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Current
Analytical Chemistry
ISSN: 1573-4110
Current Analytical Chemistry
Volume 5, Number 1, January 2009
Contents
The Use of APCI-MS with HPLC and Other Separation Techniques
for Identification of Carotenoids and Related Compounds
Pp. 1-25
Tomáš Rezanka, Jana Olšovská,
Miroslav Sobotka and Karel Sigler
[Abstract] [Full
text article]
A New Nuclear Material Safeguards Method
Using Fractal Dimension Pp. 26-28
David E. Booth and Stephane E.
Booth
[Abstract] [Full
text article]
Direct Quantitative Determination of
Total Arsenic in Natural Hotwaters by Anodic Stripping Voltammetry
at the Rotating Lateral Gold Electrode Pp.
29-34
Selehattin Yilmaz, Baris Baba, Alper Baba,
Sultan Yagmur and Meryem Citak
[Abstract] [Full
text article]
Determination of Nanomolar Mercury(II)
Concentration by Anodic-Stripping Voltammetry at a Carbon
Paste Electrode Modified with Functionalized Nanoporous Silica
Gel Pp. 35-41
Mehran Javanbakht, Hamid Khoshsafar, Mohammad
R. Ganjali, Alireza Badiei, Parviz Norouzi and Abed
Hasheminasab
[Abstract] [Full
text article]
Development of a New Combined Chemometrics
Method, Applied in the Simultaneous Voltammetric Determination
of Cinnamic Acid and 3, 4-Dihydroxy Benzoic Acid Pp.
42-47
Siavash Riahi, Mohammad R. Ganjali, Abdolmajid
B. Moghaddam, Eslam Pourbasheer and Parviz Norouzi
[Abstract] [Full
text article]
Use a Fluorescent Molecular Sensor for
the Detection of Pesticides and Herbicides in Water Pp.
48-52
François Delattre, Francine Cazier,
Fabrice Cazier and Alphonse Tine
[Abstract] [Full
text article]
Preparation and Application of Potassium
Ion-Selective Membrane Electrode Based on Benzo-15-Crown-5
Ether Pp. 53-58
Olcay Sendil, Erdal Peçenek, Güler
Ekmekci and Güler Somer
[Abstract] [Full
text article]
Diagnosis of Diabetes in a Diabetic Patient’s
Urine and Blood Using a Combination Electrode with a Ubiquitous
Handheld Analyzer Pp. 59-64
Suw Y. Ly
[Abstract] [Full
text article]
Exploiting Pulsed Flows for Heating Improvement:
Application to Determination of Total Reducing Sugars in Molasses
and Sugar Cane Juices Pp. 65-69
Evandro R. Alves, Mário A. Feres,
Elias A.G. Zagatto and José L.F.C. Lima
[Abstract] [Full
text article]
High-Resolution Solution NMR Spectra
in Inhomogeneous Magnetic Fields Pp. 70-83
Shuhui Cai, Wen Zhang and Zhong
Chen
[Abstract] [Full
text article]
Abstracts
[Back to top]
The Use of APCI-MS with HPLC and Other Separation Techniques
for Identification of Carotenoids and Related Compounds
Tomáš Rezanka, Jana Olšovská,
Miroslav Sobotka and Karel Sigler
[Full
text article]
The heat labile carotenoids cannot be analyzed by gas
chromatography (GC) and GC–mass spectrometry (GC–MS).
The only useful method appears to be high-performance liquid
chromatography (HPLC) with UV/visible (UV/Vis) or mass spectrometric
detection (LC–MS). Reversed-phase HPLC (RP-HPLC) is
a preferred method, which is frequently used with C18 stationary
phase, usually with gradient elution. In contrast to other
ionization techniques, xanthophylls and carotenes form both
molecular ions and protonated molecules during positive ion
APCI (atmospheric pressure chemical ionization). APCI is an
ideal method of ionization for low- to medium-polar compounds,
which include also carotenoids and related compounds. Since
their molecular mass does not exceed 2000 amu even in the
case of glycosides or esters with fatty acids, this method
is exceedingly suitable for their analysis. The review summarizes
the data on its use for this group of compounds.
[Back to top]
A New Nuclear Material Safeguards Method Using Fractal Dimension
David E. Booth and Stephane E.
Booth
[Full
text article]
The detection of losses from nuclear material inventories
is an important problem to be solved. The present paper considers
the detection of such losses by using the fractal dimension
of the material balance time series to detect the outliers
that are the loss points. We find the proposed method to be
successful.
[Back to top]
Direct Quantitative Determination of Total Arsenic in Natural
Hotwaters by Anodic Stripping Voltammetry at the Rotating
Lateral Gold Electrode
Selehattin Yilmaz, Baris Baba, Alper Baba,
Sultan Yagmur and Meryem Citak
[Full
text article]
A simple, rapid, selective and sensitive differential
pulse anodic stripping voltammetric (DPASV) technique for
the direct quantitative determination of inorganic total arsenic
in natural hotwater was developed. The electrochemical determination
of total arsenic has been carried out at the novel rotating
lateral gold electrode in hydrochloric acid solution (37 %
w/w). The analysis was performed with a special gold electrode
whose active surface was located on the side. Reproductivity
of measurement was achieved by the conditioning of the gold
electrode. This was done every day before the measurements
as well as when the background current varied strongly from
measurement to measurement. The determination limit of 0.5
μg
L-1 was achieved with 10
mL sample solution. The total arsenic concentration was made
by appropriate selection of the deposition potential. During
the deposition step, the total arsenic content was reduced
at -1200 mV by nascent hydogen to As°.
During the subsequent voltammetric determination, the preconcentration
As°
was again oxidized to determine the level. The method was
applied successfully to the direct quantitative determination
of total inorganic arsenic in hotwater. In order to show the
accuracy of the results developed from voltammetric technique,
the values obtained were compared with those obtained from
inductively coupled plasma mass spectrometry (ICP-MS).
[Back to top]
Determination of Nanomolar Mercury(II) Concentration by Anodic-Stripping
Voltammetry at a Carbon Paste Electrode Modified with Functionalized
Nanoporous Silica Gel
Mehran Javanbakht, Hamid Khoshsafar, Mohammad
R. Ganjali, Alireza Badiei, Parviz Norouzi and Abed
Hasheminasab
[Full
text article]
The aim of this study involves the determination of mercury
ions at nanomolar level with the employment of the dipyridyl
functionalized nanoporous silica gel - chemically modified
carbon paste electrode (DPSG-CPE) by anodic stripping voltammetry.
The experiments were conducted with a certain electrode composition
of 25% paraffin oil, 60% high purity graphite powder and 15%
DPSG as well as the usage of 0.20 M KNO3
as supporting medium. The reduction potential and time were
set at, -200 mV and 450 s, respectively, and the scan rate
at 100 mV s-1 in the scan
range of -200 to 500 mV. The analytical performance of the
modified electrode was evaluated with respect to the carbon
paste composition, the solution pH at the accumulation step,
the preconcentration time, the mercury concentration, the
possible interferences and other variables. On this modified
electrode, the anodic stripping voltammetric mercury determination
at nanomolar level concentrations was successfully attempted.
The resulting electrode demonstrated linear response across
a wide mercury(II) concentration range (20–100 nM) with
a detection limit value of 8 nM, on the basis of a signal
to noise ratio of 3. The precision for six determinations
(n=6) of 40 and 75 nM mercury(II) was 5.0% and 2.8% (relative
standard deviation), respectively. After studying the influence
of the potential interfering ions, it was found that the proposed
procedure was free from most interference. To testify the
accuracy of this method, comparative determination of mercury(II)
in wastewater samples by the proposed method and cold vapor
AAS method were done and a sufficient sensitivity for the
practical analysis of the environmental samples was attained.
[Back to top]
Development of a New Combined Chemometrics Method, Applied
in the Simultaneous Voltammetric Determination of Cinnamic
Acid and 3, 4-Dihydroxy Benzoic Acid
Siavash Riahi, Mohammad R. Ganjali, Abdolmajid
B. Moghaddam, Eslam Pourbasheer and Parviz Norouzi
[Full
text article]
The voltammetric behavior of cinnamic acid (CA) and 3,
4-dihydroxy benzoic acid (BA) at an glassy carbon disc electrode
has been investigated. The obtained cyclic voltammograms showed
that their oxidation peaks were overlapped and it was difficult
to determine them individually from a mixture without separation.
To overcome this limitation, partial least squares (PLS) modeling,
as a powerful multivariate statistical tool, was proposed
for the resolution of the overlapped voltammetric signals
from mixtures of CA and BA. With the help of the orthogonal
signal correction (OSC), the unrelated information was removed
and the results were confirmed. In this procedure, the genetic
algorithm (GA) was used for the potentials selection for PLS.
In addition, OSC-GA-PLS for the first time was used and the
results of this method were better than those of the other
methods. The proposed method was suitable for the determination
of CA and BA in mixtures.
[Back to top]
Use a Fluorescent Molecular Sensor for the Detection of Pesticides
and Herbicides in Water
François Delattre, Francine Cazier,
Fabrice Cazier and Alphonse Tine
[Full
text article]
A fluorescent chemosensor based on modified β-cyclodextrin
was used for the detection of pesticides and herbicides in
water. Binding constants, thermodynamic parameters and sensitivity
factors were calculated and supported by AM1 semi-empirical
method calculation. The results show clearly that a fluorescent
chemical sensor based on modified β-cyclodextrin
detects quantitatively the presence of pesticides or herbicides
and allow a direct analysis of these pollutants as a new method
of detection with limits of the order of ppm for the whole
of the analytes.
[Back to top]
Preparation and Application of Potassium Ion-Selective Membrane
Electrode Based on Benzo-15-Crown-5 Ether
Olcay Sendil, Erdal Peçenek, Güler
Ekmekci and Güler Somer
[Full
text article]
A new potassium ion–selective membrane electrode
has been developed based on crown ether. The membrane consisted
of benzo-15-5 crown ether as a neutral carrier, orto-nitrophenylphenyl
ether as plasticizer and PVC as membrane matrix. An analytically
useful potential change occurs in the 1x10–6-1x10–2
mol L-1 concentration range.
The slope of the linear portion (1x10-2
– 1x10-4 mol L-1)
was 56 ±
3 mV/10-fold concentration changes in potassium concentration.
In the presence of 1x10–3
mol L–1 potassium,
no interference was observed for Li+,
Na+, NH4+,
Mg2+, Ca2+,
Sr2+, Ba2+,
Cr3+, Mn2+,
Fe3+, Co2+,
Ni2+, Cu2+,
Zn2+, F-,
Br-, I-,
NO2-,
SO42-,
CO32-,
S2- ions.
The measurements were made at constant ionic strength (0.1
mol L-1 NaNO3,
medium) and at room temperature. The lifetime of the electrode
was approximately 2 months, and the response time was about
20-30 seconds. This electrode has been used for the determination
of potassium ion with standard addition method in orange juice,
vitamin, and edible salt. The amount of K+
found was 1.97 ±
0.06 mg/mL in orange juice, 0.420 ±
0.008 % (m/m) in vitamin tablet and 0.52 ±
0.08 % (m/m) in edible salt.
[Back to top]
Diagnosis of Diabetes in a Diabetic Patient’s Urine
and Blood Using a Combination Electrode with a Ubiquitous
Handheld Analyzer
Suw Y. Ly
[Full
text article]
Glucose assay was conducted on untreated diabetic patient’s
urine and blood using a combination electrode (CE) whose sensor
was interfaced with a newly constructed handheld voltammetry.
The CE was prepared using the common graphite pencil as a
working electrode, handmade reference electrode, and platinum
counter electrode, which were combined into one electrode
system. The CE was optimized through cyclic and stripping
voltammetry. Analytical working range was attained at 30.0-300.0
ugL-1 and at 100-800 ugL-1,
under different conditions. The relative standard deviation
of 0.5 mg/L that was observed at the optimum condition was
0.31% (n=15). The detection limit (S/N) was attained at 13.7
ugL-1 (7.6×10-8
M). The system that was developed in this study is compact
and can be useful in ubiquitous, self-diagnosis, and fast
assays.
[Back to top]
Exploiting Pulsed Flows for Heating Improvement: Application
to Determination of Total Reducing Sugars in Molasses and
Sugar Cane Juices
Evandro R. Alves, Mário A. Feres,
Elias A.G. Zagatto and José L.F.C. Lima
[Full
text article]
Laminar and pulsed flows typical of multi-commuted and
multi-pumping flow systems, were evaluated in relation to
analytical procedures carried out at high temperatures. As
application, the spectrophotometric determination of total
reducing sugars (TRS, hydrolyzed sucrose plus reducing sugars)
in sugar-cane juice and molasses was selected. The method
involves in-line hydrolysis of sucrose and alkaline degradation
of the reducing sugars at about 98 °C.
Better results were obtained with pulsed flows, due to the
efficient radial mass transport inherent to the multi-pumping
flow system.
The proposed system presents favorable characteristics of
ruggedness, analytical precision (r.s.d. <
0.013 for typical samples), stability (no measurable baseline
drift during 4-h working periods), linearity of the analytical
curve (r >
0.992, n = 5, 0.05 - 0.50% w/v TRS) and sampling rate (65
h-1). Results are in agreement
with ion chromatography.
[Back to top]
High-Resolution Solution NMR Spectra in Inhomogeneous Magnetic
Fields
Shuhui Cai, Wen Zhang and Zhong
Chen
[Full
text article]
A high-resolution NMR spectrum, containing fine structures
such as chemical shifts and scalar-coupling multiplet patterns,
is helpful for analyzing molecular composition and structure.
However, there are many cases where the magnetic environments
are inhomogeneous, which may lead to severe signal overlapping
and blur useful spectral information in liquid samples. Recently,
many NMR techniques have been proposed to regain high-resolution
spectral information in inhomogeneous magnetic fields. They
can be mainly classified into three types that based on intermolecular
multiple-quantum coherences, nutation echoes, and spatial
encoding respectively. These methods can be applied to a wide
range of samples, thereby opening a way to high-resolution
in vivo and ex situ NMR spectroscopy. In
this review, recent developments of these methods are presented
and their applicability and efficiency are analyzed.
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