Jegle, Simultaneous determination of inorganic anions and cations by capillary electrophoresis with indirect UV detection, J.. Richter, Simulta-neous determination of diclofenac and its
Trang 1Jorge Sáiza,b, Mai Thanh Ducc, Israel Joel Koenkad, Carlos Martín-Albercaa,b,
Peter C Hauserd,∗, Carmen García-Ruiza,b,∗∗
a Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Ctra Madrid-Barcelona Km 33.6,
28871 Alcalá de Henares, Madrid, Spain
b University Institute of Research in Police Sciences (IUICP), University of Alcalá, Ctra Madrid-Barcelona Km 33.6, 28871 Alcalá de Henares, Madrid, Spain
c Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi, Viet Nam
d University of Basel, Department of Chemistry, Spitalstrasse 51, 4056 Basel, Switzerland
a r t i c l e i n f o
Article history:
Received 15 August 2014
Received in revised form 20 October 2014
Accepted 27 October 2014
Available online 1 November 2014
Keywords:
Dual-CE
Portable CE
Concurrent determination
Anions
Cations
Fireworks
a b s t r a c t
Anewautomatedportabledual-channelcapillaryelectrophoresisinstrumentwasbuiltandappliedto theconcurrentdeterminationofcationsandanions.Thesystemusesasinglebufferandhydrodynamic injectionofthesampleisperformedautonomously.Anovelengravedflow-cellinterfaceisusedatthe injectionendsofthecapillariesallowingtheautonomousoperationofthesystem.Theengraved flow-cellreplacestraditionallyusedsplitinjectorsinpurposemadecapillaryelectrophoresissystemsand makesthesystemdesigneasier.Anewsoftwarepackagewithgraphicaluserinterfacewasemployed
tocontrolthesystem,makingitsoperationsimpleandincreasingitsversatility.Theelectrophoretic methodwasoptimizedtoallowthebaselineseparationof12cationsandanionscommonlyfoundin fireworks.Thesystemwasproventobeusefulfortheanalysisofconsumerfireworks,savingtimeand expensescomparedtoseparateanalysesforanionsandcations.Thisisthefirsttimethatcationicand anioniccompositionsoffireworksareinvestigatedtogether.Theanalysisofsamplesrevealedseveral inaccuraciesbetweenthedeclaredcompositionsforthefireworksandtheobtainedresults,whichcould
beattributedtocross-contaminationduringtheirmanufactureortoatransferbetweenothercomponents
ofthepyrotechnicitem.Thepresenceofcertainunexpectedpeaks,however,hadnoapparentreasonand mightrepresentanirregularityinthemanufactureofsomedevices
©2014ElsevierB.V.Allrightsreserved
1 Introduction
∗ Corresponding author Fax: +41 61 267 1013.
∗∗ Corresponding author Tel.: +34 91 885 6431.
E-mail addresses: Peter.Hauser@unibas.ch (P.C Hauser), carmen.gruiz@uah.es
(C García-Ruiz).
URL: http://www.inquifor.com (C García-Ruiz).
http://dx.doi.org/10.1016/j.chroma.2014.10.085
0021-9673/© 2014 Elsevier B.V All rights reserved.
Trang 2separationof both classesof species havebeenproposed They
2 Materials and methods
Trang 3Fig 1.Schematic of the portable dual-CE The pressure of the compressed air was set at 1 bar The HV side of the system was isolated into two independent safety cases.
Table1showstheprocedurefortheanalysisofsamples.First,BGE
Table 1
Normal operating procedure with the portable dual-CE for the analysis of samples.
Because V1 and V3 are normally closed valves, when they are ON the flow of solutions
is allowed throughout them The normal position of V2 is B.
Flush capillary 600 V1 ON; V2 A
Sample delivery 5 V3 ON; V2 B
Rinse grounded interface a 15 V1 ON, V2 B
Separation 540 HV ON
a
3 Results and discussion
Trang 4withdirectapplicationofpressure.Theuseoftheengraved
Trang 5Table 2
Limits of detection (LODs) and reproducibilities for the determination of anions and cations.
migration time (%RSD) b
Intraday reproducibility of peak area (%RSD) b
a Peak heights corresponding to 3 × baseline noise.
b Determined for 100 M NH 4 , K + , Ca 2+ , Na + , Mg 2+ , Sr 2+ , Ba 2+ , ClO 4 − and ClO 3 − ; 400 M Cl − and NO 3 − ; 300 M SO 4 − n = 9.
Fig 2.Concurrent separation of a standard solution of 7 cations (A) and 5 anions
(B) in a BGE composed of 60 mM MES/His at pH 6.0 in the presence of 2 mM of
18-crown-6 100 M NH 4 , K + , Ca 2+ , Na + , Mg 2+ , Sr 2+ , Ba 2+ , ClO 4 − and ClO 3 − , 400 M Cl−
and NO 3 − , 300 M SO 4 − The injection time was 1 min into capillaries of 25 m I.D.
Capillary for cations, 60 cm and 38 cm to the detector Capillary for anions, 67 cm
and 40 to the detector Separation voltage: +20 kV for anions and −10 kV for cations.
decreased
Fig 3.Determination of (A) low concentrations of ClO 3 − and ClO 4 − (1 M) together with other anions (25 M Cl−, SO 4 − and 50 M NO 3 − ) A longer injection for 4 min allowed their determination even when they are present at concentrations below their LODs with a injection of 1 min (B) Other condition as for Fig 2
Trang 6Fig 4.Separation of a standard mixture of high mobility cations together with a slow
cation with change of polarity during the separation (A) and without it (B) 100 M
NH 4 , K + , Ca 2+ , Na + , Mg 2+ , Sr 2+ , Ba 2+ and 200 M Cu 2+ The asterisk indicates the
change of voltage from −10 kV to −20 kV during the separation Other conditions as
for Fig 2
Ascanbeseen in Table3, theanalysisof thecharge ofthe
Fig 5.Electropherograms for the analysis of a complex firecracker The electro-pherogram A-a shows the determination of cations and the electropherogram A-b shows the determination of anions in the pyrotechnic charge The electrophero-gram B-a shows the determination of cations and the electropherogram B-b shows the determination of anions in the fuse Samples were diluted 10 times in water and injected for 1 min Other conditions as for Fig 2
Trang 7Table 3
Cationic and anionic composition of the charges and fuses of the firecrackers analyzed.
2-Charges
(mg/100mg)
Fuses
(mg/100mg)
declaredcomponentsforthissample,butit wasattributedtoa
contaminationfromtheclayplugsinthefireworkduetothelow
concentrationfound(0.038mg/100mg),asinprevioussamples
Themanufacturersdidnotdeclarethecompositionoffuses.For
thisreasonitwasnotpossibletocomparedeclaredcompositions
withtheresultsfromouranalysesandonlyanexpositionofour
resultsis givenhere.Theanalysisoffusesisimportantbecause
thereisfewinformationabouttheircompositionandbecausethey
areusuallyemployedinthemanufactureofimprovisedexplosive
devices.Ca2+andNa+werefoundatlowconcentrationsinallthe
fusesamplesandtheirpresencewasattributedtocontamination
fromtheclayplug,whichisdirectlyincontactwiththefuse,and
passesthroughit.Fireworksfusesaremadeofnitratesalts,
per-chloratesaltsorbothatthesametime.Mostofthefusesofour
studycontainedperchlorateandnitratesalts,whichaccordingto
thecationiccompositionscouldbeKNO3 and KClO4,duetothe
highconcentrationsofpotassiumfoundinallsamples.Thefuseof
therockethadonlyNO3 −,indicatingthatthisfusecontainsKNO3.
Mg2+wasdeterminedinthesampleofthecomplexfirecrackerand
thesingle-chargefirecrackeratverylowconcentrations(0.001and
0.003mg/100mgrespectively).Magnesiumisusedinfirecrackers
toproducewhitesparks.However,duetothelowconcentrations
found,itspresencecouldcomefromacontaminationinthe
manu-facturestep.ClO3−wasdeterminedintwofuses:thesmokebomb
fuseandthesingle-chargefirecrackerfuse.Asstatedabove,
chlo-ratesaltsareusedinsmokycompositions.Thisagreeswiththe
pyrotechniceffectofthesmokebomb,althoughitspresenceinthe
normalfirecrackerwasnotclear.Finally,Ba2+wasfoundatlow
con-centrationinthesmokebomb.Itspresencewasnotcleartousand
finallyweconcludedthat,duetothesmallconcentrationdetected
(0.227mg/100mg),itcouldbetheconsequenceofacontamination
duringitsmanufacture
Thesystemwasproventobehighlysuitableforthe
concur-rentdeterminationofanionsandcations,usingasinglebufferand
reducing thetotal timeof analysis.Thisisthefirst portableCE design,tothebestofourknowledge,thathasthedual-channel fea-ture.Theuseoftheengravedplatedesignallowedustosimplifythe designofthesystemwhiletheinjectionstepwasaverypreciseand controlledstep.Thesystemishighlyversatileandwasoptimized fordifferentpurposes,suchasthedeterminationoftraceelements,
toimprovetheseparationefficiencyortheanalysistime, depend-ingonthenecessities.Theanalysisofconsumerfireworksrevealed thatsomeitemswereslightlyaged,evidencedbythepresenceof
SO4 −andCl−inmixtureswithsulfurandperchlorateorchlorate salts.Moreover,thepresenceofCa2+andNa+incertainsamples wasattributedtoatransferfromtheclayplugs,usedtoconfinethe explosivepyrotechnics.Finally,forthefirsttimethecationicand anioniccompositionsoffireworkshavebeeninvestigatedtogether, givingamorecompleteinformationaboutthemanufactureofthis pyrotechnicdevices
Acknowledgments
JorgeSáizisthankingtheUniversityofAlcaláforhis postdoc-toralfellowship, CarlosMartín-Alberca thankstheUniversityof Alcaláfor hispre-doctoralgrantandPeterC.Hauserthanksthe SwissNationalScienceFoundationforaresearchgrant(GrantNo 200020-137676/1)
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