We report the first amperometric method for the simultaneous determination of tert-butylhydroquinone (tBHQ), propyl gallate (PG), and butylated hydroxyanisole (BHA) using flow injection analysis coupled to multiple-pulse amperometry. A sequence of potential pulses was selected in order to detect tBHQ, PG, and BHA separately in a single injection step at a glassy carbon electrode without the need of a preliminary separation. A mixture of methanol and 0.040M Britton-Robinson buffer was used both as a carrier solution and for dilution of analyzed solutions before injection. The method is precise (RSD < 5%, n = 10), fast (a frequency of 140 injections h-1), provides sufficiently low quantification limits (2.51, 1.45, and 0.85μmolL-1 for tBHQ, PG, and BHA, respectively) and can be easily applied without high demands on instrumentation. As a practical application, the determination of these antioxidants contained in commercial chewing gum samples was carried out by applying a simple extraction procedure.
Methods for determination of 2-amino-4-nitrophenol and 4-amino-2-nitrophenol, metabolites of 2,4-dinitrophenol, were developed using differential pulse (DP) voltammetry and HPLC with amperometric and spectrophotometric detection. The applicability of these methods was tested by the determination of the analytes in model samples of urine after preliminary separation by solid-phase extraction. Voltammetry enabled parallel determination of both analytes, but its application in real matrix was severely limited due to the interference of other compounds present in urine. HPLC allowed the determination in real urine matrix down to micromolar concentrations; amperometric detection proved to be more sensitive and selective than the spectrophotometric one.
Orchiektomie je operační výkon, jehož cílem je odstranit patologicky změněné varle a semenný provazec. Ač nepatří mezi chirurgicky náročné výkony, indikace musí být uvážená, protože zasahuje pro muže zvláště citlivá místa. Kromě vlastní operace je odstranění varlete spojeno s obavou o zachování kvality dalšího života, hlavně sexuálního, a fertility.
- MeSH
- dítě MeSH
- dospělí MeSH
- fertilita fyziologie MeSH
- hormonální substituční terapie metody škodlivé účinky využití MeSH
- kvalita života MeSH
- lidé MeSH
- nádory prostaty farmakoterapie chirurgie terapie MeSH
- nemoci varlat farmakoterapie chirurgie terapie MeSH
- orchiektomie metody škodlivé účinky využití MeSH
- testikulární nádory chirurgie terapie MeSH
- Check Tag
- dítě MeSH
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
Differential pulse voltammetry, direct current voltammetry, adsorptive stripping voltammetry and HPLC with electrochemical detection were used for the determination of 5-amino-6-nitroquinoline at a carbon paste electrode. The methods are based either on anodic oxidation or cathodic reduction of this substance, whose electrochemical behavior at carbon paste electrode was further studied by cyclic voltammetry. Practical applicability of these methods was demonstrated on the determination of 5-amino-6-nitroquinoline in model samples of drinking and river water. The detection limit was 2.0 × 10–6 mol l–1 for anodic differential pulse voltammetry in a mixture of Britton–Robinson buffer (pH 11)–methanol 1:1 (v/v) and 1.6 × 10–7 mol l–1 for HPLC with electrochemical detection (E = +1.2 V) in a mobile phase Britton–Robinson buffer (pH 7)–methanol 1:9 (v/v).
Direct current voltammetric (DCV) and differential pulse voltammetric (DPV) determination of antineoplastic agent doxorubicin (DOX) at a carbon paste electrode (CPE) was developed. Britton–Robinson buffer (pH 7.0) was used as a supporting electrolyte. The limits of detection are 8 × 10–7 mol l–1 (DCV) and 6 × 10–8 mol l–1 (DPV). The accumulation of DOX at the electrode surface was used to decrease the limits of detection down to 2.2 × 10–7 mol l–1 for adsorptive stripping DC voltammetry (DCAdSV) and 2.8 × 10–9 mol l–1 for adsorptive stripping differential pulse voltammetry (DPAdSV) at CPE. The results of the voltammetric methods were utilized for the development of a new determination of doxorubicin using HPLC with amperometric detection on CPE based on spherical microparticles of glassy carbon in a wall-jet configuration. A column with chemically bonded C18 stationary phase and a mobile phase containing 0.01 M phosphate buffer (pH 5.0)–methanol 25:75 (v/v) were used. The limit of detection is 4 × 10–7 mol l–1 (HPLC with electrochemical detection (ED)).
