Chelate adsorption for trace voltammetric measurements of 2-thiouracil and 4-thiouridine

Ahmed, Z. A.; Ahmed, Munawar; Ibrahim, M. S.; Kamal, Mostafa; Temerk, Y. M.

doi:10.1016/0039-9140(94)80045-6

Cited by 13 publications

(6 citation statements)

References 9 publications

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“…A lot of methods have been developed for the determination of thyreostatics residue in samples, such as high‐performance thin layer chromatography 7, HPLC with ultraviolet (UV) or electrochemical or MS detection 8–10, GC with electron‐capture or nitrogen–phosphorus or MS detection 11–14, our recently developed flow‐injection analysis equipped with electrochemiluminescent detector 15, electrochemical analysis 16–20 and electrophoresis 21–23. Although GC and HPLC are powerful analytical methods, they suffer from relatively high instrumental cost, use of too much samples and solvents, which may increase environmental burden, and too much time consumption.…”

Section: Introductionmentioning

confidence: 99%

“…Although GC and HPLC are powerful analytical methods, they suffer from relatively high instrumental cost, use of too much samples and solvents, which may increase environmental burden, and too much time consumption. The previously reported electroanalytical methods have shown that electroanalysis would become a promising technique to detect thyreostatics due to its high sensitivity and low instrumental cost 15–20; however, further work should be carried out to improve its selectivity when it is applied in the determination of different kinds of thyreostatics in a complex sample. It is well known that CE as one the most powerful separate techniques, has provided an alternative choice to HPLC in sample separation for its many merits, such as extremely high‐separation efficiency, ultra‐small sample and solvent volume used, rapid analysis and ease removal of contaminants.…”

Section: Introductionmentioning

confidence: 99%

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A Light‐Controlled Molecular Brake with Complete ON–OFF Rotation

Basheer

Oka

Mathews

et al. 2010

Chemistry A European J

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A light-controlled molecular machine based on cyclic azobenzenophanes consisting of a dioxynaphthalene rotating unit and a photoisomerizable dioxyazobenzene unit bridged by methylene spacers is reported. In compounds 1 and 2, 1,5- and 2,6-dioxynaphthalene moieties, respectively, are linked to p-dioxyazobenzene by different methylene spacers (n=2 in 1a and 2; n=3 in 1b), whereas a 1,5-dioxynaphthalene moiety is bonded to m-dioxyazobenzene by bismethylene spacers in 3. In 1b and 2, the naphthalene ring can rotate freely in both the trans and cis states at room temperature. The rotation speed can be controlled either by photoinduced reversible trans-cis (E-Z) isomerization of the azobenzene or by keeping the system at low temperature, as is evident from its NMR spectra. Furthermore, for the first time, we demonstrate a light-controlled molecular brake, wherein the rotation of the naphthalene moiety through the cyclophane is completely OFF in the trans isomer of compound 3 due to its smaller cavity size. Such restricted rotation imparts planar chirality to the molecule, and the corresponding enantiomers could be resolved by chiral HPLC. However, the rotation of the naphthalene moiety is rendered ON in the cis isomer due to its increased cavity size, and it is manifested experimentally by the racemization of the separated enantiomers by photoinduced E-Z isomerization.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Light‐Controlled Molecular Brake with Complete ON–OFF Rotation

Basheer

Oka

Mathews

et al. 2010

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…A lot of methods have been developed for the determination of thyreostatics residue in samples, such as highperformance thin layer chromatography [7], HPLC with ultraviolet (UV) or electrochemical or MS detection [8][9][10], GC with electron-capture or nitrogen-phosphorus or MS detection [11][12][13][14], our recently developed flow-injection analysis equipped with electrochemiluminescent detector [15], electrochemical analysis [16][17][18][19][20] and electrophoresis [21][22][23]. Although GC and HPLC are powerful analytical methods, they suffer from relatively high instrumental cost, use of too much samples and solvents, which may increase environmental burden, and too much time consumption.…”

Section: Introductionmentioning

confidence: 99%

Determination of thyreostatics in animal feeds by CE with electrochemical detector

et al. 2009

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A simple, rapid, reproducible and sensitive method based on CE with electrochemical detector was developed for the simultaneous determination of five thyreostatics including 2-thiouracil (TU), 6-methyl-2-thiouracil (MTU), 6-propyl-2-thiouracil (PTU), 6-phenyl-2-thiouracil (PhTU) and methimazole (TAP) in animal feeds. A home-made wall-jet electrochemical detector with a 300 microm diameter platinum-disk-working electrode was equipped at the end of separation capillary and used to detect oxidation currents of these thyreostatics. Under the optimum experimental conditions, TU, MTU, PTU, PhTU and TAP could be well separated within 15 min at the separation voltage of 16 kV in 20 mmol/L sodium borate buffer (pH 9.2). The detection limits (S/N=3) of the five thyreostatics in animal feeds were found to be 7.6 microg/kg for TAP, 25 microg/kg for PTU, 15 microg/kg for PhTU, 18 microg/kg for TU and 20 microg/kg for MTU by the developed CE with electrochemical detector method coupled with solid-phase extraction sample pretreatment technique.

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“…A cathodic stripping voltammetric method based on the complex formation reaction between Cu(II) and 2-thiouracil has been also described [15]. Finally, a voltammetric and electrochemical quartz crystal microbalance study of antithyroid drugs has been reported [1].…”

Section: Introductionmentioning

confidence: 99%