the equilibrium is established between two immiscible phases. The appearance of the two
layers can be seen. However, in a continuous approach, the balance may not be reached.
In discontinuous extraction, the most common approach is using separating funnel. In this
case, the aqueous sample (1 Litre of the sample) at a specific PH based on the optimized
condition is introduced into a large separating funnel, usually 2 liters capacity with a stopper
and 16 ml of a suitable organic solvent such as dichloromethane is added. The vessel is
then sealed with a stopper, and shaken vigorously either manually or mechanically for 1–2
min. This shaking process allows thorough interspersion between the two immiscible
solvents. It is maximizing the contact between the two surfaces and has assisting mass
transfer and thus allowing efficient partitioning to occur. It is necessary during the process
to periodically vent the excess pressure generated during this shaking process. After a
suitable resting period, the organic solvent is run off and retained in a collection flask. The
fresh organic solvent is then added again to the separating funnel, and the process is
repeated. This process should be carried out at least three times in total. So, the three
organic extracts should be combined and either ready for the analysis or pre-concentration
with exact requirements depend upon the level of contamination.
Another approach for liquid-liquid extraction is a continuous method, which can be used
when dealing with a considerable volume of sample. In this situation, a fresh organic solvent
is boiled, condensed, and allocated to percolate repetitively through the analyte-containing
aqueous sample. There are two common types of continuous liquid extractors available,
either a lighter-than-water or heavier-than-water organic solvents. These types of
extractions usually take several hours. Several systems can be operated and attended in a
series, thus allowing multiple samples to be extracted. In this continuous liquid-liquid
extraction process, typically, 1 L sample is added to the continuous extractor, and the PH
can be adjusted if necessary according to the optimized conditions. Then, 300 -500 mL of
organic solvent of the volume is added to the distilling flask together with several boiling
chips. Then, the solvent is boiled by using a water bath, and the extraction process allowed
to occur for between 18–24 h.
For example, when the extraction solvent, such as dichloromethane, is more substantial
than water, it has a higher density compared to the aqueous sample. It is consists of a tube
and a reservoir. The reservoir contains the same organic solvent. The tube is fitted with the
condenser. The solution in the reservoir is heated slowly and converted into vapors, which
move up and are condensed, and the organic solvent is transformed again into a liquid. This

solvent is denser than water. Thus it slowly descends to the bottom together with the
analyte of interest in the aqueous sample. The level of solvent is increased, and the
corresponding solvent will fall back into the reservoir. This process continues until the
maximum amount is transferred from aqueous to organic. Then, by opening the stopper at
the bottom, the organic and aqueous layer can be separated, then the solute can be
extracted from organic.
As the solvent is lighter than water, the reservoir contains an organic solvent, for example,
ethyl acetate, which has a lower density compared to the aqueous sample. The reservoir is
heated slowly and converted into vapors, which ascends and condenses in the condenser.
The organic solvent is converted into liquid. This solvent is then descended through a
bubbler-type funnel to the bottom of the aqueous sample. Since this solvent is lighter than
water, so it moves up to the top slowly by bringing together the analyte of interest in the
water sample. Thus, the level of solvent increases and the corresponding gets transferred
back into the reservoir. This process continues until the maximum amount of solute is
transferred from an aqueous solution to the organic solvent.
After completion of the extraction process and sufficient cooling time, the boiling flask is
detached, and solvent evaporation can proceed before analysis.

Schema

Question 6 - Essay (10.00 / 10.00)

a. Why is method validation is necessary? (5 marks)
b. State FIVE analytical characteristics used in method validation? (5 marks)

Answer

a. Method validation is necessary:

To prove what we claim is true
To minimize analytical and instrumental errors
To increase the trust of laboratory customers
To ensure the quality of the test results
To meet the accreditation requirement

b. There are five analytical characteristics used in method validation, such as:

Linearity
Selectivity/Specificity
Limit of Detection
Limit of Quantitation
Precision

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CENTRE OF ENVIRONMENTAL HEALTH
AND SAFETY

FACULTY OF HEALTH SCIENCES

ENV 460
ANALYTICAL TECHNIQUE AND INSTRUMENTATION

CONTINUOUS
QUALITY

IMPROVEMENT
(CDL-CQI)

CDL-CQI

Course Code : ENV460
Programme : HS243
Campus : UiTM Kampus Puncak Alam
Semester : Mar 2020 - Sep 2020 (DEGREE AND MASTER)

Overall Achievement Entrance Exit Survey SUF
3 (GOOD) 3 (GO
Course Grade
4 (VERY GOOD)

Exit - Entrance Survey (Frequency)

Score Gap -4 -3 -2 -1 0 1 2 3

Frequency 0 0 0 0 0 0 35 13

Student Feedback Online (SUFO)

Score Gap 4 3 2 1 20th Percentile 80% s
0 43.20
Frequency 130 84 2

Page 1/3

Printed By : DR. AHMAD RAZALI BIN ISHAK
Printed : 2020-12-10 15:57:55

FO OBE-SCL Implementation CO-PO-LO-KI Alignment
OOD) 5 (EXCELLENT) 5 (EXCELLENT)

4 20th Percentile 80% students Above Value CDL Indicator
6 10.80 2.00 3

students Above Value CDL Indicator
2.10 3

CDL-CQI

Exam Grade A+ A A- B+ B B- C+ C C- D

Grade

Num. of Student 0 6 60 0 0 0 0 0

OBE-SCL Iplementation (Self Evaluation)

Score 1 2 3 4 5 6 7 8 91

Result 5 5 55 5 5 5 5 5

CO-PO-LO-KI Alignment (Self Evaluation)

Score 1 2 3 4 5 6 7 8 91

Result 1 1 11 1 1 1 1 1

Page 2/3

D+ D E F 20th 80% students Above CDL
0 00 0 Percentile Value Indicator

2.40 3.67 4

10 11 12 Total Indicator
555 60 5

10 11 Total Indicator
11 11 5

CDL-CQI

Continuous Quality Improvement (CQI) Report

Critical Issue(s) Factor(s) Contributed to Issue

Practical Session Open distance learning (ODL) due to
Covid-19

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Action(s) to be taken (Process, Timeline (State Date) & Person
Procedure and/or Mechanism for Responsible
Monitoring)

Prepare a series of practical video session Next semester
for students