体外不同pH值溶液中L-抗坏血酸与硫酸镍组合时化学行为的改变
Alteration of chemical behavior of L-ascorbic acid in combination with nickel sulfate at different pH solutions in vitro.
作者信息
Maniyar Shaheen A, Jargar Jameel G, Das Swastika N, Dhundasi Salim A, Das Kusal K
机构信息
Environmental Health Research Unit, Department of Physiology, Al Ameen Medical College, Bijapur-586108 Karnataka, India.
出版信息
Asian Pac J Trop Biomed. 2012 Mar;2(3):220-2. doi: 10.1016/S2221-1691(12)60045-8.
OBJECTIVE
To evaluate the alteration of chemical behavior of L-ascorbic acid (vitamin C) with metal ion (nickel) at different pH solutions in vitro.
METHODS
Spectra of pure aqueous solution of L-ascorbic acid (E mark) compound and NiSO4 (H2O) (sigma USA) were evaluated by UV visible spectrophotometer. Spectral analysis of L-ascorbic acid and nickel at various pH (2.0, 7.0, 7.4 and 8.6) at room temperature of 29 °C was recorded. In this special analysis, combined solution of L-ascorbic acid and nickel sulfate at different pH was also recorded.
RESULTS
The result revealed that λmax (peak wavelength of spectra) of L-ascorbic acid at pH 2.0 was 289.0 nm whereas at neutral pH 7.0, λmax was 295.4 nm. In alkaline pH 8.6, λmax was 295.4 nm and at pH 7.4 the λmax of L-ascorbic acid remained the same as 295.4 nm. Nickel solution at acidic pH 2.0 was 394.5 nm, whereas at neutral pH 7.0 and pH 7.4 were the same as 394.5 nm. But at alkaline pH 8.6, λmax value of nickel sulfate became 392.0 nm. The combined solution of L-ascorbic acid and nickel sulfate (6 mg/mL each) at pH 2.0 showed 292.5 nm and 392.5 nm, respectively whereas at pH 7.0, L-ascorbic acid showed 296.5 nm and nickel sulfate showed 391.5 nm. At pH 7.4, L-ascorbic acid showed 297.0 nm and nickel sulfate showed 394.0 nm in the combined solution whereas at pH 8.6 (alkaline) L-ascorbic acid and nickel sulfate were showing 297.0 and 393.5 nm, respectively.
CONCLUSIONS
Results clearly indicate an altered chemical behavior of L-ascorbic acid either alone or in combination with nickel sulfate in vitro at different pH. Perhaps oxidation of L-ascorbic acid to L-dehydro ascorbic acid via the free radical (HSc*) generation from the reaction of H2ASc + Ni (II) is the cause of such alteration of λmax value of L-ascorbic acid in the presence of metal nickel.
目的
评估体外不同pH值溶液中L-抗坏血酸（维生素C）与金属离子（镍）的化学行为变化。
方法
用紫外可见分光光度计评估L-抗坏血酸（E标记）化合物和硫酸镍（H2O）（美国西格玛）纯水溶液的光谱。记录29℃室温下不同pH值（2.0、7.0、7.4和8.6）时L-抗坏血酸和镍的光谱分析。在该专项分析中，还记录了不同pH值下L-抗坏血酸和硫酸镍的混合溶液。
结果
结果显示，pH 2.0时L-抗坏血酸的λmax（光谱峰值波长）为289.0 nm，而在中性pH 7.0时，λmax为295.4 nm。在碱性pH 8.6时，λmax为295.4 nm，在pH 7.4时L-抗坏血酸的λmax保持在295.4 nm。酸性pH 2.0时镍溶液的λmax为394.5 nm，而在中性pH 7.0和pH 7.4时均为394.5 nm。但在碱性pH 8.6时，硫酸镍的λmax值变为392.0 nm。pH 2.0时L-抗坏血酸和硫酸镍（各6 mg/mL）的混合溶液分别显示292.5 nm和392.5 nm，而在pH 7.0时，L-抗坏血酸显示296.5 nm，硫酸镍显示391.5 nm。在pH 7.4时，混合溶液中L-抗坏血酸显示297.0 nm，硫酸镍显示394.0 nm，而在pH 8.6（碱性）时，L-抗坏血酸和硫酸镍分别显示297.0和393.5 nm。
结论
结果清楚地表明，体外不同pH值下，L-抗坏血酸单独或与硫酸镍组合时化学行为发生了变化。或许在金属镍存在的情况下，L-抗坏血酸通过H2ASc + Ni (II)反应产生自由基（HSc*）氧化为L-脱氢抗坏血酸是L-抗坏血酸λmax值发生这种变化的原因。
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