Automated 96-well solid phase extraction and hydrophilic interaction liquid chromatography–tandem mass spectrometric method for the analysis of cetirizine (ZYRTEC®) in human plasma—with emphasis on method ruggedness

Advances in Simple and Chiral-HPLC Methods for Antiallergic Drugs and Chiral Recognition Mechanism

Among many diseases, allergy appears to be a serious problem for human beings. Various forms of allergic disorders make people tense, leading to some other health issues. Many medications, including nonracemic and racemic ones, are used to treat this problem. It is important to have exact analysis strategies just to see any medication side effects, plasma profiles, and working efficiency. Therefore, efforts are made to review simple and chiral HPLC methods for antiallergic drugs; HPLC is the best analytical technique. The highlights in this article include the world scenario, causes of allergy, the effect of allergy on the economy, the mechanism of allergy in humans, classes of antiallergic drugs, simple drugs, chiral drugs, analysis by HPLC, and the chiral recognition mechanism. Moreover, attempts are also made to highlight the management of allergies and future perspectives.

Development of a sensitive and quantitative UHPLC-MS/MS method to study the whole-body uptake of pharmaceuticals in zebrafish

An analytical procedure to measure the whole-body uptake of pharmaceuticals in zebrafish has been developed using state-of-the-art methodologies. A sample preparation procedure for 9 pharmaceuticals displaying a variety in physicochemical properties was developed using 10-day old zebrafish (TG898). For an efficient homogenization of the samples and subsequent recovery of the compounds of interest, different amounts of organic solvents in combination with acidic modifiers were added to zebrafish samples. Samples were subsequently processed using a powerful bath sonicator and centrifuged. Supernatant was then removed and evaporated in a vacuum oven before being reconstituted in a mobile phase-like solvent. Samples were analyzed using ultra-high performance liquid chromatography (UHPLC) on an Acquity BEH C₁₈ column (100 × 2.1mm, d_p=1.7µm) coupled to a Waters Xevo TQ-S mass spectrometer. For this purpose, a generic gradient was run, wherein the percentage of acetonitrile was varied from 3% to 82% in 10.5min at a flow rate of 0.41mL/min. Linearity of the method was demonstrated for all compounds (R² > 0.997) in a practically relevant concentration range. Matrix effects were between 81% and 106%, except for amitriptyline (51%). Using this method, it was demonstrated that a sample pretreatment using 1:2 (v/v) water:methanol in combination with 0.1% formic acid resulted in acceptable recoveries between 74% and 100% for all compounds. Together with the obtained lower limits of quantification of the analytical method (between 0.005 and 1.5ng/mL), this allowed the use of a single zebrafish to study the whole-body uptake of a particular drug, after incubating zebrafish at the maximum tolerated concentration for this drug.

Recent advances in the application of hydrophilic interaction chromatography for the analysis of biological matrices

Hydrophilic interaction chromatography (HILIC) is being increasingly used for the analysis of hydrophilic compounds in biological matrices. The complexity of biological samples demands adequate sample preparation procedures, specifically adjusted for HILIC analyses. Currently, most bioanalytical assays are performed on bare silica and ZIC-HILIC columns. Trends in HILIC for bioanalysis include smaller particle sizes and miniaturization of the analytical column. For complex biological samples, multidimensional techniques can separate and identify more compounds than 1D separations. The high volatility of the mobile phase, the added separation power and high sensitivity make MS the detection method of choice for bioanalysis using HILIC, although other detectors such as evaporative light scattering detection, charged aerosol detection and nuclear magnetic resonance have been reported.

Recent advances in hydrophilic interaction chromatography for quantitative analysis of endogenous and pharmaceutical compounds in plasma samples

There is an increasing need for new analytical methods that can handle a large number of analytes in complex matrices. Hydrophilic interaction chromatography (HILIC) has recently been demonstrated as an important supplement to reversed-phase liquid chromatography for polar analytes, particularly endogenous compounds. With the increasing popularity of HILIC, progressively more polar phases with diverse functional groups have been developed. In addition, the coupling of HILIC to mass spectrometry offers the advantages of improved sensitivity by employing an organic-rich mobile phase. This article reviews recent applications of HILIC for the analysis of endogenous and pharmaceutical compounds in plasma samples. Furthermore, based on recent studies, we provide a discussion of column selection, sample pretreatment for HILIC analysis, and detection sensitivity.

MARS: bringing the automation of small-molecule bioanalytical sample preparations to a new frontier

Background: In recent years, there has been a growing interest in automating small-molecule bioanalytical sample preparations specifically using the Hamilton MicroLab® STAR liquid-handling platform. In the most extensive work reported thus far, multiple small-molecule sample preparation assay types (protein precipitation extraction, SPE and liquid–liquid extraction) have been integrated into a suite that is composed of graphical user interfaces and Hamilton scripts. Using that suite, bioanalytical scientists have been able to automate various sample preparation methods to a great extent. However, there are still areas that could benefit from further automation, specifically, the full integration of analytical standard and QC sample preparation with study sample extraction in one continuous run, real-time 2D barcode scanning on the Hamilton deck and direct Laboratory Information Management System database connectivity. Results: We developed a new small-molecule sample-preparation automation system that improves in all of the aforementioned areas. Conclusion: The improved system presented herein further streamlines the bioanalytical workflow, simplifies batch run design, reduces analyst intervention and eliminates sample-handling error.

An automation-assisted generic approach for biological sample preparation and LC–MS/MS method validation

Background: Although it is well known that automation can provide significant improvement in the efficiency of biological sample preparation in quantitative LC–MS/MS analysis, it has not been widely implemented in bioanalytical laboratories throughout the industry. This can be attributed to the lack of a sound strategy and practical procedures in working with robotic liquid-handling systems. Results: Several comprehensive automation assisted procedures for biological sample preparation and method validation were developed and qualified using two types of Hamilton Microlab liquid-handling robots. The procedures developed were generic, user-friendly and covered the majority of steps involved in routine sample preparation and method validation. Conclusion: Generic automation procedures were established as a practical approach to widely implement automation into the routine bioanalysis of samples in support of drug-development programs.

Automated sample preparation for regulated bioanalysis: an integrated multiple assay extraction platform using robotic liquid handling

Background: A novel approach for regulated bioanalytical sample preparation has been developed to combine multiple types of extraction techniques into one integrated and automated sample-preparation suite that pairs a graphical user interface with the Hamilton Microlab® STAR robotic liquid handler. Results: The multi-assay sample-preparation suite is composed of three bioanalytical extraction techniques: protein precipitation, solid-phase extraction and liquid–liquid extraction. Validation data provided highly reproducible and robust results for each respective automated extraction technique. Conclusion: The user-friendly graphical user interface and modular method design provide a flexible and versatile approach for routine bioanalytical sample-preparation and is the first fully integrated multiple assay sample-preparation suite for regulated bioanalysis.

Bioanalytical hydrophilic interaction chromatography: recent challenges, solutions and applications

Hydrophilic interaction chromatography (HILIC) has, in recent years, been shown to be an important supplement to reversed-phase liquid chromatography for polar analytes. HILIC, in conjunction with tandem mass spectrometry (MS/MS), has been steadily gaining acceptance in the analysis of polar compounds from complex biological matrices. This hyphenated technique offers the advantages of improved sensitivity by employing high organic content in the mobile phase, shortened sample preparation time with direct injection of the organic-solvent extracts of biological samples and the potential for ultra-fast analysis because of low-column backpressure. This article reviews recent challenges presented by HILIC, advancements in the better understanding of retention characteristics of analytes with different mobile- and stationary-phase compositions and solutions to ion suppression and interference problems encountered in HILIC–MS/MS assays. Applications of HILIC–MS/MS are summarized, including those for pharmacokinetic studies, metabolic studies, therapeutic drug monitoring and clinical diagnostics.

Analysis of carvedilol in human plasma using hydrophilic interaction liquid chromatography with tandem mass spectrometry

A rapid, sensitive and selective method for the determination of carvedilol in human plasma was developed using hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Carvedilol and cisapride (internal standard) were extracted from human plasma with methyl tert-butyl ether at basic pH and analyzed on an Atlantis HILIC Silica column with the mobile phase of acetonitrile-ammonium formate (50 mM, pH 4.5) (90:10, v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear (r=0.9998) over the concentration range of 0.1-200 ng/ml. The lower limit of quantification for carvedilol was 0.1 ng/ml using 50 microl plasma sample. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 1.6-4.5% and -6.4 to 4.8%, respectively. The absolute and relative matrix effect for carvedilol and cisapride were practically absent. The extraction recoveries of carvedilol and cisapride were 81.6 and 85.2%, respectively. This method was successfully applied to the bioequivalence study of carvedilol in humans.

Automation of solid-phase microextraction on a 96-well plate format

Studies have been performed assessing the feasibility and characterizing the automation of solid-phase microextraction (SPME) on a multi-well plate format. Four polycyclic aromatic hydrocarbons (PAHs), naphthalene, fluorene, anthracene and fluoranthene, were chosen as test analytes to demonstrate the technique due to their favorable partition coefficients, K(fw), between polydimethylsiloxane (PDMS) extraction phases and water. Four different PDMS configurations were investigated regarding their suitability. These included (i) a PDMS membrane; (ii) a multi-fiber device containing lengths of PDMS-coated flexible wire; (iii) a stainless steel pin covered with silicone hollow fiber membrane and (iv) commercial PDMS-coated flexible metal fiber assemblies. Of these configurations, the stainless steel pin covered with silicone tubing was chosen as a robust alternative. An array of 96 SPME devices that can be placed simultaneously into a 96-well plate was constructed to demonstrate the high-throughput potential when performing multiple microextractions in parallel. Different agitation methods were assessed including magnetic stirring, sonication, and orbital shaking at different speeds. Orbital shaking whilst holding the SPME device in a stationary position provided the optimum agitation conditions for liquid SPME. Once the analytes had been extracted, desorption of the analytes into an appropriate solvent was investigated. Liquid-phase SPME and solvent desorption on the multi-well plate format is shown to be a viable alternative for automated high-throughput SPME analysis compatible with both gas- and liquid-chromatography platforms.

Recent developments in extraction procedures relevant to analytical toxicology

Sample preparation is an important step in the development of an analytical method but is often regarded as time-consuming, laborious work. Optimum sample preparation leads to enhanced selectivity and sensitivity, however, and reduces amounts of interfering matrix compounds, resulting in less signal suppression or enhancement. Recent developments in extraction techniques that could be of interest in clinical and forensic toxicology, for example liquid-liquid, solid-phase, and headspace extraction, are summarized in this review. The advantages and disadvantages of several extraction techniques are discussed, to enable the reader to choose an appropriate method of extraction for his or her application. Attention is paid to current trends in analytical toxicology, for example miniaturization, high throughput, and automation.

Development and evaluation of an efficient HPLC/MS/MS method for the simultaneous determination of pseudoephedrine and cetirizine in human plasma: Application to Phase-I pharmacokinetic study

A sensitive, simple and highly selective liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and evaluated to determine simultaneously the concentrations of pseudoephedrine and cetirizine in human plasma. The chief benefit of the present method is the minimal sample preparation, as the procedure is only one-step protein precipitation. Two drugs were separated on a C(8) column and analyzed by LC/MS/MS using positive electrospray ionisation (ESI). The method had a chromatographic run time of 12.0 min and a linear calibration curve over the concentration range of 1.0-800 ng/ml for pseudoephedrine and 1.0-400 ng/ml for cetirizine, respectively. The lower limit of quantification of the two drugs was 1.0 ng/ml, respectively. The intra- and inter-batch precisions were less than 9.7%. The method described herein has been first used to reveal the pharmacokinetic characters in healthy Chinese volunteers treated with oral administration of different dosages of cetirizine dihydrochloride and controlled-released pseudoephedrine hydrochloride compound tablet, and approached the influence of a standard meal on the extent and rate of absorption of the combination tablet.

Comparison of HPLC and CE methods for the determination of cetirizine dihydrochloride in human plasma samples

Two methods, capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC), for analysis of cetirizine dihydrochloride in small sample volumes of human plasma were compared. The CE and HPLC assays were developed and validated by analyzing a series of plasma samples containing cetirizine dihydrochloride in different concentrations using these two methods. The extraction procedure is simple and no complicated purification steps or derivatization are required. The analysis time in the HPLC method was shorter than that in the CE method, but solvent consumption was considerably lower in the CE method. The calibration curve was linear to at least 10-1000 ng/mL both for CE and HPLC with r(2) = 0.9993 and r(2) = 0.9994, respectively. The detection limits for cetirizine dihydrochloride were 3 and 5 ng/mL with CE and HPLC (a UV detector was applied in the both cases), respectively. Both methods were selective, robust and specific, allowing reliable quantification of cetirizine dihydrochloride, and could be useful for clinical and biomedical investigations.

Sensitive bioassay for the simultaneous determination of pseudoephedrine and cetirizine in human plasma by liquid-chromatography–ion trap spectrometry

A liquid chromatography-ion trap mass spectrometry coupled with electrospray ionization (HPLC-ESI-ion trap mass spectrometry) method for simultaneous determination of cetirizine and pseudoephedrine in human plasma is presented. Chromatographic separation was performed on a Hypurity C18 column (Thermo Hypersil-Keystone 2.1 mm x 150 mm, 5 microm, USA), The mobile phase was composed of 65% methanol and 35% water (contained 0.1% formic acid, 10 mM ammonium formate), which was run with a flow-rate of 0.2 ml/min at 40 degrees C. Quantitation was achieved by monitoring the product ions at m/z 166-->m/z 148 (pseudoephedrine), m/z 389.9-->m/z 201.1 (cetirizine), m/z 264-->m/z 246 (tramadol, IS). The calibration curve of pseudoephedrine and cetirizine was established with standard solutions. The limit of detection for pseudoephedrine and cetirizine each was 5 ng/ml. This simplified analytical method is sensitive, specific and accurate enough for simultaneous determination of pseudoephedrine and cetirizine in human plasma and is successfully applied to the pharmacokinetic study of pseudoephedrine and cetirizine.

Hydrophilic interaction chromatography

Separation of polar compounds on polar stationary phases with partly aqueous eluents is by no means a new separation mode in LC. The first HPLC applications were published more than 30 years ago, and were for a long time mostly confined to carbohydrate analysis. In the early 1990s new phases started to emerge, and the practice was given a name, hydrophilic interaction chromatography (HILIC). Although the use of this separation mode has been relatively limited, we have seen a sudden increase in popularity over the last few years, promoted by the need to analyze polar compounds in increasingly complex mixtures. Another reason for the increase in popularity is the widespread use of MS coupled to LC. The partly aqueous eluents high in ACN with a limited need of adding salt is almost ideal for ESI. The applications now encompass most categories of polar compounds, charged as well as uncharged, although HILIC is particularly well suited for solutes lacking charge where coulombic interactions cannot be used to mediate retention. The review attempts to summarize the ongoing discussion on the separation mechanism and gives an overview of the stationary phases used and the applications addressed with this separation mode in LC.

A 96-well single-pot liquid–liquid extraction, hydrophilic interaction liquid chromatography–mass spectrometry method for the determination of muraglitazar in human plasma

A single-pot liquid-liquid extraction (LLE) with hydrophilic interaction liquid chromatography/tandem mass spectrometry (HILIC/MS/MS) method has been developed and validated for the determination of muraglitazar, a hydrophobic diabetes drug, in human plasma. To 0.050 ml of each plasma sample in a 96-well plate, the internal standard solution in acetonitrile and toluene were added to extract the compound of interest. The plate was vortexed, followed by centrifugation. The organic layer was then directly injected into an LC/MS/MS system. Chromatographic separation was achieved isocratically on a Thermohypersil_Keystone, Hypersil silica column (3 mmx50 mm, 3 microm). The mobile phase contained 85% of methyl t-butyl ether and 15% of 90/10 (v/v) acetonitrile/water with 0.3% trifluoroacetic acid. Post-column mobile phase of 50/50 (v/v) acetonitrile/water containing 0.1% formic acid was added. Detection was by positive ion electrospray tandem mass spectrometry on a Sciex API 4000. The standard curve, ranged from 1 to 1000 ng/ml, was fitted to a 1/x weighted quadratic regression model. This single-pot LLE approach effectively eliminated time-consuming organic layer transfer, dry-down, and sample reconstitution steps, which are essential for a conventional liquid-liquid extraction procedure. The modified mobile phase was more compatible with the direct injection of the commonly used extraction solvents in LLE. Furthermore, the modified mobile phase improved the retention of muraglitazar, a hydrophobic compound, on the normal phase silica column. The validation results demonstrated that this method was rugged and suitable for analyzing muraglitazar in human plasma. In comparison with a revised-phase LC/MS/MS method, this single-pot LLE, HILIC/MS/MS method improved the detection sensitivity by more than four-fold based upon the LLOQ signal to noise ratio. This approach may be applied to other hydrophobic compounds with proper modification of the mobile phase compositions.

Chiral separation of cetirizine by capillary electrophoresis

Chiral separation of cetirizine, a second-generation H(1)-antagonist, was studied by CD-mediated CE. Several parameters, including pH, CD type, buffer concentration, type of co-ion, applied voltage and temperature, were investigated. The best conditions for chiral separation were obtained using a 75 mM triethanolamine-phosphate buffer (pH 2.5) containing 0.4 mg/mL heptakis(2,3-diacetyl-6-sulfato)-beta-CD and 10% ACN. Online UV detection was performed at 214 nm, a voltage of 20 kV was applied and the capillary was temperature controlled at 25 degrees C by liquid cooling. Hydrodynamic injection was performed for 1 s. The method was validated for the quantification of levocetirizine in tablets and for enantiomeric purity testing of the drug substance. Selectivity, linearity, LOD and LOQ, precision and accuracy were evaluated for both methods. The amount of levocetirizine dihydrochloride in the commercially available tablets was quantified and was found to be within the specification limits of the claimed amount (5 mg). The amount of distomer in levocetirizine drug substance was found to be 0.87 +/- 0.09% w/w, which is in agreement with the certificate of analysis supplied by the company.

Hydrophilic interaction liquid chromatography–tandem mass spectrometry for the determination of levofloxacin in human plasma

A rapid, sensitive and selective hydrophilic interaction liquid chromatography-tandem mass spectrometric (HILIC-MS/MS) method for the determination of levofloxacin in human plasma was developed. Levofloxacin and ciprofloxacin (internal standard) were extracted from human plasma with dichloromethane and analyzed on an Atlantis HILIC Silica column with the mobile phase of acetonitrile-ammonium formate (100 mM, pH 6.5) (82:18 v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear (r>0.999) over the concentration range of 10.0-5000 ng/ml. The lower limit of quantification for levofloxacin was 10.0 ng/ml using 20 microl plasma sample. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 2.9-7.8% and -7.3% to -2.2%, respectively. The recoveries of levofloxacin and ciprofloxacin were 55.2% and 77.3%, respectively. This method was successfully applied to the pharmacokinetic study of levofloxacin in humans.

Determination of gabapentin in human plasma using hydrophilic interaction liquid chromatography with tandem mass spectrometry

A rapid, sensitive and selective method for the determination of gabapentin in human plasma was developed using hydrophilic interaction liquid chromatography/tandem mass spectrometry (HILIC/MS/MS). The devised method involved protein precipitation with acetonitrile followed by separation on an Atlantis HILIC silica column using an acetonitrile/ammonium formate mobile phase (100 mM, pH 3.0) (85:15, v/v). Analytes were detected using an electrospray ionization mass spectrometer in the multiple-reaction monitoring mode. The standard curve was linear (r = 1.000) over the concentration range of 50.0-10000 ng/mL. The lower limit of quantification for gabapentin was 50.0 ng/mL (ca. 20 pg gabapentin) using a 10-microL plasma sample. The coefficients of variation and relative errors for intra- and inter-assay at four QC levels (i.e., 50.0, 125, 750, and 7500 ng/mL) were 4.7 to 9.4% and -4.1 to 1.6%, respectively. Absolute and relative matrix effects for gabapentin and metformin were practically absent. Gabapentin and metformin recoveries were 98.5% and 99.0%, respectively. This method was successfully applied to a bioequivalence study of gabapentin in humans.

Cetirizine dihydrochloride interaction with some diclofenac complexes

IR, 1H NMR and mass spectrometric studies showed that cetirizine dihydrochloride interacted strongly with diclofenac sodium, even when the latter was metal bound, forming high molecular weight stable adducts. These new formations were unaffected by the possible steric constraints that may exist because of coordination yet did not have the power to break the formed coordinate bonds. The formed ionic bond took place between the carbonyl ion of diclofenac and the positively charged piperazine ring of cetirizine, forming a ternary compound in the case of the divalent metal clusters (Ca{(dic)2.2H2O}, Mg{(dic)2.2H2O}, Zn{(dic)2.2H2O}) and a quaternary one with the trivalent iron cluster (Fe{dic}3.3H2O). IR bands assigned to nuNH, deltaNH and nuC-N were shifted to lower frequency values in the spectra of the complexes; thus showing that coordination took place at the NH of the diphenylamine. TG and elemental analysis confirmed these results.

Quantitative determination of cetirizine enantiomers in guinea pig plasma, brain tissue and microdialysis samples using liquid chromatography/tandem mass spectrometry

Sensitive enantioselective liquid chromatographic assays using tandem mass spectrometric detection were developed and validated for the determination of S-cetirizine (S-CZE) and R-cetirizine (R-CZE) in guinea pig plasma, brain tissue, and microdialysis samples. Enantioselective separation was achieved on an alpha1-acid glycoprotein column within 14 min for all methods. A cetirizine analog, ucb 20028, was used as internal standard. Cetirizine and the internal standard were detected by multiple reaction monitoring using transitions m/z 389.1 --> 200.9 and 396.1 --> 276.1, respectively. The samples were prepared using protein precipitation with acetonitrile. For guinea pig plasma, the assay was linear over the range 0.25-5000 ng/mL for both S-CZE and R-CZE, with a lower limit of quantification (LLOQ) of 0.25 ng/mL. For the brain tissue and microdialysis samples, the assays were linear over the range 2.5-250 ng/g and 0.25-50 ng/mL, respectively, and the LLOQ values were 2.5 ng/g and 0.25 ng/mL, respectively. The intra- and inter-day precision values were < or =7.1% and < or =12.6%, respectively, and the intra- and inter-day accuracy varied by less than +/-8.0% and +/-6.0% of the nominal value, respectively, for both enantiomers in all the matrices investigated.