•Nine elements were determined in seventy-seven different rice samples using ICP OES.•Rice mass of 500 mg was digested with only 5 mL of 1 mol L−1 HNO3 and 2.5 mL of H2O2.•Digestion method was ...efficient, economical, greener and with acceptable LOD and LOQ.•Carbon was quantified in solutions and solids using a spectrophotometric method.•Spectrophotometric method indicated as possible alternative to elemental analysis.
A microwave-assisted digestion method using diluted HNO3 was developed for further determination of Al, Ca, Cr, Cu, Fe, K, Mn, Mo and Ni in rice samples by ICP OES. The following optimized conditions were established after full factorial design: digestion time of 14 min, concentration of 1 mol L−1 HNO3 and 2.5 mL of H2O2. The efficiency in decomposing organic matter with diluted acid was higher than 89%. The methodology was validated using the SRM NIST 1568a Rice Flour and recovery tests, with agreement between the determined and certified/added concentration values, and RSD of up to 12%. The limits of detection of the method were in the range of 0.0087 mg kg−1 (Mn) to 1.6 mg kg−1 (Ca). In addition, a simple and inexpensive spectrophotometric method was proposed for the quantification of organic carbon in varied samples (carbohydrates, proteins, lipids) in the form of digested or solids.
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•Fluorimetric determination of formaldehyde using a nickel complex immobilized as a solid phase.•Formaldehyde analysis was able to be conducted in 05 min with a relative standard ...deviation estimated at 1.10 %.•Nickel waste was completely recovered implementing the principles of greener and sustainable chemistry.
Formaldehyde (FA) is a highly toxic substance present in many matrices, including freshwater as well as found in natural mechanisms such as rainfall and combustion of organic matter. Consumption of water contaminated with high levels of FA can cause severe short-term or long-term health problems. Due to these health risks, procedures are necessary to determine and quantify FA in aqua sources This paper reports on a study of fluorimetric determination of FA using a nickel(2 + )-diketonate coordination compound immobilized as a solid precursor. The compound was characterized by electronic absorption, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetry (TG), optical microscopy (OM), and scanner electron microscopy (SEM). The methodology was based on the reaction of the synthesized compound with an ammoniacal buffer generating a selective reagent for formaldehyde: fluoral-P. The product of the reaction generates 3,5-diacetyl-1,4-dihydrolutidine (DDL), which is responsible for the fluorescence of the system. Several parameters such as temperature, duration of heating time, and dilution effect with the best effects were studied to carry out FA determination. Under the optimum experimental conditions, a linear response ranging from 1.0 to 10.0 mg/L FA (R = 0.997 and n = 10), and a detection (3σ criterion) and quantification (10 σ criterion) limit estimated at 0.129 and 0.389 mg/L, respectively were achieved. The FA analysis was able to be conducted in 05 min with a relative standard deviation estimated at 1.10 %.
This work aims to develop a method for the determination of simultaneous bisphenol A, dibutyl phthalates (DBP), bis-2-ethylhexyl (DEHP), di-n-octyl (DNOP) and diisodecyl (DIDP) in utensils and toys ...intended for infants, as well as to evaluate the bioaccessibility of these compounds in artificial saliva. For this purpose, we applied an optimization design of experiments (DOE) for extraction using ultrasound-assisted liquid and detection by high-performance liquid chromatography (HPLC). The method was validated, finding detection limits of 0.0035−0.0512 mg L
−1
for bisphenol A and the phthalates analyzed, linear range from 5 to100 mg L
−1
(
R
2
= 0.9989) and 0.5–10 mg L
−1
(
R
2
= 0.9993) for DIDP and other analytes, respectively. Extraction in an ultrasonic system was performed with chloroform and optimized with a 2
4
full factorial design, defined as 1.50 g of sample in 10 mL of chloroform, extraction time of 20 min and temperature at 65 °C. Matrix effect tests showed that the method did not suffer this type of interference; recovery studies showed values from 74.1 to 114.9%, with relative standard deviations (RSD) less than 9.34% (
n
= 5). Ten samples of toys and utensils for infants were analyzed using the optimized method, and the results presented concentrations between 0.09 and 30.8 mg Kg
−1
and 0.060 and 21.13 mg Kg
−1
for phthalate and bisphenol A, respectively. Migration tests with artificial saliva were performed showing concentrations between 0.06 and 10.3 mg Kg
−1
and 0.01 and 0.3 mg Kg
−1
for phthalates and bisphenol A, respectively.
•Polysiloxane crown ether column for the analysis of trace perchlorate in vegetables.•Multi-commutated flow-analysis concept with potentiometric detection.•Nanomolar perchlorate ...determination.•Perchlorate as an environmental contaminant effectively monitored.
In this work, an expeditious method based on the multi-commutated flow-analysis concept with potentiometric detection is proposed to perform determinations of the emergent contaminant perchlorate in vegetable matrices down to nanomolar concentration. To accomplish the task, a tubular shaped potentiometric sensor selective to perchlorate ion was constructed with a PVC membrane containing 12mmol/kg of the polyamine bisnaphthalimidopropyl-4,4′-diaminodiphenylmethane and 2-nitrophenyl phenyl ether 68% (w/w) as plasticizer casted on a conductive epoxy resin. Under optimal flow conditions, the sensor responded linearly in the concentration range of 6.3×10−7–1.0×10−3mol/L perchlorate. In order to extend the determinations to lower concentrations (4.6(±1.3)×10−10mol/L perchlorate), a column packed with 70mg of sodium 2,5,8,11,14-pentaoxa-1-silacyclotetradecane-polymer was coupled to the flow-system thus enabling prior pre-concentration of the perchlorate. The proposed procedure provides a simpler alternative for the determination of perchlorate in foods, nowadays only allowed by sophisticated and expensive equipment and laborious methods.
This work describes an automated procedure to determine L-malic acid (MA) in wine samples using a multicommuted flow analysis. The MA quantification was based on an enzymatic reaction between MA and ...L-malate dehydrogenase (L-MDH) in the presence of nicotinamide adenine dinucleotide (NAD+), producing nicotinamide adenine dinucleotide dehydrogenase (NADH), which was monitored at 340 nm. The L-MDH was immobilized on a surface of modified silica with amino groups in the presence of glutaraldehyde. For studying optimization, the system was maintained with 200 μL (288 U) of the L-MDH in 0.5 g of modified silica. Under the optimum experimental conditions, a linear response ranging from 0.1 to 1.5 g L−1 MA (R = 0.997 and n = 7), a detection (3σ criterion) and quantification (10σ criterion) limit estimated at 0.02 and 0.06 g L−1, respectively, a standard deviation relative of 1.8% (n = 7) for a sample of 0.5 g L−1 MA, a sampling rate of 67 samples per hour were achieved. Analyzing ten wines samples and applying the t-test to the results found and those obtained using reference procedures (HPLC) provided no significant differences at the 95% confidence level.
•The reagent generation (I3−) in line ensures stability of the pair redox I3−/I−.•The use of a gas diffusion cell minimizes interferences present in the samples.•The simplicity and precision of the ...biamperometric system is suitable for use with real samples.
This work reports an in-line electrochemical reagent generation coupled to a flow injection biamperometric procedure for the determination of SO32−. The method was based on a redox reaction between the I3− and SO32− ions, after the diffusion of SO2 through a gas diffusion chamber. Under optimum experimental conditions, a linear response ranging from 1.0 to 12.0mgL−1 (R=0.9999 and n=7), a detection and quantification limit estimated at 0.26 and 0.86mgL−1, respectively, a standard deviation relative of 0.4% (n=10) for a reference solution of 4.0mgL−1 SO32− and sampling throughput for 40 determinations per hour were achieved. Addition and recovery tests with juice and wine samples were performed resulting in a range between 92% and 110%. There were no significant differences at a 95% confidence level in the analysis of eight samples when comparing the new method with a reference procedure.
In this work a multicommuted flow system for the sequential screening/determination of dichromate, salicylic acid, hydrogen peroxide and starch in milk samples was developed. The concept of ...multicommutation in flow injection analysis was chosen, resulting in an environmentally friendly system with minimal consumption of reagents and waste generation. The proposed approach is based on a simple binary DETECT or NO-DETECT response, thereby making it possible to determine analytes quickly, with high performance and easy operation. For dichromate determination, the proposed method was based on the reaction between Cr(VI) and 1,5-diphenylcarbazide, enabling a linear working range response, between 1.0 and 10.4 mg L−1, (R = 0.999). In order to determine salicylic acid, the proposed method was based on a complexation reaction of Fe(III) and salicylic acid, with the linear working range response from 103.6 to 414.3 mg L−1 (7.5 × 10−4–3.0 × 10−3 mol L−1) (R = 0.999). The hydrogen peroxide determination was based on the oxidation reaction of hydrogen peroxide with vanadium oxide (V) in an acid environment, with a linear working range of 10.0–200.0 mg L−1 (R = 0.996). Starch determination was based on the complex reaction of starch and triiodide, with a linear working range of 12.5–150.0 mg L−1 (R = 0.999). The mean sampling rate for the four species was 83 determinations per hour. Performance curves were used to verify the quantity of false positives and false negatives. Addition and recovery tests were used for validation of the proposed procedures, resulting in variation between 90.1 and 108.7% for three different samples.
•Screening or quantification of adulterants in milk using multicommuted flow system.•The strategy of binary sampling enables the implementation of a sequential procedure.•The performance curve estimated low probability of a false positive occurrence.•The analytical procedure contributed for green analytical technologies.
Recently, consumption of collagen-based foodstuffs has grown significantly, especially collagen hydrolysate, used as a dietary supplement. Information available on the content of essential and toxic ...elements in these products, however, is incipient. This study provides a novel assessment of the mineral profile (Al, As, Ca, Cd, Co, Cr, Fe, K, Mg, Mn, Na, P, S, V, and Zn) of collagen hydrolysate and gelatin by inductively coupled plasma optical emission spectrometry (ICP OES) and mass spectrometry (ICP-MS). Thirty-two samples were digested with diluted HNO
3
and H
2
O
2
, using an efficient microwave-assisted decomposition method (11.9% residual carbon content). The methodology was validated using certified reference materials and recovery tests, with agreement between the determined and certified/added concentration values (85–124%), and relative standard deviation of up to 18%. The limits of quantification ranged from 0.33 μg kg
−1
(Cd) to 24 mg kg
−1
(Na). The contributions of collagen hydrolysate to the Dietary Reference Intake values of the evaluated minerals were low, with the highest value being 13.5% for the Adequate Intake of Cr. The findings of Permitted Daily Exposure suggest that there is no risk of contamination with As and Cd by consuming this food supplement. Concentrations of Cr, Mn, and Zn reported on product labels agreed with experimental results. For Na, these values differed, indicating that a more rigorous quality control of collagen hydrolysate is necessary, in view of the health problems caused by excessive consumption of this element.
Graphical abstract
In this work, carbon dots (CDs) prepared by a one-step hydrothermal method were employed for the determination of quercetin in teas and beers. The fluorescence quenching of CDs was proportional to ...the concentration of quercetin. Under optimum experimental conditions, linear quenching was observed for quercetin in the range of 1.0 to 10 mg L-1 (F/F0 = (0.1511 ± 0.0075)Q + (0.8922 ± 0.0384), R2 = 0.9926), at room temperature, using 80 μL CDs and 0.1 mol L-1 Na2HPO4/NaOH buffer solution (pH 11.0). A limit of detection (3σ criterion) of 0.85 mg L-1, and a relative standard deviation of 0.21% (n = 3) for 4.0 mg L-1 quercetin solution was obtained. Addition and recovery tests with tea and beer samples were performed resulting in recoveries at the range between 80 and 118%. This procedure served successfully to determine quercetin in beer and tea samples presenting high sample throughput.
This article presents the synthesis, characterization and spectroscopic study of silica modified with thenoyltrifluoroacetonate (SilTTA) and coordinated to an europium (III) ion, for the ...determination of sialic acid (NANA). Elemental analysis and infrared spectroscopy suggest silica functionalization, as well as coordination of beta-diketone to the lanthanide ion. The emission spectra of compound-free and coordinated Eu-SilTTA to NANA showed significant changes with respect to the maximum emission and spectral profile, suggesting that the NANA ion is coordinated to the Eu(III). The values of the phenomenological intensity parameters show an increase in polarizability around the Eu(III) in the case of Eu-SilTTA coordinated to NANA, as expected, since water molecules are less polarizable than sialic acid. The results of the batch assay showed that luminescent silica can be used for sialic acid determination in milk-adulterated samples, with a correlation coefficient of 0.9992; and a detection limit of 0.4 mg/L; relative standard deviation (RSD%) = 0.0028.
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