A polypyrrole-cotton pad sorbent as micro-solid phase extractor enclosed in tea bag envelope for determination of synthetic antioxidants in non-alcoholic beverage products.

A polypyrrole (PPy)-cotton pad sorbent enclosed in tea bag envelope was developed and used in micro-solid phase extraction (µ-SPE) for the determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). After extraction, the extract was qualified and quantified by a gas chromatograph equipped with a flame ionization detector (GC-FID). Parameters influencing this developed method and the efficiency of µ-SPE were studied and optimized. Under the optimal conditions, the developed method provided good linearity in a concentration range of 0.100-100 µg L-1 for BHA and 0.050-50 µg L-1 for BHT, respectively. The limits of detection were 39.27 ± 0.52 ng L-1 for BHA and 16.96 ± 0.17 ng L-1 for BHT. Satisfactory relative recoveries of BHA and BHT were achieved in the range from 86.8 ± 1.9 to 117.1 ± 2.3% with acceptable relative standard deviation (RSD) below 8.1%. Good reproducibility was obtained with RSDs < 3.1%, for n = 6. The developed adsorbent is easy to operate, low cost, eco-friendly, reusable, with high extraction efficiency, and was successfully applied in the simultaneous synthetic antioxidant determination of non-alcoholic beverage samples.

Direct determination of ethanol in alcoholic beverages based on its anti-aggregation of melamine-silver nanoparticle assembly.

We report a new method for determination of ethanol based on anti-aggregation of silver nanoparticles (AgNPs) in the presence of melamine. In the system, ethanol and melamine act as protecting and aggregating agents, respectively. Melamine can induce citrate-stabilized AgNPs to aggregate, leading to a color change from yellow to green. However, if the AgNPs are pre-incubated in ethanol, ethanol readily surrounds the particles by forming hydrogen bonds with the citrate stabilizer. An external nanoshell of ethanol hinders particle aggregation caused by melamine. Minor aggregation of AgNPs was observed, the solution color maintained its yellow-orange color. Higher ethanol concentrations result in a lower degree of particle aggregation. The colorimetric response of AgNPs was monitored using a UV-vis spectrophotometer at 390 nm. The current method could determine ethanol concentrations over a wide dynamic range of 5-80% (v/v), with a detection limit of 3.1% (v/v) (3SD of blank/slope). This method was applied for direct quantification of ethanol in alcoholic drinks without sample pretreatment and the results are well correlated with those of gas chromatography. Our method is convenient and cost effective, making it auspicious for ethanol monitoring in alcoholic drink manufacture and control.

Simplified fabrication of laminated paper-based analytical device (LPAD) with color-palette mobile app for analysis of salicylic acid in pharmaceutical products.

In this work, we present for the first time, a simplified fabrication of a laminated paper-based analytical device (LPAD) with a free-mobile app, Palette Cam, for image analysis. A filter paper is cut in a rectangular shape (9 × 3 cm) and placed between a top laminating sheet with punched holes and a bottom laminating sheet. The holes allow accessibility of liquid on the paper. Thermal lamination is then employed to complete the fabrication of LPAD. Our simplified design reduces a tedious alignment of small pieces of paper to the holes. We demonstrated the LPAD with an analysis of salicylic acid in pharmaceutical products. Each 4 µL of ferric reagent and sample was dispensed on the LPAD. Smartphone was used to capture images. The RGB (red green blue) color intensity from the Palette Cam was converted into a logarithm color ratio. Our LPAD is simplified, cost-effective and able to be a portable device.

Direct assessment of very-low-density lipoprotein by mass sensitive sensor with molecularly imprinted polymers.

Very-low-density lipoprotein (VLDL) contributes to the buildup of atherosclerotic plaque in the arteries and can lead to coronary heart disease. In clinical laboratory testing, the cholesterol content of VLDL (VLDL-C) cannot be assessed directly by the enzymatic colorimetric assay as it can for other lipoproteins, due to lack of a specific sample pretreatment technique. VLDL concentration relies on analyzing the endogenous triglycerides (TGs) bound in its particles and then converting to the VLDL-C estimate TGs/5. This estimation is valid for at least 12 h-fasted serum when exogenous TGs attached to chylomicrons (CMs) have been cleared from the circulation. A quartz crystal microbalance (QCM)-based sensor was generated using biomimetic sensing elements as a molecularly imprinted polymer (MIP) to directly measure actual VLDL. A novel VLDL-MIP was synthesized using methacrylic acid (MAA) and N-vinylpyrrolidone (VP) in the ratio 1:1 (v/v) as functional monomers in the presence of N, N'-(1,2-dihydroxyethylene) bis(acrylamide) (DHEBA) as a crosslinking agent. The VLDL-MIP sensor showed high sensitivity with a linear response from 2.5 mg dL-1 to 100 mg dL-1 of VLDL-C with a limit of detection at 1.5 mg dL-1. Recoveries of 96-103% were achieved when the VLDL-MIP sensor was used for VLDL assessment at 38-71 mg dL-1 concentrations. Repeatability and reproducibility of the sensor were very good with coefficients of variation at 1.63-4.74% and 4.25-9.04%, respectively. The sensor demonstrated low cross-reactivity with other lipoproteins; 6-7% of low-density lipoprotein (LDL) signals, 2-4% high-density lipoprotein (HDL), and 1% CMs compared to the signal of VLDL. Sensor results for 12 h-fasted serum and non-fasted serum correlated well with VLDL estimates TGs/5, with coefficients of determination (R2) at 0.9967 and 0.9932, respectively. This new sensor offers a new strategy for direct VLDL assessment from non-fasted serum without other sample pretreatment steps than dilution.

Magnetic microsphere sorbent on CaCO3 templates: Simple synthesis and efficient extraction of trace carbamate pesticides in fresh produce.

Polypyrrole magnetic microspheres were synthesized and used to extract carbaryl, carbofuran, and methomyl before analysis by a high-performance liquid chromatography with diode array detection. Under optimal conditions, four times the preconcentration was achieved with the use of only 1.2 mL of sample. Good linearity with ranges of 3.0-7.5 × 103, 6.0-4.5 × 103, and 15-3.0 × 103 ng kg-1 and limits of detection of 1.37 ± 0.10, 4.7 ± 1.2, and 10.1 ± 5.7 ng kg-1 were obtained, respectively. Good reproducibility (RSDs < 5%) was achieved over 24 cycles of extraction and regeneration. Good accuracy (recoveries 81.6 ± 1.5%-108.3 ± 2.2%) and good precision (RSDs 0.11%-4.5%) were obtained. Carbaryl was detected in apple (2.75 ± 0.23 ng kg-1), carbofuran in tomato (11.34 ± 0.61 ng kg-1), and methomyl in watermelon (34.7 ± 1.7 ng kg-1). The relative expanded uncertainty of the measurement method was less than 14% for all three pesticides.

A novel 3D-printed solid phase microextraction device equipped with silver-polyaniline coated pencil lead for the extraction of phthalate esters in cosmeceutical products.

A screw-based portable and simple solid phase microextraction device was fabricated by a 3D printer and used in combination with the developed silver-incorporated porous polyaniline film pencil lead solid-phase microextraction fiber (Ag/PANI SPME). Scanning electron microscopy revealed a porous structure of the electrodeposited Ag/PANI film. The spectrum from energy dispersive x-ray spectroscopy (EDS) and the elemental map confirmed the presence of silver in the porous polymer film. It was used under stirring for the extraction of five phthalate esters: dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP) and di-2-ethylhexyl phthalate (DEHP). The extracted solution was identified and quantified by gas chromatography using a flame ionization detector (GC-FID). Under the optimum conditions of the developed method, a good linearity was obtained in a concentration range of 5.0-1000 µg L-1 for all five phthalate esters with limits of detection (LODs) of 4.41 ±â€¯0.91 µg L-1, 3.98 ±â€¯0.92 µg L-1, 3.65 ±â€¯0.74 µg L-1, 4.91 ±â€¯0.52 µg L-1 and 4.25 ±â€¯0.66 µg L-1 for DMP, DEP, DBP, BBP and DEHP, respectively. The developed method provided good precision when tested with standard solutions (RSD < 5.5%, n = 6) and real samples (RSD < 3.4%, n = 6). Good fiber-to-fiber reproducibility was also confirmed by extraction with six newly prepared fibers; recoveries ranged from 81.09 ±â€¯0.54% to 92.92 ±â€¯0.46% with RSD <6.6%. The developed method was used to determine phthalate esters in 14 cosmeceutical samples. In rubbing alcohol samples, DEP and DEHP were detected at 7.03 ±â€¯0.76 µg L-1 and 5.89 ±â€¯0.53 µg L-1, respectively, while in contact lens cleaners, DEHP was found in a concentration range from 5.3 ±â€¯1.1 µg L-1 to 6.8 ±â€¯1.2 µg L-1. No phthalate esters contamination was detectable in saline solutions, eye cleaners and antibacterial disinfectant liquids. Recoveries in the range of 81.92 ±â€¯0.99% to 102.4 ±â€¯1.1% indicated the good accuracy of the developed method.

Zone fluidics for measurement of octanol-water partition coefficient of drugs.

A novel zone fluidics (ZF) system for the determination of the octanol-water partition coefficient (Pow) of drugs was developed. The ZF system consisted of a syringe pump with a selection valve, a holding column, a silica capillary flow-cell and an in-line spectrophotometer. Exact microliter volumes of solvents (octanol and phosphate buffer saline) and a solution of the drug, sandwiched between air segments, were sequentially loaded into the vertically aligned holding column. Distribution of the drug between the aqueous and octanol phases occurred by the oscillation movement of the syringe pump piston. Phase separation occurred due to the difference in densities. The liquid zones were then pushed into the detection flow cell. In this method, absorbance measurements in only one of the phase (octanol or aqueous) were employed, which together with the volumes of the solvents and pure drug sample, allowed the calculation of the Pow. The developed system was applied to the determination of the Pow of some common drugs. The log (Pow) values agreed well with a batch method (R(2)=0.999) and literature (R(2)=0.997). Standard deviations for intra- and inter-day analyses were both less than 0.1log unit. This ZF system provides a robust and automated method for screening of Pow values in the drug discovery process.