Comparison of Solid-Phase Extraction and Liquid-Liquid Extraction Methods for Liquid Chromatographic Determination of Diltiazem and its Metabolites in Plasma

Abstract

A rapid solid-phase extraction method for the determination of diltiazem and its metabolites from plasma was compared to a conventional liquid-liquid extraction procedure we have described previously. Analytical recovery for all compounds was greater than 90 % for solid-phase extraction whereas for liquid-liquid extraction, mean recovery ranged from 67 to 82 %. The increase of extraction efficiency was closely related to an improvement of the detection limit for the metabolites. Solid phase extraction procedure was found to be more convenient, rapid and sensitive than liquid-liquid extraction and represents a useful analytical tool for the monitoring of diltiazem and its metabolites in clinical investigations.     

Acidic Phosphorus Esters,Synthesis and Structure-Reactivity Studies as Ligands

Abstract

Methods for the synthesis of five types of acidic phosphates, phosphonates as well as phosphinates have been described. The mechanism of extraction of various metals by these compounds is examined. A free energy relationship existed in plotting equilibrium constants against either pKa or ?σ values of the acidic organophosphorus compounds under investigation. Steric effects, which is closely related to the configuration of the coordination compounds play an important role in these extraction systems as expected. A trial on estimation of Es values in extraction reaction was proposed.     

Phospholipid Composition and Differentiation of Methanotrophic Bacteria

Abstract

A combination of TLC and extraction of native cells on the layer of sorbent was used for analysis of phospholipid composition of bacteria. The method is suitable for rapid routine differentiation of genera and species of obligate methanotrophic bacteria.     

Screening of Benzoylecgonine in Urine by Cyclobond Solid Phase Extraction and High Performance TLC

Abstract

A method is described for screening of the cocaine metabolite benzoylecgonine in urine at 0.2 μ/ml using a Cyclobond cyclodex^?trin solid phase extraction cartridge and high performance thin layer chromatography. Results are compared with those obtained using liquid-liquid and diatomaceous earth column extraction and C-18 solid phase extraction.     

Solid Phase Extraction and HPLC Analysis of Tryptamide in Plasma

Abstract

A method for extraction and quantification of tryptamide in plasma is described in this report. The method employs Amberlite XAD-2 column extraction followed by HPLC with ultraviolet detection. The procedure is simple, rapid and reproducible. It has been applied to the measurement of tryptamide in plasma of rats dosed orally with this antiinflammatory and analgesic compound.     

A New Approach to the Extraction of Prostaglandins 6-Keto-F1α, F2α, E2, and E1 from Gastric Mucosa with Quantitative Analysis by Reverse Phase Liquid Chromatography

Abstract

A simple and reliable method is presented for the extraction of Prostaglandins 6-Keto-F₁ α, F₂ α, E₂ and E₁ from gastric mucosa with quantitation by Reverse Phase Liquid Chromatography. Extraction is accomplished without the need for the harsh chemicals normally associated with tissue extraction. The efficiency of prostaglandin extraction is demonstrated utilizing radiolabeled prostaglandins. Quantitation of these compounds is compared to measurement by radioimmunoasay.     

Selective Extraction and Quantitation of Polyoxyethylene Detergents and its Application in Protein Determination

Abstract

A simple, rapid and selective method for the nearly quantitative extraction of high amounts (10% w/v) of polyoxyethylene nonionic detergents like Triton X-100^R is presented based on solvent extraction with 1, 2-dichloroethane. Protein determination after extraction of protein containing solutions can be accomplished using the Bradford assay¹ or other standard methods. High protein recoveries can be obtained. The detergent analysis by HPLC using reversed-phases is not disturbed in the presence of proteins and therefore provides a fast and elegant method for the exact quantitation of nonionic detergents.     

Synthesis, conformational studies and inclusion properties of N-substituted tetrahomodiazacalix[4]arenes

A series of tetrahomodiazacalix[4]arenes (1–8) with different substituents (or substituted) at the upper rim and/or N-side arm has been synthesized with acceptable yields. The compounds were characterized by elemental analysis, IR, MS and NMR methods. In particular, 5 was shown by X-ray crystallography to adopt the cone conformation in the solid state. Two-phase picrate extraction showed that 2 and 6, bearing N-2-picolyl arms, are the best extractants. Of the cations tested, Ag(I) is the best extracted by almost all ligands and the extraction efficiency follows the order 2-picolyl > 3-picolyl > 4-picolyl.     

HPLC analysis of aspartame and saccharin in pharmaceutical and dietary formulations

Summary A reversed-phase HPLC method has been developed suitable for a reliable quality control of pharmaceutical and dietary formulations containing the synthetic sweeteners aspartame and saccharin. The proposed method is able to separate acesulfame, aspartame and saccharin, and their impurities such as 5-benzyl-3,6-dioxo-2-piperazineacetic acid (the major degradation product of aspartame) and 4-sulphamoylbenzoic acid,o- andp-toluenesulphonamides (the synthesis impurities of saccharin). A convenient solid-phase extraction (SPE) procedure using C-18 sorbent, was also developed for the determination of potential saccharin impurities.     

Determination of silver in real samples using homogeneous liquid-liquid microextraction based on ionic liquid

A new solvent-free mode of homogeneous liquid-liquid microextraction based on ionic liquid (IL) named as modified cold induced aggregation microextraction (M-CIAME), was developed. The method is a fast, solvent free, robust against high medium salt content, and simple for extraction and preconcentration of metal ions from various samples. The extraction of silver was preformed in the presence of 4,4-bis(dimethylamino)thiobenzophenone (TMK) as the complexing agent and sodium hexafluorophosphate (NaPF₆) was added to the sample solution (50°C) containing small amounts of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF₄]. Afterwards, the solution was placed in the ice bath and a cloudy solution was formed due to the decrease of IL solubility. After centrifuging, the fine droplets of extraction phase were settled of the bottom of the conical bottom glass centrifuge tube. Under the optimum conditions, the limit of detection (LOD) was 0.4 ng/mL. The relative standard deviation (RSD) was 1.8% for 50 ng/mL of silver (n = 5).     

Ester and Ketone Groups Substituted Mono- and Di- Azo-coupled Azocalix[4]arenes as Extractant for Hg+ and Hg2+, or Cr3+Cations

This article describes extraction properties of mono- (A1–A8) and di- (B1–B8) substituted azocalix[4]arene analogues. The ionophore solvent extractions of alkaline-earth (Sr²⁺), basic metal (Pb²⁺) and transition metal cations (Ag⁺, Hg⁺, Hg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cr³⁺) from aqueous phase to organic phase were carried out by azocalix[4]arene derivatives. It has been observed that they show a good extraction behavior toward selected heavy metal (Hg) and toxic metal (Cr), while A4 and B4 prefer Hg⁺, Hg²⁺ and Cr³⁺ among transition metal cations, respectively. The azocalix[4]arenes (A1–A8) and (B1–B8) are not efficient extractants for all of the selected metal cations, whereas A4 and B4 are selective only for Hg metal cation.     

Synthesis and Metal Ion Recognition Properties of a Novel Chiral Calix[4](azoxa)crown-7

A novel chiral calix[4](azoxa)crown-7 (9) has been synthesized and its metal ion recognition properties investigated. The starting reagents, chiral diamine 5 and calix[4]arene diacid chloride derivative 8, were prepared according to literature methods. ¹H and ¹³C NMR data show that 9 exists in a cone conformation. In liquid–liquid extraction experiments, 9 exhibits selectivity for Li⁺ among the other alkali metals and a good extraction ability for transition metal cations, suggesting its potential use in different fields, such as a sensor for ions as well as for chiral molecules.     

A new bile acid-derived lariat-ether: Design, synthesis and cation binding properties

A newchola lariat ether (1, a 21-crown-6) was constructed fromreadily available precursors. The association constant of compound1 with alkali metal picrates was measured using Cram’s extraction protocol. Evidence is presented for the involvement of the 3-methoxy group for the complexation. Energy minimised structures show that the A-ring gets slightly distorted upon metal ion binding. Dedicated to Professor C N R Rao on his 70th birthday     

Application of Derivative Spectroscopy to the Simultaneous Identification and Determination of Plasma Amitriptyline and Perphenazine Key Words: Derivative Spectroscopy,Amitriptyline, Perphenazine

Abstract

A derivative spectroscopy technique for the simultaneous determination of plasma amitriptyline and perphenazine is proposed. The described method is fast and requires only one extraction for both drugs.     

Comparison of green extraction methods with conventional extraction method for extract yield,L-DOPA concentration and antioxidant activity of Mucuna pruriens seed

ABSTRACT

Mucuna pruriens is a plant of Fabaceae family. Seed of M. pruriens is considered as a rich source of levo-3,4 dihydroxyphenylalanine (L-DOPA), a non-protein phenolic amino acid. In the present study, three different extraction methods were compared for extract yield, concentration of bioactive compounds such as total phenol, L-DOPA and antioxidant capacity. Extracts were prepared using water acidified with hydrochloric acid (0.1?N) by conventional method of refluxing as well as two green methods namely ultrasound and microwave assisted solvent extraction. A rapid and qualified high-performance liquid chromatography method was also developed for quantification of L-DOPA in different extracts. Among the three extraction methods, microwave assisted extraction provided the best results for yield and quality of M. pruriens extract in much shorter time in comparison to refluxing method of extraction.     

A New Procedure for the Extraction of Unconjugated Steroids from Plasma and Urine

Abstract

A procedure is described for the extraction of nanogram quantities of steroids from plasma and urine. The method involves saturation of a diluted plasma or urine sample with ammonium carbonate and extraction with an organic solvent. The application of this method to the analysis of cortisol and unconjugated estriol in plasma and to the analysis of unconjugated steroids in the urine of the newborn infant is described.     

Determination of Dimethoate in Human Blood by Impregnated Silica Plates and Gas Chromatography

Abstract

A method for the determination of Dimethoate in human blood is presented here. After extraction with acetone-hexane (1+9V/V) dimethoate is separated on p-cresol impregnated thin silica plates as well as by Gas Chromatography using nitrogen phosphorous detector. The recovery of dimethoate added to human blood was quite satisfactory.     

Multiresidue Analysis of Organic Pollutants in Water by SPE with a C8 and SDVB Combined Cartridge

Abstract

A multi-component target method for screening purposes to determine organic pollutants of different polarities in water is reported. The following classes of chemicals were tested: base-neutral and acidic herbicides, phenolic compounds, polycyclic aromatic hydrocarbons and phthalic acid esters.

Data was initially obtained from the extraction of one liter of water sample, using separate octyl bonded porous silica (C8) and highly crosslinked polystyrene based polymer columns (SDVB) cartridges. A second set of data was obtained using for the extraction a combined cartridge containing both phases. The analysis was carried out directly by GC-MS in SIM mode, without any derivatisation, with the exception of acidic herbicides, derivatised with pentafluorobenzylbromide. The obtained results showed recoveries between 75% and 98% at two different spiking levels, with relative standard deviations below 15%.     

A Green Deep Eutectic Solvent-Based Ultrasound-Assisted Method to Extract Astaxanthin from Shrimp Byproducts

The extraction of valuable compounds from waste products using green and inexpensive solvents is a significant strategy for sample preparation. Accordingly, in the present study, the use of deep eutectic solvents, an emerging green approach, was used to extract astaxanthin, a well-known and widely-used antioxidant, from shrimp byproducts. After evaluating different combinations of extraction conditions and deep eutectic solvents, an ultrasonication method was established and optimized by a systematic investigation of the influencing factors. A comparison of the amount of astaxanthin (102 μg g^{? 1} ) extracted using a traditional organic solvent, ethanol, showed that more astaxanthin (146 μg g^{? 1} ) was obtained using the reported eco-friendly method. The excellent properties of deep eutectic solvents highlight their advantages as promising inexpensive green solvents for the extraction and determination of a range of bioactive compounds from natural products.     

HPLC Analysis of Injectable Contraceptive Preparation Containing Norethisterone Enanthate and Estradiol Valerate

Abstract

A simple, accurate method for simultaneous determination of norethisterone enanthate (NET-EN) and estradiol valerate (EV) in the injectable is reported. An improved extraction procedure for steroid esters from the oily formulation was developed. Recoveries of 100.6 and 98.7% were obtained for NET-EN and EV.