We are conducting Experiment, preservation of food products (Jam, jelly) by exposed to E-Beam irradiation (2.5 -10 kGy). We are planned to analyse the effect of irradiation on food products by free radicals estimation using ESR analysis.
But, ESR is a new analysis method to me. Arise so many doubts, not know anyone to this field, in journals not give full information. So I kindly requested to all of you clear my doubts before start to analysis,
1. Free radicals production due to irradiation in food items are unstable. So my doubt is place of irradiation and free radicals analysis is different. So which time taken to delay for free radicals estimation in irradiated samples from at the time of irradiation ?
2. Which form is suitable (solid or liquid or crystal or powder) to analyse the samples for irradiated Jam and Jelly in ESR Analyzer for free radicals estimation?
3. How to compare the ESR spectrum of irradiated and non-irradiated food products
4. How to obtain 'g' value and quantify the free radicals from ESR spectrum ?
1. I see two possible approaches to quantifying the amount of radical species generated. If the decay of radical species is slow, you may be able to trap them by freezing the samples in liquid nitrogen. If the decay of the radical species is fast, then it may be possible to "trap" them using a spin-trap. You may need to try both approaches to see whether you have fast or slow radical decay rates (or both fast and slow decay rates since you may be generating many types of radicals). Once you have found a way to trap the radical species, you can quantify them by comparing the integrated signal intensity of your sample to that of samples with known concentrations of a stable radical like TEMPOL. TEMPOL is commercially available. I can direct you to the literature, if you like.
2. All forms can be observed but it is easiest to observe solids. In your case, a frozen solid may be most convenient.
3. This will be simple, once you solve item 1. You simply prepare two samples that are identical, with the exception of irradiation.
4. The g value is determined by the frequency of the spectrometer and the magnetic field value at which the signal is observed. hv=gBH where h is Planck's constant, v is frequency, g is the g-value, B is the Bohr magneton and H is the field value. Just be careful that all your units cancel. As I tell my students, "Units are our friends".
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India