اندازه گيري اكراتوكسين A در ريشه شيرين بيان با استفاده از طيف سنج تحرك يوني

چكيده انگليسي :

OTA Determination in Licorice Root During Storage Using IMS Mohammadreza Khalesi m khalesi@ag iut ac ir October 2010 Department of food science and technology Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors Mahmoud Sheikh Zeinoddin zeinodin@cc iut ac irMahmoud Tabrizchi m tabriz@cc iut ac irAbstractDespite the recent successful efforts to detect mycotoxins new methods are still required to achieve highersensitivity more simplicity higher speed and higher accuracy at lower costs This project describes thedetermination of ochratoxin A OTA using corona discharge ion mobility spectrometry IMS in the licoriceroots A quick screening and measuring method is proposed to be employed after cleaning up the extracted OTAby immunoaffinity columns The ion mobility spectrometer is used in the inverse mode to better differentiate theOTA peak from the neighboring ones After optimization of the experimental conditions such as corona voltage injection port temperature and IMS cell temperature a limit of detection LOD of 0 010 ng is obtained Furthermore the calibration curve is found to be in the range of 0 01 1 ng with a correlation coefficient R2 of0 988 To determine OTA using inverse IMS in real sample licorice root was chosen It was divided into twohalves one sent to an accredited lab Gesellschaft f r Bioanalytik Hamburg Germany GBA and one was usedfor extraction using the procedure we applied Ten L of the extracted OTA was then injected into the IMS Theamount of OTA in this sample was calculated to be 88 6 pg equivalent to 8 8 0 6 ppb ng g licorice root after recovery corrections were affected This was very close to the value 8 5 ppb reported by GBA Lab Germany for a similar sample To verify the results a similar procedure was used for a second fresh sample oflicorice root and the OTA content was found to be 0 6 0 1 ppb which is comparable to 0 5 ppb reported byGBA Lab The nature of licorice product makes this technique a potentially vital part of their quality control Licorice root is normally stocked in extraction plant in large quantities for long storage times even up to oneyear before they are processed For such plants which are typically cultivated and used in less developedcountries it is much easier to control their contamination by an easy to use and inexpensive technique such asinverse IMS Speed of the test is also vital as it enables the plant to reject consignment of contaminated licoriceroot on the spot The effects of temperature and relative humidity RH on OTA formation during licorice rootstorage were also investigated Four different conditions 9 C 51 RH 15 C 49 RH 22 C 35 RH 29C 27 RH corresponding to four seasons of Shiraz climate were simulated using different concentrations ofsulfuric acid in four incubators Sixty days was regarded as total incubation time and OTA was determined eachtwenty days by using Inverse IMS The results showed that the maximum level of OTA in roots was formed inthe summer condition after 40days equal to 24 2 2 5 ppb The minimum amount of OTA is also related towinter condition which didn t demonstrate significant increase In addition the OTA formation was stoppedafter 40days due to reaching ERH according to simulated environment Although OTA formation in licoriceroot can be affected by RH by controlling the temperature the effect of RH on OTA formation in naturalcondition seems to be really neglected Key words Ochratoxin A Licorice Ion Mobility Spectrometry Storage

خالصي، محمدرضا

اندازه گيري اكراتوكسين A در ريشه شيرين بيان با استفاده از طيف سنج تحرك يوني

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