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Friday 28 September 2012
Just Published: Analytica Chimica Acta
A new issue of this journal has just
been published. To see abstracts of the papers it contains (with links through
to the full papers) click here:
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 Jun Haginaka, Hiromi
Tabo, Hisami Matsunaga Monodisperse molecularly imprinted polymers (MIPs) for
diphenyl phosphate (DPP) and 1-naphthyl phosphate (1-NapP) have been prepared by
a multi-step swelling and polymerization method using 4-vinylpyridine as a
functional monomer, glycerol dimethacrylate as a crosslinker and cyclohexanol or
1-hexanol as a porogen. The retention and molecular-recognition properties of
these MIPs for organophosphorus compounds were evaluated by HPLC using a mixture
of phosphate buffer and acetonitrile as an eluent. In addition to shape
recognition, hydrogen bonding and hydrophobic interactions could play an
important role in the retention and molecular recognition of DPP and 1-NapP.
Furthermore, the MIPs were applied to the separation of adenosine and adenosine
phosphates (AMP, ADP and ATP). These phosphates were retained on the MIPs
according to the number of phosphate groups in the molecule and were well
separated from one another. Hydrogen bonding and hydrophobic interactions seemed
to affect the retention and recognition of adenosine phosphates in low
acetonitrile content, while hydrophilic interactions affected these properties
in high acetonitrile content. Finally, the MIPs were applied to the trapping of
phosphopeptides. The MIPs non-selectively trapped phosphopeptides, which have
phosphorylated tyrosine, serine or threonine in the sequences, and successfully
trapped four phosphopeptides in tryptic digests of bovine α-casein.
Graphical abstract
Graphical abstract Highlights
►
Monodisperse MIPs for organophosphates by multi-step swelling and
polymerization. ► Application of MIPs to the separation of adenosine phosphates.
► Application of MIPs to the trapping of phosphopeptides in tryptic
protein-digests.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 Marek Roszko,
Małgorzata Rzepkowska, Arkadiusz Szterk, Krystyna Szymczyk, Renata Jędrzejczak,
Marcin Bryła Polychlorinated biphenyls (PCBs) and polybrominated diphenyl
ethers (PBDEs) are hazardous food contaminants, their maximum legally allowable
levels in food and environment are in the low pgg−1 range. Therefore
some highly selective and sensitive analytical methods must be used to determine
them. The 96/23/EC Directive implemented by EC Decision of 12 August 2002
requires recovery rate of an analyte at a concentration below 1ngg−1
within the 50–120% range at relative standard deviation (RSD) as low as
possible. A method to determine low level PCBs and PBDEs in milk fat based on
the semi-permeable membrane dialysis/ion trap GC MS technique was developed.
Validation experiments proved that the method performance was within bounds set
by the currently standing UE regulations. Recovery rates calculated on the basis
of labeled internal standards for majority of the studied indicator PCB
congeners and PBDE congeners were close to 100% at RSD below 20%. Also,
dioxin-like PCBs recovery rates were compatible with the 1883/2006 EC Regulation
(80–120%, RSD below 15%). The developed method turned out to be linear within a
far broader concentration range than the studied 0.0025–10pgμL−1
range entirely sufficient for analyses of PCB and PBDE in milk fat. Within that
range coefficient of linear correlation (R 2) of calibration curves
exceeded 0.98.
Graphical abstract
Graphical abstract Highlights
► We
have investigated the usefulness of SPM dialysis for determination of PCB/PBDE.
► The factors affecting the dialysis process were evaluated. ► The ion trap MS
was optimized for determination of PCB/PBDE in milk fat. ► Described
extraction/clean up method proves usefulness for the milk fat
analysis.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 M.M. Parrilla
Vázquez, P. Parrilla Vázquez, M. Martínez Galera, M.D. Gil García An
ultrasound-assisted ionic liquid dispersive liquid–liquid microextraction
(US-IL-DLLME) procedure was developed for the extraction of eight
fluoroquinolones (marbofloxacin, norfloxacin, ciprofloxacin, lomefloxacin,
danofloxacin, enrofloxacin, oxolinic acid and nalidixic acid) in groundwater,
using high-performance liquid chromatography with fluorescence detection
(HPLC-FD). The ultrasound-assisted process was applied to accelerate the
formation of the fine cloudy solution using a small volume of disperser solvent
(0.4mL of methanol), which increased the extraction efficiency and reduced the
equilibrium time. For the DLLME procedure, the IL 1-octyl-3-methylimidazolium
hexafluorophosphate ([C8MIM] [PF6]) and methanol (MeOH) were used as extraction
and disperser solvent, respectively. By comparing [C8MIM] [PF6] with
1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM] [PF6]) and
1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM] [PF6]) as extraction
solvents, it was observed that when using [C8MIM] [PF6] the cloudy solution was
formed more readily than when using [C6MIM] [PF6] or [C4MIM] [PF6]. The factors
affecting the extraction efficiency, such as the type and volume of ionic
liquid, type and volume of disperser solvent, cooling in ice-water, sonication
time, centrifuging time, sample pH and ionic strength, were optimised. A slight
increase in the recoveries of fluoroquinolones was observed when an ice-water
bath extraction step was included in the analytical procedure (85–107%) compared
to those obtained without this step (83–96%). Under the optimum conditions,
linearity of the method was observed over the range 10–300ngL−1 with
correlation coefficient >0.9981. The proposed method has been found to have
excellent sensitivity with limit of detection between 0.8 and 13ngL−1
and precision with relative standard deviation values between 4.8 and 9.4% (RSD,
n =5). Good enrichment factors (122–205) and recoveries (85–107%) were obtained
for the extraction of the target analytes in groundwater samples. This simple
and economic method has been successfully applied to analyse real groundwater
samples with satisfactory results.
Graphical abstract
Graphical abstract Highlights
► A
novel method by US-IL-DLLME-LC-FD for fluoroquinolones determination. ► Simple,
rapid and efficient method for water samples. ► Advantages over conventional
methods. ► Low detection limits.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 Dayana Rubio Gouvea,
Fernando Meloni, Arthur de Barros Bello Ribeiro, João Luis Callegari Lopes,
Norberto Peporine Lopes Lychnophora salicifolia Mart., which occurs in the
Brazilian Cerrado in the states of Bahia and Minas Gerais as well as in the
southeast of the state of Goiás, is the most widely distributed and also the
most polymorphic species of the genus. This plant is popularly known to have
anti-inflammatory and analgesic activities. In this work, we have studied the
variation in terms of polar metabolites of ninety-three Lychnophora salicifolia
Mart. specimens collected from different regions of the Brazilian Cerrado.
Identification of the constituents of this mixture was carried out by analysis
of the UV spectra and MS data after chromatographic separation. Twenty
substances were identified, including chlorogenic acid derivatives, a flavonoid
C-glucoside, and other sesquiterpenes. The analytical method was validated, and
the reliability and credibility of the results was ensured for the purposes of
this study. The concentration range required for analysis of content variability
within the analyzed group of specimens was covered with appropriate values of
limits of detection and quantitation, as well as satisfactory precision and
recovery. A quantitative variability was observed among specimens collected from
the same location, but on average they were similar from a chemical viewpoint.
In relation to the study involving specimens from different locations, there
were both qualitative and quantitative differences among plants collected from
different regions of Brazil. Statistical analysis revealed that there is a
correlation between geographical localization and polar metabolites profile for
specimens collected from different locations. This is evidence that the pattern
of metabolites concentration depends on the geographical distribution of the
specimens.
Graphical abstract
Graphical abstract Highlights
Statistical analysis revealed
that there is a correlation between geographical localization of Lychnophora
salicifolia samples and polar metabolites profile for specimens collected from
different locations. ► A new HPLC-DAD-MS method for
analysis of the crude extract of L. salicifolia leaves. ► Twenty substances were
identified. ► Ninety-three wild specimens were analyzed. ► A correlation between
geographic isolation and decrease of the chemical similarity. ► The pattern of
metabolites depends on the geographical distribution of the
specimens.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 M. Kraiem, S.
Richter, N. Erdmann, H. Kühn, M. Hedberg, Y. Aregbe Uranium and plutonium
particulate test materials are becoming increasingly important as the
reliability of measurement results has to be demonstrated to regulatory bodies
responsible for maintaining effective nuclear safeguards. In order to address
this issue, the Institute for Reference Materials and Measurements (IRMM) in
collaboration with the Institute for Transuranium Elements (ITU) has initiated a
study to investigate the feasibility of preparing and characterizing a uranium
particle reference material for nuclear safeguards, which is finally certified
for isotopic abundances and for the uranium mass per particle. Such control
particles are specifically required to evaluate responses of instruments based
on mass spectrometric detection (e.g. SIMS, TIMS, LA-ICPMS) and to help ensuring
the reliability and comparability of measurement results worldwide. In this
paper, a methodology is described which allows quantifying the uranium mass in
single micron particles by isotope dilution thermal ionization mass spectrometry
(ID-TIMS). This methodology is characterized by substantial improvements
recently achieved at IRMM in terms of sensitivity and measurement accuracy in
the field of uranium particle analysis by TIMS. The use of monodisperse uranium
oxide particles prepared using an aerosol generation technique developed at ITU,
which is capable of producing particles of well-characterized size and isotopic
composition was exploited. The evidence of a straightforward correlation between
the particle volume and the mass of uranium was demonstrated in this study.
Experimental results have shown that the uranium mass per particle can be
measured via the ID-TIMS method to a relative expanded uncertainty of about 10%
(coverage factor k =2). The availability of reliable and validated methods for
the characterization of uranium particles is considered to be essential for the
establishment of SI-traceable measurement results. It is therefore expected that
the method developed in this study is valuable for the certification of
particulate materials in which the isotopic composition and the content of
uranium must be accurately known.
Graphical abstract
Graphical abstract Highlights
► A
method to quantify the U mass in single micron particles by ID-TIMS was
developed. ► Well-characterized monodisperse U-oxide particles produced by an
aerosol generator were used. ► A linear correlation between the mass of U and
the volume of particle(s) was found. ► The method developed is suitable for
determining the amount of U in a particulate reference material.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 Shunsuke Moriya,
Kaori Iwasaki, Keijiro Samejima, Koichi Takao, Kohfuku Kohda, Kyoko Hiramatsu,
Masao Kawakita An analytical method for the determination of three polyamines
(putrescine, spermidine, and spermine) and five acetylpolyamines
[N1-acetylspermidine (N1AcSpd),
N8-acetylspermidine (N8AcSpd),
N1-acetylspermine, N1,N8-diacetylspermidine,
and N1,N12-diacetylspermine] involved in the polyamine
catabolic pathway has been developed using a hybrid tandem mass spectrometer.
Heptafluorobutyryl (HFB) derivatives of these compounds and respective internal
standards labeled with stable isotopes were analyzed simultaneously by TOF MS,
based on peak areas appearing at appropriate m/z values. The isomers,
N1AcSpd and N8AcSpd were determined from their fragment
ions, the acetylamidopropyl and acetylamidobutyl groups, respectively, using
MS/MS with 13C2-N1AcSpd and
13C2-N8AcSpd which have the 13C2-acetyl group
as an internal standard. The TOF MS method was successfully applied to measure
the activity of enzymes involved in polyamine catabolic pathways, namely
N1-acetylpolyamine oxidase (APAO), spermine oxidase (SMO), and
spermidine/spermine N1-acetyltransferase (SSAT). The following
natural substrates and products labeled with stable isotopes considering the
application to biological samples were identified; for APAO,
[4,9,12-15N3]-N1-acetylspermine and
[1,4,8-15N3]spermidine (15N3-Spd), respectively; for SMO,
[1,4,8,12-15N4]spermine and 15N3-Spd, respectively; and
for SSAT, 15N3-Spd and
[1,4,8-15N3]-N1-acetylspermidine, respectively.
Graphical abstract
Graphical abstract Highlights
►
Compounds in polyamine catabolic pathway were determined by a column-free
ESI-TOF MS. ► N1- and N8-acetylspermidine were determined
by a column-free ESI-MS/MS. ► The method was applied to determine activities of
APAO, SMO, and SSAT in the pathway. ► The assay method contained stable
isotope-labeled natural substrates. ► It is applicable to biological samples
containing natural substrate and product.
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