optimized a methodology for ephedrine using acetic anhydride as

optimized a methodology for ephedrine using acetic anhydride as

OPTIMIZED A METHODOLOGY FOR EPHEDRINE USING
ACETIC ANHYDRIDE AS DERIVATIZING AGENT
Paliosa PK; Santos, MK; Mariotti, KC; Jacques, ALB; *Limberger, RP
Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul
Av. Ipiranga, 2752/605; CEP: 90610-000, Bairro Santa Cecília, Porto Alegre/RS
*
E-mail: [email protected]
INTRODUCTION
Ephedrine is a sympatomimetic amine with β-feniletilamine structure, caracterizing amphetamine stimulants.
Due to various adverse effects reported, its use were restricted by Food and Drug Administration in 2004,
and, in Brazil, has its sale regulamented by Portaria 344/1998 (1). However, weight loss products containing
ephedrine are still being sold in drugstore or online. Therefore, methods efficient to detect and quantify
ephedrine are required. For Gas Chromatography analysis, the derivatizations is an essencial step to improve
chromatographic profile, increase the thermal stability and volatility, improves the specificity, precision and
sensitivity, a lower polarity, to prevent loss of analyte by adsorption column or by thermal decomposition (2).
Thus, this study aimed to optimized a methodology for ephedrine in the Gas Chromatography Flame
Ionization Detector (GC-FID) using acetic anhydride as derivatizing agent.
MATERIALS AND METHODS
From a stock solution (SM) at 1000mcg/mL of ephedrine in methanol:isopropanol:NH4OH, 100mcL was
taken to dryness at 40°C under N2 flow, and derivatizated with 20mcL of acetic anhydride. Different times (5,
10, 15, 30, 60, 70 or 80 minutes) and temperature (60 ºC, 80 °C or 100 °C) reaction were tested.
Subsequently, the sample was taken to dryness at 40°C under N2 flow and reconstituted with 50mcL
methanol. An aliquot of 1mcL was injected into GC-FID under the following conditions: column temperature
of 80 °C for 2 minutes, from 40 °C/min until reaching 250 °C, remaining for 1 minute, from 40 °C/min until
reaching 290 °C and lasting for 2 minutes. Injector and detector temperature was 300 ºC and 250 °C,
respectively.
RESULTS
To 60 ºC were tested five times, 10, 15, 30 and 60 minutes for derivatization, though were observed ephedrine
without derivatized. At 80 °C were tested 15, 30, 60 and 80 minutes. For 30 minutes of reaction, the largest
area corresponds to pseudoephedrine, and in 60 minutes, corresponds to ephedrine. For 100 ºC were tested 15,
30, 60 and 80 minutes. The largest area corresponds to ephedrine with 60 minutes of reaction was reached its
largest area.
CONCLUSION
Due to varied temperatures and derivatization time described in literature for ephedrine, we conclude that due
higher area, lower intensity peak of pseudoephedrine, and absent of non derivatizated substances, the best
results was 100 °C for 60 minutes.
(1) BRASIL. Ministério da Saúde. Secretaria de Vigilância Sanitária. Portaria nº 344, de 12 de maio de 1998.
Regulamento Técnico sobre substâncias e medicamentos sujeitos a controle especial. D.O.U. - Diário Oficial
da União, Brasília, DF, 19 de maio de 1998.
(2) LANÇAS, F.M. Cromatografia em fase gasosa. São Carlos: Acta, 1993. P.240