Antioxidants detection systems

Gallate (and Other Antioxidant) Detection System Detection Limit Application Reference... 

The multichannel coulometric detection system serves as a highly sensitive tool for the characterization of antioxidant phenolic compounds because they are electroactive substances that usually oxidize at low potential. The coulometric efficiency of each element of the array allows a complete voltammetric resolution of analytes as a function of their oxidation potential. Some of the peaks may be resolved by the detector even if they coelute (Floridi and others 2003). 

Serotonin can be measured in whole blood, serum, platelet-rich plasma, platelet-poor plasma (i.e., platelet-free plasma), isolated platelet pellets, urine, and CSF. Most blood serotonin is stored in the platelets and is easily released during sample preparation. For whole blood serotonin, venous blood (10 mL) is drawn into a tube containing potassium EDTA as an anticoagulant, gently mixed, placed on ice, and transferred to a storage tube. An aliquot of blood is then removed for a platelet count alternatively, a simultaneous EDTA blood sample can be collected. Antioxidants such as ascorbic acid or metabisulfite are conveniently added to the storage tube when a fluorometric detection system is used. Blood serotonin samples are stored frozen at -20 °C, preferably within 2 hours after collection. 

Flow injection methods for the determination of alkyl gallates have been mainly focused on the determination of PG alone or together with other additives, principally other antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tertiary butylhydroquinone (TBHQ) (Table 14.1). Both optical and electrochemical detection systems have been used for this purpose. 

Antioxidant Assay Flow Method pH Value Type of Sample Detection System Determination Rate (h-i) Reference... 

The second maximum is riboflavin-independent (Fig. 1). In this case, luminol obviously plays a double role it is the chemiluminogenous detection compound for free radicals and photosensitizer as well. It is a remarkable characteristic of this system that the signal intensity decreases only very slowly, giving an opportunity for detection of nonenzymatic antioxidants. 

Hermann (2000) described a rapid automated method involving generation of a known amount of free radicals and the detection of the excess by photochemiluminescence. Test kits are available for determination of total water-soluble antioxidants, fat-soluble antioxidants and ascorbic acid. A luminometric method was developed for the determination of antioxidative activity and was subsequently applied to anthocyanin and betalaine colour concentrates (Kuchta et al., 1999). The method involved quantification of the interruption in luminescence from the hydrogen peroxide-horse radish peroxidase-luminol system in the presence of antioxidants. 

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