Single-step extraction for simultaneous quantification of desvenlafaxine and alprazolam in human spiked plasma by RP-HPLC.

Desvenlafaxine (DES) and Alprazolam (ALP) are the drugs commonly prescribed together for the treatment of Major Depressive Disorders (MDD). A literature survey revealed, there is no method for the simultaneous determination of these two drugs. The purpose of this research was to develop and validate a simple, accurate, precise, robust, and isocratic RP-HPLC method for simultaneous determination of DES and ALP in human spiked plasma using UV-detector in short analysis time. The method utilized Hypersil BDS C18 (250 mm×4.6 mm, 5 µm) through an isocratic mode of elution using HPLC grade acetonitrile and 0.02M KH2PO4 buffer (65:35) and 0.1% Tri Fluoro Acetic acid (TFA) with pH 4.00 adjusted with 1M KOH. The flow rate was 1.00 mLmin-1 and elution of the drugs was monitored at 230nm. The elution time of DES and ALP was 4.011 and 5.182 minutes respectively. The method was linear for the concentration range 10-150 µgmL-1 for DES and 5.0-75.0 µgmL-1 for ALP. According to the validation results, the method is sensitive with Limit of Detection (LOD) 4.740 µgmL-1 and Limit of Quantification (LOQ) of 14.365 µgmL-1 for DES and LOD 1.891 µgmL-1 & LOQ 5.730 µgmL-1 for ALP. The reproducibility of results with minute deliberate variations in method parameters has proven that the method is robust. The data from stability studies show a non-significant change in drugs solutions for 2 months. The optimized method was validated as per International Conference for Harmonisation (ICH) Q2(R1) guidelines. This method can be used for the estimation of DES and ALP in plasma and can evaluate pharmacokinetic parameters of both drugs simultaneously.

Evaluation of an activated carbon disposal system for safe disposal of model prescription sedative medications.

Lack of a safe and convenient disposal method for expired and unused medications may lead to many problems such as accidental exposure, intentional misuse, and food and water contamination. Activated carbon can offer safe disposal of medications due to its highly porous structure, which exerts strong physical adsorption forces with chemicals. This study aimed to evaluate the efficiency of an activated carbon-based drug disposal system for deactivating three model sedative prescription medications. Deactivation was performed by mixing the medication, activated carbon, and tap water. Desorption was evaluated by exposing the deactivation system to wash-out solutions. Rapid, precise, accurate, and sensitive HPLC-UV method for each drug was successfully developed, validated and employed. Results of the 28-day deactivation study showed that on average, more than 94.00% of drugs were rapidly deactivated within 8 hours. All drugs reached more than 99.00% deactivation by the end of 28-day period. Desorption study demonstrated that all medications were retained by the system, with insignificant amount of drug (0.25%) leached into the washout solutions within 24 hours. In conclusion, activated carbon rapidly and successfully deactivated the medications tested, suggesting activated carbon-based drug disposal system provides a convenient, secure, and effective method for unused medication.

Characterization and performance evaluation of functional monomer effect on molecular imprinted polyurethane foam.

Herein we describe a methodology to synthesis polyurethane foam molecularly imprinted polymer (PUF-MIP) by using functional monomer for selective extraction of alprazolam. For this purpose, the various percentages of functional monomer are used to synthesis PUF-MIP of alprazolam. To evaluate the selectivity of synthesized PUF-MIP HPLC analysis is applied by introducing caffeine and methadone as an interference. To optimize the proposed technique, effective parameters in the SPE procedure including pH, flow, and salt present is investigated by experimental design. Finally, this method is evaluated in urine sample to monitor alprazolam dosage. In the optimized condition, the synthesized polymer indicates high selectivity value about 71% for alprazolam and 96.8% recovery for MIPUF compared with non-imprinted polyurethane foam (NIPUF). The linear dynamic range (LDR) of 0.03-60 mg L-1, the limit of detection of 8-10 µg L-1, the relative standard deviation (RSD, n = 3) of 2.88-3.65 % and quantification of 25-30 µg L-1 is obtained for HPLC analysis based on PUF-MIP extraction.

Evaluation of an Experimentally Designed Molecular Imprinted Polyurethane Foam Performance for Extraction of Alprazolam.

Industrial polyurethane rigid foam (PUF) was selected as a substrate for selective solid phase extraction of Alprazolam. Effective parameters for raising selectivity of the PUF were evaluated. Synthetic molecularly imprinted polyurethane foam (MIPUF) was tracked as selective adsorbent and its characteristic was pondered by analytical methods. Optimization was done by central composite design (CCD) to have high efficiency of the polymer adsorption. Two different extraction methods were compared in the selective adsorption processes using MIPUF and NIPUF, batch system and continuous (cartridge) system. Results of the adsorption of alprazolam on the MIPUF had 39% more recovery than NIPUF (reference polymer). Then, the proposed method suggests a selective extraction of mentioned analyte from urine and tablets as complex matrixes.

Development of an ultra-high-performance liquid chromatography coupled to high-resolution quadrupole-Orbitrap mass spectrometry method for the rapid detection and confirmation of illegal adulterated sedative-hypnotics in dietary supplements.

A novel method using ultra-high performance liquid chromatography coupled to hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap) was developed and validated for the simultaneous screening, identification and quantification of sedative-hypnotics in dietary supplements. Chromatographic conditions were optimised and a full data-dependent MS(2) scan (MS/dd-MS(2)) in positive and negative ion mode was used. A single injection was sufficient to perform the simultaneous screening and identification/quantification of samples. The response showed a good linear relationship with analyte concentrations over wide ranges (e.g., 1.0-1000 ng g(-1) for diazepam) with all the determination coefficients (r(2)) > 0.9985. The method was validated, obtaining accuracy (intra- and inter-day) in the range of 94.5-105.3% and precision (intra- and inter-day) in the range of 0.4-8.9%, respectively. The detection limits (LODs) were in the range of 0.3-1.0 ng g(-1) for different analytes. Recoveries were performed and ranged from 74.1% to 90.2%, while all matrix effects were over the range of 85.4-93.6%. Finally, this method was used to detect sedative-hypnotics in commercial dietary supplements. Of a total of 45 batches of dietary supplements, only three batches were found to be positive samples with concentrations of diazepam, clonazepam and alprazolam at high levels (≥ 8.22 mg g(-1)).

A novel microextraction by packed sorbent-gas chromatography procedure for the simultaneous analysis of antiepileptic drugs in human plasma and urine.

A simple, accurate, and sensitive microextraction by packed sorbent-gas chromatography-mass spectrometry method has been developed for the simultaneous quantification of four antiepileptic drugs; oxcarbazepine, carbamazepine, phenytoin, and alprazolam in human plasma and urine as a tool for drug monitoring. Caffeine was used as internal standards for the electron ionization mode. An original pretreatment procedure on biological samples, based on microextraction in packed syringe using C(18) as packing material gave high extraction yields (69.92-99.38%), satisfactory precision (RSD < 4.7%) and good selectivity. Linearity was found in the 0.1-500 ng/mL range for these drugs with limits of detection (LODs) between 0.0018 and 0.0036 ng/mL. Therefore, the method has been found to be suitable for the therapeutic drug monitoring of patients treated with oxcarbazepine, carbamazepine, phenytoin, and alprazolam. After validation, the method was successfully applied to some plasma samples from patients undergoing therapy with one or more of these drugs. A comparison of the detection limit with similar methods indicates high sensitivity of the present method over the earlier reported methods. The present method is applied for the analysis of these drugs in the real urine and plasma samples of the epileptic patients.

The limit of detection in generalized least-squares calibrations: an example using alprazolam liquid chromatography-tandem mass spectrometry data.

Limit of detection (LOD) values provide useful indicators for the suitability of an analytical method for samples with low analyte levels. An LOD value can also be used to estimate the false positive probability (p(x >or= LOD)) of a result for a sample with no analyte present, as well as the false negative probability (p(x

Preparation and characterization of poly(methyltetradecylsiloxane) stationary phases immobilized by gamma radiation onto zirconized silica.

The preparation of stationary phases with enhanced chemical stability in alkaline eluents has been the principal objective of many chromatographers. New and improved silica substrates and advanced chemical modification methods are among the possibilities being investigated to reach this objective. The present work has evaluated these two possibilities for new stationary phases. First, the silica surface was modified by reaction with zirconium tetrabutoxide to produce zirconized silica particles having about 21% (w/w) of zirconium. Then poly(methyltetradecylsiloxane) (PMTDS) was immobilized onto this surface using different doses (50-120 kGy) of gamma radiation. These new phases were characterized using elemental analysis and infrared and solid-state (29)Si-nuclear magnetic resonance (NMR) spectroscopies. These new stationary phases presented column efficiencies of about 68,000 plates m(-1), symmetric peaks for apolar compounds and retention factors that depend on the irradiation dose and show improved stability in high pH mobile phases. The separation of several pharmaceuticals at pH 11 is presented.

High-speed liquid chromatography/tandem mass spectrometry using a monolithic column for high-throughput bioanalysis.

With the ever-increasing workload from a variety of in vitro and in vivo screening procedures, new analytical methodologies to perform bioanalysis in an accurate and high-throughput manner are in great demand. In this work, monolithic columns were used instead of conventional particulate HPLC columns to perform chromatographic separations. Because the pressure drop on a monolithic column was considerably lower than that on a particulate column, a high flow rate (6 mL/min) was used for a 4.6 x 50 mm monolithic column with a total backpressure of about 61 bar measured using acetonitrile/water (50:50). The capability of using a regular column length at high flow rates, combined with the extremely small dependency of separation efficiency on linear flow velocity, allowed for the generation of sufficient chromatographic resolving power in a significantly reduced runtime. As demonstrated in this work, a plasma extract of a mixture of tempazepam, tamoxifen, fenfluramine, and alprozolam were baseline separated within a total analysis time of one minute. An average peak width at half maximum of approximately one second was noted using a generic broad gradient. It was also found that the separation efficiency and signal/noise (S/N) ratios for this separation remained almost constant at flow rates of 1, 3, and 6 mL/min, respectively. The ruggedness of the separation was evaluated by injecting 600 plasma extracts containing the replicates of a standard curve of the above mixture during an overnight run. The chromatographic retention time, separation quality, peak response and sensitivity were highly reproducible throughout the run. This high-speed liquid chromatography/tandem mass spectrometry (LC/MS/MS) system has been used routinely in the authors' laboratory to support drug discovery programs.