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determination of anti oxidants

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Quantitative determination of Anti-oxidants By T.Pravallika 11031s0406 m.pharm (pa.qa) jntu

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Contents: Introduction Definition Need of addition Types of anti-oxidants Analytical techniques for determination of anti-oxidants

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What are antioxidants?? The chemical substances which inhibit the oxidation reaction Why they are added to pharmaceuticals? They are added to protect the drug / excipient from autoxidation deterioration

Types of anti-oxidants: 

Types of anti-oxidants True antioxidants ( phenolic ): butylated hydroxyanisole (BHA) Butylated hydroxytoluene (BHT) , ter - butyl-hydroquinone(TBHQ) Reducing agents: -ascorbic acid & its salts: (ABA), thioglycolic acid (TGA), ascorbyl palmitate (ASP) - sulphites : sod.sulphite , sod.metabisulphite . Synergistics & chelating agents: ( EDTA), lecithins

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Analysis of anti-oxidants HPLC TLC GC ELECTROCHEMICAL METHOD FIA CE METHOD ELECTROCHEMICAL METHOD TITRIMETRIC ANALYSIS

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Capillary electrophoresis methods: CE for the resolution and determination of nine phenolic antioxidants; using uncoated fused silica capillary column, and an applied voltage of 22 Kv , , the detection was carried out using UV detector . HPLC: RP-HPLC procedure for the determination of phenolic antioxidants. The Separation was carried out over Spherisorb column and the detection was carried out using UV-VIS spectrophotometer at 280 nm . Other HPLC methods such as high performance capillary gel electrochromatography , HPLC coupled with TLC , micellar liquid chromatography , capillary HPLC with amperometric detection and others were published for the determination of phenolic antioxidants. Phenolic Antioxidants:

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GC: Phenolic antioxidants were methylated by mixing with 10% methanolic tetramethyl ammonium hydroxide, followed by water and 0.2% tetra- decanol . The extract was concentrated and subjected to gas chromatography on a fused-Silica column, coated with CP-SIL8CB dervitized with pentafluorobenzoyl chloride in toluene in the presence of dry sodium hydroxide and benzyltriethyl ammonium chloride as a catalyst. The resulting solution was analyzed by gas chromatography on a glass column packed with 3% of SP-2100 with FID

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TLC: chromatography coupled with photodensitometric detection The products were dissolved in toluene, dried and extracted with methanol. The methanolic extract was applied to a RP- HPTLC , using acetonitrile -methanol- tetrahydrofuran mixture and detected photodensitometrically Flow injection analysis: A flow–injection biamperometric method for the determination of gallic acid and tannic acid in pharmaceutical products The method is based on the electrocatalytic oxidation of pyrogallol compounds at one pretreated platinum electrode and the reduction of platinum oxide at the other pretreated electrode to form a biamperometric detection system with applied potential difference of 10 mV.

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Spectrophotometric methods: Tocopherol was determined by formation of a ternary complex with copper (II) chloride and neocuproin in acetate buffer. The formed color was measured at 450 nm . a direct UV-spectrophotometric method for determination of α- tocopherol in pharmaceutical products. α- tocopherol from the products into carbon tetrachloride and measured at 287 nm. Chemiluminesce methods: Tocopherol was assayed by the quenching effect of the anthracene -sensitized electrochemi -luminescence. A chemiluminescene biosensing system for antioxidants such as propyl gallate was developed based on luminol and haematin co-immobilized on a cellulose membrane disc . BHA and PG were determined simultaneously by coupling stopped-flow mixing technique and diode-array detection . The method is based on the reaction between antioxidants and 3-methylbenzothiazolin-2-one hydrazone in the presence of Ce (IV) and the reaction was monitored at 442 and 486 nm using a diode-array detector.

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Applied partial least squares regression to differential pulse voltammograms for the simultaneous determination of phenolic antioxidants (PG and 2-3-t-butyl-4-methoxy phenol. The voltammetric behavior of BHA, BHT, PG and TBHQ at a glassy carbon electrode in solution of 0.1 M perchloric acid containing 1% methanol had been investigated Electrochemical methods :

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Analysis of reducing agents: Ascorbic acid (ASA) and its salts:

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Capillary electrophoresis methods: ASA and other vitamins were analyzed by CE using fused-silica column. The detection was carried out using amperometric detector . determined the active constituent in vitamin C tablets by MECC, using fused-silica capillary column, sodium borate and sodium deoxycholate at pH range 9-11 as running buffer. The detection was carried out using UV-VIS spectrophotometer at 254 nm. High performance liquid chromatographic methods : The degradation of ASA stored in parenteral nutrition and pharmaceutical products occurs initially by oxidation with oxygen and is catalyzed by trace elements, in particular copper ions HPLC with fluorimetric detection using 4,5-dimethyl-o-phenylenediamine as reagent for the analysis of total ASA and dehydro -ASA .The method is based on the oxidation of all ASA to dehydro -ASA prior to the analysis.

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Spectrophotometric methods : A simultaneous spectrophotometric method for the determination of anti oxidants . Solid phase extractions coupled with UV spectrophotometer were applied for determination of ASA in pharmaceutical products . The measurements carried out at 267 nm Ascorbyl palmitate and other phenolic antioxidants were determined by HPLC with UV detection at 255 nm for ascorbyl palmitate and at 280 nm for other phenolic antioxidants

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sensitive and simple method for measuring the antioxidant activity which based on antioxidant-dependent quenching of the chemiluminescence generated from photolysed acridine and methanolic potassium hydroxide. Chemiluminescence methods : ASA in tablets and injections preparations by chemiluminescence spectroscopy after treatment with potassium permanganate in sulfuric acid medium and the chemiluminescence intensity was measured Electrochemical methods : It is almost too difficult to determine this compound electrochemically by direct oxidation on a convenient electrode because of its large over potential and fouling by the oxidation products . Therefore, some chemically modified electrodes (CME) with active mediators immobilized at the electrode surface have been used for the catalysis of electrooxidation Differential pulse voltammetery was applied for the determination of ASA with CME

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Titrimetric methods: ASA and cysteine in eye drops products were determined by potentiometric titration. The aqueous sample solution in potassium dihydrogen phosphate was titrated potentiometrically against diperoxyadipic acid Sulfites: This group of chemicals includes: sulfite, bisulfite and metabisulfite (Table II). They are strong reducing agents and are widely used as antioxidants in solutions especially those containing drugs which are readily oxidized to form highly coloured decomposition products Capillary Electrophoresis method: CZE with indirect UV detection have been successively applied for the analysis of inorganic anions. simultaneous CE with indirect UV method for the determination of metabisulfite and sulphite in pharmaceutical products.

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HPLC: high performance ion chromatographic (HPIC) method for the determination of sodium metabisulfite in parentral products. HPLC was also applied for the determination of metabisulphite in antrheumatic injections and in penicillins with or without derivatization . Flow injection analysis : A FI- coulometric flame ionization analysis of metabisulfite with iodine in the presence of starch Sulfite in capsules containing vitamin K was determined by chemiluminescence in flow system Spectrophotometric methods: Colorimetric methods were reported for the determination of sodium bisulfite in parenteral mixture or in inhalation solutions the reaction of cis -platinum (antitumor agent) with pharmaceutical additives as sodium bisulfite (antioxidant) in acetate buffer with absorbance at 280 nm .

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Titrimetric methods : Direct and indirect titrimetric methods with potentiometric end point detections were described for the determination of metabisuphit using different oxidizing agents. Analysis of synergists antioxidants (EDTA and its salts): Ethylene diamine tetra acetic acid (EDTA), is an organic complexant . These are added to compds which have little antioxidant effect themselves but probably enhance the action of other antioxidants by reacting with heavy metal ions which catalyse oxidation

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Capillary electrophoresis methods: CE was utilized for the determination of Fe(III)-EDTA chelate and EDTA itself in solutions. EDTA was complexed with Ni (II) salt prior to analysis, separated in a fused-silica capillary filled with a borate buffer of pH 8.5 and detected at 214nm using UV detector High performance liquid chromatographic methods: HPLC coupled with mass spectrometry (MS) via electrospry interference has exhibited a powerful capacity in the measurement of EDTA, in the form of its iron complex. The complex was eluted through a stationary phase under slightly acidic conditions and detection was performed by mass spectrometry Spectrophotometric methods: Several spectrophotometric methods have been reported for the determination of EDTA. Most of these methods are based on the formation of ternary complex between EDTA and metal cations followed by coupling with another chelating agent.

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Electrochemical methods: The polarographic technique has been applied for the determination of EDTA in pharmaceutical products, after complex formation with europium (III) chloride. Copper (II) complex with EDTA was also used for polarographic determination of EDTA in solutions A potentiometric method for the determination of EDTA involved the use of a urease -based inhibition biosensor was also reported Titrimetric methods: determined EDTA in injections (containing morphine, codiene , narcotine , papaverine and thebaine ) by titration with ferrous ammonium sulfate in the presence of ammonium persulfate using sulphonsalicylic acid solution as indicator.

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W. J. Reilly, "Pharmaceutical Necessities", in: "Remington: The Science and Practice of Pharmacy“ Wikipedia. Org/preservatives. Analysis of preservatives in pharmaceutical products .html references