Multivariate Optimization for the Development of a Fast and Simple Ultrasound-Assisted Extraction Procedure for Multielemental Determination in Tea Leaves by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES)

Fast and Greener Ultrasound-Assisted Acid Extraction for the Determination of Potentially Toxic Elements in Fluorescent Lamp Waste Using ICP OES

BACKGROUND

Understanding the chemical composition of fluorescent lamp residue, particularly potentially toxic elements, is crucial for reducing environmental impacts and human health risks after disposal. However, the challenge lies in effectively analyzing these heterogeneous solid samples. Techniques involving quantitative dissolution become imperative, playing a fundamental role in quantifying trace elements.

OBJECTIVE

The aim of this work is to develop and present a new, faster, and more efficient and environmentally friendly method using ultrasound-assisted acid extraction to quantify potentially toxic elements (Cu, Mn, Ni, Sr, and Zn) present in fluorescent lamp waste using the inductively coupled plasma-optical emission spectrometry technique.

METHODS

An ultrasound-assisted acid extraction method for the quantification of potentially toxic elements in fluorescent lamp waste was developed and applied as a greener alternative to conventional digestion methods. For variable optimization, a full factorial design with two levels and two variables (time and temperature) was used to determine which factors significantly affected the observed response.

RESULTS

The results obtained for the developed extraction method were compared with a reference method employing a heating acid digestion (with a mixture of HCl, HClO4, and HF) using statistical tools. The best results were obtained using an extraction time of 10 min and a temperature of 25°C. Inductively coupled plasma optical emission spectrometry was applied for element quantification.

CONCLUSION

The proposed extraction method showed good results for Cu, Mn, Ni, Sr, and Zn. Furthermore, the proposed method based on ultrasound radiation presents additional criteria that align with the concepts of green analytical chemistry.

HIGHLIGHTS

A greener alternative method for the determination of Cu, Mn, Ni, Sr, and Zn in fluorescent lamp waste was developed. Optimal conditions for ultrasound extraction of potentially toxic elements were achieved in 10 min at a temperature of 25°C. Environmentally friendly aspects of ultrasound align with the requirements of green analytical chemistry.

Impact of resistant starch: Absorption of dietary minerals, glycemic index and oxidative stress in healthy rats

BACKGROUND & AIMS

Resistant starch (RS) is a prebiotic fiber that has been scientifically shown to control the development of obesity. Prebiotic role of RS has also seen to be very important as it helps gut bacteria to regulate fermentation and fatty acid production. This study aimed to check the different levels of RS on glycemic index, oxidative stress and mineral absorption rate in healthy rat models. To evaluate these objectives, the trial was conducted for 40 days of follow up; 10 days were the adjustment period and the collection period over 30 days.

METHODS

Thirty-six healthy female Wistar rats were divided into 4 groups of (9 animals each) NC (Normal Control: without resistant starch), RS0.20 (resistant starch: 0.20 g/kg body weight), RS0.30 (resistant starch: 0.30 g/kg body weight), RS0.40 (resistant starch: 0.40 g/kg body weight). All the diets were isocaloric and isonitroginous.

RESULTS

The impact of different levels of RS on the dry-matter intake (DMI) presented statistically significant results (p ≤ 0.05): DMI was reduced in RS (0.02) fed rats as compared to NC rats in first 3 weeks; and after 4th and 5th weeks, there was a DMI reduction of 28% in RS (0.04) fed rats. Moreover, there was no significant increase in the nutrient intake in all RS diets. The dry-matter (DM) digestibility was statistically significantly (P ≤ 0·05), which increased in all rats fed with different level of RS. The weight loss showed statistically significant results: RS (0.04) exhibited 19 g reduction in weight as compared with NC rats. Significant increase was observed in total oxidant status (TOS), in all the RS fed rats when compared with NC rats. The levels of Mg, Ca, Fe and Zn were shown to be decrease in feces analysis, which proves their better absorbance in gut. Statistically significant increase was observed in antioxidant capacity, whereas significant decrease was observed in the total weight of the animals, showing the role of RS in controlling obesity.

CONCLUSIONS

Overall, significant results were found in all dosage level of RS but long term administration of the higher dosage level (RS0.40) may need to be studied for enhanced results. RS can help improve insulin sensitivity in overweight adults.

Direct determination of nutrient elements in plant leaves by double pulse laser-induced breakdown spectroscopy: evaluation of calibration strategies using direct and inverse models for matrix-matching

This study aims to develop a single calibration model to determine nutrient elements directly (Ca, Mg, Mn, and P) in soybean and sugar cane leaf samples by double pulse laser-induced breakdown spectroscopy (DP LIBS). Matrix-matching calibration (MMC) was evaluated using direct and inverse models. Forty-five samples were used to build the calibration model (23 soybean leaves and 22 sugar cane leaves), and fifteen were used for the prediction test (8 soybean leaves and 7 sugar cane leaves) models. In the direct model, the analyte concentration in the sample is the independent variable, and the analytical signal is the dependent variable. In the inverse model, the analytical signal is the independent variable, and the analyte concentration in the sample is the dependent variable. In general, both models presented satisfactory results; however, the inverse model performed better. Emission lines used to propose calibration models were selected using a linear Pearson's correlation (R) strategy between each spectral point and the Ca, Mg, Mn, and P concentration measured by reference methods using inductively coupled plasma optical emission spectrometry (ICP OES). The root mean square errors of prediction (RMSEP) for the direct models were 0.60 g kg^-1 to (Ca), 0.47 g kg^-1 (Mg), 9.3 mg kg^-1 to (Mn), and 0.28 g kg^-1 to (P); for inverse model was 0.55 g kg^-1 to (Ca), 0.39 g kg-1 (Mg), 10.5 mg kg^-1 to (Mn), and 0.21 g kg^-1 to (P). The calibration strategies proposed in this study may minimize matrix effects in direct solid analysis in soybean and sugar cane leaf samples, performing the determination of Ca, Mg, Mn, and P by DP LIBS using a single calibration model.

Multivariate optimization of an ultrasound-assisted extraction procedure for the determination of Cu, Fe, Mn, and Zn in plant samples by flame atomic absorption spectrometry

In this work, a simple, easy, and fast ultrasound-assisted extraction procedure for the determination of Cu, Fe, Mn, and Zn in plant samples was developed. Sample preparation conditions were optimized in a multivariate manner using mixture design and Box-Behnken. The extraction conditions adequate to obtain the maximum response were 90% power, 10 minutes, 40 °C temperature, and using an extraction solution composed of HNO3 and HCl at a concentration of 0.5 and 1.1 mol L-1, respectively, for a volume of 10 mL and 250 mg of samples. Accuracy was verified from the analysis of a certified reference material (Apple leaves, NIST 1515) yielding recoveries between 89 and 98% for the procedure. Precision was evaluated in a repeatability study (n = 10), yielding RSDs less than 6.7%, and the limits of quantification (mg kg-1) were 0.95, 2.42, 1.31, and 1.18 for Cu, Fe, Mn, and Zn, respectively. The concentrations determined in the stem and leaf of the mangrove species varied according to the collection point and the tissue, being consistent with other studies. The proposed procedure was efficient and reliable for elemental determination in plant samples, with the advantages of low cost and reagent consumption besides short analysis time as a valid alternative to the conventional sample preparation procedure.