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Authors: Stefano Dugheri, Giorgio Marrubini, Nicola Mucci, Giovanni Cappelli, Alessandro Bonari, Ilenia Pompilio, Lucia Trevisani and Giulio Arcangeli

Abstract

Sample pretreatment is one of the most crucial and error-prone steps of an analytical procedure; it consents to improve selectivity and sensitivity by sample clean-up and pre-concentration. Nowadays, the arousing interest in greener and sustainable analytical chemistry has increased the development of microextraction techniques as alternative sample preparation procedures. In this review, we aimed to show two different categorizations of the most used micro-solid-phase extraction (μSPE) techniques. In essence, the first one concerns the solid-phase extraction (SPE) sorbent selection and structure: normal-phase, reversed-phase, ion-exchange, mixed-mode, molecular imprinted polymer, and special techniques (e.g., doped cartridges for specific analytes). The second is a grouping of the commercially available μSPE products in categories and sub-categories. We present every device and technology into the classifications paying attention to their historical development and the actual state of the art. So, this study aims to provide the state-of-the-art of μSPE techniques, highlighting their advantages, disadvantages, and possible future developments in sample pretreatment.

Open access

Abstract

A sensitive RP-HPLC method is presented for the simultaneous quantification of Fluorometholone (FLM) and Tetrahydrozoline hydrochloride (THZ). The method has the advantages of being rapid, accurate, reproducible, ecologically acceptable and sensitive. The separation utilized C8 Xbridge® column and mobile phase mixture of Acetonitrile/phosphate buffer pH 3 ± 0.1 (70:30, v/v) with UV detection at 230 nm. Stepwise optimization and factors affecting separation are properly discussed. Different factors were optimized such as stationary phase, selection of organic solvent and its content, buffer pH and concentration, flow rate, elution type and detection wavelength. The studied drugs were efficiently separated in 3.4 min with high resolution. Also, two univariate spectrophotometric methods have been optimized for the quantification of the studied drugs. Method 1: dual wavelength for THZ and iso-absorptive point for FLM, Method 2: ratio difference (RD) for THZ and first derivative FLM utilizing methanol as a solvent. These methods are accurate, precise with minimal data manipulation. Greenness of the methods was estimated using eco-scale tool where the presented methods were found to be excellent green with eco-score of 83 for HPLC and 80 for spectrophotometry. The methods are validated in conformance with ICH guidelines, with acceptable accuracy, precision, and selectivity. The suggested methods can be employed for the economic analysis of THZ and FLM in their pure form and binary ophthalmic formulation, that can be employed by quality control laboratories.

Open access

Abstract

A method for simultaneous determination of trace of four organophosphorus pesticides residues in animal liver samples has been developed and validated. This method is based on the preliminary sample preparation using extraction of target compound with a mixture of toluene-cyclohexane by means of up-to-date accelerated solvent extraction (ASE), liquid-liquid partitioning with acetonitrile and hexane, additional clean up step using QuEChERS method. Further the obtained analytes are determined by gas chromatography with ion-trap detector. The validation of the method is performed in accordance with the recommendations in Document SANTE/11945/2015 and it meets the acceptability criteria for precision, mean recovery and limits of quantification. The samples were investigated by analysing blank liver samples and samples spiked with the target analytes chlorpyrifos-methyl, parathion and pirimiphos-methyl at levels of 25, 50, and 75 ng/g and with diazinon at levels of 15, 30, and 45 ng/g. The recovery for all compounds were in the range from 73 to 104% which perfectly fit with requirements of documents and European legislations. The repeatability and within-laboratory reproducibility also reveal acceptable in documents coefficient of variation and uncertainty less than 20 and 18%, respectively. The limits of quantification were less than 3 ng/g for all compounds and allowed determination of residues below the maximum residue levels (MRLs) set in Regulation (EC) Nº 396/2005.

Open access
Authors: Kisantini Murugesu, Sultan Ayesh Mohammed Saghir, Amirin Sadikun, Kooi-Yeong Khaw and Vikneswaran Murugaiyah

Abstract

A simple and sensitive high-performance liquid chromatography-ultraviolet (HPLC-UV) method was developed by exploiting the benefits of phenyl-hexyl column for the simultaneous determination of mono- and di-caffeoylquinic acids in Gynura procumbens plant samples. An optimal chromatographic separation was achieved by using a mobile phase of acetonitrile: 0.25% acetic acid in water (12.5:78.5, v/v) and detection at 330 nm. The limits of detection (LOD) and quantification (LOQ) for the six caffeoylquinic acid standards were in the range of 0.078–0.653 and 0.259–1.795 μg/mL, respectively. The accuracies of the developed method were in the range of 96.84–103.08%, while the corresponding precisions were between 0 and 2.94% for both within-day and between-day analyses, indicating that the method is repeatable and reliable. The mean recoveries were between 87.08 and 117.83%. The method was successfully applied for quantification of caffeoylquinic acids in G. procumbens plant samples. This is the first study on di-caffeoylquinic acids quantification in G. procumbens. Leaves samples contained higher amount of the caffeoylquinic acids compared to stem samples. Of the compounds, 3,5-dicaffeoylquinic acid was found to be the major compound in almost all G. procumbens samples. The method has advantages such as sensitive ultraviolet (UV) detection, short run time with simple isocratic elution system compared to other methods which involved the use of costly instruments, laborious procedures with long run time and complex gradient system. This method can be further extended for routine quality control and analysis of plants or herbal products containing the caffeoylquinic acids.

Open access
Authors: Muhammad Hanif, Shahid Shah, Nasir Rasool, Ghulam Abbas, Malik Saadullah, Sajid Mehmood Khan, Muhammad Masood Ahmed, Nazar Abbas, Mehran Ashfaq and Omeira Iqbal

Abstract

The high performance liquid chromatographic (HPLC) method was developed for the combined estimation of sodium alginate and pectin in raft forming pharmaceuticals on C18 column ZORBAX ODS (1.5 cm × 4.6 mm, 5 μm) with UV detection at 378 nm. The assay condition comprised of phosphate buffer pH 7.4 and methanol 60:40% v/v at a flow rate of 1.25 mL/min. The separation of sodium alginate and pectin with good resolution and a retention time less than 8 min was attained. The method was linear over a range of 200–800 μg/mL of sodium alginate and pectin. The regression values obtained from linearity curve of sodium alginate and pectin were 0.9993 and 0.9991, respectively. The retention time of sodium alginate and pectin was 3.931 and 7.470 min, respectively. The percent recovery of sodium alginate and pectin ranged from 94.2–98.5% and 92.1–98.4% respectively. The limit of detection (LOD) and limit of quantification (LOQ) of sodium alginate were found to be 2.443 and 3.129 μg/mL and the LOD and LOQ of pectin were 3.126 and 3.785 μg/mL, respectively. The resolution of sodium alginate and pectin was found in the range of 1.03–1.89 and 1.10–1.91, respectively. This method has been successfully applied to analyze the concentrations of sodium alginate and pectin in raft forming drug delivery systems.

Open access

Abstract

Toddalia asiatica (Linn) Lam (T. asiatica) as a traditional Miao medicine was investigated to find rational alternative medicinal parts for T. asiatica root bark and its antitumor chemical constituents by quantitative pharmacognostic microscopy, high performance liquid chromatography (HPLC) fingerprint and multivariate statistical analysis. A bivariate correlation analysis method based on microscopic characteristics and content of chemical constituents was established for the first time, there were some regular discoveries between powder microscopic characteristics and common chromatographic peaks of T. asiatica through quantitative pharmacognostic microscopy, cork cells, calcium oxalate square crystal, brown clump, starch granule and phloem fiber, as powder microscopic characteristics may be placed where the main chemical constitutes were enriched. Scores plot of principal component analysis (PCA) and dendrogram of hierarchical clustering analysis (HCA) showed that 18 T. asiatica samples were distinguished correctly, clustered clearly into two main groups as follows: S01∼S03 (root bark) and S07∼S09 (stem bark) in cluster 1, S04∼S06 and S10∼S18 in cluster 2. Nineteen common peaks were obtained in HPLC fingerprint of T. asiatica, loadings plot of PCA indicated seven compounds played important roles in different part of samples (P10 > P08 > P07 > P14 > P16 > P17 > P19), peaks 04, 06, 07, 08, 10 were identified as hesperidin, 4-methoxycinnamic acid, toddalolactone, isopimpinlline and pimpinellin. MTT assay was used to determine the inhibitory activity of different medicinal parts of T. asiatica on human breast cancer MCF-7 cells, all parts of T. asiatica had different inhibitory effects on MCF-7 cell lines, root and stem barks of T. asiatica showed the best inhibitory activity. The relationship between chemical constituents and the inhibitions on MCF-7 cell had been established, significant antitumor constituents of T. asiatica were identified by correlation analysis, the order of the antitumor effect of the main compounds was P07 (toddalolactone) > P16 > P06 (4-methoxycinnamic acid), P11 > P18 > P10 (pimpinellin) > P08 (isopimpinellin) > P01 > P19 > P14 > P04 (hesperidin) > P17, which were antitumor chemical constituents of T. asiatica root bark. T. asiatica stem bark was the most rational alternative medicinal part for T. asiatica root bark.

Open access
Authors: Ramia Z. Al Bakain, Yahya S. Al-Degs, James V. Cizdziel and Mahmoud A. Elsohly

Abstract

In this research, cannabis varieties represent 23 USA States were assayed by GC-FID to generate their complex chemical profiles informative for plants clustering. Results showed that 45 cannabinoids and terpenoids were quantified in all plant samples, where 8 cannabinoids and 18 terpenoids were identified. Among organics, Δ9-THC, CBN (cannabinoids) and Fenchol (terpenoid) not only showed the highest levels overall contents, but also were the most important compounds for cannabis clustering. Among States, Washington, Oregon, California and Hawaii have the highest cannabis content. GC-FID data were subjected to PCA and HCA to find (1) the variations among cannabis chemical profiles as a result of growing environment, (2) to reveal the compounds that were responsible for grouping cultivars between clusters and (3) finally, to facilitate the future profile prediction and States clustering of unknown cannabis based on the chemical profile. The 23 cannabis USA States were grouped into three clusters based on only Δ9-THC, CBN, C1 and Fenchol content. Cannabis classification based on GC-profile will meet the practical needs of cannabis applications in clinical research, industrial production, patients' self-production, and contribute to the standardization of commercially-available cannabis cultivars in USA.

Open access

Abstract

Fifty four domestically produced cannabis samples obtained from different USA states were quantitatively assayed by GC–FID to detect 22 active components: 15 terpenoids and 7 cannabinoids. The profiles of the selected compounds were used as inputs for samples grouping to their geographical origins and for building a geographical prediction model using Linear Discriminant Analysis. The proposed sample extraction and chromatographic separation was satisfactory to select 22 active ingredients with a wide analytical range between 5.0 and 1,000 µg/mL. Analysis of GC-profiles by Principle Component Analysis retained three significant variables for grouping job (Δ9-THC, CBN, and CBC) and the modest discrimination of samples based on their geographical origin was reported. PCA was able to separate many samples of Oregon and Vermont while a mixed classification was observed for the rest of samples. By using LDA as a supervised classification method, excellent separation of cannabis samples was attained leading to a classification of new samples not being included in the model. Using two principal components and LDA with GC–FID profiles correctly predict the geographical of 100% Washington cannabis, 86% of both Oregon and Vermont samples, and finally, 71% of Ohio samples.

Open access

Abstract

Sodium polystyrene sulfonate (SPS) powder is in use for over 50 years for the treatment of hyperkalemia. SPS powder is official in United States Pharmacopoeia, British Pharmacopoeia and European Pharmacopoeia. However, till date, no study has been published on the assessment of organic impurities for this drug. The organic impurities in bulk drug and finished product are associated with their safety, efficacy and stability. A simple, rapid, specific, precise and an accurate HPLC method has been developed for the estimation of toxic organic impurities like styrene, naphthalene, divinyl benzene (DVB) and ethylvinyl benzene (EVB) from SPS bulk drug and finished product. The developed method was validated for specificity, accuracy, precision, linearity, limit of detection (LOD), limit of quantitation (LOQ), solution stability, ruggedness and robustness. The influence of acid, alkali, oxidative stress, photolytic stress, thermal stress and humidity stress conditions on SPS bulk powder and finished product has been studied and reported. The proposed method can be successfully employed for the impurity testing of commercial batches of the bulk drug and finished products of both sodium salt and calcium salt of polystyrene sulfonate.

Open access

Abstract

Mono- and bis-pyridinium quaternary aldoximes (K-oximes) have long been employed as cholinesterase reactivator components of antidotes against lethal cholinesterase-inhibiting organophosphorous chemicals. Their positive charge poses difficulties in their chromatographic analysis, resulting in the publication of different approaches for each K-oxime. A multiplexed method is presented for the rapid quantitation of 10 K-oximes in blood with its utility demonstrated in vivo. Liquid chromatography with absorbance detection was employed. Reversed-phase separation was achieved on a highly nonpolar stationary phase. Method validation was based on the respective guideline of the European Medicines Agency. Times to peak concentrations and 120-min areas under the time–concentration curves were determined in rats following intraperitoneal administration. Adequate retention and separation of K-oximes with acceptable peak shapes in short isocratic runs was achieved by adjusting ionic strength, organic content and the concentration of the ion-pairing agent of the mobile phase. Chromatographic properties were governed by optimizing the concentration of dissolved ions. Accurate adjustment of the organic content was indispensable for avoiding peak drifting and splitting. Dose-adjusted exposure to K-347 and K-868 was exceptionally low, while exposure to K-48 was the highest. The method is suitable for screening systemic exposure to various K-oximes and can be extended.

Open access