UV-Vis Spectrometric Detection of Biodiesel/Diesel Blend Adulterations with Soybean Oil

Flow-batch analysis of clenbuterol based on analyte extraction on molecularly imprinted polymers coupled to an in-system chromogenic reaction. Application to human urine and milk substitute samples

“…The reaction was performed offline and the absorbance was measured after heating the reaction mixture in a water bath from 0 to 7 min. It was found that temperatures higher than 37 °C inhibited color development, which is in agreement with former observations [25]. A slight but not significant increase of the signal at temperatures between 20 °C and 35 °C was observed as a function of time.…”

“…FBA has mostly been used to develop several analytical applications based on either selective chromogenic reactions [23,24] or in combination with chemometric approaches [25], potentially including SPE analyte preconcentration [26].…”

Free and Total Glycerin Analyses in Biodiesel–Diesel Blends

“…On the other hand, most of the techniques developed to quantify the biodiesel content of B-D blends do not take into account the presence of glycerides (MAG, DAG, TAG). [14][15][16][17]20,21 Due to the importance of the presence of these contaminants in the fuel, there have been several reports of studies related to techniques to quantify specifically the adulterations with vegetable oils in the B-D blends, such as NIR, 22−25 MIR, 26,27 FTIR, 28 FT-Raman, 29 UV−vis, 30,31 spectrofluorimetric, 32,33 Electrospray Ionization Mass Spectrometry (EIS-MS), 34 and Easy Ambient Sonic-Spray Ionization Mass Spectrometry (EASI-MS). 35 All of these works used different techniques to analyze vegetable oil−biodiesel−diesel blends (O-B-D).…”

“…In most cases, the vegetable oil concentrations are relatively high. In other words, the vegetable oil content used in the B-D blends corresponded to partial or total substitution of the biodiesel; therefore, the vegetable oil concentration related to the biodiesel concentration was in the range 10–100%, and even more. − The objective of these techniques is to detect adulteration of B-D blends with vegetable oil, but they cannot detect the level of triacylglycerides that could be present in the blend if a good quality biodiesel is used in its preparation. The biodiesel used in the blends can contain up to 0.2 wt % of triacylglycerides .…”