Efficiency of three different sample preparation methods for GC/MS determination
of bifenthrin residues in wheat (Triticum spelta) samples fermented by Lactobacillus
plantarum was tested. The first method was based on a methanol:acetone=1:1 extraction
folowed by a purification on columns containing mixture of aluminium oxide and activated
charcoal slurry-packed and eluted with dichlormethane, the second was based on
methanol:acetone=1:1 extraction folowed by the purification on florisil column and elution
by ethil acetate:acetone=4:1, while the third tested method was based on a combination
of the first two mentioned methods, thus methanol:acetone=1:1 extraction and clean-up
throught columns filled with a mixture of aluminum oxide and activated charcoal slurrypacked
and eluted with ethil acetate:acetone=4:1. The second method was the most effective
for obtaining satisfactory recoveries for bifenthrin in a range of 79-83% for four fortification
levels, with good reproducibility i.e. RSD% in a range of 2.2-7.4%. The chosen method
was further optimized by assessing the optimum volume of elution solvent used during
the clean-up procedures. The highest recovery of 82.1% was obtained after elution with
25 ml of solvent. Overall, two-step extraction with 25 ml of methanol:acetone=1:1 solvent
mix for 30 min, followed by clean-up procedure through a glass column with florisil coupled
with elution with 25 ml of ethyl acetate: acetone=4:1, allows simple, efficient and reliable
GC/MS detection of bifenthrin residues from wheat grain fermented by L. plantarum.Testirane su efikasnosti tri različite metode pripreme uzoraka za određivanje ostataka
bifentrina u uzorcima pšenice (Triticum spelta) fermentisane pomoću Lactobacillus plantarum.
Prva metoda zasnivala se na metanolsko-acetonskoj (1:1) ekstrakciji i prečišćavanju
kroz kolonu punjenu smešom aluminijum-oksida i aktivnog uglja u kombinaciji sa dihlormetanom
kao eluentom, druga se zasnivala na metanolsko-acetonskoj (1:1) ekstrakciji i prečišćavanju
kroz kolonu punjenu florisilom u kombinaciji sa smešom etil-acetata i acetona
(4:1) kao eluentom, dok se treća zasnivala na kombinaciji prve dve, tj. metanolsko-acetonskoj
(1:1) ekstrakciji i prečišćavanju kroz kolonu punjenu smešom aluminijum-oksida i aktivnog
uglja u kombinaciji sa smešom etil-acetata i acetona (4:1) kao eluentom. Pokazalo se
da je druga testirana metoda najefikasnija, pri čemu su dobijeni prinosi bifentrina u opsegu
79-83% za četiri koncentraciona nivoa obogaćivanja, sa RSD% u opsegu 2,2-7,4%. Odabrana
metoda je dodatno optimizovana variranjem različitih zapremina korišćenog eluenta.
Najveći prinos metode postignut je pri zapremini eluenta od 25 ml. Predložena metoda,
bazirana na 30-minutnoj ekstrakciji sa 25 ml smeše metanol:aceton=1:1, prečišćavanju na
florisilskoj koloni i eluiranju sa 25 ml smeše etil-acetat:aceton=4:1, pokazala se kao efikasna,
jednostavna i pouzdana metoda za određivanje ostataka bifentrina u fermentisanom žitnom
supstratu