ABSTRACT Moringa stenopetala (Ms) is a drought-tolerant fast-growing indigenous tree in Ethiopia. The leaf part of the plant attracted research attention due to multiple nutritional and health benefits. The health benefits were usually attributed to the presence of compounds having antioxidant properties. One of such compounds is ascorbic acid. The aim of this study was to develop a spectrophotometric method to determine the level of ascorbic acid in the edible leaf parts of the plant. In this method, a decrease in the absorbance of Cr(VI) solution as a result of its reaction with AA was used as a basis for the analysis. Mn(II) was used as a catalyst. The described method was validated against HPLC as a standard technique. Factors influencing the reduction of Cr(VI) by AA, including incubation time, solution pH, and background concentration ratio, were optimized. The theoretical detection limit and limit of quantification were calculated to be 0.00154 and 0.0171 mg/ml, respectively. Out of the three different areas of Ms leaf samples studied, fresh Ms leaves from Arba Minch contained highest concentration (237 0.001 mg/100 g) of AA, followed by Konso (233 0.48 mg/100 g) and Dilla (21 0.48 mg/100 g), respectively. It was reduced significantly after boiling for 10 min and found to decrease with increasing cooking time. All Ms samples used in this study contained a relatively acceptable range or moderate amount of total AA (200–250 mg/100 g). The results obtained using the current method were in good agreement with that of HPLC methods (237 (UV–Vis) vs 239 (HPLC) and 233 (UV–Vis) vs 237 (HPLC)). The developed method is simple, fast, and can be successfully applied for selective determination of AA in the presence of other interfering species.

中文翻译：

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六价铬催化滴定分光光度法测定紫荆叶中抗坏血酸的含量及其验证

摘要辣木（Ms）是埃塞俄比亚一种耐旱速生的本土树种。由于多种营养和健康益处，植物的叶子部分引起了研究的关注。健康益处通常归因于具有抗氧化特性的化合物的存在。这种化合物之一是抗坏血酸。本研究的目的是开发一种分光光度法来确定植物可食用叶子部分中的抗坏血酸含量。在该方法中，Cr(VI) 溶液与 AA 反应导致其吸光度的降低被用作分析的基础。Mn(II)用作催化剂。所描述的方法已针对 HPLC 作为标准技术进行了验证。影响 AA 还原 Cr(VI) 的因素，包括孵育时间、溶液 pH 值和背景浓度比，进行了优化。计算出的理论检测限和定量限分别为 0.00154 和 0.0171 mg/ml。在所研究的三个不同区域的 Ms 叶子样本中，来自 Arba Minch 的新鲜 Ms 叶子含有最高浓度的 AA（237 0.001 毫克/100 克），其次是 Konso（233 0.48 毫克/100 克）和 Dilla（21 0.48 毫克/ 100 克），分别。煮沸 10 分钟后显着降低，并发现随着烹饪时间的增加而降低。本研究中使用的所有 MS 样品都含有相对可接受的范围或中等量的总 AA（200-250 毫克/100 克）。使用当前方法获得的结果与 HPLC 方法（237 (UV-Vis) vs 239 (HPLC) 和 233 (UV-Vis) vs 237 (HPLC)）的结果非常一致。所开发的方法简单、快速、