A comparison of gas–liquid chromatography, NMR spectroscopy and Raman spectroscopy for determination of the substituent content of general non-ionic cellulose ethers

Alvarez‐Lorenzo, Carmen; Lorenzo-Ferreira, R.A.; Gómez-Amoza, J.L.; Martínez‐Pacheco, Ramón; Souto, C.

doi:10.1016/s0731-7085(99)00066-7

Cited by 24 publications

(7 citation statements)

References 29 publications

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“…[18] The general appearances of the Raman spectra of HPC (2d) and HPMC (2e) are similar, although there are differences between the relative intensities of the Raman bands. For instance, when comparing the intensity of δ(CH 2 ) deformations at ca 1360 cm −1 relative to the band at ca 1450 cm −1 it shows an increase when HPC is compared to HPMC, [21] which is consistent with the higher number of -CH 3 groups in HPMC. Tragacanth is a gum which has different characteristics in the Raman spectrum ( Fig.…”

Section: Polysaccharidesmentioning

confidence: 56%

“…2(a)) an additional Raman band at 1093 cm −1 is present which is very characteristic of unsubstituted cellulose rings. [21] In the region between 300 and 700 cm −1 , there are clear differences between the Raman spectra of the polysaccharides and on the basis of these Raman bands, the spectra can be distinguished from each other. For instance, microcrystalline cellulose (2a) has additional Raman bands between 380 and 460 cm −1 which can be assigned to δ(CCC), δ(CO), δ(CCO) binding vibrations and ring deformations.…”

Section: Polysaccharidesmentioning

confidence: 99%

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Reference database of Raman spectra of pharmaceutical excipients

Veij

Vandenabeele

Beer

et al. 2008

J Raman Spectroscopy

196

100

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Raman spectroscopy has evolved into an important fast, direct and nondestructive technique in pharmaceutical analysis. Usually, the focus in this field is mainly on the active ingredients and not on the excipients present in the drugs. A collection of Raman spectra of widely used pharmaceutical excipients is presented in this article, which can serve as a reference for the interpretation of Raman spectra during drug analysis (including classical qualitative and quantitative pharmaceutical analysis, counterfeit tracing and process analytical technology (PAT) applications). The 43 analyzed excipients can be classified into seven categories: mono-and disaccharides (dextrose, lactitol, maltitol, lactose and sucrose), polysaccharides (microcrystalline cellulose, methylcellulose (MC), carboxymethylcellulose (CMC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), wheat starch, maltodextrin, primojel, tragacanth and pectin), polyalcohols (propylene glycol, erythritol, xylitol, mannitol and sorbitol), carboxylic acids and salts (alginic acid, glycine, magnesium stearate, sodium acetate and sodium benzoate), esters (arachis oil, lubritab, dibutyl sebacate, triacetin, Eudragit E100 and Eudragit RL100), inorganic compounds (calcium phosphate, talc, anatase and rutile (TiO 2 ), calcium carbonate, magnesium carbonate, sodium bicarbonate and calcium sulfate) and some unclassified products [gelatin, macrogol 4000 (polyethylene glycol (PEG), polyvinyl pyrrolidone and sodium lauryl sulfate].

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Section: Polysaccharidesmentioning

confidence: 56%

Section: Polysaccharidesmentioning

confidence: 99%

Reference database of Raman spectra of pharmaceutical excipients

Veij

Vandenabeele

Beer

et al. 2008

J Raman Spectroscopy

196

100

View full text Add to dashboard Cite

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“…To reduce the scan times and increase the resolution of the spectra, the analyses were carried out after hydrolysis of the samples. 22 The n values higher than 1 (Table 1) indicate that some of the substituents form side chains with two to three oxyethylene units, due to the reaction, during the synthesis of the cellulose ether, of ethylene oxide with the hydroxyl group of the previously attached hydroxyethyl groups. 25 The distribution of the hydroxyethyl substituents indicated that the C6 is the most reactive position (Table 1).…”

Section: Preparation and Characterization Of Cationic Cellulose Dispe...mentioning

confidence: 99%

“…The substitution patterns of the two cationic celluloses were evaluated by 13 C NMR spectroscopy of the hydrolysates as follows. 21,22 First, 0.5 g of polymer was added to 30 mL of 6 M sulfuric acid and mixed for 1.5 h at 20 °C. The mixture was made up to 90 mL with deionized water, heated at 90 °C for 2 h, and then cooled to room temperature, neutralized with barium carbonate, filtered, and concentrated to 2 mL in a rotary evaporator at 40 °C.…”

Section: Introductionmentioning

confidence: 99%

Rheological Evaluation of the Interactions between Cationic Celluloses and Carbopol 974P in Water

Rodrı́guez

Alvarez‐Lorenzo

2001

Biomacromolecules

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This paper reports on the influence of the structural properties of two cationic hydroxyethylecelluloses, polyquaternium-4 (PQ-4; 1.13-1.27% N) and polyquaternium-10 (PQ-10; 1.88-1.95% N), on the rheological behavior of their dispersions and of the dispersions of their blends with Carbopol 974P (60.9% COOH) in water. Dynamic shear oscillation measurements showed that the rheological behavior of 1 and 2% (w/w) cellulose polymers was mainly viscous. Flow curves of PQ-10 dispersions presented a higher consistency and pseudoplasticity than PQ-4 dispersions, in which the thixotropy was higher. Structural features, such as type and distribution of substituents and molecular weight, explain why they behave different. The presence of 0.00125-0.02% Carbopol in diluted cationic cellulose (0.01-0.08%) dispersions produced an important decrease in viscosity, due to a strong associative process via an electrostatic interaction phenomenon. Similar results were obtained when sodium acetate was added instead of Carbopol. In contrast, in the concentrated range (1% cellulose polymer), the viscous (G") and especially the elastic (G') moduli of the dispersions increased monotonically with Carbopol concentration (0.010-0.125%) and became physical gels, except in the proximity of the neutralization of the ammonium groups (0.07% Carbopol for PQ-4, and 0.1% Carbopol for PQ-10) in which G" and G' decreased. The concentrated dispersions showed pH-sensitivity when the Carbopol added was around or above the neutralization point. In dispersions with this composition, consistency increased dramatically when pH changed from 4.5 to 7.4. This property can open a wide range of applications, especially in the pharmaceutical field to prepare gelling in situ systems.

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“…Furthermore, unlike infrared spectroscopy, Raman spectroscopy allows the measurement of samples in an aqueous environment. Raman spectroscopy can also be used to determine the substitution degree of non-ionic cellulose ethers as an alternative method to NMR and gasliquid chromatography (Alvarez-Lorenzo et al 1999). Electron optical methods are meaningful and popular to visualize morphological observations.…”

Section: Introductionmentioning

confidence: 99%

Interaction of water with different cellulose ethers: a Raman spectroscopy and environmental scanning electron microscopy study

Fechner

Wartewig

Kiesow

et al. 2005

Journal of Pharmacy and Pharmacology

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Different non-ionic cellulose ethers like methyl cellulose (MC), hydroxypropyl cellulose (HPC) and hydroxypropylmethyl cellulose (HPMC) were investigated. The characterization of the cellulose ethers was carried out by thermogravimetry and sorption/desorption isotherms. Differences in the properties of the cellulose ether films were described by time-dependent contact angle measurements. Changes in molecular structure of the raw materials, gels and films caused by water contact were studied using Raman spectroscopy. Differences between the substitution types and changes due to the gel or film formation were observed. An environmental scanning electron microscopy (ESEM) technique was used to distinguish the morphological behaviour of the cellulose ether films in contact with water. Based on in-situ ESEM experiments, the swelling and drying behaviour of the various stages of cellulose ether films (film-hydrated film-dried film) were quantified by using image analysis.

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A comparison of gas–liquid chromatography, NMR spectroscopy and Raman spectroscopy for determination of the substituent content of general non-ionic cellulose ethers

Cited by 24 publications

References 29 publications

Reference database of Raman spectra of pharmaceutical excipients

Reference database of Raman spectra of pharmaceutical excipients

Rheological Evaluation of the Interactions between Cationic Celluloses and Carbopol 974P in Water

Interaction of water with different cellulose ethers: a Raman spectroscopy and environmental scanning electron microscopy study

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