Determination of Three Nonsteroidal Anti-Inflammatory Drugs in Human Plasma by LC Coupled with Chemiluminescence Detection

A simple and sensitive method was developed for the determination of three nonsteroidal anti-inflammatory drugs (NSAIDs)—ibuprofen, naproxen and fenbufen in human plasma. The method involved in column liquid chromatographic separation and chemilumenescence (CL) detection based on the CL reaction of NSAIDs, potassium permanganate (KMnO₄) and sodium sulfite (Na₂SO₃) in sulfuric acid (H₂SO₄) medium. The chromatographic separation was carried out using a reversed-phase C₁₈ column, which allowed the selective determination of the three medicines in the complicated samples. The special features of the CL detector provided lower LOD for determination than that of existing chromatographic alternatives. The results indicated that the linear ranges were 0.01–10.0 μg mL⁻¹ for ibuprofen, 0.001–1.0 μg mL⁻¹ for naproxen, and 0.01–10.0 μg mL⁻¹ for fenbufen. The limits of detection were 0.5 ng mL⁻¹ for ibuprofen, 0.05 ng mL⁻¹ for naproxen and 0.5 ng mL⁻¹ for fenbufen (S/N = 3). All average recoveries were in the range of 90.0–102.3%. Finally, the method had been satisfactorily applied for the determination of ibuprofen, naproxen and fenbufen in human plasma samples.

     

HPLC and UPLC Methods for the Simultaneous Determination of Enalapril and Hydrochlorothiazide in Pharmaceutical Dosage Forms

High efficiency and less elution are the basic requirements of high-speed chromatographic separation. In this study, a new gradient reverse phase chromatographic methods were developed using HPLC and UPLC systems for simultaneous determination of enalapril maleate (ENL) and hydrochlorothiazide (HCZ) in pharmaceutical dosage forms. The chromatographic separations of ENL and HCZ were achieved on a Waters μ-Bondapak C 18, (300 × 3.9 mm, 10 μm) and Waters Acquity BEH C18 (100 × 2.1 mm, 1.7 μm) columns for HPLC within 5.30 min and UPLC within a short retention time of 1.95 min, respectively. A linear response was observed over the concentration range 0.270–399 μg mL^?1 of ENL, 0.260–399 μg mL^?1 of HCZ for HPLC system and 0.270–399 μg mL^?1 of ENL and 0.065–249 μg mL^?1 of HCZ for UPLC system. Also, limit of detection for ENL was 1.848 ng mL^?1 and 31.477 ng mL^?1 for HCZ, 2.804 ng mL^?1 for ENL and 2.943 ng mL^?1 for HCZ using HPLC and UPLC, respectively. The proposed methods were validated according to ICH guideline with respect to precision, accuracy, and linearity. Forced degradation studies were also performed for both compounds in bulk drug samples to demonstrate the specificity and stability indicating power of the HPLC method. Comparison of system performance with conventional HPLC was made with respect to analysis time, efficiency, and resolution.     

Application of DLLME to Isolation and Concentration of Non-Steroidal Anti-Inflammatory Drugs in Environmental Water Samples

Dispersive liquid–liquid microextraction (DLLME) coupled with liquid chromatography-tandem mass spectrometry detection was applied for determination of selected anti-inflammatory pharmaceuticals: ibuprofen, ketoprofen, naproxen and diclofenac. Development of DLLME procedure included optimisation of several important parameters such as kind and volume of extracting and dispersive solvents as well as sample pH. Under optimised conditions a two-step extraction with sonication was used. Chloroform was applied as the extracting and acetone as dispersing solvent. Calibration curves ranges were 1–500 μg L^?1 for naproxen and ibuprofen and 0.25–500 μg L^?1 for ketoprofen and diclofenac with correlation coefficients at least 0.997. Limits of quantitation were from 0.5 to 10 ng L^?1. The developed analytical method was employed for determination of ibubrofen, ketoprofen, naproxen and diclofenac in river and tap water samples. The results showed that DLLME is a simple, rapid and sensitive analytical technique for the pre-concentration of trace amounts of pharmaceuticals in environmental water samples.     

A New Flow‐Injection Chemiluminescence Method for the Determination of Acyclovir and Gancyclovir

Abstract

A rapid and sensitive flow‐injection chemiluminescence (FI‐CL) method, which is based on the CL intensity that generated from the redox reaction of Ce(IV)‐rhodamine B in H₂SO₄ medium, for the determination of acyclovir and gancyclovir is described. For acyclovir, the determination range is 3×10^?8 g mL^?1–7×10^?5 g mL^?1, with 1.56×10^?8 g mL^?1 as its determination limit. During 11 repeated measurements for 1×10^?6 g mL^?1 acyclovir, the relative standard deviation was 2.08%. For gancyclovir, the determination range was 5×10^?8 g mL^?1–7×10^?5 g mL^?1, with 2.35×10^?8 g mL^?1 as its determination limit. The relative standard deviation is 2.83% with 11 repeated measurements of 1×10^?6 g mL^?1 gancyclovir. This method can be successfully used to determine the content of acyclovir and gancyclovir in injections, acyclovir in eye drops, and, maybe, also for other ciclovirs.     

A novel chemiluminescence reaction system for the determination of lincomycin with diperiodatonickelate(IV)

A sensitive and high selective chemiluminescence (CL) method was developed for the determination of lincomycin in acid medium using diperiodatonickelate as a reagent. The mechanism leading to luminescence is discussed by comparing the spectra of fluorescence and CL. Relative CL intensity is linear in the range from 8.0 ng mL^?1 to 1.0 µg mL^?1, the limit of detection is 2.5 ng mL^?1 (3σ), and the relative standard deviation is 4.0% at 0.1 µg mL^?1 of lincomycin (n?=?7). The method was successfully applied to the determination of lincomycin in injections, human urine, and in serum samples.     

Simultaneous Determination of Hydrochlorothiazide, Cilazapril and Its Active Metabolite Cilazaprilat in Urine by Gradient RP-LC

A rapid and simple liquid chromatographic method with UV detection has been developed for the determination of hydrochlorothiazide (HCTZ), cilazapril (CL) and its active metabolite cilazaprilat (CLT) in urine. Sample preparation for urine consisted of solid-phase extraction using styrene-divinylbenzene (SDB-2) cartridges. The chromatographic system was a Zorbax Eclipse XDB-C₁₈ column with a mixture of methanol and 10 mM phosphate buffer, pH 2.3 with gradient (20 to 60% of methanol) as mobile phase at a flow rate of 1.0 mL min^?1. The detection was performed at the wavelength of 206 nm. Enalapril maleat was used as an internal standard. The detector response was linear in the range of 2.4–30.0, 1.6–15.0 and 1.8–20.0 μg mL^?1 for HCTZ, CL and CLT, respectively. LOQ was determined to be 2.4, 1.6 and 1.8 μg mL^?1 for HCTZ, CL and CLT, respectively. Both intra- and inter-day precision were within acceptable limits. The method has been applied to urine samples obtained from three hypertensive patients after intake of HCTZ and CL therapeutic dose.     

Simultaneous Determination of Paracetamol and Caffeine in Human Plasma by LC–ESI–MS

A rapid, selective and convenient liquid chromatography–mass spectrometric method for the simultaneous determination of paracetamol and caffeine in human plasma was developed and validated. Analytes and theophylline [internal standard (I.S.)] were extracted from plasma samples with diethyl ether-dichloromethane (3:2, v/v) and separated on a C₁₈ column (150 × 4.6 mm ID, 5 μm particle size, 100 Å pore size). The mobile phase consisted of 0.2% formic acid–methanol (60:40, v/v). The assay was linear in the concentration range between 0.05 and 25 μg mL^?1 for paracetamol and 10–5,000 ng mL^?1 for caffeine, with the lower limit of quantification of 0.05 μg mL^?1 and 10 ng mL^?1, respectively. The intra- and inter-day precision for both drugs was less than 8.1%, and the accuracy was within ±6.5%. The single chromatographic analysis of plasma samples was achieved within 4.5 min. This validated method was successfully applied to study the pharmacokinetics of paracetamol and caffeine in human plasma.     

HPLC and UPLC Methods for the Simultaneous Determination of Enalapril and Hydrochlorothiazide in Pharmaceutical Dosage Forms

High efficiency and less elution are the basic requirements of high-speed chromatographic separation. In this study, a new gradient reverse phase chromatographic methods were developed using HPLC and UPLC systems for simultaneous determination of enalapril maleate (ENL) and hydrochlorothiazide (HCZ) in pharmaceutical dosage forms. The chromatographic separations of ENL and HCZ were achieved on a Waters μ-Bondapak C 18, (300 × 3.9 mm, 10 μm) and Waters Acquity BEH C18 (100 × 2.1 mm, 1.7 μm) columns for HPLC within 5.30 min and UPLC within a short retention time of 1.95 min, respectively. A linear response was observed over the concentration range 0.270–399 μg mL⁻¹ of ENL, 0.260–399 μg mL⁻¹ of HCZ for HPLC system and 0.270–399 μg mL⁻¹ of ENL and 0.065–249 μg mL⁻¹ of HCZ for UPLC system. Also, limit of detection for ENL was 1.848 ng mL⁻¹ and 31.477 ng mL⁻¹ for HCZ, 2.804 ng mL⁻¹ for ENL and 2.943 ng mL⁻¹ for HCZ using HPLC and UPLC, respectively. The proposed methods were validated according to ICH guideline with respect to precision, accuracy, and linearity. Forced degradation studies were also performed for both compounds in bulk drug samples to demonstrate the specificity and stability indicating power of the HPLC method. Comparison of system performance with conventional HPLC was made with respect to analysis time, efficiency, and resolution.

     

Simultaneous Determination of Ibuprofen and Diphenhydramine Citrate in Tablets by Validated LC

A stability-indicating LC method was developed for the simultaneous determination of ibuprofen and diphenhydramine citrate in pharmaceutical dosage forms. The chromatographic separation was achieved on an Inertsil ODS 3V, 150 × 4.6 mm, 5 μm, column. The mobile phase contained a mixture of 50 mM potassium dihydrogen phosphate buffer:acetonitrile:triethylamine:glacial acetic acid (55:45:0.2:0.2, v/v/v/v). This method allowed the determination of 2.85–9.14 mg mL^?1 of ibuprofen and 0.54–1.73 mg mL^?1 of diphenhydramine citrate, in a diluent consisting of pH 7.2, 50 mM potassium dihydrogen phosphate buffer:acetonitrile (40:60, v/v). The flow rate was 1.2 mL min^?1 and the detection wavelength was 260 nm. The limit of detection for ibuprofen and diphenhydramine citrate was 1.72 and 0.54 μg mL^?1 and the limit of quantification was 5.73 and 1.64 μg mL^?1, respectively. This method was validated for accuracy, precision and linearity. The method was also found to be stability indicating.     

N-bromosuccinimide-fluorescein system for the determination of protein by flow injection chemiluminescence

A method for flow injection with chemiluminescence (CL) detection has been developed for the determination of proteins. It is based on the luminescence of the N-bromosuccinimide-fluorescein-protein system, where fluorescein is used as an energy transfer reagent in alkaline medium. The CL of the system is strongly enhanced by hexadecyl trimethyl ammonium bromide. Optimum conditions and possible mechanisms have been investigated. Under optimum experimental conditions, the linear range is from 0.4 to 40 µg·mL^?1 for egg albumin, 0.2 to 20 µg·mL^?1 for bovine serum albumin, and from 1 to 100 µg·mL^?1 for bovine hemoglobin. The detection limits are 37, 62, and 240 ng·mL^?1, respectively.     

GC Determination of Cisplatin in Serum and Urine of Cancer Patients after Chemotherapy as Platinum (II) Pyrrolidinedithiocarbamate Chelate

A gas chromatographic procedure has been developed for determination of cisplatin from pharmaceutical preparation, serum and urine after chemotherapy of cancer patients as platinum(II) pyrrolidinedithiocarbamate chelate. The elution was carried from the column DB-1701 (30 m × 0.32 mm i.d.) coupled with FID detection. Cu(II), Ni(II), Co(III), Mn(II), Fe(III), Zn(II) and VO(II) when present together with Pt(II) separated completely and did not affect the determination of platinum. The linear calibration curve for platinum (II) was within 1–30 μg mL^?1 with a detection limit of 300 ng mL^?1. The amount of cisplatin detected from serum and urine was 250–325 and 20–116 ng mL^?1 with relative standard deviations (RSD) of 0.8–1.2%, and 0.9–1.2%. The % recovery of Pt from serum and urine by standard addition was 98 and 98.2% with RSD 1.4 and 1.1%.     

Nonextractive Trace Level Simultaneous Determination of Mercury(II) and Zinc(II) in Environmental Samples with 2‐(5‐Bromo‐2‐pyridylazo)‐5‐diethylaminophenol and Cetylpyridinium Chloride

Abstract

A simple, rapid, selective, and sensitive method for the derivative spectrophotometric determination of Hg(II) and its simultaneous determination in the presence of Zn(II) using 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol in the presence of cetylpyridinium chloride, a cationic surfactant, has been developed. The molar absorption coefficient and analytical sensitivity of the 1∶1 Hg(II) complex at 558 nm (λ_max) are 5.78×10⁴ L mol^?1 cm^?1 and 0.67 ng mL^?1, respectively. The detection limit of Hg(II) is 1.40×10^?2 ng mL^?1, and Beer's law is valid in the concentration range 0.05–2.40 µg mL^?1. Overlapping spectral profiles of Hg(II) and Zn(II) complexes in zero‐order mode interfere in their simultaneous determination. However, 0.10–2.00 µg mL^?1 of Hg(II) and 0.065–0.650 µg mL^?1 of Zn(II), when present together, can be simultaneously determined at zero cross point of the derivative spectrum, without any prior separation. The relative standard deviation for six replicate measurements of solutions containing 0.134 µg mL^?1 of Hg(II) and 0.620 µg mL^?1 of Zn(II) is 1.72 and 1.47%, respectively. The proposed method has successfully been evaluated for trace level simultaneous determination of Hg(II) and Zn(II) in environmental samples.     

An Experimental Design Approach to Selecting the Optimum LC Conditions for the Determination of Local Anaesthetics

A sensitive high performance liquid chromatographic (HPLC) method has been developed and validated for the simultaneous determination of four local anaesthetics: lidocaine, proparacaine, bupivacaine and oxybuprocaine. A full factorial design was used. The chromatographic separation was achieved using a Bondesil C₈ (4.6 × 2.5 mm i.d., particle size 5 μm) analytical column. An optimised mobile phase consisted of acetonitrile and sodium dihydrogen phosphate (pH = 3.0, 20 mM) (30:70, v/v) at a flow rate of 1.2 mL min^?1. Local anaesthetics detection was performed by UV-Vis detector at 220 nm. The retention times for lidocaine, proparacaine, bupivacaine and oxybuprocaine were 5.74, 9.28, 16.84 and 26.26 min, respectively. HPLC-UV-Vis method was linear in the range of 50–5,000 ng mL^?1 for lidocaine and proparacaine and 100–5,000 ng mL^?1 for bupivacaine and oxybuprocaine. The limit of detection (LOD) was 25 ng mL^?1 for lidocaine, proparacaine and 30 ng mL^?1 for bupivacaine and oxybuprocaine. The limit of quantification (LOQ) was found to be 50 ng mL^?1 for lidocaine, proparacaine and 100 ng mL^?1 for bupivacaine, oxybuprocaine. In intra-day and inter-day precision and accuracy analysis, the relative standard deviation was found to be less than 8%.     

Simultaneous Determination of Theobromine,Paraxanthine, Theophylline,and Caffeine in Urine by Reversed-Phase High-Performance Liquid Chromatography with Diode Array UV Detection

A reversed-phase high performance liquid chromatographic method was improved for the simultaneous determination of theobromine, paraxanthine, theophylline, and caffeine in urine. The method includes a liquid-liquid extraction at alkaline pH with ethylacetate. The 7-(2,3-dihidroxypropyl) theophylline was used as an internal standard (ISTD). The separation was achieved on a C₁₈ column using 14:86 methanol:buffer (25 mM KH₂PO₄ adjusted to pH 4 with ortho-phosphoric acid) solution as mobile phase under isocratic conditions at a flow rate 1 mL min^?1. An ultraviolet absorption at 274 nm was monitored. In these conditions, the LOD was 0.03 μg mL^?1 for theobromine, 0.02 μg mL^?1 for paraxanthine, 0.04 μg mL^?1 for theophylline, and 0.08 μg mL^?1 for caffeine. The method has been applied to urine samples.     

Chemiluminometric Determination of the Pesticide Pirimicarb by a Flow Injection Analysis Assembly

Abstract

A flow injection (FI) method is described for the determination of pirimicarb. It was found that an enhanced chemiluminescence (CL) signal is obtained when employing the luminol–H₂O₂–horseradish peroxidase (HRP) system. Under the optimum experimental conditions, the enhanced CL intensity was linear with the concentration 4.25–30.75 ng mL^?1 (r = 0.997, n = 8) with a relative standard deviation of 0.99%, containing 12.75 ng mL^?1 (n = 8). The limit of detection of the investigated compound was 0.12 ng mL^?1. The method shows a moderate selectivity against other pesticides (Amitrole, Atrazine, 2,4,5-T, Dichlorprop, and Metamidophos).The proposed method was sensitive, simple, rapid, and successfully applied to the determination of pirimicarb when it is applied in freshwater; the mean recoveries were 98.3–118.5%.     

Determination of Pantoprazole, Rabeprazole, Esomeprazole, Domperidone and Itopride in Pharmaceutical Products by Reversed Phase Liquid Chromatography Using Single Mobile Phase

A simple, sensitive, and precise high performance liquid chromatographic method for the analysis of pantoprazole, rabeprazole, esomeprazole, domperidone and itopride, with ultraviolet detection at 210 nm, has been developed, validated, and used for the determination of compounds in commercial pharmaceutical products. The compounds were well separated on a Hypersil BDS C18 reversed-phase column by use of a mobile phase consisting of 0.05 M, 4.70 pH, potassium dihydrogen phosphate buffer - acetonitrile (720:280 v/v) at a flow rate of 1.0 mL min^?1. The linearity ranges were 400–4,000 ng mL^?1 for pantoprazole, 200–2,000 ng mL^?1 for rabeprazole, 400–4,000 ng mL^?1 for esomeprazole, 300–3,000 ng mL^?1 for domperidone and 500–5,000 ng mL^?1 for itopride. Limits of detection (LOD) obtained were: pantoprazole 147.51 ng mL^?1, rabeprazole 65.65 ng mL^?1, esomeprazole 131.27 ng mL^?1, domperidone 98.33 ng mL^?1 and itopride 162.35 ng mL^?1. The study showed that reversed-phase liquid chromatography is sensitive and selective for the determination of pantoprazole, rabeprazole, esomeprazole, domperidone and itopride using single mobile phase.     

UPLC-PDA Analysis for Simultaneous Quantification of Four Active Compounds in Crude and Processed Rhizome of Polygonum multiflorum Thunb

A novel, rapid and specific ultra performance liquid chromatography-photo diode array detection method was developed for the simultaneous determination of 2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside (TSG), emodin-8-O-β-d-glucoside (EMG), emodin (EM) and physcion (PS). The chromatographic separation was performed on an Acquity BEH C₁₈ column (100 × 2.1 mm i.d., 1.7 μm). The mobile phase was a mixture of 0.3% acetic acid–water and 0.3% acetic acid–acetonitrile employing gradient elution at the flow rate of 0.4 mL min^?1. The four compounds behaved linearly in the concentration range between 60.80–3040.00 μg mL^?1 (TSG), 0.50–25.00 μg mL^?1 (EMG), 2.16–108.00 μg mL^?1 (EM) and 1.56–78.00 μg mL^?1 (PS), respectively with correlation coefficients >0.999. The precision of the method were below 5% RSD. Recoveries of the four compounds ranged from 95.71 to 102.97%, with RSD values less than 2%.     

Magnetic solid-phase extraction of imatinib and doxorubicin as cytostatic drugs by Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/graphene oxide nanocomposite

Magnetic solid-phase extraction based on Fe₃O₄/graphene oxide nanocomposites was investigated for the separation, preconcentration and determination of imatinib and doxorubicin in aqueous solutions. Synthesis of Fe₃O₄/graphene oxide was characterized by transmission electron microscopy, energy-dispersive X-ray analyzer and vibrating sample magnetometer. After optimizing the conditions, optimal experimental conditions including sample pH, the amount of the magnetic nanoparticles, the effect of salt concentration and other chemotherapy medications, eluent type and extraction time were studied and established. The method showed good linearity for the determination of doxorubicin and imatinib in the concentration range of 0.01–100 μg mL^?1 in aqueous solutions with limit of detection 1.8 ng mL^?1 for doxorubicin and 1.9 ng mL^?1 for imatinib. The relative recoveries of doxorubicin and imatinib levels were 96.7 and 88.4%, respectively. The results indicate that the present procedure is a suitable method for extraction of imatinib and doxorubicin from environmental water samples.     

N-(1-Naphthyl)ethylenediamine, a New UV Labeling Reagent Used for LC Determination of Valproic Acid in Human Plasma

A high performance liquid chromatography method is presented for the determination of valproic acid levels in human plasma. The method was based on pre-column derivatization using N-(1-naphthyl)ethylenediamine as a new labeling agent. The calibration curve was linear in the investigated concentration range between 0.1 and 100 μg mL^?1 and showed good accuracy and reproducibility. The assay provided a limit of quantification of 0.1 μg mL^?1 for valproic acid and a limit of detection of 10 ng mL^?1, respectively. The presented method was successfully applied to the determination of valproic acid levels in plasma after oral administration of 600 or 800 mg of sodium valproate.     

Determination of Vitamin A in Infant Milk-Based Formulas and Pharmaceutical Formulations Using Flow Injection with Ce(IV)–Na2SO3 Chemiluminescence Detection

A rapid and simple flow injection (FI) method is reported for the determination of vitamin A (retinol) based on its strong enhancing effect on the Ce(IV)–Na₂SO₃ chemiluminescence (CL) reaction in an acidic solution. The effect of key chemical and physical parameters (i.e., reagent concentrations, flow rate, and sample volume) was optimized and potential interferences examined. Under the selected experimental conditions, a linear calibration was obtained between the CL intensity and vitamin A concentration in the range 0.1–8.0 µg mL^?1 (r ²  = 0.9986, n = 8). The limit of detection (3 s x blank) was 0.01 µg mL^?1 retinol (n = 6) and the relative standard deviation (RSD) for 0.25 µg mL^?1 retinol was 2.3% (n = 10) with a sampling rate of 180 h^?1. The method was successfully applied to infant milk-based formulas and pharmaceutical formulations and the results were not significantly different at 95% confidence interval with those obtained by using a spectrophotometric reference method. The possible CL mechanism is also discussed briefly supporting with UV-visible, fluorescence, and CL spectra.