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Papers by Ramy Sayed
Analytical Chemistry Letters, 2019
In this paper, reported a simple, relatively fast and very sensitive method for the enantiomeric ... more In this paper, reported a simple, relatively fast and very sensitive method for the enantiomeric separation of racemorphan (i.e. dextrorphan and levorphanol) by using normal phase chiral liquid chromatography mass spectrometry. The resolution (R = 1.54) of dextrorphan and levorphanol was achieved using the Lux i-amylose-1 column (5 μm, 150 x 4.6 mm) with a mixture of mobile phases consisting of 0.1 % DEA in n-hexane and 0.1 % DEA in 2-propanol (90:10, v/v). To demonstrate the efficacy of the developed method, linearity, accuracy, precision, recovery, sensitivity and effect on matrix in equine urine samples were carried out. For both analytes, the method was linear over the concentration range of 1-50 ng/mL in equine urine. The intra and inter-day precisions expressed as relative standard deviation and the inter-day precisions of dextrorphan, levorphanol were 3.45 % and 3.63 % respectively. The accuracy was in the range of 97-102 %. The limit of detection was 0.1 ng/mL and that of quantification was 0.5 ng/mL for both analytes. Recovery and matrix effect on the analytes were also evaluated. This method is capable of distinguishing racemorphan enantiomers when both of the isomers are simultaneously present in equine urine.
Forensic Toxicology, 2018
Steroids, 2018
Chirality is one of the most important considerations when controlling doping. The epimeric corti... more Chirality is one of the most important considerations when controlling doping. The epimeric corticosteroids dexamethasone and betamethasone are significantly potent and long-acting, and they are highly abused in equestrian sports. The scope of this study was to develop a simple and reliable analytical method for simultaneously identifying and separating regularly abused co-eluting corticosteroids in equine urine and plasma. In this paper, we present a simple and rapid method for the chiral separation and identification of epimeric mixtures of dexamethasone and betamethasone using a Thermo Q Exactive high resolution accurate mass spectrometer. The high resolution accurate mass spectrometer system provided extremely high sensitivity, enabling detection of each isomer at a very low concentration from complex biological matrices. Chromatographic separation was performed using amylose and cellulose chiral columns. Reversed phase media showed very good potential for providing a successful chiral resolution in LC-MS analysis. This study also focused on optimizing the mobile phase for elution strength, nature of the organic modifier, additives, and column temperature.
Chirality, 2019
Chiral considerations are found to be very much relevant in various aspects of forensic toxicolog... more Chiral considerations are found to be very much relevant in various aspects of forensic toxicology and pharmacology. In forensics, it has become increasingly important to identify the chirality of doping agents to avoid legal arguments and challenges to the analytical findings. The scope of this study was to develop an liquid chromatography-mass spectrometry (LCMS) method for the enantiomeric separation of typical illicit drugs such as ephedrines (ie, 1S,2R(+)-ephedrine and 1R,2S(−)-ephedrine) and pseudoephedrine (ie, R, R(−)-pseudoephedrine and S,S(+)-pseudoephedrine) by using normal phase chiral liquid chromatography-high-resolution mass spectrometry technique. Results show that the Lux i-amylose-1 stationary phase has very broad and balancing-enantio-recognition properties towards ephedrine analogues, and this immobilized chiral stationary phase may offer a powerful tool for enantio-separation of different types of pharmaceuticals in the normal phase mode. The type of mobile phase and organic modifier used appear to have dramatic influences on separation quality. Since the developed method was able to detect and separate the enantiomers at very low levels (in pico grams), this method opens easy access for the unambiguous identification of these illicit drugs and can be used for the routine screening of the biological samples in the antidoping laboratories.
Analytical Chemistry Letters, 2019
In this paper, reported a simple, relatively fast and very sensitive method for the enantiomeric ... more In this paper, reported a simple, relatively fast and very sensitive method for the enantiomeric separation of racemorphan (i.e. dextrorphan and levorphanol) by using normal phase chiral liquid chromatography mass spectrometry. The resolution (R = 1.54) of dextrorphan and levorphanol was achieved using the Lux i-amylose-1 column (5 μm, 150 x 4.6 mm) with a mixture of mobile phases consisting of 0.1 % DEA in n-hexane and 0.1 % DEA in 2-propanol (90:10, v/v). To demonstrate the efficacy of the developed method, linearity, accuracy, precision, recovery, sensitivity and effect on matrix in equine urine samples were carried out. For both analytes, the method was linear over the concentration range of 1-50 ng/mL in equine urine. The intra and inter-day precisions expressed as relative standard deviation and the inter-day precisions of dextrorphan, levorphanol were 3.45 % and 3.63 % respectively. The accuracy was in the range of 97-102 %. The limit of detection was 0.1 ng/mL and that of quantification was 0.5 ng/mL for both analytes. Recovery and matrix effect on the analytes were also evaluated. This method is capable of distinguishing racemorphan enantiomers when both of the isomers are simultaneously present in equine urine.
Forensic Toxicology, 2018
Steroids, 2018
Chirality is one of the most important considerations when controlling doping. The epimeric corti... more Chirality is one of the most important considerations when controlling doping. The epimeric corticosteroids dexamethasone and betamethasone are significantly potent and long-acting, and they are highly abused in equestrian sports. The scope of this study was to develop a simple and reliable analytical method for simultaneously identifying and separating regularly abused co-eluting corticosteroids in equine urine and plasma. In this paper, we present a simple and rapid method for the chiral separation and identification of epimeric mixtures of dexamethasone and betamethasone using a Thermo Q Exactive high resolution accurate mass spectrometer. The high resolution accurate mass spectrometer system provided extremely high sensitivity, enabling detection of each isomer at a very low concentration from complex biological matrices. Chromatographic separation was performed using amylose and cellulose chiral columns. Reversed phase media showed very good potential for providing a successful chiral resolution in LC-MS analysis. This study also focused on optimizing the mobile phase for elution strength, nature of the organic modifier, additives, and column temperature.
Chirality, 2019
Chiral considerations are found to be very much relevant in various aspects of forensic toxicolog... more Chiral considerations are found to be very much relevant in various aspects of forensic toxicology and pharmacology. In forensics, it has become increasingly important to identify the chirality of doping agents to avoid legal arguments and challenges to the analytical findings. The scope of this study was to develop an liquid chromatography-mass spectrometry (LCMS) method for the enantiomeric separation of typical illicit drugs such as ephedrines (ie, 1S,2R(+)-ephedrine and 1R,2S(−)-ephedrine) and pseudoephedrine (ie, R, R(−)-pseudoephedrine and S,S(+)-pseudoephedrine) by using normal phase chiral liquid chromatography-high-resolution mass spectrometry technique. Results show that the Lux i-amylose-1 stationary phase has very broad and balancing-enantio-recognition properties towards ephedrine analogues, and this immobilized chiral stationary phase may offer a powerful tool for enantio-separation of different types of pharmaceuticals in the normal phase mode. The type of mobile phase and organic modifier used appear to have dramatic influences on separation quality. Since the developed method was able to detect and separate the enantiomers at very low levels (in pico grams), this method opens easy access for the unambiguous identification of these illicit drugs and can be used for the routine screening of the biological samples in the antidoping laboratories.