•Synthetic dyes determination in yogurts and milk drinks using HPLC–DAD.•Extraction of colorants from samples employed MeOH:NH4OH.•All samples had concentrations below the maximum level allowed for ...use in yogurt.•Recovery for 10 synthetic dyes was in the range of 83.2–110.5%.
This article reports on a method to determine synthetic dyes in yogurts and milk drinks. Initially a method for extraction of artificial dyes was developed to pretreat samples in order to extract most of the artificial colorants. Then, the colorants were analyzed by HPLC–PAD using gradient elutions. The method was linear in the range of 0.5–25mgL−1 colorants (0.9991<R2<0.9998), with LOD of 0.18–4.58μgL−1. The results recovery test on two levels ranged from 82% to 115%. The reference solution of the analytes remained stable for 3months. In the yogurt samples analyzed, the dye E122 (1.4–11.75mgL−1) was found in most samples, followed by dye E123 (3.12 and 12.56mgL−1). All samples had concentrations below the maximum level allowed for use in yogurt (100mg/100g dyes).
Poly (ethylene terephthalate)-PET is a thermoplastic polymer that occupies a significant place in the food and medicine market, where PET pellets are used in the manufacturing of packages. ...One-quality criterium for PET is the control of inorganic contaminants, which is indispensable for quality control and the safety of the final plastic product. The present study proposes a microwave-assisted decomposition methodology using diluted acid mixtures, for better quantification of boron (B), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), magnesium (Mg), sodium (Na), phosphorus (P), and lead (Pb) in pellets of PET resin, purchased in Pernambuco, Brazil, and analyzed by inductively coupled plasma optical emission spectrometry (ICP OES). In order to overcome the difficulties faced in the pellet’s decomposition and the detection of the inorganic content by ICP OES, an experimental design was carried out, using the strategy of polar coordinates as a statistical tool for the simultaneous analysis of mixing and processing variables. The following optimal parameters were established after full factorial design: 100 mg of resin and 10 mL of a digesting mixture composed of 40% water, 54% of nitric acid and 6% of sulfuric acid, digestion time of 20 min with heating at 220 ºC. The resins analyzed in this study showed higher levels of Ba (0.79 µg g
−1
) and Pb (1.64 µg g
−1
), compared to other studies in the literature.
A cold vapor atomic fluorescence spectrometry method (CV-AFS) has been developed for the determination of Hg in rice samples at a few ng
g
−1 concentration level. The method is based on the previous ...digestion of samples in a microwave oven with HNO
3 and H
2O
2 followed by dilution with water containing KBr/KBrO
3 and hydroxylamine and reduction with SnCl
2 in HCl using external calibration. The matrix interferences and the effect of nitrogen oxide vapors have been evaluated and the method validated using a certified reference material. The limit of detection of the method was 0.9
ng
g
−1 with a recovery percentage of 95
±
4% at an added concentration of 5
ng
g
−1. The concentration level of Hg found in 24 natural rice samples from different origin ranged between 1.3 and 7.8
ng
g
−1.
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.
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•Direct analysis of Hg in nuts has been improved by a previous fat removal.•Comparison of cold vapour atomic fluorescence and direct analysis of Hg in nuts.•Mercury content in tree ...nuts was determined.
Total mercury, at μgkg−1 level, was determined in different types of nuts (cashew nut, Brazil nuts, almond, pistachio, peanut, walnut) using a direct mercury analyser after previous sample defatting and by cold vapour atomic fluorescence spectrometry. There is not enough sensitivity in the second approach to determine Hg in previously digested samples due to the strong matrix effect. Mercury levels in 25 edible nut samples from Brazil and Spain were found in the range from 0.6 to 2.7μgkg−1 by using the pyrolysis of sample after the extraction of the nut fat. The accuracy of the proposed method was confirmed by analysing certified reference materials of Coal Fly Ash-NIST SRM 1633b, Fucus-IAEA 140 and three unpolished Rice Flour NIES-10. The observed results were in good agreement with the certified values. The recoveries of different amounts of mercury added to nut samples ranged from 94 to 101%. RSD values corresponding to three measurements varied between 2.0 and 14% and the limit of detection and quantification of the method were 0.08 and 0.3μgkg−1, 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.
The fluorescence quenching of TGA-CdSe quantum dots (QDs) was used for Cr(3+) quantification in vitamin supplements. The QD was electrochemically synthesized, demonstrating high reproducibility with ...control of particle size, thus making it a clean method, without the presence of reducing agents. Under ideal conditions, with the fluorescence band at 551 nm (excitation 365 nm), the maximum fluorescence quenching was observed at pH 4.0, with a time of 200 s for each data acquisition. Under optimum experimental conditions, linear quenching was observed for Cr(3+) in the range of 25.0-325.0 ng L(-1) (R=0.9996, n=6), a limit of detection of 5.67 ng L(-1), and relative standard deviation of 4.43% (n=10). The recovery test for Cr(3+) quantification in vitamin supplements presented results from 82% to 98%. These Cr(3+) determination results were compared to the same vitamin supplement sample using flame atomic absortion spectrometry (FAAS) method, and no significant differences were observed at 95% confidence level.
Dry decomposition, wet digestion, and dissolution in aqueous medium for direct analysis were evaluated for the preparation of eight samples of liquid and bar soap and one powder detergent for later ...determination of Cd, Mg, Pb, and Zn by inductively coupled plasma optical emission spectroscopy (ICP OES). The evaluation of the best conditions for digestion of the samples were chosen from a set of tests where conventional heating using 1 mol L-1 HNO3 with addition of 30% H2O2 proved to be the most efficient method. The average hydrodynamic diameter of 525 nm was determined using dynamic light scattering measurements. The concentrations found were: Cd and Pb (< limit of detection (LOD)), Mg (50.89 to 1119 μg g-1), and Zn (280.25 to 537.54 μg g-1). After evaluating the sample preparation methods, the accuracy of the methodology was verified through recovery tests of analytes, obtaining values between 83 and 119% and a relative standard deviation (RSD) ≤ 4.30% (n = 6; 4 mg L-1). The LOD ranged from 0.015 to 0.5 µg g-1 and the limits of quantification (LOQ) from 0.045 to 2 µg g-1. The soaps and powder detergent samples studied here may be used without any harm to health as the contents were within the limits established by the legislation.
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 work describes determining urea in milk samples using a multicommuted approach with a urease enzyme immobilized in bacterial cellulose and solid MOF as a colorimetric reagent. The Cu(2+)-MOF was ...characterized by FTIR spectroscopy, XRD, and SEM. The urea quantification was based on the urea hydrolysis reaction catalyzed by urease and reacted with Cu(2+)-MOF forming Cu(NH3)42+, monitored at 450 nm. Linear responses were obtained from 1.0 to 50.0 mg dL−1 urea (R = 0.9959, n = 11), detection and quantitation limits of 0.082 mg dL−1 and 0.272 mg dL−1 respectively, analytical frequency of 8 determinations per hour, 0.8 mL sample solution consumption. Potential interfering studies have shown the selectivity of the proposed method. Addition and recovery tests were performed obtaining variation from 90 to 103%. Applying the F-test and t-test, the results showed no significant difference at the 95% confidence level Comparing the proposed and the reference method.
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•Cu(2+)-MOF was used as an enzyme-based sensor for colorimetric detection of urea in milk.•The flow system using cellulose-immobilized urease in bacterial cellulose (BC).•Detection (LD) and quantification limits (LQ) were estimated at 0.082 mg dL−1 and 0.272 mg dL−1, respectively.•The analytical system has a significant reduction in reaction time and quantity of reagents.•The proposed analysis system is simple, versatile, and robust way and is viable to determine the urea in milk.
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