The present study describes an effect of reaction condition of pre-column derivatization of alkylphenols (APs): bisphenol A (BPA), 4-tert-octylphenol (4-t-OP), 4-octylphenol (4-OP), 4-n-nonylphenol (4-n-NP), and isomers of 4-nonylphenol (iso-NP) with 5-(dimethylamino) naphthalene-1-sulfonyl chloride (dansyl chloride, DNSC) on their LC-ESI-MS/MS determination in water samples. Chemical derivatization improves the sensitivity and selectivity of LC-MS/MS analysis. In principle, alkylphenols can be analyzed by LC-MS/MS without derivatization. However, pre-column derivatization of APs increases the sensitivity up to 1000 times in comparison with the analysis of underivatized alkylphenols. Reaction conditions affecting formation of the DNSC-derivatives, such as various solvent, reaction temperature, reaction time, DNSC concentration and pH values were tested. The most suitable conditions, in terms of achieving a high sensitivity, resulting from this study are: acetonitrile as reaction solvent, 60 min as reaction time, 60 °C as reaction temperature, pH values 10.5, 0.5 mg mL(-1) as DNSC concentration. Calibration curves are linear at least in the range of 1-1000 ng mL(-1), limits of detection (LOD) and limits of quantification (LOQ) ranging from 0.02 to 0.25 pg/injection and from 0.08 to 0.83 pg/injection, respectively. The improved procedure was successfully applied for the analysis of APs and BPA in real water samples. The median concentration of BPA and iso-NP obtained in bottled waters was 4.7 ng L(-1) and 33.5 ng L(-1), respectively. The median concentration of 4-t-OP was 1.3 ng L(-1.)
- MeSH
- Benzhydryl Compounds analysis MeSH
- Water Pollutants, Chemical analysis MeSH
- Chromatography, Liquid methods MeSH
- Phenols analysis MeSH
- Indicators and Reagents MeSH
- Limit of Detection MeSH
- Drinking Water analysis MeSH
- Dansyl Compounds chemistry MeSH
- Tandem Mass Spectrometry methods MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Theanine, a non-proteinogenic amino acid present in tea leaves, is well known for its health promoting effects such as lowering blood pressure, reducing caffeine side effects, improving memory and supporting the immunity system. Theanine occurs in dietary supplements as racemate, while they should contain only the L-enantiomer. The article deals with the optimization of separation and detection of underivatized and derivatized theanine enantiomers on a chiral teicoplanin-based stationary phase. The chromatographic limits of detection and quantification were determined with the aim to assess the content of the theanine enantiomers in dietary supplements.
- MeSH
- Amino Acids * analysis MeSH
- Chemistry Techniques, Analytical MeSH
- Indicators and Reagents MeSH
- Complementary Therapies MeSH
- Analytic Sample Preparation Methods MeSH
- Dietary Supplements * analysis MeSH
- Dansyl Compounds MeSH
- Chromatography, High Pressure Liquid * methods utilization MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
A rapid, sensitive and low-cost method for the determination of methamphetamine and its metabolites in urine was developed. The tested substances were isolated by SPE, dansylated and analyzed by HPLC with fluorescence detection. The method was validated, the limit of detection for methamphetamine was lower than 1 ng ml–1; the limit of quantitation was 3 ng ml–1.
- MeSH
- Amphetamine * analysis urine MeSH
- Chemistry Techniques, Analytical * methods instrumentation utilization MeSH
- Spectrometry, Fluorescence * methods utilization MeSH
- Indicators and Reagents MeSH
- Humans MeSH
- Methamphetamine * analogs & derivatives analysis urine MeSH
- Analytic Sample Preparation Methods MeSH
- Substance-Related Disorders MeSH
- Dansyl Compounds chemistry MeSH
- Chromatography, High Pressure Liquid * methods instrumentation utilization MeSH
- Check Tag
- Humans MeSH
A novel HPLC method for determination of a wide variety of S-substituted cysteine derivatives in Allium species has been developed and validated. This method allows simultaneous separation and quantification of S-alk(en)ylcysteine S-oxides, gamma-glutamyl-S-alk(en)ylcysteines and gamma-glutamyl-S-alk(en)ylcysteine S-oxides in a single run. The procedure is based on extraction of these amino acids and dipeptides by methanol, their derivatization by dansyl chloride and subsequent separation by reversed phase HPLC. The main advantages of the new method are simplicity, excellent stability of derivatives, high sensitivity, specificity and the ability to simultaneously analyze the whole range of S-substituted cysteine derivatives. This method was critically compared with other chromatographic procedures used for quantification of S-substituted cysteine derivatives, namely with two other HPLC methods (derivatization by o-phthaldialdehyde/tert-butylthiol and fluorenylmethyl chloroformate), and with determination by gas chromatography or capillary electrophoresis. Major advantages and drawbacks of these analytical procedures are discussed. Employing these various chromatographic methods, the content and relative proportions of individual S-substituted cysteine derivatives were determined in four most frequently consumed alliaceous vegetables (garlic, onion, shallot, and leek).
- MeSH
- Allium chemistry MeSH
- Cysteine analogs & derivatives analysis isolation & purification MeSH
- Electrophoresis, Capillary MeSH
- Plant Roots chemistry MeSH
- Analytic Sample Preparation Methods MeSH
- Flame Ionization MeSH
- Gas Chromatography-Mass Spectrometry MeSH
- Dansyl Compounds MeSH
- Chromatography, High Pressure Liquid MeSH
- Publication type
- Comparative Study MeSH
Teicoplanínová a vancomycínová kolóna sa použila na separáciu niektorých dansyl derivátov α-aminokyselín. Navrhli sa separačné mechanizmy separácie chirálnych látok na základe nameraných chromatografických údajov použitím rôznych kolón. Skúmali sa interakcie medzi molekulami separovaných látok a stacionárnou fázou.
Teicoplanin and vancomycin columns were used for the separation of some dansyl derivates of α-amino acids. By comparison of chromatographic data which were measured in various column it is possible to propose the separation mechanisms of chiral compounds. The interaction between molecules of compound of interest and the stationary phase was investigated.
