This document discusses polluted sample preservation and collection for further laboratory study. It provides information on different types of pollutants and their effects. It also describes various methods for sampling air, water, soil, and materials in containers to test for pollutants. Proper collection and preservation techniques are outlined to ensure sample integrity for accurate laboratory analysis.
Here you will find brief description about water sampling. actually it's so important to examine the water we use our daily life in order to avoid negative impact of water.
Ensuring potable water for public consumption is a major Public Health Concern. This presentation sums up all the necessary and prioritized parameters conducted for water analysis.
A report for my Environmental Management for Food Industries Class
This discussed the significance of trace and heavy metals present in wastewater and also the methods that can be used to lessen and remove them.
Here you will find brief description about water sampling. actually it's so important to examine the water we use our daily life in order to avoid negative impact of water.
Ensuring potable water for public consumption is a major Public Health Concern. This presentation sums up all the necessary and prioritized parameters conducted for water analysis.
A report for my Environmental Management for Food Industries Class
This discussed the significance of trace and heavy metals present in wastewater and also the methods that can be used to lessen and remove them.
This Presentation Clarifying about potable Water analysis and their methods which i gave training on operation and maintenance team for Oman Al Ghubrah Independence Water Project (SWRO Desalination 42 MIGD)
Deals with the measurement of organic matter concentration in water and wastewater. BOD, BOD kinetics and COD tests are discussed at length. Further, as part of the ultimate BOD measurement, other associated tests like Dissolved Oxygen and Ammonical, Nitrate and Nitrite forms of nitrogen are also discussed.
Generally soaps create foam in water, but in present of some materials the foam creation is reduced and need more soap for producing foam, and this condition of water is called water hardness.
The presence of Calcium, Magnesium salt i.e. bicarbonates, sulphates, chloride in water is called causes of hardness of water. The water which contains these salts is called hard water. Hard water does not easily form lather with soap as the salt of Calcium and Magnesium react with soap to form insoluble organic salts.
Water quality is one of the most important factors in a healthy ecosystem. Clean water supports a diversity of plants and animals.
The quality of the water you consume or use in municipal or industrial processes must meet specific parameters to ensure that drinking water remains free from contaminants that could cause health issues.
Water quality measurements include physical, chemical, and biological parameters.
This presentation describes, how the water can be analyzed using the basic parameters like DO, COD, BOD, Alkalinity and so on. The physical, chemical, and biological parameters were discussed here.
This Presentation Clarifying about potable Water analysis and their methods which i gave training on operation and maintenance team for Oman Al Ghubrah Independence Water Project (SWRO Desalination 42 MIGD)
Deals with the measurement of organic matter concentration in water and wastewater. BOD, BOD kinetics and COD tests are discussed at length. Further, as part of the ultimate BOD measurement, other associated tests like Dissolved Oxygen and Ammonical, Nitrate and Nitrite forms of nitrogen are also discussed.
Generally soaps create foam in water, but in present of some materials the foam creation is reduced and need more soap for producing foam, and this condition of water is called water hardness.
The presence of Calcium, Magnesium salt i.e. bicarbonates, sulphates, chloride in water is called causes of hardness of water. The water which contains these salts is called hard water. Hard water does not easily form lather with soap as the salt of Calcium and Magnesium react with soap to form insoluble organic salts.
Water quality is one of the most important factors in a healthy ecosystem. Clean water supports a diversity of plants and animals.
The quality of the water you consume or use in municipal or industrial processes must meet specific parameters to ensure that drinking water remains free from contaminants that could cause health issues.
Water quality measurements include physical, chemical, and biological parameters.
This presentation describes, how the water can be analyzed using the basic parameters like DO, COD, BOD, Alkalinity and so on. The physical, chemical, and biological parameters were discussed here.
This PPT contains all the information related to Environmental Forensics.
You can understand the concept explained in the PPT by watching the video:
https://youtu.be/Fyp0kgw2LWc
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As our environment is degrading day by day it's an important tool for the study of environmental health. Ecological indicators provide us information about the sudden change in the environment. So that we can take appropriate steps for its protection.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
1. ASSIGNMENT 2
Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya
COLLEGE OF AGRICULTURE GWALIOR (M.P.)
SUBMITTED BY GUIODED BY
DR.P.A.KHAMBALKAR OMPRAKASH PARIHAR
Dept. of SSAS, COA GWALIOR Roll No.20111109
M.Sc (Ag), AGRONOMY
POLLUTED SAMPLE PRESERVATION AND COLLECTION FOR FURTHER STUDY IN
LABORATORY
2. A pollutant is a substance or energy introduced into the
environment that has undesired effects, or adversely
affects the usefulness of a resource. A pollutant may
cause long- or short-term damage by changing the
growth rate of plant or animal species, or by interfering
with human amenities, comfort, health, or property
values. Some pollutantsare biodegradableand therefore
will not persist in the environment in the long term.
Different types of pollutantsin nature
Stock Pollutants:-Stockpollutantstowards which the
environment has low absorptive capacity are called
stock pollutants. (e.g. persistent organic pollutantssuch
as PCBs, non-biodegradableplastics and heavy metals).
Stock pollutantsaccumulatein the environment over
time.
Notable pollutants:-
Mercury (Hg)
Persistent organic pollutants(POPs)
Ozone (Ozone)
Particulatematter (PM)
Environmental Persistent Pharmaceutical Pollutants
(EPPP)
Polycyclic aromatic hydrocarbons(PAHs)
Volatile organic compounds(VOCs)
3. Fund pollutants:-
Fund pollutantsare those for which the environment has
the moderate absorptive capacity. Fund pollutantsdo
not cause damage to the environment unless the
emission rate exceeds the receiving environment's
absorptive capacity (e.g. carbon dioxide, which is
absorbed by plants and oceans.
Light pollutant:-
Light pollution is the impact that anthropogenic light
has on the visibility of the night sky. It also
encompasses ecological light pollution which describes
the effect of artificial light on individual organisms and
on the structure of ecosystems as a whole.
Water quality:-Refers to the chemical, physical, and
biological characteristics of water based on the
standards of its usage. It is most frequently used by
reference to a set of standards against which
compliance, generally achieved through treatment of
the water, can be assessed.
Objectives of Water Sampling
Baseline Water quality
Impact assessment
4. Assessment of Technology
Performance assessment of treatment plant
Assessment of products and processes
Crop performance
Environmental water quality, also called ambient water
quality:- relates to water bodies such as lakes, rivers,
and oceans. Water quality standards for surface waters
vary significantly due to different environmental
conditions, ecosystems, and intended human uses.
Toxic substances and high populations of certain
microorganisms can present a health hazard for non-
drinking purposes such as irrigation, swimming,
fishing, rafting, boating, and industrial uses.
Sampling and measurement:-
The complexity of water qualityas a subject is reflected
in the many types of measurements of water quality
indicators. Some measurements of water quality are
most accuratelymade on-site, because water exists in
equilibriumwith its surroundings.
Sample collection:-
More complex measurements are often made in a
laboratoryrequiring a water sample to be collected,
5. preserved, transported,andanalyzed at another location.
The process of water sampling introducestwo
significant problems:-
The first problem is the extent to which the sample
may be representative of the water source of interest.
Water sources vary with time and with location.
The second problem occurs as the sample is removed
from the water source and begins to establish chemical
equilibriumwith its new surroundings
Drinking water indicators
Alkalinity
Colorof water
pH
Taste and odor(geosmin, 2-Methylisoborneol
(MIB), etc.)
Dissolved metals and salts (sodium, chloride,
potassium, calcium, manganese, magnesium)
Microorganisms such as fecal coliform bacteria
(Escherichia coli), Cryptosporidium, and Giardia
lamblia; see Bacteriological water analysis
6. Dissolved metals and metalloids (lead, mercury,
arsenic, etc.)
Dissolved organics: colored dissolved organic
matter (CDOM), dissolved organic carbon (DOC)
Radon
Heavy metals
Pharmaceuticals
Hormone analogs
Physical indicators
Specific conductanceor electrical conductance(EC) or
conductivity
Total suspended solids (TSS)
Transparency or turbidity
Total dissolved solids (TDS)
Odour of water
Colorof water
Taste of water
Chemical indicators:-
pH
Biochemical oxygen demand (BOD)
Chemical oxygen demand (COD)
Dissolved oxygen (DO)
Total hardness (TH)
Heavy metals
8. Sample Preservation and Transport
Samples for BOD and bacteriological analyses should
be stored at a temp. < 4oC (ice/cold packs) and in the
dark as soon as possible after sampling. Once in the
laboratory, samples should betransferred as soon as
possible to a refrigerator. COD analysis is to be done
on the day of collectionor they should be preserved
below pH 2 by addition of conc. H2SO4. This
procedureshouldalso be followed for samples for
ammoniacal nitrogen, total oxidized nitrogen and
phenol analysis.
9. For metals:-
Samples should be acidified to below pH 2 with
conc. HNO3. Such samples can then be kept up to
6 months before they need to be analysed; mercury
determinationsshould be carried out within 5
weeks.
Samples should be transported to concerned
laboratoryas soon as possible, preferably within 48
hours. Analysis of bacteriological samples should
be started and analysed within 24 hours of
collection.
Air quality monitoring:-
Air quality monitoring station
10. Air pollutants are atmospheric substances—both
naturally occurring and anthropogenic—which may
potentially have a negative impact on the environment
and organism health.
With the evolution of new chemicals and industrial
processes has come the introduction or elevation of
pollutants in the atmosphere, as well as environmental
research and regulations, increasing the demand for air
quality monitoring.
Air quality monitoring is challenging to enact as it
requires the effective integration of multiple
environmental data sources, which often originate from
different environmental networks and institutions.
These challenges require specialized observation
equipment and tools to establish air pollutant
concentrations, including sensor networks, geographic
information system (GIS) models, and the Sensor
Observation Service (SOS), a web service for querying
real-time sensor data. Air dispersion models that
combine topographic, emissions, and meteorological
data to predict air pollutant concentrations are often
helpful in interpretingair monitoring data. Additionally,
consideration of anemometer data in the area between
11. sources and the monitor often provides insights on the
source of the air contaminants recorded by an air
pollution monitor.
Air sampling
Passive or "diffusive" air sampling depends on
meteorological conditions such as wind to diffuse air
pollutants to a sorbent medium. Passive samplers have
the advantage of typically being small, quiet, and easy
to deploy, and they are particularly useful in air quality
studies that determine key areas for future continuous
monitoring.
12. Air pollution can also be assessed by biomonitoring
with organisms that bioaccumulate air pollutants, such
as lichens, mosses, fungi, and other biomass.One of the
benefits of this type of sampling is how quantitative
information can be obtained via measurements of
accumulated compounds, representative of the
environment from which they came.
However, careful considerations must be made in
choosing the particular organism, how it's dispersed,
and relevance to the pollutant.
Soil contamination or soil pollution:- as part of land
degradation is caused by the presence of xenobiotics
(human-made) chemicals or other alteration in the
natural soil environment. It is typically caused by
industrial activity, agricultural chemicals or improper
disposal of waste. The most common chemicals
involved are petroleum hydrocarbons, polynuclear
aromatic hydrocarbons (such as naphthalene and
benzo(a)pyrene), solvents, pesticides, lead, and other
heavy metals. Contamination is correlated with the
degree of industrialization and intensity of chemical
substance.
Soil pollutioncan be caused by the following (non-
exhaustive list)
13. Microplastics
Oil spills
Mining and activities by otherheavy industries
Accidental spills may happen during activities, etc.
Corrosion of underground storage tanks
Acid rain
Intensive farming
Agrochemicals, such as pesticides, herbicides and
fertilizers
Petrochemicals
SOIL SAMPLING:-
Soil is quite heterogeneous containing rocks, trapped
gases, and liquids. It varies across the surface, and with
depth. This variation is caused by contact with the
atmosphere and the biosphere, as well as by the flow of
ground water. Soil sampling devices must be made of
tough material which can be forced into the soil. These
are usually brass, steel sometimes Teflon coated to
prevent contamination of the samples by the metals
used in construction of the sampler. Stainless steel
sampling devices are most popular. Chrome and nickel
plated devices should be avoided since scratches and
flaking can contaminate samples with trace elements.
When the sampling device is forced into the soil, there
14. is much friction between the tool and the soil sample.
SAMPLING STRATIFIED LEVELS IN
CONTAINERS
Sampling the contentsof containersof non-
homogeneous materials, for example, barrels of
hazardouswaste, can offer additional challenges
especially when the liquid is stratified within the
container.
An oily liquid will float over an aqueouswaste, while
solids may settle to the bottom. Several different types
of samplers have been developed for taking samples
from containersof this type.
This consists of an outer sheath and an inner rod. Along
the rod round, flexible wipers are positioned to hold the
sample in place, and prevent the different layers of
liquid from mixing with one another.
15. First the outersheath is raised, exposing the centerrod.
The rod is gently lowered into the containerfrom which
the sample is to be collected.Then the outersheath is
moved down, trappingthe liquid in place. When the
sampler is withdrawn, samples of the liquid at each
level can be recovered.
PRESERVATION OF SAMPLES
The sample must be representative of the environment.
Both physical and chemical processes may be involved
in changing the composition of a sample after it is
collected. Common physical processes which may
degrade a sample are volatilization, diffusion, and
adsorption. Possible chemical changes include
photochemical reaction, oxidation and microbial
degradation.
The collected sample is invariably exposed to
conditions very different from the original source. For
example, if a ground water sample is exposed to
sunlight after it is collected, photochemical reactions
may degrade some of the analytes of interest. Samples
often must be preserved in some way, to keep them
stable until the analysis is completed. shows some
16. sample types and the appropriate preservation methods.
These methods must not only keep the sample stable,
but must not interfere with the analyses to be done.
Volatilization:-
Analytes with high vapor pressures, such as volatile
organic compounds and dissolved gases, such as HCN,
SO2, will readily escape from the sample by
evaporation. Filling sample containers to the brim, so
that they contain with no head space is the most
common practice to minimize volatilization. The
volatiles cannot not equilibrate between the water and
the vapor phase above, if no air space is present at the
top of the container. The samples are usually held at
4oC, on ice, to lower the vapor pressure. Agitation
during sample handling should also be avoided, to
minimize air-sample interaction.
Choice of Proper Containers
The surface of the sample containermay interact with
the analyte. For example, metals can adsorb irreversibly
17. on glass surfaces, so plastic containersare often chosen
for water samples to be analyzed for their metal content.
These samples are also acidified with HNO3 to help
keep the metal ions in solution.
Absorption of Gases from the Atmosphere
Water samples can dissolve gases from the atmosphere
as they are being poured into containers. Such
componentsas O2, CO2 as well as volatile organic
compoundsmay dissolve in the samples. Oxygen may
oxidize species such as sulfite or sulfide to sulfate.
Absorption of CO2 may change conductanceor pH
measurements.
Chemical Changes
A wide range of chemical changes in the sample are
possible. For inorganic samples, controllingthe pH can
be useful in prevention of chemical reactions. For
example, metal ions may react with oxygen to form
insolubleoxides or hydroxides. The sample is usually
acidified with HNO3 to a pH less than 2, as most
nitrates are solubleand excess nitrateions will prevent
precipitation.
Sample Preservation for Soil, Sludges, and Hazardous
Wastes:-
18. Handling of water samples is betterunderstood than
solid and sludge samples, as these can be more varied in
composition, but similar methods are used. Commonly
encounteredproblems are biodegradation, oxidation-
reduction and volatilization. Storing the sample at low
temperatureis always recommended to reduce
volatilization, chemical reaction, and biodegradation.
preservation temperatureof 4oC is most commonly
used, because ice storage is convenient, and because a
lower temperaturemay freeze the water, and separate
the organic phase from the aqueous. Minimizing head
space is also important for reducing volatilization
losses.
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