diode-array detection
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The separation of seven phenolic compounds including gallic acid, chlorogenic acid, epicatechin, quercitrin, rutin, phloridzin, and phloretin present in apple peel and pulp and differing in elution properties has been optimized using high-performance liquid chromatography with diode array detection. Several stationary phases were tested to achieve the efficient separation of phenolic compounds in fruit extracts and C18 was found to be the most efficient. Core-shell and fully porous C18 packings were assessed with respect to the complex composition of the fruit extracts. The developed high-performance liquid chromatography method comprised gradient elution in which mobile phase A was water at pH 2.8 adjusted with acetic acid and B was acetonitrile. The gradient shape was the following: 0 min 95% A/5% B, 2.5 min 85% A/15% B, 12 min 50% A/50% B, 15 min 95% A/5% B. The flow rate was 1 mL/min, injection volume 10 μL, and UV detection at 255, 280, 320, and 365 nm was applied. Our method was validated for both C18 core-shell and fully porous packings. The resolution 6.2-14.8, symmetry 0.99-1.34, peak capacity 18-60, peak area repeatability 0.45-1.00% relative standard deviation, calibration range 0.125-5 mg/mL (0.25-10 mg/mL for chlorogenic acid and rutin), correlation coefficients of calibration curve 0.9976-0.9997, and accuracy evaluated as recovery 95.56-107.54% were determined for the core-shell column.
- MeSH
- fenoly analýza MeSH
- Malus chemie MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Publikační typ
- časopisecké články MeSH
In this study a novel, simple and rapid reversed-phase high performance liquid chromatography (HPLC) procedure for simultaneous determination of vitamins A and E (retinol and alpha-tocopherol) in blood serum has been developed and validated using monolithic column and diode-array detection (DAD). The monolithic column Chromolith Performance RP-18e (100 mm x 4.6 mm) was operated at ambient temperature. One hundred percent methanol at flow rate 2.5 ml min(-1) was used as a mobile phase. Detection of both compounds was performed with diode-array detector, retinol was monitored at 325 nm and alpha-tocopherol at 295 nm. The linear dependence between peak area and concentration ranged from 0.25 to 10.00 micromol l(-1) for retinol and 0.5-50.0 micromol l(-1) for alpha-tocopherol. The limit of detection (LOD) for retinol was 0.02 micromol l(-1) and limit of quantification (LOQ) was 0.07 micromol l(-1). The limit of detection (LOD) for alpha-tocopherol was 0.1 micromol l(-1) and limit of quantification (LOQ) was 0.3 micromol l(-1). Retinol was eluted in 0.8 min and alpha-tocopherol in 1.4 min. The simultaneous analysis of vitamin A and E can be achieved in less than 2 min. The implementation of monolithic column Chromolith Performance shortens the time of analysis of both vitamins four times in comparison with using traditional particulate column Pecosphere C18 (150 mm x 4.6 mm), 5 microm. This fact may play an important role for routine clinical analysis of biological samples
The new screening method for rapid evaluation of major phenolic compounds in apples has been developed. Suitability of coupling HPLC/UHPLC separation with the diode-array detection and universal charged aerosol detection with respect to the presence of interfering substances was tested. Characteristics of both detection techniques were compared and method linearity, limits of detection and quantitation, and selectivity of them determined. Student t-test based on slopes of calibration plots was applied for the detailed comparison. The diode-array detection provided the best results regarding sensitivity and selectivity of the developed method in terms of evaluation of phenolics profiles. The response of the charged aerosol detector was negatively affected by co-eluting substances during rapid-screening analyses. Coulometric detection was used for advanced characterization of extracts in terms of antioxidant content and strength to obtain more complex information concerning sample composition. This detection also allowed evaluation of unidentified compounds with antioxidant activity. HPLC/UHPLC separation using a combination of diode-array and coulometric detectors thus represented the best approach enabling quick, yet complex characterization of bioactive compounds in apples.
- MeSH
- aerosoly chemie MeSH
- antioxidancia chemie MeSH
- chromatografie metody MeSH
- elektrochemie metody MeSH
- fenol chemie MeSH
- fenoly analýza MeSH
- kalibrace MeSH
- limita detekce MeSH
- Malus metabolismus MeSH
- potravinářská technologie MeSH
- reprodukovatelnost výsledků MeSH
- vysokoúčinná kapalinová chromatografie metody MeSH
- Publikační typ
- časopisecké články MeSH
Counterfeit steroids are available on the black market, ultimately to consumers who believe they are buying a legitimate pharmaceutical item from the labeled company. In many cases, counterfeit steroids can contain lower doses or some products can be overdosed. This can unwittingly expose users to a significant health risks. The mixture of testosterone propionate, phenylpropionate, isocaproate and decanoate in an oil-based injectable dosage form belongs to the one of the most misused illicit drugs by a variety of athletes. This study developed a new, fast, simple and reliable HPLC method combined with a simple sample preparation step to determine testosterone propionate, phenylpropionate, isocaproate and decanoate in an oil-based injectable dosage form without the use of sophisticated and expensive instrumentation. The developed analytical procedure provides high throughput of samples where LC analysis takes only 6min and sample preparation of oil matrix in one step takes approximately 10min with precision ranging from 1.03 to 3.38% (RSD), and accuracy (relative error %) within ±2.01%. This method was found to be precise, linear, accurate, sensitive, selective and robust for routine application in screening of commercial pharmaceutical products based on content of mentioned testosterone esters in their oil-based injectable dosage form for counterfeit drugs. This method was successfully applied to the analysis of nine samples of commercial testosterone mixtures purchased from various sources and will be further used as an effective screening method for determination of previously mentioned testosterone esters in samples confiscated by Institute of Forensic Science (Slovakia) during the illegal trade.
This paper describes a single-laboratory validation of a liquid chromatography-diode array detection (LC-DAD) method for quantification of 12 major cannabinoids in Cannabis dried plant materials, concentrates, and oils. The method met Standard Method Performance Requirements for quantitative analysis of cannabinoids in Cannabis concentrates and Cannabis dried plant materials. The LOQs were in the range 0.003-0.10% (w/w), depending on the analyte and matrix. Spike recoveries were between 96.7 and 101.3% with relative SDs (RSDs) ≤2.3%. Precision expressed as repeatability and intermediate precision was within 0.3-4.8 and 1.1-5.1%, respectively. The chromatographic separation conditions used in this versatile method are compatible with both DAD-UV and MS detection. During method validation, high-resolution quadrupole time-of-flight MS was employed as a secondary detector (connected in series to the LC-DAD instrument) to provide high confidence identification of target analytes and as a tool for monitoring other cannabinoids for which reference standards were not available. The obtained results demonstrate applicability of the method to quantitative analysis of important cannabinoids in dried plants, concentrates, and oils. Limited data were generated for a food matrix (Cannabis-containing cookies) using this method with LC coupled to a compact single quadrupole mass spectrometer.
CAD (charged aerosol detector) has recently become a new alternative detection system in HPLC. This detection approach was applied in a new HPLC method for the determination of three of the major statins used in clinical treatment-simvastatin, lovastatin and atorvastatin. The method was optimized and the influence of individual parameters on CAD response and sensitivity was carefully studied. Chromatography was performed on a Zorbax Eclipse XDB C18 (4.6 mm x 75 mm, 3.5 microm), using acetonitrile and formic acid 0.1% as mobile phase. The detection was performed using both CAD (20 pA range) and DAD (diode array detector-238 nm) simultaneously connected in series. In terms of linearity, precision and accuracy, the method was validated using tablets containing atorvastatin and simvastatin. The CAD is designated to be a non-linear detector in a wide dynamic range, however, in this application and in the tested concentration range its response was found to be perfectly linear. The limits of quantitation (0.1 microg/ml) were found to be two times lower than those of UV detection.
