Chemometric analysis based on high-performance liquid chromatographic data in the fingerprint construction of selected Achillea species

Fourteen Achillea species were collected, extracted using Soxhlet apparatus with dichloromethane and methanol as solvents. The obtained methanolic extracts were analyzed using the reversed-phase high-performance liquid chromatography–diode array detector (RP-HPLC-DAD) with the Kinetex C18 column and the mobile phase consisting of methanol–water–0.1% formic acid mixture (gradient 5–85% (v/v)) at 30°C with the run time of 45?min and the detection wavelength 320?nm. Next, the chromatograms were preliminarily processed with smoothing, noise reduction, background subtraction, and alignment in the SpecAlign program (version 2.4.1) to construct the fingerprints of studied extracts. Selected standards (phenolic acids and flavonoids) were analyzed in the same chromatographic conditions and its presence in extracts was confirmed based on their spectra and the retention time values. The chemical similarity between the samples was evaluated using the Pearson correlation coefficient as similarity parameter, Euclidean distance index, the principal component analysis, and cluster analysis (CA).     

Image analysis of phenylisothiocyanate derivatised and charge-couple device-detected glyphosate and glufosinate in food samples separated by thin-layer chromatography

The paper presents the application of pre-chromatographic derivatisation reaction of aminophosphonic acids (glyphosate and glufosinate) with phenylisothiocyanate in thin-layer chromatography (TLC). Silica gel as stationary phase and a mixture of methanol–water–diethyl ether (2:1:1, v/v/v) and ethanol–water–diethyl ether (4:1:2, v/v/v) were used as the mobile phase, respectively. Detection was performed by spraying TLC plates with a freshly prepared mixture of sodium azide (1%), starch solution (1% for glyphosate and 2% for glufosinate), and potassium iodide (1.0 × 10^–2 mol L^?1) adjusted to pH 6.0 and exposed to iodine vapour for 15 s. Both glyphosate and glufosinate as phenylthiocarbamates (PTC-derivatives) were visible as white spots against a violet background which were converted into chromatograms using TLSee software. The calibration curves for glyphosate and glufosinate were within the ranges of 8.45–84.5 ng and 1.98–79.2 ng per spot, respectively. The limits of detection and quantification for glyphosate were at a level of 4 and 8.45 ng per spot, and for glufosinate were 0.99 and 1.78 ng per spot, respectively. The proposed method was successfully used in the determination of aminophosphonic acids in spiked plants samples.     

Determination of BTEX Compounds by Dispersive Liquid–Liquid Microextraction with GC–FID

Rapid, inexpensive, and efficient sample-preparation by dispersive liquid–liquid microextraction (DLLME) then gas chromatography with flame ionization detection (GC–FID) have been used for extraction and analysis of BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) in water samples. In this extraction method, a mixture of 25.0 μL carbon disulfide (extraction solvent) and 1.00 mL acetonitrile (disperser solvent) is rapidly injected, by means of a syringe, into a 5.00-mL water sample in a conical test tube. A cloudy solution is formed by dispersion of fine droplets of carbon disulfide in the sample solution. During subsequent centrifugation (5,000 rpm for 2.0 min) the fine droplets of carbon disulfide settle at the bottom of the tube. The effect of several conditions (type and volume of disperser solvent, type of extraction solvent, extraction time, etc.) on the performance of the sample-preparation step was carefully evaluated. Under the optimum conditions the enrichment factors and extraction recoveries were high, and ranged from 122–311 to 24.5–66.7%, respectively. A good linear range (0.2–100 μg L⁻¹, i.e., three orders of magnitude; r ² = 0.9991–0.9999) and good limits of detection (0.1–0.2 μg L⁻¹) were obtained for most of the analytes. Relative standard deviations (RSD, %) for analysis of 5.0 μg L⁻¹ BTEX compounds in water were in the range 0.9–6.4% (n = 5). Relative recovery from well and wastewater at spiked levels of 5.0 μg L⁻¹ was 89–101% and 76–98%, respectively. Finally, the method was successfully used for preconcentration and analysis of BTEX compounds in different real water samples.

     

An LC Ion-Pairing Method for the Determination of Fe(II) in Ferrous Bisglycinate Pharmaceutical Formulation

A reversed-phase ion-pairing liquid chromatographic method was developed and validated for the assay of Fe(II) in ferrous bisglycinate (Fe-bis-gly) capsules using 4-(2-pyridylazo) resorcinol reagent. The analysis was carried out using a Gemini RP-18 (150 mm × 4.6 mm I.D., particle size 5 μm) analytical column; the mobile phase consisted of a mixture of acetonitrile–water (28:72 v/v) containing 1 mM tetrabutylammonium hydrogensulfate and 1% phosphate buffer (pH 8.0). The flow rate was 1.0 mL min⁻¹ and the detection was achieved with a photodiode array (PDA) detector at 706 nm. The specificity of the method was proved using stress conditions and evaluated using a PDA detector. The data validation showed that the method is specific, fast, accurate, and reproducible for the determination of Fe-bis-gly in dosage form. The response was linear over a range of 1.0–2.6 μg mL⁻¹ (r = 0.9999). The accuracy of the method ranged from 98.02 to 102.75%. The RSD values for intra- and inter-day precision studies were below 1.3 and 1.1%, respectively. There was no interference of the excipients on the determination of the active pharmaceutical ingredient.

     

A Stability-Indicating LC Method for Lumefantrine

A simple, rapid, and precise method is developed for the quantitative determination of lumefantrine (Lume) in active pharmaceutical ingredient (API). A chromatographic separation of Lume and its degradants were achieved with an X-Terra RP18, 250 × 4.6 mm, and 5 μ analytical column using buffer–acetonitrile (30:70 v/v). The buffer used in mobile phase contains 0.1 M sodium perchlorate monohydrate in double distilled water pH adjusted to 2.1 with trifluoroacetic acid. The instrumental settings are flow rate of 0.5 mL (L), column temperature at 35 °C, and detector wavelength of 235 nm using a photodiode array detector. Lume was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the stressed samples were analysed by the proposed method. Peak homogeneity data of Lume obtained by photodiode array detection, in the stressed sample chromatograms, demonstrated the specificity of the method for estimation in the presence of degradants. The described method shows excellent linearity over a range of 10–200 μg L⁻¹ for Lume. The correlation coefficient is 1. The relative standard deviation of peak area for six measurements is always less than 2% between days. The proposed method was found to be suitable and accurate for quantitative determination and stability study of Lume in API.

     

Multiwalled Carbon Nanotubes as SPE Adsorbents for Simultaneous Determination of Seven Sulfonylurea Herbicides in Environmental Water by LC–MS–MS

An effective and rapid method was developed for simultaneous determination of seven sulfonylurea herbicides in environmental water using multiwalled carbon nanotubes as solid-phase extraction sorbent coupled with liquid chromatography–tandem mass spectrometry. Important parameters influencing the extraction efficiency such as pH of the sample solution, flow rate of sample loading, the eluent and its volume were optimized. Under optimum conditions, good linearity was obtained for all herbicides (r ² > 0.99) over the range of 0.05–5,000 ng L^?1, and precisions (RSD) for nine replicate measurements of a standard mixture of 200 ng L^?1 were 1.9–7.4%. The limits of detection and quantification were 0.01–0.20 and 0.05–1.00 ng L^?1, respectively. The proposed method was successfully applied to the analysis of tap water, spring water, ground water and well water, and mean recoveries for seven analytes at three spiked concentration levels were from 81.5 to 110.5% with RSDs between 0.3 and 7.0%. The results showed that the established method has wide application to analyze sulfonylurea herbicides at trace level in water.     

Colorimetric Determination of Lead Using Gold Nanoparticles

A combined homogeneous assay and colorimetric determination method using gold nanoparticles was developed for rapid determination of lead(II) in contaminated natural waters. The presence of lead(II) in the colloidal gold suspension causes a change in the absorbance of the suspension. An increase in the absorption property at 595 nm is accompanied by a change in the size of the gold nanoparticles. High concentrations of lead cause aggregation of the gold colloids. Colloidal gold nanoparticles were synthesized using tannic acid as the reducing agent; this reagent allowed selective determination of lead in 10 µL of water, with a detection limit of 310 ng mL^?1 with an analysis time of 5 min. The coefficient of variation for lead(II) within the working range of the assay (520 ng mL^?1–13 µg mL^?1) varied from 1.3% to 9.2%. The limit of detection using this method with a sample volume of 50 µL was 60 ng mL^?1. The coefficient of variation for lead over the working range of the determined concentrations (80 ng mL^?1–25 µg mL^?1) varied from 0.2% to 9.3%, while the values for the inter-day assay (n = 8) were less than 10%. The method was employed for the analysis of river, lake, marsh, and spring water; the recovery of lead was determined to be 72.5%–130% for 10 µL of water and 93.6%–114.7% for 50 µL.     

Ultra-Preconcentration and Determination of Multiple Pesticide Residues in Water Samples Using Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction and GC-FID

In this study, a simple and efficient method has been developed to analyze pesticides in water samples using ultrasonic-assisted dispersive liquid–liquid microextraction (UA-DLLME) combined with gas chromatography-flame ionization detection (GC-FID). Several parameters, including type and volume of extractant and dispersant, extraction time, and amount of salt on extraction performance, were optimized in detail. A mixture of acetonitrile (1.0 mL, dispersant) and carbon tetrachloride (15 μL, extractant) was used for extraction. Under optimal conditions, enrichment factors were obtained between 315 and 1153. The linearity of the method ranged from 1 to 100 μg L⁻¹ with correlation coefficients ≥0.9990. Limits of detection (S/N = 3) ranged between 0.09 and 0.57 μg L⁻¹, depending on the compounds. Relative standard deviations were <8.0 % (n = 5) for both intra- and inter-day analyses. The proposed method was successfully applied for the preconcentration and determination of pesticides in water samples (river water, tap water, and lake water) with recoveries that varied from 90.5 to 107.7 %.

     

Homogeneous Liquid–Liquid Microextraction Via Flotation Assistance (HLLME-FA) Method for the Pretreatment of Organochlorine Pesticides in Aqueous Samples and Determination by GC–MS

This work proposes a new, rapid and simple homogeneous liquid–liquid microextraction via flotation assistance technique for the analysis of six organochlorine pesticides in water samples. A special extraction cell was used to facilitate collection of the low-density solvent extract. No centrifugation was required in this procedure. Determination was carried using gas chromatography–mass spectrometry. The water sample solution was then added into the extraction cell containing appropriate mixture of extract and homogeneous solvents. In the first step, a homogeneous solution and then with the continuation of water sample injection, a cloudy solution was formed. Using air flotation, the organic solution was collected at the conical part of the designed cell. The optimized levels of effective parameters were found based on response surface methodology approach. Applying the optimized conditions to the system understudy, the limits of detection of all target analytes were obtained in the range of 1.4–7 ng mL⁻¹, while the precisions were found to be in the range of 11.08–14.87 (RSD, n = 3). The linearity of the method lay in the range of 10–150 ng mL⁻¹ with the coefficients of correlation (r ²) ranging from 0.998 to 0.999.

     

Improving the radiochemical purity determination of 123I-labeled metaiodobenzylguanidine

The HPLC method originally applied at the Nuclear Engineering Institute (IEN) for the radiochemical purity determination of ¹²³iodine labeled m-iodobenzylguanidine (¹²³I-mIBG) takes 18.5 min. The final product release also depends on this result, and to facilitate this stage, we aimed to decrease this analysis time. We also intended to use fewer toxic compounds, if feasible. The optimization approach used herein was a combination of factorial and mixture designs to study simultaneously the selected variables. Analysis time, resolution and chromatograms aspect were the measured responses. The qualitative analysis of these responses provided the best chromatographic separation conditions that were 52 mM KH₂PO₄ in a solution of ethanol and water (1:1), applying a flow rate of 0.50 mL min^?1 and C18 column (4.6 × 250 mm, 5 μm). These optimum conditions not only decreased the analysis time in 61 %, but also allowed the reduction of mobile phase toxicity. To assure reliable data, method validation was performed for these conditions. The method has proved its specificity, the detection limit found was 3.70 × 10^?4 MBq mL^?1 and the quantification limit has corresponded to 1.11 × 10^?3 MBq mL^?1. Repeatability and intermediate precision has not exceeded 3 and 5 %, respectively, and the accuracy has matched the interval of 95–105 %. This new method has been routinely applied in the radiochemical purity determination of ¹²³I-mIBG at IEN.     

Monitoring of Polychlorinated Biphenyls in Surface Water Using Liquid Extraction,GC/MS,and GC/ECD

Abstract

A rapid and reliable analytical method, at trace level concentration was developed and validated for monitoring polychlorinated biphenyls (PCBs) in Jordanian surface water. The method combines the advantage of liquid extraction together with gas chromatography‐mass spectrometry (GC/MS) and gas chromatography‐electron capture detector (GC/ECD). The performance of the method was evaluated by analyzing certified reference material (CRM) of the analytes and applied on real water samples collected from different sites in Jordan. A mixture of 60∶40 dichloromethan‐petroleum ether was chosen as a convenient binary solvent for liquid–liquid extraction. The GC conditions for GC/MS were optimized using He as a carrier gas, temperature programming, and chlorpropham as an internal standard (IS).

The conditions for GC/ECD were performed using N₂ gas and a temperature program from 160 to 280°C with different increasing rates. The method of GC/MS in the selective ion mode (SIM) gave linear relationships for all PCBs tested between 0.60–6.0 µg/l with R ²=0.9934 (n=7×18). Recoveries from spiked water samples ranged between 87.6 and 91.4%. The mean accuracy and precision obtained were 4.9% and 2.16%, respectively. The mean of detection limit was 0.14±0.04 µg/l. In GC/ECD, linear relationships for all PCBs examined over the range of 0.3–2.4 µg/l was verified as characterized by a linear regression equation and correlation coefficient, R ²=0.9915 (n=12). The average precision and accuracy were 4.86% and 5.21%, respectively. Analyses results clarified that none of the examined Jordanian water samples contained any of the searched for PCBs within the detection limit achieved.     

Flow injection determination of cyromazine in natural water samples using diperiodatoargentate(III)–H2SO4–chemiluminescence system

A simple and sensitive chemiluminescence (CL) procedure is proposed for the determination of cyromazine (CYR) using flow injection technique. CYR has strong enhancing effect on the CL reaction of diperiodatoargentate-(III) complex (DPA) in H₂SO₄ medium. The CL intensity with solid phase extraction (SPE) technique and with and without using online ion exchange resin column (IERC; OH-form) was proportional to the concentration of CYR over the range 0.1–200, 10–1000 and 2–2500 µg L^–1 (R² = 0.9974, 0.9980 and 0.9990, n = 7 each), respectively. Under the conditions, the limits of detection (S/N = 3) 0.029, 2.5 and 0.5 µg L^–1, relative standard deviations (n = 3) 1.9–3.6%, 1.4–2.7% and 1.0–3.0% and sample throughputs were 120, 80 and 120 h^–1. The effect of reagents concentration, flow rate, sample loop volume, photomultiplier voltage and IERC length was optimised. The mean results for natural water samples analysed by the proposed method were not significantly different at 95% confidence limit with the previously reported HPLC method. Interference from chloride ions could be eliminated by using SPE procedure or incorporating an in-line IERC. The CL mechanism of DPA–H₂SO₄–CYR system was also discussed briefly.     

Development of a green effervescence-assisted dispersive liquid–liquid microextraction method using a home-made tablet disperser for trace analysis of Cd(II) and Pb(II)

An analytical approach for the determination of trace amounts of Cd(II) and Pb(II) has been developed using a home-made tablet-based effervescence-assisted dispersive liquid–liquid microextraction (DLLME) method which was performed in a narrow-bore tube, followed by flame atomic absorption spectrometry. In this method, a mixture of tartaric acid, sodium bicarbonate and NaCl was used to make the disperser tablet. Then, microlitre level of an extraction solvent was added in the tablet, and then, it was released into a narrow-bore tube containing sample solution and a complexing agent. An acid–base reaction immediately occurred between tartaric acid and sodium bicarbonate, and the produced CO₂ led to the dispersion of the extraction solvent into the solution as tiny droplets and subsequent extraction of the analytes. The method made possible the determination of Cd(II) and Pb(II) in the ranges of 0.1–10 and 1.0–20 µg L^?1, respectively. The limits of detection were obtained 0.43 and 0.05 µg L^?1 for Pb(II) and Cd(II), respectively. The limits of quantifications were 0.80 and 0.09 µg L^?1 for Pb(II) and Cd(II), respectively. Repeatability of the method, which is expressed as relative standard deviation, was obtained 3.1% (n = 6, C = 2 µg L^?1) and 1.3% (n = 6, C = 0.2 µg L^?1) for Pb(II) and Cd(II), respectively. The accuracy of the developed method was verified by analysing a certified reference material, namely SPS-WW2 Batch 108. Relative recoveries (84–107%, obtained at three fortification levels) confirmed the usefulness of the method for analysis of the analytes in the environmental water samples and fruit juices. The method was shown to be fast, reliable and environmentally friendly with low organic solvent consumption.     

Stir Bar Sorptive Extraction and LC–MS/MS for Trace Analysis of UV Filters in Different Water Matrices

A simple, selective and highly sensitive method was developed and optimized to determine the most commonly used UV filters with endocrine-disrupting potential in water, namely benzophenone-3 (BP-3), octocrylene (OC), ethylhexyl dimethyl p-aminobenzoate (OD-PABA), ethylhexyl methoxycinnamate, ethylhexyl salicylate (EHS) and homosalate (HMS). Samples were extracted by stir bar sorptive extraction followed by liquid desorption (SBSE-LD). The important factors influencing SBSE-LD were optimized. Under optimal conditions, assays were performed on 50 mL of water sample using stir bars (0.5 mm in film thickness, 10 mm in length) at room temperature. The analytes were determined by liquid chromatography–tandem mass spectrometry with triple quadrupole analyzer using atmospheric pressure chemical ionization. The main parameters in HPLC–APCI–MS/MS were also optimized to provide the best performances for all analytes. Moreover, matrix effect was investigated using two methods the post-column infusion system and the method of spiked matrices after extraction. As a result, no significant matrix effect on the analysis was observed. The method showed good linearity (R ² coefficients greater than 0.996 in different water samples after SBSE-LD). Recoveries of the analytes were close to 90%, except for BP-3 (64%) and OC (76%) with relative standard deviation lower than 11%. Detection limits were between 0.6 and 3.3 ng L⁻¹ for all the analytes except for HMS (94 ng L⁻¹) and EHS (114 ng L⁻¹). This methodology was applied to measure UV filters in seawater, river water and wastewater in different sites of Liguria; BP-3 and OC were found in most of the considered samples at rather low concentration level.

     

Viscosities of Binary and Ternary Mixtures of Water,Alcohol, Acetone,and Hexane

This articles studied and determined the viscosities of the binary mixtures of water–methanol, water–ethanol, water–propanol, water–acetone, acetone–ethanol, methanol–ethanol, and acetone–hexane and the ternary mixtures of water–methanol–ethanol and water–ethanol–acetone at 20°C. It is shown that the mixing of water with the alcohols and acetone resulted in a positive deviation of viscosity, which reached the maximum value at the water mole fraction x ₁ ～ 0.7 for water–methanol, x ₁ ～ 0.72 for water–ethanol, x ₁ ～ 0.74 for water–propanol, and x ₁ ～ 0.83 for water–acetone binary mixture. This viscosity deviation can be mainly attributed to the formation of micelles of alcohol or acetone molecules in water because of the hydrophobic attraction between the hydrocarbon chains. The micelle surfaces are surrounded by hydration layers, leading to the positive viscosity deviation in the liquid mixtures because the water in hydration layers has a much higher viscosity than bulk water. Also, the contrary observation was found in the binary mixtures of acetone–ethanol and acetone–hexane, having a negative viscosity deviation.     

Speciation of Organotin Compounds by Capillary Electrophoresis Coupled with Hydride Generation Atomic Fluorescence Spectrometry

Abstract

Capillary electrophoresis (CE) coupled with hydride generation atomic fluorescence spectrometry (HG‐AFS) was developed for the speciation analysis of organotin compounds. The four organotin cations of trimethyltin (TMT), monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) were completely separated by CE in a 50 cm×75 µm i.d. fused‐silica capillary at 15 kV and using a mixture of 50 mmol l^?1 H₃BO₃?50 mmol l^?1 Tris‐5% v/v methanol (pH 7.10) as electrolyte. 0.008 mmol l^?1 cetyltrimethylammonium bromide (CTAB) added to the electrolyte suppressed the adsorption of the organotin cations on the inner wall of capillary. The generated hydride species were detected on‐line with AFS. The precisions (RSD, n=5) were in the range of 1.7–3.1% for migration time and 3.8–4.7% for peak area response for the four organotin species. The detection limits ranged from 1–10 µmol l^?1 (as Sn).     

Metal content in mosses from the Metropolitan Area of the Toluca Valley: a comparative study between inductively coupled plasma optical emission spectrometry (ICP-OES) and total reflection X-ray fluorescence spectrometry (TXRF)

The comparison between inductively coupled plasma optical emission spectrometry (ICP-OES) and total reflection X-ray fluorescence spectrometry (TXRF) for simultaneous determination of metal content (Cr, Cu, Fe, Mn, Pb and Zn) in mosses from the Metropolitan Area of the Toluca Valley was performed. Epiphytic mosses (Fabriona ciliaris and Leskea angustata) were collected in two sampling campaigns and were digested with HNO₃, HCl and HF for ICP-OES method and HNO₃ and HCl for TXRF method. The certified reference material (IAEA-336, Lichen) and the Standard Reference Material (SRM-1573, tomato leaves) were used for the quality control and to evaluate trueness and precision. Linearity, detection and quantification limits were also determined. Results show an ICP-OES and TXRF trueness mean of 101 ± 5% and 97 ± 9%, respectively; the relative standard deviation (RSD percent) was less than 17% in both methods. The moss samples exhibit a satisfactory precision (RSD ≤ 20%), because the RSD percent for ICP-OES, from 2% to 15%, and that for TXRF, from 1% to 17%, were obtained. One factor experimental design and simple regression analysis (α = 0.05) were used to compare the ICP-OES and TXRF metal concentrations. The statistical results do not show significantly different values for Cu, Mn, Pb and Zn in both the sample campaigns. In addition, the average results for Cr in the first sample campaign (30.3 ± 11.4 mg/kg for ICP-OES and 18.6 ± 9.8 mg/kg for TXRF) and Fe values in the second sample campaign (10,810 ± 2980 mg/kg for ICP-OES and 8380 ± 2350 mg/kg for TXRF) were significantly different in both methods. These differences are attributed to an incomplete sample digestion in the TXRF sample preparation. The results of the simple regression analyses show p-value less than 0.05, which indicates an equivalent and significant relation between ICP-OES and TXRF.     

Optimal Development of a New Stable Nutraceutical Nanoemulsion Based on the Inclusion Complex of 2-Hydroxypropyl-β-cyclodextrin with Canthaxanthin Accumulated by Dietzia natronolimnaea HS-1 Using Ultrasound-Assisted Emulsification

Solubilizing the potent anticancer pigments in nanoemulsion (NE) systems containing 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) is a novel and promising strategy to incorporate them into water-based drug formulations. The concentration effects of sunflower oil (SO, 5.61–17.39% w/w), surfactant mixture of Tween 80 (T80) and Span 20 (S20) (1:1 weight ratio, 3.95–14.05% w/w), and the inclusion complex of HP-β-CD with canthaxanthin (CTX) synthesized by Dietzia natronolimnaea HS-1 (2.61–14.39% w/w) were evaluated to formulate a stable NE using ultrasound-assisted emulsification. The NEs were evaluated regarding droplet size and polydispersity index (span), physical stability, turbidity, and loss of antioxidant activity (LAA). Response surface modeling showed that the NEs containing 12% T80/S20, 8.30% SO, and 12% CTX/HP-β-CD had the lowest droplet size (105.5 nm), span (0.394), droplet growth ratio (0.112), turbidity (0.139), and LAA (9.36%). The predicted values obtained were close to the experimental values, indicating the suitability of the constructed models. Transmission electron microscopy and confocal laser-scanning microscopy also demonstrated that the formed droplets of the NEs produced at optimal formulation were spherical in the range of 20–100 nm. A significant correlation was found between droplet size with stability (r = ?0.960, p < 0.01) and turbidity (r ² = 0.876, p < 0.01) values.     

RP–LC Simultaneous Determination of Aconitine,Solanine and Piperine in an Ayurvedic Medicine

By optimizing the extraction, separation and analytical conditions, a reliable, rapid, simple and accurate liquid chromatography method with UV detection was developed for the simultaneous quantitative determination of aconitine, solanine and piperine in an ayurvedic preparation prepared from Aconitum ferox, Solanum indicum, Piper nigrum and Piper longum. The separation of these alkaloids was achieved on an reversed phase C-18 column (250 mm × 4.6 mm ID, 5 μm particle size), with isocratic elution using a mixture of acetonitrile–potassium hydrogen phosphate buffer (10 mM, pH 7.5)–methanol (60:25:15, v/v) at a flow rate of 1 mL min⁻¹ with UV detection at 227 nm for aconitine and solanine while 343 nm for piperine. The calibration curves were linear with correlation coefficients of 0.9990, 0.9942, 0.9989 for solanine, piperine and aconitine, respectively. The % Relative standard deviation (%RSD) values were less than 2% in the concentration range of 10–100 μg mL⁻¹ for all the three alkaloids. Intra-day assay and inter-day assay precision of the analytes were less than 2%, and the average recovery rates obtained were in the range of 98–102% for all with %RSD below 2%. Quantitative analysis of the alkaloids in the laboratory and marketed formulations showed that the contents of the alkaloids varied significantly. This method can provide a scientific and technical platform to the product manufacturers for setting up a quality control standard as well as to the public for quality and safety assurance of the proprietary ayurvedic formulations.

     

Microwave Synthesis of 5-Substituted 1H-Tetrazoles Catalyzed by Bismuth Chloride in Water

Bismuth chloride was used to catalyze the [2 + 3] cycloaddition between sodium azide with aryl nitriles, aliphatic nitriles, and vinyl nitriles. A number of 5-substituted 1H-tetrazoles were synthesized in water or isopropanol/water mixtures using microwave heating. Good yields were obtained for these reactions when heated for 1 h at 120–160 °C in a 3:1 isopropanol/water mixture. A few of the less reactive nitriles required longer reaction times for good yields.