advanced analytical methods

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W.W.KUBIAK - ADVANCED ANALYTICAL METHODS

ADVANCED ANALYTICAL METHODS

ANALYTICAL SCIENCE


W.W.KUBIAK - ADVANCED ANALYTICAL METHODS W.W.KUBIAK - ADVANCED ANALYTICAL METHODS

Pass of subject:

Laboratory part – dr Reczyński (L)Lecture part – exam (E)Seminar part – presentation (P)

Final evaluation = 0.5E + 0.3L + 0.2P

Forms:Lecture ~ 12 hSeminar ~ 5 hLaboratory 28 h


Information sources:• lectures• net: http://galaxy.uci.agh.edu.pl/~kca/• manual: W.W.Kubiak, J.Gołaś (ed), „ Instrumentalne metody analizy chemicznej” Wyd. AKAPIT, Kraków 2005• R.Kellner, J.M.Mermet, M.Otto, M.Valcarcel, H.M.Widmer, “Analytical Chemistry: A ModernApproach to Analytical Science”, Wiley-VCH, Weinheim 2004 • Southampton Electrochemistry Group, “Instrumental methods in Electrochemistry” Ellis Horwood, Chichester 1990


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Results of anonymous quiz

2012 2013 2014 2015 2016 2018 2019

Good answers 35% 43% 40% 43% 45% 38% 37%

Wrong answers 25% 34% 44% 45% 35% 32% 32%

I do not know 40% 23% 16% 12% 20% 30% 31%


Good answers in the levels of analyticalknowledge

2012 2013 2014 2015 2016 2018 2019

Basic level 67% 58% 52% 50% 53% 43% 44%

Intermediate level 17% 38% 37% 40% 40% 20% 29%

Advanced level 17% 31% 28% 30% 40% 58% 29%


Areas of analytical science:

- Chemical composition analysis

Qualitative and/or quantitative information on chemical composition of material objects (sample).



- Process analysis

Composition analysis with additional independent variable time



- Distribution analysis

Composition analysis with additional independent geometric variables in micro- or macroscale

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- Structure analysis

Composition analysis with additional independent geometric variables in atomscale (nanoscale)


The result of analytical determination is always information of sample composition and uncertanity of this determination

Xsr – average concentration or content of specific compound (element – in case of elementar analysis, compound – in case of specific analysis or group of compounds in case of speciation analysis)

ε – uncertanty of analysis. May be expressed in various ways but must be presented


STEPS OF THE ANALYTICAL PROCESS


OBJECT OFINVESTIGATION

SAMPLE


DIMINISHED AND

HOMOGENIC SAMPLE

DIGESTED SAMPLE

OBJECT OF MEASUREMENT


MEASUREMENT SIGNAL

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RECORDED SIGNAL


RESULT OF ANALYSIS

Co2O3 – 2.4±0.2%;

Al2O3 – 24.4±0.8%;

SiO2 – 54.5±1.5%;

Ba0 – 4.6±0.4%

ANALYTICAL PROCESS


OBJECT OF MESUREMENT

SAMPLE

SIGNAL

RESULT OF MEASUREMENT

RESULT OFANALYSIS

INFORMATION

HIDDENVARIABLES

OBJECT OFINVESTIGATION PROBLEM

STRATEGY OF SAMPLINGSAMPLING

SAMPLE PREPARATION

MEASUREMENT

REGISTRATION/EVALUATION

CALIBRATION

INTERPRETATION

PERCEPTION SOLUTION OF

THE PROBLEM

MEASURINGSYSTEM

CHEMOMETRICMETHODS


LIST OF THE PARAMETERS OF ANALYTICAL PROCESS

Accuracy Precision Sensitivity Linear range Limit of detection Limit of determination Selectivity Specifity Repeatability Reproducibility Uncertanity Traceability

OBJECT OFINVESTIGATION


ANALYTICAL PROCESS


OBJECT OF MESUREMENT

SAMPLE

SIGNAL

RESULT OF MEASUREMENT

RESULT OFANALYSIS

INFORMATION

HIDDENVARIABLES

OBJECT OFINVESTIGATION PROBLEM

STRATEGY OF SAMPLINGSAMPLING

SAMPLE PREPARATION

MEASUREMENT

REGISTRATION/EVALUATION

CALIBRATION

INTERPRETATION

PERCEPTION SOLUTION OF

THE PROBLEM

MEASURINGSYSTEM

CHEMOMETRICMETHODS

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SAMPLE (PRIMARY AND ANALYTICAL)

Chemical analysis is performed usuallyregarding small part of the object ofinvestigation. This small part is calledsample. The process of extracting the samplefrom the object of investigation is calledsampling .

Sampling - operation resulting in obtaining sample, which isrepresentative to the object of investigation in regard to aim ofanalysis.


SAMPLE


Sampling is the most important stage of theanalytical process. The information obtainedas the result of the analytical process will benot better than quality of the sample.Quality of sample depends on the strategy ofsampling which must assure that sample isreprsentative.The sample must be representative inrespect to the object of investigation andthe analytical problem.


Representative and non-representative sample



Characteristic of sample which impact the sampling process

Solid, liquid, gas

Phase constitution

Homogenity

Size

Hardness

Voliatility

Durability

Size of the analytical sample P which is necessary to performingdetermination depends on determinability of the analytical methodA and the average content of determined substance G in theobject:

where:A – determinability of the method [g];G – assumed content of determined substance in the sample(mx mass of the determined substance, my mass of the samplematrix):


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Size of the sample n which should be taken from discreteobject (for example set of N pills) may be estimated roughly onbasis of square root:

More reliable and economic results are obtained fromhyphergeometric distribution, binormal distribution or Baye’stheorem. Statistical methods require to define confidence limitand assume number of analytical objects which may exceedlimiting concentration of analyte.


Strategy of sampling

Random sampling – samplesare randomly extracted fromobject of investigation.

Systematic sampling –samples are extracted on thebasis of geometric or timescheme.

•Stratum sampling – very large object of investigation isdivided on several stratum (layers). At each stratum randomsampling is performed.

•Represenative sampling - very large object of investigation isdivided on several stratum (layers). At each stratumsystematic sampling is performed. Number of samples ineach stratum should be proportional to its size.


Sample labelling – each container with sample must be labelled. The label should provide following information:

• venue of sampling

• time of sampling

• number of samples taken

• preservation or stabilisatin method (if any)

• for what method sample is intended

• additional information (who perform sampling, sample description etc)


Requirements for sample containers:

• material – inert to sample constituents (also preventing adsorption and absorption)

• durability (during sampling and transportation)

• size (appropriate to sample volume)


Sample containers

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Sample storage – samples should be analyzed as soon as possible. If interval between sampling and analysis time is longer nacessary is to use methods which prevents changes in the sample:

• low temperature (~4°C)

Laboratory refrigerators are equippedto keep an average temperature at+4°C while storing all different types ofsamples from reagents, whole bloodand culture media to test samples andbiologicals.


- deep freezing (-20°C; -40°C or temperature of liquid nitrogen)

The SWFSC Marine Mammaland Turtle Molecular ResearchSample Collection houses over70,000 DNA samples. Thesamples are stored in severalfreezers held at a constanttemperature of minus 80degrees Celsius.


- lyophilisation (freeze-drying)

Drying the samples to a powderform. Such samples can beaccurately weighed, easily sub-sampled and redissolved. Freezedrying is the preferred technology.Fast lyophilisation (LyoSpeed™)methodology developed byGenevac1 is implemented in theGenevac HT-12 centrifugalevaporation systems. The processof freeze drying requires threesteps:- Pre-freezing- Primary Drying- Secondary Drying


- application of preservatives, stabilizing-agents and other substances which prevents changes in the sample.

Influence of preservatives

Urine sample preservation (there is no single „all purpose” preservative): For determination of urea, ammonia, nitrogen and calcium- Hydrochloric acid is used (2 N or

concentrated HCL) For determination of sodium, potassium, chloride, bicarbonate, calcium, phosphorus, urea,

ammonia, amino acids, creatinine, proteins, reducing substances and ketone -thymol is used

For determination of ascorbic acid - acetic acid is used


Remember!

- Analytical process is the multistageprocess in which each stage isimportant and influence theuncertanity of final result.

- The sample MUST berepresentative to the object ofinvestigation

advanced analytical methods

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