Glucose Ascorbic acid

Although different nanomaterials such as nanoparticles, nanowires and nanotubes are used for the construction of biosensor, this chapter is mainly devoted to the use of AuNPs for the construction of electrochemical biosensor and their analytical performances. Further, in this chapter we restrict ourselves in the electrochemical sensing of glucose, ascorbic acid, uric acid and dopamine derivatives using the AuNPs modified electrodes. 

Another application of Zinc oxide nanostructure is immobilization of uricace onto ZnO nanorod and fabrication a sensitive biosensor for uric acid detection [167], The biosensor successfully used for micromolar detection of uric acid in the presence serious interferences, glucose, ascorbic acid, and 1-cysteine. The apparent KM value for the uric acid biosensor is 0.238 mM, showing high affinity of the biosensor. Direct electron transfer of SOD at a physical vapor deposited zinc oxide nanoparticles surface was investigated [168], In comparison to SOD immobilized onto ZnO nanodisks [169], the electron transfer rate constant is small and a quasi- reversible electrochemical behavior observed. A novel... 

FIGURE 7.19 Layout of the separation/reaction microchip for bioassays of glucose, ascorbic acid, uric acid, and acetaminophen (upper panel). Enzymatic and separation processes along the reaction/separation channel of the CE biochip (lower panel). (Adapted from Wang, J. et al. Anal Chem, 72, 2514, 2000. With permission.)... 

There are a number of reports on the synthesis of Au NPs-rGO composites by adopting in situ methods such as chemical reduction, electrochemical deposition, microwave irradiation, and sonochemical reduction [14, 18, 23]. In most of the reduction methods, a GO suspension in water or ethanol is mixed with Au salt, the resulting mixture is then reduced with different reducing agents like sodium borohydride, hydrazine hydrate, glucose, ascorbic acid, sodium citrate, beer solution, oleylamine, ethylene glycol, etc., which results in. simultaneous reduction of the Au ions and GO to form Au NPs-rGO composites. 

Folate is absorbed by active transport and by diffusion, mainly in the upper part of the small intestine, although some is absorbed along the entire length of the small intestine glucose, ascorbic acid, and some antibiotics facilitate its absorption. 

FDA-approved tin(II) 2-ethylhexanoate (Sn(EH)2), glucose,ascorbic acid, phenol, hydrazine and phenylhydrazine, excess inexpensive ligands,or selected nitrogen-containing monomers. Cu° also works as a reducing agent in an ARGET ATRP but it increases the level of transition metal halides (CuX and CuXj) in the reaction system due to continuous reduction of Cu formed by tma-voidable termination reactions (Cu° + Cu = 2Cu ). 

Apart from glucose, ascorbic acid is another commonly found biochemical in food and clinical samples. Whilst analytical measurements for ascorbic acid have made use of spectrophotometric methods, amperometric detection or volumetric titration, we have herein relied on colour changes of the polymer matrix during the reduction of doped polybithiophenes by ascorbic acid as a mean of analytical detection and measurement. This approach utilizes the redox property and the electrochromatic nature of polybithiophenes upon reduction by ascorbic acid. 

A large number of organic compounds, including aldehydes, ketones, lactones, carboxylic acids, chlorides and anhydrides, esters, amides, anilides and alcohols, ketals, epoxides, nitro compounds, glucose, ascorbic acid, and some ethers, have been analyzed by Dahn et al. (1959)... 

M.p. 190-192 C. The enolic form of 3-oxo-L-gulofuranolactone. It can be prepared by synthesis from glucose, or extracted from plant sources such as rose hips, blackcurrants or citrus fruits. Easily oxidized. It is essential for the formation of collagen and intercellular material, bone and teeth, and for the healing of wounds. It is used in the treatment of scurvy. Man is one of the few mammals unable to manufacture ascorbic acid in his liver. Used as a photographic developing agent in alkaline solution. 

Sorbitol is manufactured by the reduction of glucose in aqueous solution using hydrogen with a nickel catalyst. It is used in the manufacture of ascorbic acid (vitamin C), various surface active agents, foodstuffs, pharmaceuticals, cosmetics, dentifrices, adhesives, polyurethane foams, etc. 

Another group of compounds called oxygen scavengers retard oxidation by reducing the available molecular oxygen. Products in this group are water soluble and include erythorbic acid [89-65-6] C HgO, and its salt sodium erythorbate [6381-77-7] C HgO Na, ascorbyl pahnitate [137-66-6] 22 38 7 ascorbic acid [50-81-7] C HgO, glucose oxidase [9001-37-0] and sulfites (23). 

Of the water-soluble vitamins, intakes of nicotinic acid [59-67-6] on the order of 10 to 30 times the recommended daily allowance (RE)A) have been shown to cause flushing, headache, nausea, and moderate lowering of semm cholesterol with concurrent increases in semm glucose. Toxic levels of foHc acid [59-30-3] are ca 20 mg/d in infants, and probably approach 400 mg/d in adults. The body seems able to tolerate very large intakes of ascorbic acid [50-81-7] (vitamin C) without iH effect, but levels in excess of 9 g/d have been reported to cause increases in urinary oxaHc acid excretion. Urinary and blood uric acid also rise as a result of high intakes of ascorbic acid, and these factors may increase the tendency for formation of kidney or bladder stones. AH other water-soluble vitamins possess an even wider margin of safety and present no practical problem (82). 

L-Ascorbic acid biosynthesis in plants and animals as well as the chemical synthesis starts from D-glucose. The vitamin and its main derivatives, sodium ascorbate, calcium ascorbate, and ascorbyl palmitate, are officially recognized by regulatory agencies and included in compendia such as the United S fates Pharmacopeia/National Formula (USP/NF) and the Food Chemicals Codex (FCC). 

Most current industrial vitamin C production is based on the efficient second synthesis developed by Reichstein and Grbssner in 1934 (15). Various attempts to develop a superior, more economical L-ascorbic acid process have been reported since 1934. These approaches, which have met with htde success, ate summarized in Crawford s comprehensive review (46). Currently, all chemical syntheses of vitamin C involve modifications of the Reichstein and Grbssner approach (Fig. 5). In the first step, D-glucose (4) is catalytically (Ni-catalyst) hydrogenated to D-sorbitol (20). Oxidation to L-sotbose (21) occurs microhiologicaRy with The isolated L-sotbose is reacted with acetone and sulfuric acid to yield 2,3 4,6 diacetone-L-sorbose,... 

D-Glucose to L-Ascorbic Acid Fermentation. The direct heterotrophic fermentation of D-glucose to L-ascorbic acid with algae is... 

In all plants and most animals, L-ascorbic acid is produced from D-glucose (4) and D-galactose (26). Ascorbic acid biosynthesis in animals starts with D-glucose (4). In plants, where the biosynthesis is more compHcated, there are two postulated biosynthetic pathways for the conversion of D-glucose or D-galactose to ascorbic acid. 

Fig. 8. Pathway for the biosynthesis of L-ascorbic acid in rats using C-l-labeled D-glucose indicates position of C.

Fig. 10. Suggested pathway for the biosynthesis of L-ascorbic acid (with retention of configuration) in higher plants based on D-glucose-l- C...

Bromophenol blue (3.0...4.6) aliphatic carboxylic acids [225 — 228] malonic and lactic acids [229] palmitic and lactic acids [230] malonic, glycolic, malic, citric, tartaric, ketoglutaric, galacturonic and oxalic acids [196] dicarboxylic acids, succinic acid [231] indoleacetic acid, trichloroacetic acid [232] palmitic acid, palmityl- and stearyllactic acid [223] benzoic, sorbic and salicylic acid [234] metabolites of ascorbic acid [235] chloropropionic acid [236] oligogalacturonic acids [237] amino acids, hydrocarbons, mono-, di- and triglycerides [238] xylobiose, xylose, glucose and derivatives [239] sugar alcohols [91] toxaphene [240]... 

Figure 20.7 The industrial synthesis of ascorbic acid from glucose.

Garg A, Kunwar K, Das N, et al. 1980. Endosulfan intoxication Blood glucose, electrolytes, Ca levels, ascorbic acid and glutathione in rats. Toxicol Lett 5 119-123. 

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