The use of slurry sampling for the determination of manganese and copper in various samples by electrothermal atomic absorption spectrometry

Evaluation of slurry sampling preparation of enteral nutrition formulations for multielement determination using inductively coupled plasma optical emission spectrometry

An analytical procedure for the multielement determination in enteral nutrition formulations employing slurry sampling and inductively coupled plasma optical emission spectrometry (ICP OES) is proposed. A two-level full-factorial design was applied to assess the influence of the presence of stabilizing agents (HNO₃, Triton X-100 and ethanol) on the composition of the slurry. Multiple response was established as a dependent variable. The experimental conditions for the preparation of the slurry were: 2.0 mL of sample and 8.0 mL of 10% (v/v) HNO₃. The limits of detection (LOD) were 5; 9; and 10 µg L^-1 for Cu, Fe, Zn, respectively. For P, and K, the LOD were 8 and 24 mg L^-1, respectively. The method was applied for the analysis of three enteral nutrition formulation samples and the obtained concentrations ranges were (in mg L^-1): 0.41-0.43 (Cu), 2.0-2.9 (Fe), 1.7-3.1 (Zn), 682-1409 (K), and 217-344 (P).

Determination of lead in human placenta tissue employing slurry sampling and detection by electrothermal atomic absorption spectrometry

A new analytical procedure was developed for the determination of lead in human placental tissue by direct ultrasonic slurry sampling combined with electrothermal atomic absorption spectrometry (SS-ET AAS). Samples of dried and crushed placental tissue were mixed with 10 mL of 0.20% (v/v) HNO₃ and homogenised. The slurries were then transferred to autosampler cups where they were sonicated using an ultrasonic probe prior to injection into a graphite tube with an L'vov platform. The effects of several chemical modifiers, including Mg(NO₃)₂, Pd(NO₃)₂, and NH₄H₂PO₄, were investigated for the stabilisation of lead during thermal pre-treatment. Lead in the slurries was effectively stabilised up to 1200 °C with the Pd(NO₃)₂ modifier providing the best results with complete atomisation at 1900 °C. H₂O₂ was used as a chemical modifier; dilute HNO₃ and HCl were examined as slurry media. The limit of detection and the limit of quantification for lead obtained under optimised conditions were 0.17 μg g^-1 and 0.56 μg g^-1, respectively. The relative standard deviation estimated from twenty replicate measurements of spike solution at a concentration of 50.00 μg L^-1 for lead was 1.51%. The accuracy of the method was confirmed by analysis of the standard reference material BCR 185R "Bovine Liver". The proposed technique is simple, sensitive and environmentally friendly, and the risk of contamination is low. The method was applied to lead determination in real samples of human placental tissue. The 14 samples were taken just after delivery at the Gynaecology and Obstetrics Department of the Faculty Hospital with Outpatients Clinic in Bratislava over the course of 2019.

In situ trapping of As, Sb and Se hydrides on nanometer-sized ceria-coated iron oxide-silica and slurry suspension introduction to ICP-OES

A procedure is developed for the analysis of sub-μg L(-1) levels of arsenic, antimony and selenium after preconcentration of their hydrides. The study highlights the capability of an aqueous suspension of a nanometer-sized magnetic ceria, in the presence of iodide, to function as a sorbent for the in situ trapping and preconcentration of the hydrides of certain metalloids. After extraction, the material is magnetically separated from the trapping solution and analyzed. A slurry suspension sampling approach with inductively coupled plasma-optical emission spectrometry (ICP-OES) is employed for measurements, as the quantitative elution of the adsorbed metalloids is not feasible. The whole analytical procedure consists of five steps: (i) pre-reduction of As, Sb and Se, (ii) generation of the hydrides AsH3, SbH3 and SeH2, (iii) in situ collection in the trapping suspension of magnetic ceria, (iv) isolation of the particles by applying a magnetic field, and (v) measurement of As, Sb and Se concentrations using ICP-OES. Under the established experimental conditions, the efficiency of trapping accounted for 94 ± 2%, 89 ± 2% and 98 ± 3% for As, Sb and Se, respectively, signifying the effective implementation of the overall procedure. The applicability of the procedure has been demonstrated by analyzing tap and lake water and a reference material (soft drinking water). The obtained analytical figures of merit were satisfactory for the analysis of the above metalloids in natural waters by ICP-OES.

Evaluation and simulation of silver and copper nanoparticle migration from polyethylene nanocomposites to food and an associated exposure assessment

Silver nanoparticles (nanosilver) and copper nanoparticles (nanocopper) exhibit antimicrobial activity and have been incorporated into polymers to create antimicrobial packaging materials. Their use in conjunction with food has caused concerns regarding the potential risk of particle migration, resulting in human exposure to nanoparticles. A migration experiment was carried out to investigate the effect of time and temperature on the migration of nanosilver and nanocopper particles from polyethylene (PE) nanocomposites to boneless chicken breasts. Migration of silver ranged from 0.003 to 0.005 mg/dm², while migration of copper ranged from 0.024 to 0.049 mg/dm², for a set of four different scenarios representing typical storage conditions. Effects of time and temperature were not significant (p > 0.1). A migration and exposure model was developed on the basis of mathematical relationships defining migratability and subsequent migratables using the Williams-Landel-Ferry equation for time-temperature superposition. The results of the model accurately predicted the nanosilver levels detected in the laboratory migration tests (R values ranging from 0.43 to 0.99); however, the model was less accurate in predicting nanocopper levels (R values ranging from 0.65 to 0.99), probably because of the highly variable background levels of copper observed in the real food matrix. The 95th percentile of the simulated human exposure to nanosilver based on laboratory experimental results of four scenarios ranged from 5.89 × 10⁻⁵ to 8.9 × 10⁻⁵ mg kg(bw)⁻¹ day⁻¹. For the measured migration of copper under the same storage conditions, the exposure ranged from 2.26 × 10⁻⁵ to 1.17 × 10⁻⁴ mg kg(bw)⁻¹ day⁻¹. This study highlights the potential migration of nanoparticles from PE composite packaging to a food material and the potential for simulation models to accurately capture this migration potential; however, variable background levels of copper in the food matrix can make prediction more difficult for trace migration of nanocopper.

Dispersive liquid-liquid microextraction for the determination of copper in cereals and vegetable food samples using flame atomic absorption spectrometry

Dispersive liquid-liquid microextraction (DLLME) is applied for the determination of copper in cereals and vegetable food samples using flame atomic absorption spectrometry (FAAS). The maximum extraction efficiency of copper was obtained after the optimisation of parameters such as extraction and dispersing solvents, pH, concentration of 2,9-dimethyl-1,10-phenanothroline (DPT), N-phenylbenzimidoyl thiourea (PBITU) and salt. The optimised methodology exhibited a good linearity in the range of 0.2-20 ng/mL copper with relative standard deviations percentage (RSD,%) from ±1.5% to 3.5%. The method is found to be simple and rapid for the analysis of copper in food samples with the limit of detection (LOD) and quantitation (LOQ) were 0.05 and 0.16 ng/mL, respectively. Good recoveries of copper were obtained in the range of 93.5-98.0% in food samples as well as in Certified Reference Material (99.1%). The application of the proposed method has been successfully tested for the determination of copper in cereals (maize, millet, rice, wheat, gram, lentils, kidney beans and green beans) and vegetable (potato, cauliflower, tomato, spinach, green beans, lettuce, egg plants and bitter gourd) food samples.

Slurry analysis of cadmium and copper collected on 11-mercaptoundecanoic acid modified TiO2 core-Au shell nanoparticles by flame atomic absorption spectrometry

Separation/preconcentration of copper and cadmium using TiO(2) core-Au shell nanoparticles modified with 11-mercaptoundecanoic acid and their slurry analysis by flame atomic absorption spectrometry were described. For this purpose, at first, titanium dioxide nanoparticles were coated with gold shell by reducing the chloroauric acid with sodium borohydride and then modified with 11-mercaptoundecanoic acid. The characterization of modified nanoparticles was performed using ultra-violet spectroscopy and dynamic light scattering. Copper and cadmium were then collected on the prepared sorbent by batch method. The solid phase loaded with the analytes was separated by centrifugation and the supernatant was removed. Finally, the precipitate was slurried and directly aspirated into the flame for the determination of analytes. Thus, elution step and its all drawbacks were eliminated. The effects of pH, amount of sorbent, slurry volume, sample volume and diverse ions on the recovery were investigated. After optimization of experimental parameters, the analytes in different certified reference materials and spiked water samples were quantitatively recovered with 5% RSD. The analytes were enriched up to 20-fold. Limits of detection (N=10, 3σ) for copper and cadmium were 0.28 and 0.15 ng mL(-1), respectively.

Slurry analysis after lead collection on a sorbent and its determination by electrothermal atomic absorption spectrometry

In this study, in order to eliminate the drawbacks of elution step and to reach higher enrichment factors, a novel preconcentration/separation technique for the slurry analysis of sorbent loaded with lead prior to its determination by electrothermal atomic absorption spectrometry was described. For this purpose, at first, lead was collected on ethylene glycol dimethacrylate methacrylic acid copolymer (EGDMA-MA) treated with ammonium pyrolidine dithiocarbamate (APDC) by conventional batch technique. After separation of liquid phase, slurry of the sorbent was prepared and directly pipetted into graphite furnace of atomic absorption spectrophotometer. Optimum conditions for quantitative sorption and preparation of the slurry were investigated. A 100-fold enrichment factor could be easily reached. The analyte element in certified sea-water and Bovine-liver samples was determined in the range of 95% confidence level. The proposed technique was fast and simple and the risks of contamination and analyte loss were low. Detection limit (3delta) for Pb was 1.67 microg l(-1).