PMR Determination of Isoniazid

A PMR analytical procedure is described for the quantitation of isoniazid (4-pyridinecarboxylic acid hydrazide) as a drug entity and in tablets dosage form. The method is accurate and precise with a standard deviation of ± 1.51 and ± 1.34 in the bulk drug and in tablets respectively. The results obtained comply with the official standards required by different pharmacopeias. The PMR spectrum, in addition, provides a very specific mean for identification of isoniazid.     

Determination of Mefenamic Acid Using PMR Technique

A simple, rapid and efficient new quantitative proton magnetic resonance method has been achieved for determination of Mefenamic acid and its capsule form (Ponstan^R). The method is based on comparison between the sum integrals of the two methyl singlets of Mefenamic acid and that integral of the sharp singlet of p-methoxy-benzylidenemalinonitrile ⁽¹⁾. It was found that the novel method gives accurate and reproducible results.     

毛细管柱气相色谱法测定樟脑丸中萘

毛细管柱气相色谱法测定樟脑丸中萘 ,含量在 0 .0 0 5— 0 .2 0 mg/ m L范围内有良好的线性关系 ,线性回归方程为 :y=0 .35 6 5 5 6 .2 x,相关系数 r=0 .9999。测定下限为 0 .0 0 5 mg/ m L。方法简便、快速、准确     

PMR Spectrometric Analysis of Nikethamide

Abstract

An NMR procedure is described for the quantitation of nikethamide in bulk drug and injectable dosage formulation. The determination is based on the integration of the 4- and 5- Pyridine protons of the nikethamide relative to that of the methylene protons of succinimide (internal standard). The method is simple, rapid and accurate with a standard deviation of +?0.48% and +?1.39 % in the pure drug and injections, respectively.     

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.     

Electronic Structure and PMR Characteristics of Substituted Nitroanilines

We have investigated the influence of volumetric (heterocyclic) substituents on the PMR characteristics of substituted nitroanilines depending on their position relative to the nitro group. Using quantum chemical simulation (the PM3 method), data on the position of the proton signals in the PMR spectra of 3-nitro-6-piperidinoaniline and 3-nitro-4-piperidinoaniline are interpreted. It is established that for structures in which the nitro group is removed from the benzene ring plane it does not appear possible to calculate the PMR spectrum using the Beeby–Sternhell increments.     

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.     

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.     

PMR Spectrometric Analysis of Trimipramine Maleate in Pharmaceutical Preparation

A new method is described for the assay of Trimipramine maleate, the hydrogen maleate of 5-(3-dimethyl amino-2-methyl-propyl)-10,11-dihydrodibenz-[b,f]-azepine and its base using pmr technique. The method employed is precise, accurate, rapid and helpful in qualitative identification and purity of the drug.     

Minimization of erase-band in shingled PMR with asymmetric writer

To make the write-field much stronger with sharper cross-track field gradient in Shingled perpendicular Magnetic Recording (SMR), we have successfully developed asymmetric SMR heads with one-side shield design. Using these heads, higher track density capability on the shielded-side was demonstrated, which came from narrower erase-band width at shielded side.     

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.     

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.     

Application of PMR Spectroscopy in Pharmaceutical Analysis Assay of Furosemide

An analytical method is described for the analysis of furosemide, [4-chloro-2-furfurylamino-5-sulfamoylbenzoic acid], using PMR. The procedure reported in this study is simple, rapid and gives accurate results 98.19 ± 1.34% and 99.23 ± 0.88% for furosemide ampoules and tablets respectively. Furthermore, the PMR spectrum obtained provides a mean for qualitative identification of the drug and checking its purity.     

PMR Spectrometric Analysis of Stilbestrol and Some of Its Pharmaceutical Preparations

A novel method is developed using PMR technique for quantitative determination of stilbestrol and some of its pharmaceutical preparations. The method developed is accurate, rapid, and precise. It involves comparing the integral of the nice triplet system of stilbestrol spectrum (positioned at 0.73 δ) to that of the sharp singlet signal (positioned at 6.25 δ) of maleic acid which is used as internal standard.     

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.     

Improvement of recording performances through exchange coupling in triple-layered PMR media

Improved recording performances with exchange coupling between bottom magnetic layer and medium magnetic layer in triple-type perpendicular magnetic recording (PMR) media are presented. Fundamentally, triple-type PMR media with exchange coupling between magnetic layers reduces DC erase noise and improves writability. Furthermore, triple-type PMR media could be expected clear magnetic cluster as well as relatively sharp transition pattern. Consequently, better spectral integral signal-to-noise ratio (SpiSNR), improved OW and about 1.5–2.0 order better bit error rate (BER) performances in triple-type PMR media with exchange coupling between magnetic layers were attributed to the reduction of DC erase noise and sharp transition as well as improved writability. In addition, work of micro-magnetic modeling on SNR profiles could help to verify the understanding on the role of exchange coupling between magnetic layers in triple-type PMR media.