A Rapid and Simultaneous Determination of Several Analgesic Antiinflammatory Agents by Capillary Zone Electrophoresis

An ultra-rapid drug screening method for acetaminophen in blood serum based on probe electrospray ionization-tandem mass spectrometry

Poisoning incidents caused by drugs, accidental ingestion of poisons, attempted suicide, homicide, and exposure to toxic compounds occur frequently every year across the globe. This raises the need to rapidly identify toxic agents in poisoned patients in a clinical emergency setting. In addition, determining drug/poison concentration is undoubtedly necessary to arrive at a toxicological treatment plan. The purpose of this study was to develop an ultra-rapid drug screening method for the clinical treatment of poisoning. Probe electrospray ionization (PESI), one of the ambient ionization techniques, is able to detect compounds from various biological materials almost directly. We applied the PESI technique to the rapid detection of acetaminophen (APAP). Blood serum samples were diluted 100-fold with 10 mM ammonium formate/ethanol (1:1 v/v) solution including deuterium-labeled internal standards (IS; APAP-d4). Only 10 μL of the diluted sample was used for measurement. The tandem mass spectrometer (MS/MS) equipped with a PESI was used in selected reaction monitoring mode for the quantitation of APAP; the measurement time was only 18 s. Transitions were set at 152 > 110 for quantitation, 152 > 65 for qualifier, and 156 > 114 for IS (APAP-d4). All measurements were conducted in positive mode. The calibration curve (1/x²) was linear over the range of 1.56–200 μg/mL (r² = 0.998), and the limit of detection and quantitation were 0.37 μg/mL and 1.56 μg/mL, respectively. The accuracy (bias) and precision (RSD%) of the method were within an acceptable range (−0.15–2.8% and 2.3–6.1%, respectively) and matrix effect at 3 concentrations (95.1–104%) indicated that PESI-MS/MS is only slightly affected by matrices. In real forensic cases, quantitative values of APAP determined by the PESI-MS/MS were almost identical to those determined by the liquid chromatography-MS/MS method. Since PESI-MS/MS is a simple, reliable, and rapid determination method for toxic agents with virtually no need for blood serum pretreatment, it would be highly suitable for poisoning cases in clinical emergency settings. In the future, a method for simultaneous rapid determination of multiple toxic agents will be developed.

Application of a lanthanide composite nanoparticle-sensitized luminescence method for the determination of salicylic acid in pharmaceutical formulations and human plasma

Terbium-acetylacetone (Tb-acac) composite nanoparticles were synthesized using the ultrasonic method. The nanoparticles are water-soluble, stable and have extremely narrow emission bands and high internal quantum efficiencies. They were used as fluorimetric probes in the determination of salicylic acid (SA), based on the fluorescence enhancement of nanoparticles through fluorescence resonance energy transfer (FRET). The influence of buffer solution was investigated. Under the optimum conditions, a linear calibration graph was obtained over the SA concentration range 5 x 10(-7)-1 x 10(-4) mol/L. The limit of detection was found to be 2.5 x 10(-8) mol/L. The relative standard deviation (RSD) for six repeated measurements of 1 x 10(-4) mol/LSA was 1.75%. The method was applied to the determination of SA in pharmaceutical formulations and human plasma. We believe that the proposed approach has great potential for clinical purposes.

Sequential injection analysis (SIA)-chemiluminescence determination of indomethacin using tris[(2,2′-bipyridyl)]ruthenium(III) as reagent and its application to semisolid pharmaceutical dosage forms

Automated sequential injection (SIA) method for chemiluminescence (CL) determination of nonsteroidal anti-inflammatory drug indomethacin (I) was devised. The CL radiation was emitted in the reaction of I (dissolved in aqueous 50% v/v ethanol) with intermediate reagent tris(2,2'-bipyridyl)ruthenium(III) (Ru(bipy)(3)(3+)) in the presence of acetate. The Ru(bipy)(3)(3+) was generated on-line in the SIA system by the oxidation of 0.5mM tris(2,2'-bipyridyl)ruthenium(II) (Ru(bipy)(3)(2+)) with Ce(IV) ammonium sulphate in diluted sulphuric acid. The optimum sequence, concentrations, and aspirated volumes of reactant zones were: 15 mM Ce(IV) in 50mM sulphuric acid 41 microL, 0.5 mM Ru(bipy)(3)(2+) 30 microL, 0.4M Na acetate 16 microL and I sample 15 microL; the flow rates were 60 microLs(-1) for the aspiration into the holding coil and 100 microLs(-1) for detection. Calibration curve relating the intensity of CL (peak height of the transient CL signal) to concentration of I was curvilinear (second order polynomial) for 0.1-50 microM I (r=0.9997; n=9) with rectilinear section in the range 0.1-10 microM I (r=0.9995; n=5). The limit of detection (3sigma) was 0.05 microM I. Repeatability of peak heights (R.S.D., n=10) ranged between 2.4% (0.5 microM I) and 2.0% (7 microM I). Sample throughput was 180 h(-1). The method was applied to determination of 1 to 5% of I in semisolid dosage forms (gels and ointments). The results compared well with those of UV spectrophotometric method.

Determination of ibuprofen in pharmaceutical formulations using time-resolved terbium-sensitized luminescence

A sensitive and specific luminescence method for the determination of ibuprofen (IB) in pharmaceutical formulations in aqueous solution is described. The method is based on the luminescence sensitization of terbium (Tb(3+)) by formation of ternary complex with IB in the presence of tri-n-octylphosphine oxide (TOPO) and Tween-20 as surfactant. The luminescence signal for Tb-IB-TOPO is monitored at lambda(ex) = 229 nm and lambda(em) = 545 nm. Optimum conditions for the formation of the complex in aqueous system, were 16 mmol/L TRIS buffer, pH 5.7, TOPO 200 micromol/L and 15 micromol/L of Tb(3+), which allows for the determination of 9.7 x 10(-7) - 9.7 x 10(-6) mol/L IB with a detection limit of 1.2 x 10(-7) mol/L. The relative standard deviations of the method were <1.4%, indicating excellent reproducibility. The proposed method was successfully applied for the assays of IB in pharmaceutical formulations with average recoveries of 100.3-102.5%.

Capillary electrophoresis and the clinical laboratory

Over the past 15 years, CE as an analytical tool has shown great promise in replacing many conventional clinical laboratory methods, such as electrophoresis and HPLC. CE's appeal was that it was fast, used very small amounts of sample and reagents, was extremely versatile, and was able to separate large and small analytes, whether neutral or charged. Because of this versatility, numerous methods have been developed for analytes that are of clinical interest. Other than molecular diagnostic and forensic laboratories CE has not been able to make a major impact in the United States. In contrast, in Europe and Japan an increasing number of clinical laboratories are using CE. Now that automated multicapillary instruments are commercially available along with cost-effective test kits, CE may yet be accepted as an instrument that will be routinely used in the clinical laboratories. This review will focus on areas where CE has the potential to have the greatest impact on the clinical laboratory. These include analyses of proteins found in serum and urine, hemoglobin (A1c and variants), carbohydrate-deficient transferrin, forensic and therapeutic drug screening, and molecular diagnostics.

Analysis of salicylic acid based on the fluorescence enhancement of the As(III)–salicylic acid system

A new, simple and sensitive spectrofluorimetric method for the determination of salicylic acid (lambda(ex)=315 nm, lambda(em) = 408 nm) using As(III) as a sensitizing reagent has been investigated by measuring the increase of fluorescence intensity of salicylic acid due to the complexation of As(III)-salicylic acid in presence of sodium dodecyl sulfate (SDS) 10(-3) M. Under optimum conditions, a significant relationship was obtained between the fluorescence intensity and salicylic acid concentration. A linear calibration curve was obtained in the range 13.8-13812 microg l(-1) with product-moment correlation coefficient (R) 0.99985 and detection limit 4.2 microg l(-1). The R.S.D. is 2.35% (n=5). The method was applied successfully to the determination of salicylic acid in human serum.

Optimization of a capillary zone electrophoresis method by using a central composite factorial design for the determination of codeine and paracetamol in pharmaceuticals

Capillary zone electrophoresis was optimized to quantitatively determine codeine and paracetamol via central composite factorial design. Critical parameters (concentration, buffer, pH, voltage) assessed effects on resolution, analysis time and efficiencies. Optimum separation conditions were achieved using phosphate buffer 20 mM (pH 6.8) and voltage (15 kV). The optimized procedure easily determined codeine and paracetamol with separation in less than 3 min. Calibration curves (R > 0.999) were prepared, with LODs of 13.5 and 340 ng mL(-1) for codeine and paracetamol, respectively, and a good R.S.D.% (<3%). This method was applied to determine codeine and paracetamol in pharmaceutical formulations; recoveries coincided with stated contents.

Determination of ibuprofen and flurbiprofen in pharmaceuticals by capillary zone electrophoresis

Capillary zone electrophoresis with spectrophotometric detection was used for the determination of ibuprofen (IB) and flurbiprofen (FL) in pharmaceuticals. The separation was carried out in a fused silica capillary (60 cm x 100 microm i.d. effective length 45 cm) at 30 kV with UV detection at 232 nm. The optimized background electrolyte was 20mM N-(2-acetamido)-2-aminoethanesulfonic acid (ACES) with 20mM imidazole and 10mM alpha-cyclodextrin of pH 7.3. 2-Naphthoxyacetic acid was used as internal standard. A single analysis took less than 5 min. Rectilinear calibration ranges were 2-500 mg l(-1) for IB and 1-60 mg l(-1) for FL. The relative standard deviations (R.S.D.) values (n=6) were 1.53% for IB and 1.29% for FL (for 200 mg l(-1) IB and 10 mg l(-1) FL). This validated method has been successfully applied for the routine analysis of 10 commercially available pharmaceutical preparations (syrup, tablets, cream and gel).

Determination of indomethacin in plasma by micellar electrokinetic chromatography with UV detection for premature infants with patent ducts arteriosus

A simple and selective micellar electrokinetic chromatography (MEKC) is described for determination of indomethacin in plasma. Plasma proteins are precipitated by acetonitrile. An aliquot of supernatant was evaporated and reconstituted with Tris buffer for MEKC analysis. The separation of indomethacin was performed at 25 degrees C using a background electrolyte consisting of Tris buffer (30 mM; pH 8.0) with 100 mM sodium octanesulfonate (SOS) as an anionic surfactant. Under this condition, a good separation with high efficiency and short analysis time is achieved. Several parameters affecting the separation of indomethacin were studied, including pH and concentrations of the Tris buffer and SOS. The linear range of the method for the determination of indomethacin was over 0.3-10.0 microg/mL; the detection limit (signal-to-noise ratio=3; injection 0.5 psi 5s) was 0.1 microg/mL. The proposed method for determination of indomethacin in premature infants with patent ducts arteriosus has been demonstrated.

Preparative method ofR-(−)-ibuprofen by diastereomer crystallization

The economic and effective method for preparation of R-(-)-ibuprofen by diastereomer crystallization was developed. R-(-)-ibuprofen was resolved from racemic ibuprofen by forming R-(-)-ibuprofen-R-(+)-alpha-methylbenzylamine diastereomeric salt with R-(+)-alpha(-methylbenzylamine and crystallization. The purity of R-(-)-ibuprofen-R-(+)-alpha-methylbenzylamine diastereomeric salt was tested and confirmed using HPLC and 1H-NMR method. The pure diastereomeric salt collected from repeated recrystallization was further fractionated by liquid-liquid extraction to the pure enantiomer without racemization. R-(-)-ibuprofen was recovered producing overall yield of 2.4% with the purity more than 99.97%.

Position of chromatographic techniques in screening for detection of drugs or poisons in clinical and forensic toxicology and/or doping control

This paper reviews chromatographic screening procedures for simultaneous detection of several drug classes relevant to clinical and forensic toxicology or doping control in urine or blood using gas chromatography-mass spectrometry (GC-MS), liquid chromatography coupled with a diode-array detector (LC-DAD) or a mass spectrometer (LC-MS). The pros and cons of the different techniques and procedures are discussed leading to the following conclusions and perspectives. GC-MS, especially in the electron ionization full-scan mode, is still the method of choice for comprehensive screening providing best separation power, specificity and universality, although requiring derivatization. LC-DAD is also often used for screening, but its separation power and its specificity are still inferior to those of GC-MS. Finally, LC-MS has shown to be an ideal supplement, especially for the detection of more polar, thermolabile and/or low-dose drugs, especially in blood plasma. It may become the gold standard in clinical and forensic toxicology and doping control if, at a later date, the costs of the apparatus will be markedly reduced, the current disadvantages like irreproducibility of fragmentation, reduction of ionization by matrix, etc. will be overcome, and finally if one of the increasing number of quite different techniques will become the apparatus standard.