Development of an extraction technique of determination of trace strontium

Along with strontium toxicity, two extractionmethods which are solid phase extraction SPE and vortex-assisted liquid-liquidmicroextraction method VALLME are presented with methodology, r

THAI NGUYEN UNIVERSITY

UNIVERSITY OF AGRICULTURE AND FORESTRY

NGUYEN HONG KIEN TOPIC TITLE: DEVELOPMENT OF AN EXTRACTION TECHNIQUE FOR DETERMINATION OF TRACE

STRONIUM

BACHELOR THESIS

Study mode : Full-time

Major : Environmental Science and Management

Faculty : International Training and Development Center Batch : 2010-2015

Supervisor : Assoc Prof Do Thi Lan

Prof Wu, Chien Hou

Thai Nguyen, 15/01/2015

THAI NGUYEN UNIVERSITY

UNIVERSITY OF AGRICULTURE AND FORESTRY

INTERNATIONAL DEVELOPMENT AND TRAINING CENTER

DEVELOPMENT OF AN EXTRACTION TECHNIQUE FOR DETERMINATION OF TRACE STRONIUM

BACHELOR THESIS

Student name : Nguyen Hong Kien

Major : Environmental Science and Management Faculty : International Training and Development Batch : 2010-2015

Supervisor : Assoc Prof Do Thi Lan

Prof Wu, Chien Hou

Thai Nguyen - 2015

DOCUMENTATION PAGE WITH ABSTRACT

Thai Nguyen University of Agriculture and Forestry

Degree Program Bachelor of Environment Science and Management

Student name Nguyen Hong Kien

Strontium with its availability in environment and harmfulness to human healthhas pulled a lot of attention as well as the studies from researchers all around theworld Even though there are a lot of extraction methods for substance traces ingeneral and for strontium in particular, they still show their own drawbacks andstrengths Therefore, it is very essential to develop more techniques for extractionwith the improvements from the previous methods SPE and VALLME methods aretwo of new extraction methods which are under progress of development, whichrequires a lot of work in scientific field study

This study delivers an overview picture for strontium toxicity which is currentlygot the low awareness from people Along with strontium toxicity, two extractionmethods which are solid phase extraction (SPE) and vortex-assisted liquid-liquidmicroextraction method (VALLME) are presented with methodology, results anddiscussion The SPE-VALLME combined technique in order to maximize theefficiency from SPE and VALLME had also been experimented

This study has contributed knowledge and confirmation to SPE and VALLMEabout its potential capacity in extraction and its reliability and accuracy forextraction method study, especially for strontium extraction in water sample orenvironmental sample

Keywords Strontium toxicity, extraction method, SPE, VALLME,

chromatographyNumber of pages 44 pages

Date of submission Jan 15th2015

First of all, I would like to express sincere thanks to the school board ThaiNguyen University of Agriculture and Forestry, Faculty of International Trainingand Development; Advanced Education program, thanks to the teachers who hasimparted to me the knowledge and valuable experience during the process oflearning and researching here

This study was also supported and instructed by professor Do Thi Lan (Dean ofFaculty of Environment, Thai Nguyen University of Agriculture and Forestry,Vietnam) and professor Wu, Chien-Hou (Department of Biomedical Engineeringand Environmental Sciences, College of Nuclear Science, National Tsing HuaUniversity, Hsinchu, Taiwan) I would like to give a special appreciation to MrWang Chin-Yi for helping me in time of doing this study

I sincerely thank you!

Taiwan, 2014 Student signature

NGUYEN HONG KIEN

TABLE OF CONTENT

PART 1 INTRODUCTION 4

1.1 RESEARCH RATIONALE 4

1.2 RESEARCH’S OBJECTIVES 4

1.3 RESEARCH QUESTIONS AND HYPOTHESES 5

1.4 STUDY SIGNIFICANCE 5

1.4.1 Scientific significance 5

1.4.2 Practical significance 5

PART 2 LITERATURE REVIEW 7

2.1 STRONTIUM 7

2.1.1 Strontium related definitions 7

2.1.2 Strontium when entering the environment 9

2.1.3 Strontium impact on health 11

2.2 STRONTIUM EXTRACTION 13

2.2.1 IC (Ion Chromatography) machine 13

2.2.2 Research’s ion chromatography 16

2.2.3 Solid Phase Extraction (SPE) method 17

2.2.4 Vorted-Assisted Liquid-Liquid Mircoextraction (VALLME) 18

2.3 RESEARCH RELATED DOCUMENTS 19

PART 3 METHODS 25

3.1 MATERIALS 25

3.2 EXPERIMENT 25

3.2.1 Solid Phase Extraction 25

3.2.2 Heating 28

3.2.3 Vortex-Assisted Liquid-liquid Microextraction 28

3.2.4 SPE-VALLME combined method 29

PART 4 RESULTS 30

4.1 SOLID PHASE EXTRACTION(SPE) 30

4.2 VORTEX-ASSISTEDLIQUID-LIQUIDMICROEXTRATION(VALLME) 32

4.3 SPE-VALLMECOMBINED METHOD 33

PART 5 DISCUSSION AND CONCLUSION 35

5.1 DISCUSSION 35

5.1.1 Solid phase extraction (SPE) 35

5.1.2 Vortex-Assisted Liquid-liquid Microextration (VALLME) 36

5.1.3 SPE-VALLME combined method 38

5.2 CONCLUSION 40

REFERENCES 42

APPENDICES 44

LIST OF FIGURES

Figure 2.1 Methyl Methanesulfonate 16

Figure 2.2 Crown ether of Sr resin 18

Figure 3.1 Spe method 26

Figure 3.2 Illustration of study experiment (SPE + VALLME) 29

figure 4.1: Elution curves of strontium with repeated condition (1ppm sr in 3m nitrate acid, 2ml of sample, 2ml of elution 30

figure 4.2 Recoveries of SPE processes with repetition (2 ml of 1ppm sr sample in 3m nitric acid, 6 ml of elution) 31

figure 4.3 The improvement in signals from standard solution, solution with SPE applied and solution of SPE-VALLME combined method (100 ml of 20ppb strontium sample) 34

figure 5.1 Illustration of VALLME experiment data for reliability (experiment with 10ppb, 25ppb, 50ppb, 100ppb, 300ppb, 500ppb, 1ppm, 1.5ppm) 37

figure 5.2 The connection of SPE-VALLME combined method experiments’ results and reliability of the result (concentrations: 1ppb, 10ppb, 20ppb and 40ppb) 39

LIST OF TABLES

Table 4.1 Data for SPE experiment with peak area, peak height, recovery(experiment with: 2 ml of 1ppm Sr sample in 3M nitric acid, 6 ml of elution) 32Table 4.2 Data for VALLME experiment with concentration and peak area(experiment with 10ppb, 25ppb, 50ppb, 100ppb, 300ppb, 500ppb, 1ppm,1.5ppm) 33Table 4.3 Peak areas of standard and SPE-VALLME applied solutions withconcentration of 1ppb, 10ppb, 20ppb, 40ppb 34

LIST OF ABBREVIATIONS

DIW : Deioned water;

SPE : Solid phase extraction;

VALLME : Vortex-Assisted Liquid-liquid Microextraction

PART 1 INTRODUCTION

1.1 Research rationale

Strontium extraction is rising as a hot topic in scientific study field Strontium hastwo types: the neutral and the radioactive Both of them have significant impacts tohuman health While the toxicity of strontium is still mysterious to humanunderstanding due to its long-term impact for number of reasons, extraction methodfor strontium is very essential Currently, there are many extraction methods forstrontium available, however each of them has its own strengths and weakness whilethe development of extraction method is never enough for scientific study, SPE andVALME could be a suggestion contributing to lists of extraction methods for not onlystrontium but for other substances (Chang W Y et al, 2012; Jakopic R and Benedik L,2005) In addition, even Vietnamese people are not familiar with the strontiumespecially strontium toxicity due to low level of strontium in its natural condition,Vietnamese government is planning to build couple of nuclear power plants whichwould accidently release some radioactive fallouts- one of them could be strontiumninety With study of SPE and VALLME for strontium extraction, it could help toextract strontium ninety from environmental sample while with modification, SPE andVALLME are able to work not only with strontium but other substances orcompounds

1.2 Research’s objectives

- To study on the extraction methods for strontium which mostly focus on SPE,VALLME and the combination of those two methods

1.3 Research questions and hypotheses

- What are the possible enrichment factor, recovery and reliability of SPEmethod?

- What are the possible enrichment factor, recovery and reliability of VALLMEmethod?

- What are the possible enrichment factor, recovery and reliability of VALLME combined method?

SPE What are the limitations of extraction method of SPE-VALLME combined?

1.4 Study significance

1.4.1 Scientific significance

With strontium toxicity and development of extraction techniques which focus onSPE and VALLME, this study has succeeded some other studies’ knowledge withfurther technical work and more specific substance trace With its contribution, thisstudy also suggested a new way of study as well as the practical extraction method- thecombination of two extraction methods with their own modification as crown etherapplied in VALLME

1.4.2 Practical significance

In context of globalization, environmental issues will become the hot topic not only

in single region but also in the world As the increase of human awareness to substancetoxicity, the extraction methods for specific trace are highly required More choicesand more applications for extraction methods will be studied and applied byresearchers all around the world By the strength of SPE and VALLME and itsflexibility in modification, SPE and VALLME are promised to be a fast, simple

extraction method with high accuracy especially in context of Vietnam’s buildingnuclear power plants and establishment of ASEAN community which possibly leads to

a lot of environment issues not only for Vietnamese but also for ASEAN researchers

PART 2 LITERATURE REVIEW

2.1 Strontium

2.1.1 Strontium related definitions

Strontium is a chemical element with atomic number of 38 and symbol Sr It is anearth alkaline metal and has highly reactive chemical ability in group IIA Strontium inpure form has soft silver-white color and turn to yellow just in condition of exposure

to air Strontium is stable in nature under form of compound with another elementbecause of its highly reactivity to air and water However synthetic90Sr is a radioactive

fallout with half-life of 28.90 years in naturally physical process and 49.3 years inbiological process

In nature, strontium is a common occurring element with two oxidation levels: 0and +2 Mostly, in nature, due to high chemical ability, only +2 oxidation state ofstrontium is stable and important Pure strontium is a hard, white-colored metal, butthis form is not commonly existed in environment, but in form of compounds inminerals There are variety forms of strontium which do not give any smell exactly.People can categorize strontium compounds in two different types: soluble and non-soluble Strontium in nature is not radioactive and exists in four different isotopeswhich are strontium eighty-four, eighty-six, eighty-seven, eighty-eight, symbolized as84

Sr, 86Sr, 87Sr, 88Sr They have the same chemical behavior which leads them get thesame effects on health when entering the body

Minerals in general (rocks, soil, dust, coal, oil, surface, ground water), air, plant,animal or even human bodies contain certain amount of strontium Typicalconcentration in most of them are few parts per million (ppm) For industrialproduction, strontium ore is taken from minerals of celestite (SrSO4) and strontianite

(SrCO3) After extracting from strontium ore, strontium is stored in form of compound

with other acid groups, such as carbonate, nitrate… through number of chemicalprocesses The compound of strontium has varied applications in daily life products,for instrance, glass products, pyrotechnics, paint paigments, fluorescent lights,medicines and other…

There are several radioactive isotopes of strontium and one of those is strontiumninety or90Sr, which is most dangerous isotopes of strontium Strontium ninety can be

formed in processes in nuclear reactors or nuclear weapon bomb Radioactivechemicals in general and strontium ninety in specific give off radiation to environmentwhich transform those chemical to other isotope of same or other element, nameddecay process Strontium ninety gives off radiation to turn to yttrium ninety (90Y)

which decays again to zirconium ninety (90Zr), being more stable isotope The first

decay process (from 90Sr to 90Y) has half-life of 29 years, which contributes more to

strontium toxicity Because 90Sr has very limited use, it is considered as the waste of

production while 89Sr is used as a cancer therapeutic to alleviate bone pain and 85Sr is

used in medical treatment1

For radioactive 90Sr, it is formed via nuclear fission processes and has been

released to natural environment by atmospheric nuclear explosion, nuclear plant wastedischarge, nuclear weapon testing and Chernobyl accident in 1986 90Sr has its

daughter which is 90Y and the process of decay into 90Y takes 28.90 years but 90Y

decays to 90Zr taking only 64 hours Additionally in human body, 90Sr mostly

accumulates in bone tissues because of its biochemical, atomic structure similaritywith its neighbor elements Calcium and Barium Most of Sr in human body deposits inbone, which is possibly the reason for bone cancer and nearby tissue cancer Because

of its danger to health,90Sr has got a lot of attention from scientific field

Agency for toxic substances and disease registry (ATSDR) of United Stated hasgiven their own health statement for strontium toxicity.

There are a lot of disposal places in the world and most of them are not authorized

to anyone for cleanup activities Just in the US, at least 102 and 12 of 1,636 sites ofNational Priorities List (NPL) sites, which contain names and places of all the wastesite with hazardous in US have been found strontium and strontium-90 in current listand former list, respectively Indeed total number of hazardous waste sites in specificand disposal places in the world have not named fully, which leads to be underevaluated and misinformative of strontium reserve and impacts of strontium to humanbeing As the increasing of awareness of people, number of disposal sites which havebeen detected for strontium is increased This is very important because the exposure

of strontium especially radioactive strontium to community is very harmful

As the other external exposure to radiation, strontium radiation exposure can befrom both nature and human activities Natural sources of radiation could be fromouter space, radioactive materials from soil or building Man-made sources forradiation may be products, industrial material, nuclear weapon fallout or nuclearreactors Depending on the level of exposure to strontium and type of strontium,victim’s status of health, people could suffer the different harmful impacts fromstrontium

2.1.2 Strontium when entering the environment

Stable and radioactive strontium compounds in the air are presented as dust.Emissions from burning coal and oil increase stable strontium levels in the air, whichmakes particles of strontium in air are mostly stable or non-radioactive strontium.After time floating in air, strontium particles will be settled down to water, land, plant

surface by themselves or precipitation processes (rain, snow, smog,…) They couldfollow the water current to take place in the bottom of river or lake where they willstay or mix with other strontium particles including radioactive ones that already there.

In water, strontium is normally dissolved no matter it is stable or radioactive.Because of taking place in earth alkaline group, strontium is easily dissolved in waterwhich is run over or through, which means in natural aquatic environment, strontiumfrom dust falling down to water is very few Generally, amount of strontium found inwater is 1ppm, which is because of the falling down strontium from dust into water.There are limited sources of information about 90Sr in drinking water, according to a

report of EPA (Environment Protection Agency) in US, 90Sr in drinking water in

different parts of US is less than 0.1 pCi/l or 0.004 Bq/l (1 litter of drinking water has0.004 atoms transforming per second) (Agency for toxic substances and diseaseregistry, 2014)

In soil, there is very wide range of strontium amount but typically from 0.2milligrams per kg (mg/kg) of soil (Agency for toxic substances and disease registry,2014) This value could vary, depending on the location or concentration of strontium

in releasing places and waste However the radioactive strontium occupies very smallfraction to strontium in soil but could be more if it is close to hazardous waste place orradioactive waste site

Strontium is found naturally in soil in amounts that vary over a wide range, but thetypical concentration is 0.2 milligrams per kilogram (kg) of soil (or 0.2 mg/kg)(Agency for toxic substances and disease registry, 2014) The disposal of coal ash,incinerator ash, and industrial wastes may increase the concentration of strontium insoil Generally, the amount of strontium ninety in soil is very small and is only a

fraction of the total concentration of strontium in soil Higher concentrations ofstrontium ninety in soil may be found near hazardous waste sites, radioactive wastesites Because of its easily soluble, strontium is likely to follow water to go deeper tothe ground but sometimes it could stay years in soil without going deeper because innature, there are a lot of chemical reactions making strontium compound from solubleinto insoluble form and reverts.

2.1.3 Strontium impact on health

Because of social reasons, harmful impact of toxic chemicals to human health will

be tested with scientific method which mostly focuses on procedure of absorption,circulation, elimination of toxics by body To understand that, scientists need to look atthe doses and behaviors of patients or testing animal For radioactive chemicals ingeneral and strontium in specify, animal testing and case study are very necessary.Strontium effect to human health is not an exception

It is clear to state that there is no or very minor effects of stable strontium in humanwith the typical amount in natural environment The problem with stable strontium isnormally the lack of calcium and protein in diet for children, plus with the unusuallyhigh level of strontium in food and drinking water, which leads to the formation ofbone by strontium rather than calcium (as mentioned above) This problem wouldmake the weakness in bone Recently, there is no report on strontium with directcontact with skin because of low level of strontium, short time of interacting.Additionally, it is not known yet whether stable strontium has effect on reproduction

of human or animal

Beside of effects on bone growth in young animals, there is very limitedinformation on effects of stable on cancer causing in human or animals However,

radioactive strontium has a lot of impacts on human health, mostly because of itsradioactive effect.

Since the radioactive strontium accumulates in bone, it has a lot of harmful effects

to health because of long time of half-life and radiation effects to function of bones.Firstly, due to radiation of strontium, the bone tissue and soft organs nearby get theimpact from radiation Bone has biologically function as source of blood cells, whichmeans radiation from strontium to bone can cause the reduction in blood cells Thiscould be witnessed in people who have injected 89Sr for cancer treatment in bone

marrow (Agency for toxic substances and disease registry, 2014) This phenomenon isalso observed in animals that breathe or eat food contaminated with radioactivestrontium When blood cells are reduced, many problems could occur They are theloss in ability of taking oxygen, leading to tiredness, or the loss in platelets whichresults in clothing following with abnormal bleeding The loss in white blood makesthe lower resistance to disease

There is also evidence that impacts from radioactive strontium can occur even byskin contact For medical purpose, radioactive can be used to eliminate unwantedtissues on eye or skin, which leads to the thin eye or skin tissues after the long time

It is lacked of evidence showing the effect of radioactive strontium to humanreproduction Reverse effects on animal reproduction happen when high level ofexposure to radioactive strontium which is much higher than typical level in nature.However the destruction in genetic material (DNA) in cells has been reported Therewas a significant increase in leukemia in population that use the river water containinglarge amount of90Sr and other radioactive materials releasing by nuclear weapon plant

Cancers of bone, nose and lung is the main consequence, which is also witnessed in

animals in neighbor area The International Agency for Research on Cancer (IARC)has listed radioactive strontium as carcinogenic to human because of its beta radiationemission and deep deposit in human body.

2.2 Strontium extraction

As the enhancement to the awareness of strontium toxicity, people tend to paymore attention to it, along with its related study Strontium has been raised as a favorstudy research because of its availability in nature, toxicity in radioactive form Thereare a lot of methods to extract strontium Each method has its own disadvantages andadvantages which could relate to time consuming, equipment requirement, complexity,low efficiency etc This study would be a suggestion for extraction technique fordetermination of traces which has its own advantages: less time consuming, equipmentindependence and disadvantages: resin reliability More information about strontiumextraction will be discussed in following parts of this report

2.2.1 IC (Ion Chromatography) machine

Ion Chromatography is application of ion-exchange resins to analytical separation

by using materials of stationary phase and mobile phase to separate charged species Inmost of cases, conductivity is the parameter for separation

There are two types of ion chromatography currently using: suppressor-based andsingle-column They differ in the method used to prevent the conductivity of theeluting electrolyte from interfering with the measurement of analyte conductivities

2.2.1.1 Ion Chromatography based on Suppressors

Conductivity detectors have many of the properties of the ideal detector They can

be highly sensitive, they are universal for charged species, and, as a general rule, they

respond in a predictable way to concentration charges Furthermore, such detectors aresimple to operate, inexpensive to construct and maintain, easy to miniaturize, andordinarily give prolonged, trouble-free service The only limitation to the use ofconductivity detectors, which delayed their general application to ion chromatographyuntil the mid-1970s, was that the high electrolyte concentration is required to elute themost analyte ions in a reasonable time As consequence, the conductivity from themobile-phase components tends to swamp that from the analyte ions, thus greatlyreducing the detector sensitivity.

In 1975, the problem created by the high conductance of eluents was solved by the

introduction of an eluent suppressor column immediately following the ion-resin that

effectively converts the ions of the eluting solvent to a molecular species of limitedionization without affecting the conductivity due to analyte ions For example, whencations are being separated and determined, hydrochloric acid chosen as the elutingreagent, and the suppressor column is an anion-exchange resin in the hydroxide form.The product of the reaction in the suppressor is water That is,

H+(aq) + Cl- (aq) + resin+OH-(s) → resin-Cl-(s) + H2O

The analyte cations are not retained by this second column

For anion separations, the suppressor packing is the acid form of a cation-exchangeresin, and sodium bicarbonate or carbonate is the eluting agent The reaction in thesuppressor is

Na+(aq) + HCO3-(aq) + resin-H+(s) → resin-Na+(s) + H2CO3(aq)

The largely undissociated carbonic acid does not contribute significantly to theconductivity

An inconvenience associated with the original suppressor columns was the need toregenerate them periodically (typically, every 8 to 10 hours) to convert the packingback to the original acid or base form, Recently, however, micromembranesuppressors that operate continuously have become available For example, whensodium carbonate or bicarbonate is to be removed, the eluent is passed over a series ofultra-thin cation-exchange membranes that separate it from a stream of acidicregenerating solution that flows continuously in the opposite direction The sodiumions from the eluent exchange with hydrogen ions on the inner surface of theexchanger membrane and then migrate to the other surface for exchange withhydrogen ions from the regenerating reagent Hydrogen ions from the regenerationsolution migrate in the reverse direction, thus preserving electrical neutrality.

2.2.1.2 Single-Column ion Chromatography

Recently, commercial ion-chromatography instrumentation that requires nosuppressor column has become available This approach depends on the smalldifferences in conductivity between sample ions and the prevailing eluent ions Toamplify these diffences, low-capacity exchangers are used that permit elution withsolutions with low electrolyte concentrations Furthermore, eluents of low conductivityare chosen

Single-column ion chromatography offers the advantage of not requiring specialequipment for suppression It is a somewhat less sensitive method of determininganions than are suppressor column methods, however

2.2.2 Research’s ion chromatography

IC machine is well known since the modern analysis science requires a methodwith rapid analyte and high performance of result The primary operation of thismachine is to separate the different pore and non-pore components from sample, based

on the affinity to ion exchanger Whole process would mostly happen in the columnwhere different analytes (separated chemicals) come to detector at different time,making the chromatography

IC machine in this study is the most common type:

column chromatography (not planar chromatography)

The principle of chromatography is the combination of stationary phase and mobilephase The different ions from the different components of sample will be carried bythe mobile phase which in this case is Methyl Methanesulfonate and are separated bythe difference in their migration rate The column contains only stationary phase which

in this study, the column is a commercial product- IonPac CS12A described inWebsite of DIONEX Company After going through the chromatography column, thesignal will be detected by the detector in the machine

This type of column was applied for this study which more specifically is IonPacCS12A The flowrate and eluent as the producer was 30mM MSA at 1ml/min Sampleloop was 100μl and suppressor was electrochemical with conductivity detection Fromthe previous study related to this type of machine, when the concentration of analytedeclines to lower than 20ppm This was the reason of difficulties in getting recovery inVALLME experiment, which would be discussed more in result and discussion part

Figure 2.1 Methyl Methanesulfonate

2.2.3 Solid Phase Extraction (SPE) method

There are several limitations to liquid-liquid extractions With extractions fromaqueous solutions, the solvents that can be used must be immiscible with water andmust not form emulsions Another difficulty is that liquid-liquid extraction userelatively large volumes of solvent, which can cause a problem with waste disposal.Also, most extractions are performed manually and as such are somewhat slow andtedious

Solid-phase extraction, or liquid-solid extraction, can overcome several of these

problems Solid-phase extraction techniques use membranes or small disposablesyringe-barrel columns or cartridges

Solid Phase Extraction (SPE), or called liquid-solid extraction This method isperformed in a cartridge with sample, phase extractant For strontium extraction, solid-phase microextraction is further required for detection Strontium because of smallquantity of target substance For SPE method, there are 4 steps: Conditioning, SampleLoading, Washing, Elution Column of special resin (described below) is the mainphase extractant which forms the crown ether Crown ether is a cyclic chemicalcompound which strongly binds to specific cations, forming complexes Examples ofcommon of crown ethers are 12C6 (which has 12 atoms and 6 oxygen atoms, used forbinding to potassium) or 12-crown-4 (which has 12 atoms and 4 oxygen atoms, usedfor binding to lithium ions) For this study, to bind Sr in water sample, crown ether of4,4'(5')-di-t-butylcyclohexano 18-crown-6 which is a commercial product of EIChromwith particle size 100-150μ

*About Sr resin: this is a commercial product

of Eichrom Technologies Company (USA)

There are 3 types of Sr resin provided EIChrom

company but for this study, Sr resin with particle

size of 100-150μm is applied

2.2.4 Vorted-Assisted Liquid-Liquid Mircoextraction (VALLME)

Liquid-liquid extraction (LLE) is branch of extraction method It bases on relativesolubilities of two different compounds in two different immiscible liquids, normallyorganic and inorganic solvent (water is very common use), however sometimes theycould be all either organic or inorganic solvents It helps to extract a target chemicalfrom a liquid phase to the other phase Normally, due to immiscible abilities ofsolvents, solvent will separate in two different layers, the organic compoundcommonly floats on inorganic compound because of lower density hence people canextract compound with chosen ions This technique is mostly applied in analytical orchemistry laboratory There are different branch of LLM since it was introduced as anew technique for extraction Many of techniques with different modified componentshave been developed to give the better result with more specific purpose of extractionand unique properties of analytes Vortex-Assisted Liquid-Liquid Microextraction(VALLME) technique is one of those

With number of overcome properties, VALLME has pulled a lot of attention fromscientific research field as a new technique needed to develop VALLME uses thecombination of derivatization and extraction to simplify and shorten the analyticaltime In this study, tetraphenylborate (TPB) acts as counter ion Counter ion helps to

Figure 2.2 Crown ether of Sr resin

maintain the electrical neutrality in the solution 4,4(5), di-t-butyl DC18-crown-6 is acommercial product which is another type of crown ether This compound traps thestrontium, leading to strontium stuck with organic compound However, IC machinecould not resistant to organic chemical (IC machine analyzes the inorganic ions)therefore VALLME needs to be repeated to transfer strontium from organic compound

to inorganic compound The stripping agent used in the second time of VALLME is0.1M of HNO3 Additionally, 4,4(5), di-t-butyl DC18-crown-6 used in this study was

the highlight of study because this was assumed as a innovation method whenapplying crown ether to VALLME Traditional VALLME was only used the different

in solubility of substances combining with the vortex machine to increase theinteraction surface area to strengthen the reaction ability By adding crown ether tosolution, this study opened the new method for extraction technique for strontiumextraction in specify and for analyte extraction in general

2.3 Research related documents

Because of familiar knowledge for modern extraction study, VALLME and SPEhave been practiced and tested in a lot of occasion and location in the world Eachexperiment and study gives its own point of view, helping to broaden the knowledgeand application of SPE and VALLME Experiments and studies can be set with variety

of traces and modification to method depending on purposes of study and experiments

In this part, number of studies related to strontium toxicity, strontium extraction, SPEmethod related to strontium extraction and VALLME application which have