In this work, the direct determination methodology of glyphosate and aminomethylphosphonic acid (AMPA) by high performance liquid chromatography (HPLC) using inductively coupled plasma with triple quadrupole mass spectrometer (ICP-MS/MS) was compared with the conventional method using diode array detector (HPLC-DAD). Both methods were selective, but the chromatographic analysis using ICP-MS/MS as detector was four times faster than DAD. The methodology using ICP-MS/MS as detector was linear from 27 to 218 μg L-1 , while by the conventional method it was 1 to 8 mg L-1. Detection limits of the glyphosate achieved with the HPLC-ICP-MS/MS and HPLC-DAD methods were 8.2 and 300 μg L-1 , respectively. The direct determination using ICP-MS/MS as detector showed a lower number of stages in sample preparation because it did not need the derivatization step. Seven real samples were analyzed by HPLC-ICP-MS/MS and the results showed that these analytes were not detected.
Catharanthus roseus(L.) G. Don is a medicinal plant known for its important constituent aromatic compounds. In the literature, no detailed studies elucidating the methods of extraction of phenolic compounds for this species are available. Therefore, the present study was aimed at evaluating the maceration parameters for determining the total phenols content in C. roseus. The parameters of plant mass, extraction phase composition, homogenization type, extraction time, and temperature were evaluated in terms of improving the extraction conditions. The plant extracts were subjected to specific spectrophotometric analysis designed for each parameter, and the total phenols content was determined. After establishing the optimal conditions, the extracts were prepared from C. roseus cultivars, followed by evaluation of antioxidant activity using spectrophotometry, phenolic acid content using GC-MS, and dissimilarity using Unweighted Pair Group Method in combination with the Arithmetic Mean method. The optimal extraction conditions obtained were: 30 mg of dry plant tissue in 0.72 mL of extraction phase ethanol:water, 50:50 (v/v) at 50 °C for 1 h. The average total phenols content was 30.3 mg g-1 of gallic acid equivalents (GAE) and 20.0 mg g-1 of flavonoid quercetin equivalents (QE). The antioxidant activities determined using the DPPH, ABTS, and FRAP methods were 19.4, 11.8, and 23.3 mg g-1 of Trolox equivalent antioxidant capacity (TEAC), respectively. There was a predominance of ferulic (42%-56%) and caffeic (21%-52%) acids in the leaf extracts of C. roseus. The extraction process increased the total phenol content by 55%, from 18 to 28 mg GAE.
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