Monitoring of fluoroquinolone residual levels in chicken eggs by microbiological assay and confirmation by liquid chromatography.
The primary objective of this study was to develop a simple, rapid, and efficient method for the simultaneous determination of four fluoroquinolone residues, ciprofloxacin (CFX), danofloxacin (DFX), enrofloxacin (EFX) and norfloxacin (NFX), in chicken eggs. The samples were first monitored by microbiological assay using Escherichia coli as the reference organism, and were then quantified using HPLC with a fluorescence detector. Egg samples were extracted by the liquid-phase extraction process, and the analytes were analyzed via an ODS column using a mixture of acetonitrile and 0.4% phosphoric acid-0.4% triethylamine (15: 85, v/v) as a mobile phase (pH=2) without purification. The calibration curves were linear (r2>or=0.999) over a concentration range of 0.1-1.0 microg/mL. The majority of the mean recoveries at four different fortification levels, 0.1, 0.2, 0.5 and 1.0 ppm, ranged from 73.7+/-7.2% to 87.1+/-12.7%, and the repeatability (as the relative standard deviation) from three repetitive determinations of recovery was between 1.03 and 18.83%. The calculated limit of quantitation (LOQ) was 9 ppb for CFX, EFX and NFX and 0.6 ppb for DFX. Both the bioassay and HPLC methods were applied to 120 total egg samples collected from the six major cities in the Republic of Korea. The bioassay, showed that two samples were positive (i.e contained inhibiting substances). On the other hand, the results of HPLC only identified and quantified the residues of enrofloxacin (from 0.43 to 1.02 ppm) in three samples out of 120. We concluded that the bioassay can be used as a routine screening method for the presence of fluoroquinolones in chicken eggs, which can be confirmed and quantified using LC.
Cho
Hee-Jung
HJ
Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Kwangjin-gu, Seoul 143-701, Republic of Korea.
Abd El-Aty
A M
AM
Goudah
Ayman
A
Sung
Gi-Min
GM
Yi
Hee
H
Seo
Dong-Cheol
DC
Kim
Jin-Suk
JS
Shim
Jae-Han
JH
Jeong
Ji-Yoon
JY
Lee
Soon-Ho
SH
Shin
Ho-Chul
HC
D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000737:chemistry / Q000627:therapeutic use; D001681:Biological Assay / Q000379:methods; D002138:Calibration; D005591:Chemical Fractionation; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D002939:Ciprofloxacin / Q000032:analysis; D004350:Drug Residues / Q000032:analysis*; D004531:Eggs / Q000032:analysis*; D000077422:Enrofloxacin; D004926:Escherichia coli / Q000737:chemistry / Q000254:growth & development; D024841:Fluoroquinolones / Q000032:analysis* / Q000737:chemistry / Q000627:therapeutic use; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination / Q000032:analysis; D013058:Mass Spectrometry; D009643:Norfloxacin / Q000032:analysis; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence
D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; C068581:danofloxacin; D000077422:Enrofloxacin; D002939:Ciprofloxacin; D009643:Norfloxacin