Chapter 1 Introduction Environmental Analytical Chemistry Environmental Analytical Chemistry Chapter...
-
Upload
blaze-asher-mccoy -
Category
Documents
-
view
232 -
download
3
Transcript of Chapter 1 Introduction Environmental Analytical Chemistry Environmental Analytical Chemistry Chapter...
Chapter 1 Introduction
Environmental Analytical
Chemistry
Environmental Analytical Chemistry
Chapter 1Introduction
精品课程
Chapter 1 Introduction
Environmental Analytical
Chemistry
Teaching materials and reference books
Environmental Analytical Chemistry (Second Edition)
环境分析化学 - 但德忠主编分析化学(双语版 )- 大连理工大学分析化学教研室主编
Chapter 1 Introduction
Environmental Analytical
Chemistry
Total mark
Chapter 1 Introduction
Environmental Analytical
Chemistry
Contents
Contents
Chapter 1 Introduction
Environmental Analytical
Chemistry
Key points and Difficulties
Key points Definition and characteristics of environmental analytical chemistry; Basic concepts and definitions of sample, analyte, matrix, qualitative and quantitative analysis.
Difficulty The relationship between qualitative and quantitative analysis;
Environmental science presents some very difficult problems for
analytical chemists.
Key points and difficulties
Chapter 1 Introduction
Environmental Analytical
Chemistry1.1 Definition and characteristics of environmental analytical chemistry
人口、资源、环境是当今社会关注的三大主题 定义:它是研究环境污染物的组成、结构、状态以及含量的分析化学的一个新分支,是 21 世纪分析化学的一个重点研究领域。从某种意义上讲,环境科学的发展依赖于环境分析化学的发展。 特点:涉及范围广;对象复杂;变异性;定量分析;普遍性、实用性强。 — 摘自《 21世纪的分析化学》(汪尔康主编)
1.1 Definition and characteristics of environmental analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry1.2 Environmental science and analytical chemistry
Environmental science encompasses 包含 the study
of the whole human environment and in doing so 这样做 makes use of all scientific disciplines科学学科 . In a
vast number of studies the need emerges for information
on the composition of the parts of the environment
concerned. It is not possible for example, to study the
natural transport of substances, as in the water cycle, or
other natural processes, without measurement of the
substances being transported.
1.2 Environmental science and analytical chemistry
Chapter 1 Introduction
Environmental Analytical
ChemistryThe assessment of the depletion of the ozone layer 臭氧层耗 尽 requires measurements of the amount of ozone present
just as any investigation of the greenhouse effect demands
measurement on the concentrations of greenhouse gases.
Heavy metals and pesticides (杀虫剂) are substances
whose use and environmental concentrations are now
controlled by legislation 立法 in many countries, which
cannot be enforced 实施 unless the
concentration can be measured. Hence measurements must
be accurate, precise and fully validated.充分验证,完全有效
1.2 Environmental science and analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry
In some cases it is necessary to know the exact chemical
structure of compounds. Organic compounds, which differ
structurally only in minor and subtle ways在小的和微妙的方式 , can have very different physiological effects 生理效应 and pose very different levels of health hazards
健康危害 . Heavy metals such as lead and mercury are
dangerous pollutants in their inorganic forms. If, however,
they are converted into organo-metallics by either natural
or anthropogenic人为的 action, they are conferred 赋予additionally with lipid solubility 脂溶性 .
.
1.2 Environmental science and analytical chemistry
Chapter 1 Introduction
Environmental Analytical
ChemistryAs a result, their mobility in the human body is substantially
enhanced, and they become much more hazardous.
Two aspects of environmental science which frequently
arise, are requirements for the surveillance 监 管 or
monitoring of a particular area or ecosystem. Although
related, and often utilizing the same measurements, the two
concepts are different. Surveillance implies the assessment
and continued observation of a particular system to ensure
that it is ‘health’ and remains so. This is obviously a
difficult problem because every parameter cannot be
identified (识别 ) and continuously checked.
1.2 Environmental science and analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry On the precept 从技术规则上讲 that the health of the
system is measured by the health of the living organisms
生物体 that it supports, biological monitoring is often
employed. This approach, which is developed more fully
in chapters 12 and 20, selects certain monitoring
organisms to represent the overall system and keeps a
check on their health. This use of biological monitoring
leads on to the general principles of monitoring.
Individual parameters are selected and regularly 定期地assessed by appropriate measurements.
1.2 Environmental science and analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry
For example, in order to comply with 符合 legislation on
the release of pollutants into the environment, specified
elements or compounds will need to be measured on a
regular basis 定期地 , either in environmental samples,
or for instance in factory discharges 排放物 . Similarly,
in order that 为了 food and drinking water are known to
be suitable for consumption, the monitoring of specified
qualities and particular components will be needed.
1.2 Environmental science and analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry Some of the most newsworthy aspects of environmental
science are what might be termed ‘pollution incidents’.
These generally involve the sudden release of pollutants
from a point source such as an oil tanker 油轮 , mine
workings 矿山巷道 or factory. Extensive measurements
will be required for the assessment of the short and longer
term effects of an incident, as well as in the forensic task 司 法 任 务 of providing an unambiguous 清 晰 的
identification of the source of pollution. A high proportion of
the measurements needed in the circumstances outlined
above 以上概述 fall within the realm 范围;王国 of
analytical chemistry.
1.2 Environmental science and analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry1.3 Analytical chemistry
Analytical chemistry employs physico-chemical
principles to make measurements of chemical species i.e.
atoms, ions, molecules and free radicals 自由基,游离基 . The material collected and subjected to analysis is
know as the sample. It consists of two parts, the analyte
or analytes which are the substances to be determined, and
the rest of the sample which comprises the matrix. The
matrix can exert considerable influence over the way 方式 in which the analysis is carried out and the quality of
the results obtained.
1.3 Analytical chemistry
Chapter 1 Introduction
Environmental Analytical
ChemistryWhere the aim is to identify or detect the presence of a
species qualitative analysis is carried out. The detailed
determination of molecular structure is known as
structural analysis and is regarded as 被认为是 a
specialized form 特殊形式 of qualitative analysis. In
circumstances where the amount of a substance present is
measured, quantitative analysis is used. It is easy to
define different types of analysis, but in practice the
distinctions 区别 are less clear cut. For example, a
qualitative test may involve the use of a reagent which
develops a colour 显色 in the presence of the
analyte.
1.3 Analytical chemistry
Chapter 1 Introduction
Environmental Analytical
ChemistryHowever, below a certain concentration or detection limit the
colour will not be detectable. Thus, the qualitative test is
quantitative also in the sense 从… . 意义上说 that it can
only show that the analyte concentration does not exceed a
certain detection limit. Zero concentration of an analyte can
never be demonstrated in practice and does not exist in
principle. It should be noted that the situation with regard to
关 于 living organisms is different and it is sometimes
possible to say for a sample that no organisms of a particular
type are present. The framework 框架 within which a zero
result is reported must be very carefully defined.
1.3 Analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry Environmental science presents some very difficult problems
for analytical chemists. Some of the principal factors
underlying 构成… 的基础 these difficulties are listed
below.
1. The range of analyte types is very wide. They vary from
simple inorganic species at one end of the scale 天平 to
complex bio-molecules at the other.
2. Sample matrices [’meitrisiz] are frequently complex and
unknown. They may be solid, liquid or gaseous.
3. Analytes may have to be measured at very low
concentrations , e.g. a few ppb (μg kg-1).
1.3 Analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry
4. Environmental programmes often generate very large numbers
of samples and place a premium (额外)费用 on
automation.
5. Some analyses can only be made at, or very close to, the
sampling site. Readily portable and robust 易便携和强大的analytical equipment or remote sensing devices 遥感设备are thus required.
1.3 Analytical chemistry
Chapter 1 Introduction
Environmental Analytical
Chemistry
Review
Review
Chapter 1 Introduction
Environmental Analytical
Chemistry
Self – study exercises
1. Write down the definition and characteristics of
environmental analytical chemistry.
2. What is the principal factors underlying some very
difficult problems to analytical chemists in
environmental analytical?
3. Preview section1.3 - overall analytical process.
Self –study exercises
Chapter 1 Introduction
Environmental Analytical
Chemistry
References
1. Fifield F W, Haines P J. Environmental Analytical
Chemistry (Second Edition). Blackwell Science Ltd, 2000.
2. 但德忠 . 环境分析化学 . 北京 : 高等教育出版社 , 2009.
3. 大连理工大学分析化学教研室 . 分析化学 (双语版 )(国家精
品课程教材 ). 大连 : 大连理工大学出版社 , 2008.
4. 汪尔康 . 21世纪的分析化学(中国科学院研究生教学
丛书) . 北京 : 科学出版社 , 2001.
References
Chapter 1 Introduction
Environmental Analytical
ChemistryContent
Content
Chapter 1 Introduction
Environmental Analytical
Chemistry
Key points and Difficulties
Key pointsSelection of an appropriate method; sampling plan, sample
collection, sample handling and pretreatment ; analytical
measurement ; method validation and quality assurance ; data
assessment and interpretation.
Difficulty Definition of the aim of overall analytical process; Method
validation and quality assurance.
Key points and difficulties
Chapter 1 Introduction
Environmental Analytical
Chemistry1.4 Overall analytical processes The practical sequence of operations which is used to
obtain an analytical result from a sample, is known as the
analytical method. Its constituent [kən'stɪtʃuənt] parts
are often based upon different chemical principles, e.g.
precipitation, distillation, titration. These are called
techniques. An illustrative list 说明性清单 of some
groups of techniques appears in Table 1.1. If relevant and
reliable analytical information is to be obtained in an
environmental investigation more than a mastery of
analytical techniques and method is required.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry
Table 1.1 A classification of some analytical techniques
Type Properties measured
Gravimetric Weight of pure analyte or of a stoichiometric compound of it
Volumetric Volume of a solution containing a known amount of a reagent reacting with the analyte
Spectrometric Wavelengths and intensity of electromagentic radiation电磁辐射 emitted or absorbed by the analyte
Mass spectrometric Abundance 丰度 of atomic ions or molecular fragments 碎 片 derived from 衍生于 the analyte
Electrochemical Electrical properties of analyte solutions
Chromatographic Physico-chemical properties of analytes following separation
Nuclear or radiochemical
Energy and intensity of nuclear radiations emitted by the analyte
Thermal Physico-chemical properties of the analyte as heat is applied to it
Chapter 1 Introduction
Environmental Analytical
Chemistry It is essential to have a unified view 统一的观点 of the whole
process from the definition of the aims of the investigation through to
the final interpretation and presentation of the results. It is convenient to
do this in a number of stages 阶段 , i.e.
1. Definition of the aims;
2. Selection and development of an appropriate method
3. Sampling plan, sample collection, sample handling an pretreatment;
4. Separations;
5. Final measurement;
6. Method validation 方法验证 ;
7. Assessment and interpretation of results;
8. Safety
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry1.4.1 Defining the aims of an analytical programme This stage is clearly the fundamental one in designing an overall
analytical procedure. Sometimes it is straightforward, as in the
case of monitoring a system to comply with( 符合 , 遵守 )
specified legal requirements. Indeed, it is increasingly common
to find a standard overall procedure also specified. In other
circumstances the problem can be much more difficult. This is
especially so in investigatory or research situations. It may not
even be obvious what measurements are needed, let alone 更何 况 the levels of sensitivity, precision and accuracy required. To
define the analytical requirement, unquestionably requires full
consultation 充分协商 between the environmental scientists
and the analytical chemists.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry1.4.2 Selection of an analytical method
Having defined the aims of the analysis it is possible to
proceed to 着手 the selection of an appropriate method. A
whole range of factors needs to be taken into account in
this selection process. It is as important to avoid ‘over
analysing’ as it is to avoid producing data which are
inadequate in quality or quantity. Some of the important
factors are listed below. These are not in any strict order of
significance as this may change from one situation to
another.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry1. What is the analyte?
2. Detection limits;
3. Precision;
4. Accuracy;
5. Turn-round time; 周转时间6. Are analyses needed ‘on-site’?
7. Number of samples and any consequent automation;
8. Cost.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry1.4.3 Sampling, sample handing and pretreatment
Samples must be collected according to a plan which ensures that
they are representative of the original aims. Throughout
subsequent handling and treatment 在后续整个操作处理 they
must remain so. Many variables need to be taken into account
when producing a sampling plan. Obviously the plan must be
consistent with the principles set out 陈述 in sections 1.3.1 and
1.3.2, above. It must be borne in mind that the overall variability
of the results and the precision of the analysis can be significantly
influenced by variations in the compositions of replicate samples,
and that whatever care is taken such variations can never be
entirely eliminated. These variations must be assessed and
allowed for.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry At the initial stage of formulating a plan 制定某个计划 as
much information as possible about the proposed sampling
location must be sought. If little is available a pilot study 初 步研究 may well be justified 证明合理 before any
hypothesis can be generated.
Sampling can be divided into following types:
Hypothesis guided sampling (假设引导性采样) , which
employs the combined technical expertise 专业知识 of the
environmental scientists and the analyst, is frequently used.
Judgements are made about likely analyte distributions in an
attempt to focus the programme efficiently on to the
established objectives.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry Random sampling can be usefully applied if no obvious
patterns of analyte exist. The essence 本 质 , from the
statistical point of view, is that all blocks 街区 or containers
have the same chance of being sampled.
A practical form of random sampling for a surface, is to
collect samples along the lines of a ‘W’ pattern across the
sampling area. This approach is useful in initial surveys, and
provides a reasonable [ˈri:znəbl] 合理的 chance of obtaining
information on the general distribution 总体分布 of an
analyte while limiting the total number of samples.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry
Systematic sampling involves collecting samples
according to a rigid 严格的 , predetermined 预定的 plan
with respect to 关于,同…有关的 e.g. location, time
depth. It assumes no previous knowledge with regard to
analyte distribution, or indeed a particularly well-developed
hypothesis. The results should be free from bias 无偏见
but typically, large numbers of samples are generated, and
this may lead to a programme that is expensive to
implement [ˈɪmpləmənt] 实施,执行 .
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry
Stratified sampling may be employed in circumstances
where the system to be studied contains a number of regions
层,界 that are distinctly different. For example in a study
involving depth, the strata are selected on the basis of depth
and random sampling carried out within each stratum.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
ChemistryStratified sampling in vertical profile of soil
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
ChemistryStratified sampling in horizontal profile
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry Continuous monitoring demands a continuous analytical
signal from the sample. Its use is exemplified by the monitoring
of a waste discharge 排废 from a factory or the quality of water
in a river or stream. The need for the continuous signal places
restrictions on 限制 the nature 性质 of the analytical
procedure used. Methods based on batch processes 成批处理
such as chromatography 色谱 法 are unsuitable whereas those
derived from electrical 电学的 or spectroscopic 光谱学的
signals have more promising 有希望的 characteristics. The
practical situation is best illustrated by considering some typical
examples.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry In a land survey for a particular analyte, both lateral
[ˈlætərəl] 横向的 and vertical variations in concentration need to
be assessed. A routinely used approach is to divide the study area
with a regular grid pattern 网格 , taking samples at the centre of
each grid square and at predetermined 预定的 depths. The
dimensions 尺寸 of the grid will clearly be related to the size of
the area to be covered. For relatively small sites such as industrial
ones, 10 m squares may be appropriate. On the geochemical
scale, 1 km squares are more likely, with a more detailed study to
follow, if an initial, large-scale 大比例尺的 survey, indicates
local areas of interest. In completing the picture, other attributes
of the site might be examined, such as groundwater, streams or
vegetation.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
ChemistryFinally, temporal [ˈtempərəl] 时间的 variations and the effects
of the seasons need to be borne in mind. For example, nitrate
concentrations will depend on the stage of the agricultural cycle
at which nitrate fertilisers are used, and the degree of leaching
浸出程度 by rainfall 降雨 .
In the survey of a large body of water such as a lake, the same
spatial 空间的 parameters need to be considered and a similar
pattern of grid and depth sampling employed. Given 给定 the
capacity 容积 of a liquid for ready mixing, it is unlikely in most
cases that samples as closely spaced 紧密间隔 as 10m would be
collected. Depth studies might also be required over rather greater
distances.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry
It may well be that the dilution effected by the water means that
analytes are present at very low concentrations. The use of
pollution indicators 指标 such as sediments or filter-feeding
shellfish 滤食性贝类 , may be advantageous [ˌædvənˈteɪdʒəs]
有利的 in such circumstances. Seasonal effects here would be
exemplified by seasonal overturn 季节性翻转 , which occurs in
many lakes. In this process thermal effects 热效应 acting on
the water bring about 造成 mixing of the upper and lower
strata twice yearly 每年两次 , in spring and autumn.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry The sampling of vapours and gaseous [ˈgæsiəs] materials
presents its own special problems. Physically 从体力上看 , the
samples are difficult to handle, and the high mobility of substances
leads to rapid dispersion. Analytes may thus need to be trapped and
concentrated, for example by cooling to 冷却到 a liquid form, or
sorption on to 吸 附 到 a solid surface.
Maintenance 保持 of the integrity [ɪnˈtegrəti] 完整 of the samples cannot be stressed too strongly, and accordingly 因此,于是 their handling and storage after collection, and prior to
analysis, must be given careful consideration. Losses of the analyte
or contamination can occur by simple mechanical means, 手工方 法 evaporation [ɪˌvæpə'reɪʃn], or absorption from external sources.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
ChemistryDecomposition is a possibility and is a particular problem with
对于 organic and biological samples. Refrigerated storage 冷藏is one obvious possible solution. The difficulties outlined above
以上概述 are of especial concern where sampling is being carried
out at site remote from full laboratory facilities. Measurement
on-site 现场 with portable field equipment 便携式野外装备
must then be effected 实 行 where necessary.
In many cases it will not be appropriate to carry out the analysis
on the whole of the sample that has been removed to the laboratory
and it will need to be subdivided 细分 . Care must be exercised in
this subdivision process to ensure that the portion separated for
analysis is truly representative of the whole.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
ChemistryWhere the material is entirely homogeneous [ˌhoʊməˈdʒi:niəs] or is in a homogeneous solution, this clearly presents no
difficulties. Particulate solids with particles of varying sizes and
densities present special problems. The process of coning and
quartering 堆锥四分法 is often used here. In this, the total
sample is poured into a cone-shaped heap 锥形堆 so that the
heavier particles concentrate at the bottom of the cone [koʊn]
and the lighter ones at the top. One quarter of the cone is then
separated by vertical division, and the process repeated until a
portion of appropriate size for analysis is obtained.
This final portion should contain the same ratio of
particle types as in the original.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry Sample pretreatments constitute the stage in the analytical
process in which the sample is prepared for measurement of the
analyte. There is no general standard procedure and considerable
variations will be encountered. The analytes in water, for
example, may well need to be concentrated prior to
measurements. Simple evaporation [ɪˌvæpə'reɪʃn], solvent
extraction or other chemical separation procedures may be
required. Solid samples will usually need to be solubilised.
Crushing or grinding 破碎或研磨 followed by treatment with
aggressive 侵蚀性的 chemical reagents, including strong acids
or alkalis, are often used for this. Analyte losses must be carefully
guarded against 预防 at this stage, as must contamination.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry In ideal circumstances direct measurements can be made on
对 analytes without 如果没有 significant 严重的 matrix
effects
基体效应 or interference. Sometimes this is possible, especially
where spectrometric [spektroʊ‘metrɪk] methods 光谱法 are
employed to distinguish the analyte signal from others. Often,
however, this cannot be achieved and separations are needed.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry1.4.4 Analytical measurements
The making of an analytical measurement is often the
simplest and most straightforward 直截了当 stage in the
overall process. This is especially so in modern laboratories
where instrumental and automated procedures now dominate.
Many of the important measurement techniques are reviewed
in later chapter. It is timely 及时的 to recall 回想 here that
unless the earlier stages in the analytical process have been
properly executed [ˈeksɪkju:t] 实行 , the results obtained will
be meaningless [ˈmi:nɪŋləs] or, perhaps worse, misleading.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry1.4.5 Method validation and quality assurance
It is axiomatic [,æksɪə‘mætɪk] ( 不言 ) 自明的 that the
experimental results obtained must give a good indication of the
true result 真值 . The calibrations carried out in setting up the
method go part of the way 走了一段路 to ensuring this. Matrix
effects have previously been mentioned and these are difficult to
allow for fully in calibration standards, unless the matrix is very
simple. Analysis of validated standards, often known as standard
reference materials (SRMs), to check the performance of a method
is almost always essential. Standards used should have a
composition, which is closely similar to 十分类似于 the sample,
both in term of 在… 方面 its analyte concentration and matrix.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
ChemistryAs a result of extensive previous analysis by a variety of methods,
the analyte content of the standard is known within narrow limits.
Standards used can be ‘in-house’机构内部的 ones, which have
been established within the laboratory and which are valuable for
the routine checking 例 行 检 查 of method performance.
However, reference must also be made to others which are
accepted nationally and internationally. An extensive range of
such standards is available for many different analytes in widely
varying matrices. They can be obtained from bodies 团体 like
the National Institute of Standards and Testing (NIST), in the
United States, the Bureau of Certified Reference Materials (BCR)
in Europe, or the Laboratory of the Government Chemist (LGC)
in the UK.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry An initial validation 确认,认可 of a procedure is not in
itself sufficient to guarantee the continuing quality of the data
generated over an extended period. 在一段长时间 In order to
do this, an ongoing 不间断的 quality assurance (QA)
programme must be employed. Results obtained in
environmental analysis, frequently have legal [‘ligl] 法律的
as well as scientific implications. Hence the quality of the data
is doubly important 倍加重要 , as it may have to be
defended in a court of law, and match legal standards of proof.
A QA programme must be comprehensive and inclusive 具综合性和包容性 of the whole analytical operation. It has two
main elements.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry
The first is the development, validation and recording of the
overall procedure and ensuring that as far as possible 尽可能地 samples are all handled in exact compliance with 严格遵守 the defined procedure. This procedure must ensure the
traceability 溯 源 性 of the processing 处 理 of each
individual sample and measurement. The second requires
regular 定期的 performance monitoring. Routine analysis of
reference samples and maintenance 保持 of quality control
charts (section 2.5.5), are important tools in this.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry1.4.6 Data assessment and interpretation The data yielded by an analytical programme are used to try to fulfil
the original aims defined at the beginning. A two-stage process is
required for this. The reliability of the data must first be assessed. As
discussed in chapter 2, errors are implicit in all measurements and
correct procedures must be used to ensure that data with excessive
errors, which may endanger the validity 有效性 of the conclusions,
are not used. It is then possible to attempt to interpret the data in the
light of 按照 ,根据 the defined aims of the measurement. A blend
of environmental, analytical and statistical expertise [‘ɛkspɝ’tiz] 专 门知识 will be required to do this soundly. Careful thought should
also be given to data presentation, so that it is readily digested and
conclusions are clearly demonstrated.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
Chemistry1.4.7 Safety
A safety assessment for the programme 计划 and the
activities within it must be routinely made 进行 . It is
important to bear in mind, that the initial interest in
environmental analytes often derivers from their hazardous
properties, and that special precautions 预防措施 may well
be needed when dealing with some analytes. The main
problem will often arise not so much with 由于 the samples
themselves, as with the preparation and handling of standards
which utilize higher concentrations of the analyte.
1.4 Overall analytical processes
Chapter 1 Introduction
Environmental Analytical
ChemistryReview
Review
Chapter 1 Introduction
Environmental Analytical
Chemistry
Self – study exercises
• 1. Write down the stages of overall analytical process
in an environmental investigation. What needs to be
taken into account in each stage?
• 2. How to select an analytical method?
Self – study exercises
Chapter 1 Introduction
Environmental Analytical
ChemistryReferences• 1. Fifield F.W. and Haines P.J. Environmental
Analytical Chemistry (Second Edition). Blackwell
Science Ltd, 2000.
• 2. 但德忠主编 . 环境分析化学 . 高等教育出版社 , 2009.
• 3. 大连理工大学分析化学教研室主编 . 分析化学 (双 语版 )(国家精品课程教材 ). 大连理工大学出版社, 2008.
• 4. 汪尔康主编 . 21世纪的分析化学(中国科学院研究 生教学丛书) . 科学出版社 , 2001.
References
Chapter 1 Introduction
Environmental Analytical
Chemistry
Thank you!