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Titre du document / Document title

A near-infrared method for the assay of cineole in eucalyptus oil as an alternative to the official BP method

Auteur(s) / Author(s)

WILSON Nicola D. (1) ; WATT Robert A. (1) ; MOFFAT Anthony C. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Centre for Pharmaceutical Analysis, The School of Pharmacy, University of London, 29-39 Brunswick Square, London, WC1N 1AX, ROYAUME-UNI

Résumé / Abstract

Eucalyptus oil of British Pharmacopoeia (BP) and European Pharmacopoeia standard must contain not less than 70.0% w/w 1,8-cineole (eucalyptol). The official assay is a freezing-point method which involves the addition of o-cresol to the eucalyptus oil, whereupon the o-cresol and the 1,8-cineole form a solid complex. The assay has several disadvantages and we aim to show that near-infrared (NIR) spectroscopy is an attractive alternative to this method, in that it is simple to use, requires no sample preparation and is potentially as accurate as the traditional method. Thirty different eucalyptus oil samples were scanned on the FOSS NIRSystems 6500 Rapid Content Sampler using a reflectance vessel as sample presentation method. The cineole content of each sample was determined by the BP method and these reference data were used to construct two calibration equations for cineole content in the oils using Vision software. The mean accuracy for the NIR method differed by 1.01 % or less, and the mean bias by ±0.33% or less, compared with the BP method. Calculation of the 95 % confidence intervals for the slope and intercept of plots of NIR predicted values against BP method reference values showed that there was no evidence of fixed or relative systematic errors. Tests for short-term and intermediate repeatability were conducted. The standard deviation was 0.83% W/W or less and the coefficient of variation was 1.11% or less. The confidence intervals for both short-term and intermediate repeatability overlapped with that for the BP method, suggesting that there was no evidence for a difference in values obtained by the BP and NIR methods. The range of cineole contents used in the calibrations was extended by incorporating five samples of eucalyptus oil spiked with cineole, and five samples of two essential oils known to have a lower cineole content than eucalyptus oil, to give a range of 52.5 to 99.0% w/w. The mean accuracy decreased to an error of 1.26% or less and the bias to ±0.50% or less. Again, confidence intervals suggested there was no evidence for fixed or systematic errors in the NIR calibrations. We propose that NIR spectroscopy could be used as an alternative method for the determination of cineole content in eucalyptus oils.

Revue / Journal Title

Journal of pharmacy and pharmacology    ISSN  0022-3573   CODEN JPPMAB 

Source / Source

2001, vol. 53, no1, pp. 95-102 (10 ref.)

Langue / Language

Anglais

Editeur / Publisher

Wiley, Chichester, ROYAUME-UNI  (1949) (Revue)

Mots-clés anglais / English Keywords

Eucalyptus

;

Vegetal oil

;

Eucalyptol

;

Quantitative analysis

;

Near infrared spectrometry

;

Pharmacopeia

;

Validation

;

Prediction

;

Myrtaceae

;

Dicotyledones

;

Angiospermae

;

Spermatophyta

;

Mots-clés français / French Keywords

Eucalyptus

;

Huile végétale

;

Eucalyptol

;

Analyse quantitative

;

Spectrométrie IR proche

;

Pharmacopée

;

Validation

;

Prédiction

;

Myrtaceae

;

Dicotyledones

;

Angiospermae

;

Spermatophyta

;

Mots-clés espagnols / Spanish Keywords

Eucalyptus

;

Aceite vegetal

;

Eucaliptol

;

Análisis cuantitativo

;

Espectrometría IR próximo

;

Farmacopea

;

Validación

;

Predicción

;

Myrtaceae

;

Dicotyledones

;

Angiospermae

;

Spermatophyta

;

Localisation / Location

INIST-CNRS, Cote INIST : 984, 35400009433559.0120

Nº notice refdoc (ud4) : 846202



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