- MeSH
- Chemistry Techniques, Analytical * MeSH
- Dielectric Spectroscopy methods utilization MeSH
- Caffeine * analysis pharmacology therapeutic use MeSH
- Humans MeSH
- Gas Chromatography-Mass Spectrometry methods utilization MeSH
- Polarography methods utilization MeSH
- Spectrum Analysis methods utilization MeSH
- Chromatography, High Pressure Liquid methods utilization MeSH
- Check Tag
- Humans MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
Optimum conditions were found for the determination of nanomolar and subnanomolar concentrations of genotoxic 2-aminofluoren-9-one (2-AFN) by adsorptive stripping differential pulse voltammetry (AdSDPV) at a hanging mercury drop minielectrode (HMDmE) after preliminary separation and preconcentration by solidphase extraction (SPE) in LiChrolut RP-18 E (500 mg) columns. The adsorbed analyte was eluted with acetone, the solution then evaporated to dryness, and the residue dissolved in acetate buffer (pH 4.0) (AcB). A sample was then measured by AdSDPV at the HMDmE, with the accumulation potential 100 mV (vs. Ag|AgCl in 1 mol l–1 KCl) and the accumulation time 120 s. Linear calibration curves were obtained for 2·10–11 – 1·10–9 mol l–1 2-AFN, with the limit of quantification (LQ) ≈ 4·10–11 mol l–1. The method was verified by the determination of 2-AFN in model samples of drinking and river water at concentrations 4·10–11 – 1·10–9 and 2·10–10 – 1·10–9 mol l–1 (LQ ≈ 6·10–11 and 4·10–10 mol l–1, respectively).
- MeSH
- Water Pollution, Chemical * MeSH
- Electrochemical Techniques * methods instrumentation utilization MeSH
- Fluorenes analysis MeSH
- Indicators and Reagents * MeSH
- Drinking Water MeSH
- Polarography * methods instrumentation utilization MeSH
- Polycyclic Aromatic Hydrocarbons * adverse effects toxicity MeSH
- Aquaculture MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
A new, rapid and very sensitive electrochemical method for the determination of a new pesticide clothianidin in tap and river water was developed. The electrochemical reduction and determination of clothianidin have been carried out at a hanging mercury drop electrode (HMDE) in various aqueous solutions in the pH range of 2–10 by cyclic voltammetry (CV) and cathodic stripping square wave voltammetry (SW CSV). The best results were obtained for the clothianidin determination by SW CSV method in 0.04 mol l–1 Britton Robinson buffer at pH 8.1. Various conditions of the procedure were checked. Elaborated electroanalytical procedure enable clothianidin determination in the concentration range of 2.0 × 10–8–9.9 × 10–7 mol l–1. The limit of detection (LOD) and limit of quantification (LOQ) were obtained as 2.00 × 10–9 and 2.36 × 10–8 mol l–1, respectively. Precision and accuracy of the developed method were checked by recovery studies in spiked tap and river water. The voltammetric determination has been validated using HPLC with UV detection.
A differential pulse polarographic (DPP) method has been developed for the determination of ascorbic acid (AA) and dehydroascorbic acid (DHA), the two main forms of Vitamin C. The method consists of the DPP analysis of a quinoxaline obtained by the derivatization of DHA with o-phenylenediamine. Results using the proposed method correlated well with those obtained by two reference methodologies: the common iodometric method and a published chromatographic methodology. It was also used in the study of Vitamin C degradation in fruit juices, showing that it involves an initial oxidation of AA to DHA, followed by hydrolytic degradation of the latter.
We have found that the determination of thiodiglycolic acid (TDGA) in urine may help to characterize metabolic imbalance of substances participating in methionine synthesis, which leads to hyperhomocystinuria. From the metabolic scheme, based on a proper combination of known facts, we attempted to theoretically explain and to demonstrate the possibilities of TDGA formation via different ways of homocysteine transformation. This scheme was used in evaluating the results obtained by testing urine of a woman suffering from impaired function of methionine synthase reductase (CblE type of homocystinuria). The amount of TDGA excreted in her morning urine was very sensitive to the changes in her treatment based upon a combination of N5-formyl tetrahydrofolate, betaine and vitamin B12. Vitamin B12 given in the evening either alone or together with betaine increased the TDGA excretion in the morning urine up to ten times. On the other hand, in the absence of vitamin B12, betaine in combination with N5-formyl tetrahydrofolate hindered the appearance of TDGA in the morning urine. Generally, the determination of TDGA in urine of an appropriately pretreated patient may indicate the degree of success of the treatment.
- MeSH
- Betaine metabolism urine therapeutic use MeSH
- Financing, Government MeSH
- Formyltetrahydrofolates metabolism urine therapeutic use MeSH
- Homocysteine metabolism urine MeSH
- Humans MeSH
- Polarography methods utilization MeSH
- Thioglycolates isolation & purification urine MeSH
- Vitamin B 12 metabolism therapeutic use MeSH
- Check Tag
- Humans MeSH
- Publication type
- Comparative Study MeSH
- MeSH
- Urinalysis MeSH
- Glutathione * metabolism MeSH
- Creatine * metabolism MeSH
- Dicarboxylic Acids * analysis metabolism urine MeSH
- Humans MeSH
- Metabolism MeSH
- Polarography methods utilization MeSH
- Check Tag
- Humans MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
- MeSH
- Chemistry Techniques, Analytical methods standards MeSH
- Electrochemistry methods trends MeSH
- Chemistry, Physical methods standards MeSH
- Clinical Laboratory Techniques utilization MeSH
- Organic Chemicals chemistry isolation & purification standards MeSH
- Polarography methods trends utilization MeSH
- Chromatography, High Pressure Liquid utilization MeSH
