| Popis: |
A gas chromatographic-mass spectrometric (GC-MS) method for the simultaneous identification and quantification of seven major phenolic and terpenic compounds in Rosmarinus officinalis L. was developed. The compounds were identified as trimethylsilyl (TMS) derivatives of phenolic acids (caffeic and rosmarinic acid), phenolic diterpene (carnosic acid), and pentacyclic triterpenes (ursolic, oleanolic, betulinic acid and betulin). These compounds have been identified by retention time and comparison of mass spectra. The procedure involves ultrasonic extraction using solvent mixture of tetrahydrofuran and ethanol. Extracts were fractionated by size exclusion chromatography (SEC) after purifying on graphitised carbon. The fraction with phenolic and terpenic compounds was derivatised prior to GC-MS analysis using N-methyl-N-trimethylsilyl trifluoroacetamide (MSTFA) as a derivatisation reagent. The derivatisation process was optimized regarding temperature and reaction time. The linearity of the method was tested in concentration range 4-25 mg L$^{–1}$. The correlation coefficients ($r^2$) were in the range of 0.997 to 0.999. The average recoveries for all compounds ranged from 80 to 82%. The GC-MS technique is specific and sensitive, and can be used for simultaneous identification and determination of a wide range of phenolic and terpenic compounds in different plants even at trace levels. Razvili smo metodo za sočasno identifikacijo in kvantitativno določitev sedmih fenolnih in terpenskih spojin v rožmarinu (Rosmarinus officinalis L) s plinsko kromatografijo in masno spektrometrijo (GC-MS). Spojine smo identificirali kot trimetilsilil (TMS) derivate fenolnih kislin (kofeinske in rožmarinske kisline), fenolnega diterpena (karnozolne kisline) in pentacikličnih triterpenov (ursolne, oleanolne, betulinske kisline in betulina). Naštete spojine so bile potrjene s primerjavo retencijskih časov in masnih spektrov derivatov preiskovanih spojin. Metoda vključuje ultrazvočno ekstrakcijo preiskovanih spojin z mešanico topil tetrahidrofuran in etanol. Ekstrakte smo po čiščenju na aktivnem oglju, frakcionirali z velikostno izkjučitveno kromatografijo. Frakcijo, ki je vsebovala fenolne in terpenske spojine, smo pred GC- MS analizo derivatizirali z N-metil-N-trimetilsilil trifluoroacetamidom (MSTFA). Postopek derivatizacije smo optimirali glede na čas reakcije in temperaturo. Linearnost metode smo preverili v koncentracijskem območju 4–25 mg L$^{–1}$. Povprečni izkoristki za preiskovane spojine so bili med 80 to 82 %, korelacijski koeficienti ($r^2$) so bili med 0,997 in 0,999. GC-MS tehnika je specifična in občutljiva, omogoča dobro ločevanje spojin in je zato primerna za sočasno identifikacijo in določevanje širokega spektra fenolnih in terpenskih spojin v različnih rastlinah, tudi ko so spojine prisotne v sledovih. |
