Application of PMR Spectrometry in Quantitative Analysis of Praziquantel in Pharmaceutical Preparations

A simple, accurate and specific proton magnetic resonance (PMR) procedure is developed for the assay of praziquantel and its tablets. The method involves comparing the integral of the multiplet of praziquantel (positioned at δ 7.3 ppm) to that of the sharp singlet signal (positioned at δ 6.3 ppm) of maleic acid which is used as intenal standard. The method reported in this study gives accurate and reproducible results when applied for the analysis of both authentic drug and its tablets. In addition the PMR spectrum helps in confirming the identity and purity of the drug.     

Application of PMR Spectroscopy in Pharmaceutical Analysis Assay of Piperazine

A new method, involving the application of PMR spectroscopy for the assay of piperazine anhydrous, hydrate and its salts is described. The PMR spectrum of piperazine in D₂o has a well-defined singlet system for the piperazine ring protons which is chosen for the quantitative measurement. The principal of the method involves comparing the integral of this signal to that of the sharp singlet (positioned at 0.00 ppm) of trimethyl silyl propane sulfonate sodium salt which is used as PMR reference and internal standard.

The proposed method which is simple and rapid gives results of high degree of accuracy and percision when applied to the assay of pure piperazine anhydrous, hydrate and dihydrochloride samples. An average recovery percent of 100.24 ± 0.89 was obtained. The method was used for the analysis of piperazine hydrate in syrup and effervecent granules. The average recovery percent of the added piperazine was 99.64 ± 0.75. In addition the PMR spectrum obtained helps in confirming the identity and purity of the drug or its salts.     

Quantitative Proton Magnetic Resonance Analysis of Primidone in Solid Dosage Forms

A rapid and specific proton magnetic resonance (PMR) spectroscopic method was developed for determining primidone in tablets. Maleic acid was used as the internal standart and DMSO-d₆ served as the PMR solvent.     

Application of PMR Spectrometry In The Analysis of Diethylstilbestrol and its Tablets

A new, simple and rapid quantitative proton magnetic resonance method has been developed for determination of Diethylstilbestrol and its tablets. Among other peaks the PMR spectrum of stilbestrol has a well defined triplet (0.73ppm) and quartet (near 7 ppm), which are chosen for quantitative measurements. The principle of the method involves comparing the integral of these signals to that of a sharp singlet of maleic acid (6.3 ppm) which is used as internal standard. The proposed procedure gives accurate and reproducible results when applied for the analysis of both authentic drug and its tablets. In addition, the PMR spectrum obtained helps in confirming the identity and purity of the drug.     

Quantitative Analysis of Acetazolamide in Solid Dosage Forms with 1H-Nmr Spectroscopy

A rapid and specific proton magnetic resonance spectroscopic method was developed for determining acetazolamide in tablets. Maleic acid was used as the internal standard and DMSO-d₆ served as the NMR solvent. the concentration of drug per unit dose was calculated from the integration values for the resonance signals of acetazolamide at 2.14 ppm and maleic acid at 6.20 ppm. the method using commercial products gave comparable results of those obtained by the method of USP XXIII.     

Development of an Analytical Proton Magnetic Resonance (PMR) Spectroscopic Method for the Determination of Etilefrine in Bulk and Pharmaceutical Forms

An analytical proton magnetic resonance (PMR) spectroscopic method was developed for the determination of etilefrine hydrochloride [943–17–9] in bulk, I, tablets, II, drops, III, and injectables, IV,. The method is advantageous over those in the literature offering a fast, simple, specific, and accurate procedure.     

Pharmaceutical polymorphs quantified with transmission Raman spectroscopy

The quantification of polymorphs in dosage forms is important in the pharmaceutical industry. Conventional Raman spectroscopy of solid‐state pharmaceuticals may be used for this, but it has some limitations such as sub‐sampling and fluorescence. These problems can be mitigated through the use of transmission Raman spectroscopy (TRS). The efficacy of TRS measurements for the prediction of polymorph content was evaluated using a ranitidine hydrochloride test system. Four groups of ranitidine hydrochloride‐based samples were prepared: three containing form I and II ranitidine hydrochloride and microcrystalline cellulose (spanning the ranges 0–10%, 90–100% and 0–100% form I fraction of total ranitidine hydrochloride), and a fourth group comprising form I ranitidine hydrochloride (0–10%) spiked commercial formulation. Transmission and conventional Raman spectroscopic measurements were recorded from both capsules and tablets of the four sample groups. Prediction models for polymorph and total ranitidine hydrochloride content were more accurate for the tablet than for the capsule systems. TRS was found to be superior to conventional backscattering Raman spectroscopy in the prediction of polymorph and total ranitidine hydrochloride content. The prediction model calculated for form I content across the 0–100% range was appropriate for process control [ratio of prediction to deviation (RPD) equal to 14.62 and 7.42 for tablets and capsules, respectively]. The 10% range calibrations for both form I and total ranitidine hydrochloride content were sufficient for screening (RPDs greater than 2.6). TRS is an effective tool for polymorph process control within the pharmaceutical industry. Copyright © 2011 John Wiley & Sons, Ltd.     

PMR Spectrometric Analysis of Chloramphenicol in Pharmaceutical Preparations

A new method is developed using PMR for the assay of chloramphenicol and its pharmaceutical forms. The method is rapid, accurate, precise and helps in confirming the identity and purity of the drug. The principle of the method involves comparing the integral of the well-defined doublet system of chloramphenicol spectrum (positioned at 7.6 δ and 7.5 δ) to that of the sharp singlet (positioned at 6.25 δ) of maleic acid which is used as internal standard.     

Application of PMR Spectrometry in Pharmaceutical Analysis I. Assay of Clofibrate

A new method, involving the application of PMR spectrometry for the assay of clofibrate and its capsules, is proposed. Among other peaks the PMR spectrum of clofibrate has a well-defined singlet system which is chosen for quantitative measurement. The principle of the method involves comparing the integral of this signal to that of the sharp singlet (positioned at 0.00 ppm) of hexamethylcyclotrisilazane which is used as internal standard.     

Quantitative Determination of 2.5-Diaziridinyl-3.6-Bis (Carboethoxyamino-1.4-Benzquinone) and its Degradation Products by PMR Spectroscopy

A new proton magnetic resonance (PMR) method for the quantitative determination of 2,5-Diaziridinyl-3,6-bis (carboethoxyamino)-1,4-benzoquinone and its acid decomposition products in dimethylsulfoxide-d₆, and at 35 ± l° is described. The PMR spectrum of 2,5-Diaziridinyl-3,6-bis (carboethoxyamino) -1,4-benzoquinone shows singlet system at Δ 2.2 due to the protons of the two aziridine rings. The integral ratio of this signal to that of the methyl protons signal at Δ 1.2 and the methalene protons signal at Δ 4.05 is 4:3:2 in the intact molecule. The acid catalayzed decomposition results in disturbance of this ratio since the two aziridine rings are opened consecutively and a new multiplet signal appear at Δ 3.4–3.7 due to the ethelene group protons of the hydroxyethylamino group formed upon decomposition of aziridine moiety. Comparing the integral of the signal at Δ 1.2, 2.2, 3.4–3.7 and 4.03 to that of the sharp singlet at Δ 6.83 of 1,4 p-benzoquinone which is used as internal standard constitute the basis of the method.

The proposed method is in addition of being simple and rapid it offers accuracy and reproducibility when applied for the determination of the pure crystalline compound. An average recovery percent of 100.41 ± 0.1 was obtained. While in acid catalyzed decomposed samples reasonably accurate results are obtained, the method is inapplicable for base-catalyzed decomposed samples due to the rapid conversion of benzoquinone to hydroquinone which results in inaccuracies in the determinations.

The method is based on the PMR spectrum that could be used to assure the identity and purity of the drug compound.     

Stability - Indicating Method For The Determination of Bromazepam And Delorazepam Via Proton Magnetic Resonance Spectroscopy

A new, simple proton magnetic resonance method (¹HNMR) for the rapid and direct quantitation of intact bromazepam and delorazepm in presence of their acid - induced degradation products is presented. DMSO - d₆ is used as a solvent and maleic acid as internal reference standard. The resonance peak of the two hydrogens of the methylene group of each drug near 4.2 ppm is integrated as a measure for the drug in comparison to the sharp singlet of maleic acid at about 6.25 ppm.

The proposed procedure gives accurate and reproducibe results when applied for the anlaysis of both drugs either per se, in mixtures with their degradation products or in their tablets.     

Application of PMR Spectrometry in Quantitative Analysis of Tiaprofenic Acid in Some Pharmaceutical Preparations

A simple, accurate and specific proton magnetic resonance (PMR) procedure was developed for the assay of tiaprofenic acid and its tablets. The method involves comparing the integral of the nice doublet signal of tiaprofenic acid (positioned at 1.60 δ) to that of the sharp singlet signal (positioned at 2. 1 δ) of acetanilide which is used as internal standard. The method reported in this study gives accurate and reproducible results; 100. 16 ± 0. 23% for authentic tiaprofenic acid and 100.00 ± 1. 05% for tiaprofenic acid tablets (Surgam^R). In addition, the PMR spectrum obtained helps in confirming the identify and purity of the drug.     

Search for proton magnetic resonance in ferromagnetic Β-uranium hydride

Proton magnetic resonance (PMR) in a ferromagnetic-uranium hydride at 77 K has been searched unsuccessfully between 4 and 420 MHz. The present communication reports this experiment and its objectives, and justifies the swept frequency range on the basis of PMR data obtained in the paramagnetic phase and of a new analysis of the Flotow and Osborne low temperature specific heat data. It is shown that experimental conditions were at least as favourable as those for observing PMR in the paramagnetic phase. Specific heat measurements below 1 K, using the Dempesey et al. method, seem necessary before pushing experimental efforts further.Work partially supported by FINEP-Brasil.     

Cyanine-based Fluorescent Probe for Cyanide Ion Detection

Cyanine-based probe-possessing indolium iodide and indole unit were synthesized in two-step with easy available raw material: a potential probe for the cyanide ion detection. The detecting ability of the probe was investigated and confirmed by a visual and instrumental approach. A noticeable color change from orange to colorless obtained only for cyanide ions and other added ions does not impart any changes visually and through UV and Fluorescence technique. To confirm the mechanism of sensing 1H-NMR recorded. From the result, the peak belonging to N-methyl displayed an upfield shift from 4.01 δ ppm to 2.74 δ ppm due to the disappearance of indolium iodide ion and the olefin protons peaks were shifted from 7.19 to 6.17 and 8.70 to 7.20 δ ppm confirms the nucleophilic addition of cyanide ion to the probe. Test kit from filter paper prepared for the real-time monitoring cyanide ion. The prepared strip is effective in detecting cyanide ion with a visual color change.

     

PMR Spectrometric Analysis of Tolmetin Sodium in Capsules Forms

An analytical method is described for the assay of tolmetin, 1-methyl-5-(4-methylbenzoyl)-1H-pyrrole-2-acetic acid, as sodium salt, (Tolectin[rgrave] - 200 mg) using PMR. The protocol reported in this study is simple, precise and yields accurate results of 99.78±0.84 and 100.67±2.08 for the authentic material and capsules respectively. In addition, the PMR spectrum obtained provides a means for qualitative identification of the drug and checking its purity. The principle of the method involves comparison of the integral of the well-defined singlet (positioned at 2.41 Δ) to that of the sharp singlet due -CH₃ (positioned at 1.91 Δ) of sodium acetate as an internal standard in presence of maleic acid using DMSO-d₆ solvent. The rationale for the use of maleic acid in the assay procedure has been discussed.     

Adsorbed layers of O2 on graphite studied by heat capacity measurements

Using a comparative method (quotient method) we determined the temperature dependence of the heat capacity of different layers of O₂ adsorbed on Grafoil between 23.5 and 26.5 K. The specific heat of layers below monolayer completion shows a large delta-function shaped anomaly at the phase boundary between the δ phase and the fluid phase. The anomaly is tentatively interpreted as due to a two-dimensional phase transition at the quadruple point of the adsorbate (the triple point of the monolayer). The investigation of other monolayers including the magnetic transition between αO₂ and βO₂ and the δ + β coexistence region is presently being carried out.     

Deuteron chemical shift and EFG tensors in α-glycine

By computer fitting of resonance lines in deuteron spectra of perdeuterated crystals, deuteron chemical shifts in crystals are measured with an accuracy of ±0.3 ppm. Second-order quadrupole shifts must be taken into account. An important advantage of the method is that the measured chemical shifts and the shift tensors are automatically related to EFG tensors which can be assigned easily. The method is applied to α-glycine for which a shift anisotropy Δσ = 21 ± 9 ppm has been reported for the methylene protons. Full EFG and chemical-shift tensors are reported at both methylene deuteron sites, and motionally averaged tensors are reported for the ND₃⁺ sites. The shift anisotropies Δσ for the methylene deuterons are 4.7 and 9.4 ppm, respectively. Significant differences of the isotropic shifts and quadrupole coupling constants are also observed for these two deuterons. They are interpreted as evidence for the formation of a weak CH … O hydrogen bond in α-glycine.     

The NMR Spectra of the Ortho-and Para-Adamantyl Groups of Anisole

The 1-adamantyl group because of its rigid diamondoid st has three chemically distinct sets of protons. When substitu a benzene ring¹ the chemical shifts of the different sets of would be affected to different extents by the ring current eft the aromatic ring and by the electrostatic field effect³ of any proximate electronegative substituent. The nmr spectrum of the 1-adamantyl group of p-adamantyl anisole in chloroform solution sho three broad bands with unresolved fine structure at δ 2.08 (3H, γ protons), δ 1.89 (6H, β protons) and δ 1.75 (6H, δ protons), whereas in the case of o-adamantyl anisole the corresponding spectrum shows two broad bands at δ 2.10 (9H, β and γ protons) and δ 1.77 (6H, δ protons), as shown in the Figure. It is to be noted that the chemical shift of the β-protons of the o-adamantyl group is 0.20 ppm downfield from that of the p-adamantyl group. Clearly, this difference arises from the electrostatic field effect of the methoxyl on the β-protons of the o-adamantyl group. 1-Adamantyl substitution ortho to an electronegative substituent is therefore easily distinguished from the para case on the nmr spectrum.     

On the dynamic Jahn-Teller effect of Er3+ in Pd-Er

The values of the Lea, Leask and Wolf parameters x, W, the off-diagonal matrix element of the vibrational Hamiltonian δ and the three independent coupling constants to Γ₅ lattice modes have been calculated and shown to be consistent with inelastic neutron data and EPR field for resonance results.     

An NMR Phantom Mimicking Intramyocellular (IMCL) and Extramyocellular Lipids (EMCL)

Intramyocellular lipids (IMCL) play an important role in muscle metabolism. ¹H magnetic resonance spectroscopy is the method of choice for non-invasive assessment of IMCL. However, IMCL quantitation is hampered by the larger overlapping resonances of extramyocellular lipids (EMCL). A phantom that mimics EMCL and IMCL, i.e., the 0.2-ppm resonance splitting, would be useful for testing acquisition strategies and post-processing algorithms. Here, we propose a phantom that consists of a cylindrical bottle filled with dairy cream and sunflower oil. Similar to EMCL, the oil (CH₂) _n protons resonate at 1.5?ppm; similar to IMCL, the spherical shape of droplets in cream results in (CH₂) _n protons resonating at 1.3?ppm. The relative amount of IMCL versus EMCL can be easily controlled in a systematic and exact fashion by displacing the voxel of interest across the cream–oil interface. This phantom is of simple construction and made of inexpensive and readily available materials, and should be of value in testing both acquisition and spectral analysis strategies in the context of ICML/ECML studies.