Dynamic ultrasound-assisted extraction coupled on-line with solid support derivatization and high-performance liquid chromatography for the determination of formaldehyde in textiles

Green Extraction Processes for Complex Samples from Vegetable Matrices Coupled with On-Line Detection System: A Critical Review

The detection of analytes in complex organic matrices requires a series of analytical steps to obtain a reliable analysis. Sample preparation can be the most time-consuming, prolonged, and error-prone step, reducing the reliability of the investigation. This review aims to discuss the advantages and limitations of extracting bioactive compounds, sample preparation techniques, automation, and coupling with on-line detection. This review also evaluates all publications on this topic through a longitudinal bibliometric analysis, applying statistical and mathematical methods to analyze the trends, perspectives, and hot topics of this research area. Furthermore, state-of-the-art green extraction techniques for complex samples from vegetable matrices coupled with analysis systems are presented. Among the extraction techniques for liquid samples, solid-phase extraction was the most common for combined systems in the scientific literature. In contrast, for on-line extraction systems applied for solid samples, supercritical fluid extraction, ultrasound-assisted extraction, microwave-assisted extraction, and pressurized liquid extraction were the most frequent green extraction techniques.

Occurrence, behavior, and fate of organophosphate esters (OPEs) in subtropical paddy field environment: A case study in Nanning City of South China

Occurrence, behavior, and fate of 11 OPEs in multiple environmental matrices, which include air, rainwater, dustfall, paddy soil, irrigation water, and rice plants from nine subtropical paddy fields of South China, were investigated. The total concentrations of 11 OPEs (∑₁₁OPEs) in all matrices are generally higher in the urban areas than in rural areas, and they are higher in summer than in fall. However, both urban and rural areas showed a similar composition profile of OPEs, indicating that the OPEs come from similar sources in the two areas. Except for irrigation water, significant positive correlations of ∑₁₁OPEs were observed between air and the other five matrices. The exchange and partition of OPEs among air, soil, and water demonstrate that most of OPEs were transferred from air into water and soil, and from water into soil. Thus, the air may be an important source of OPEs in the paddy fields, and the soil may act as a principal environmental reservoir of OPEs. The contribution of air-soil exchange, atmospheric deposition (rainwater plus dustfall), and irrigation water to the total input fluxes of OPEs (2100 ± 980 ng/m²/day) reached an average of 19%, 38% (37% + 1%), and 43%, respectively. The water (rainwater plus irrigation water) is the primary medium transferring the OPEs into the paddy fields and contributed to the input flux by 80%. Output flux of OPEs via mature rice plants was about 220 μg/m², 2% of which were presented in rice, and the remaining 98% may be re-released into the environment through the pathway of straw turnover or burning. Dietary exposure via rice was much higher than inhalation exposure, dust ingestion, and dermal absorption via dust. However, no data shows that all of the intakes via the four exposure pathways could cause the risks to human health at present.

On-line extraction coupled to liquid chromatographic analysis of hydrophobic organic compounds from complex solid samples-Application to the analysis of UV filters in soils and sediments

This work investigates the applicability of on-line extraction (OLE) directly coupled to liquid chromatography (LC) for the dynamic extraction of hydrophobic organic compounds from complex solid samples. The method operates within the existing apparatus of the LC by replacing the valve loop with an extraction vessel comprised of an empty guard column loaded with the sample. In this manner, extraction is accomplished by the mobile phase as it flows through the extraction vessel under high pressure without the need for additional apparatus other than those comprising the LC system or additional sample pretreatment steps. The experimental parameters affecting the extraction efficiency of the method were investigated and discussed in relation to both the extraction performance and the chromatographic efficiency. The method was optimized and applied for the first time to the extraction of hydrophobic UV filters from spiked soil and sediment samples yielding recoveries between 59 and 117% and reproducibility from 4.8 to 14.3%, which are comparable to those reported from more advanced sample preparation methods.

A novel mass spectrometric method for formaldehyde in children's personal-care products and water via derivatization with acetylacetone

RATIONALE

New legislation in the state of Minnesota prohibits the sale of children's personal-care products (PCPs) that contain more than 500 ng/mg formaldehyde. Previous attempts to quantify formaldehyde in PCPs use nonspecific derivatization procedures that employ harsh reagents and/or nonspecific detection. Derivatization of formaldehyde by acetylacetone occurs under mild conditions and is specific for formaldehyde but it has not been investigated using high-performance liquid chromatography/tandem mass-spectrometry (HPLC/MS/MS).

METHODS

To determine formaldehyde, PCPs were dissolved and then interferences were minimized by graphitized-carbon solid-phase extraction. Formaldehyde was derivatized to 3,5-diacetyl-1,4-dihydrolutidine (DDL) using an acetylacetone solution. Post-derivatization, samples were diluted and analyzed by HPLC/MS/MS. Quantification was performed by isotopic dilution. Product-ion spectra were acquired for DDL and D₁₂ -DDL. The mass shifts between the two product-ion spectra were used to assign fragment structures. To confirm molecular formulas, high-resolution accurate-mass analysis of the DDL product ions was performed by quadrupole time-of-flight MS.

RESULTS

Structures were proposed for all product ions of DDL above 10% relative intensity. Method accuracy ranged between 96-104% for all matrices at all concentrations tested. Method precision was less than 4% relative standard deviation. The reporting limit was 10 ng/mg in PCPs and 100 μg/L in water. Twenty children's PCPs were tested to demonstrate the method and formaldehyde was reported in five from 23-1500 ng/mg. Of those five, two samples contained formaldehyde above the Minnesota regulatory limit.

CONCLUSIONS

The developed method allows for the accurate quantification of formaldehyde in PCPs at levels below those required by a new regulation on children's products in Minnesota. The method includes a derivatization procedure that is newly adapted to HPLC/MS/MS; therefore, structures were proposed for the product ions of the derivative (DDL). Copyright © 2017 John Wiley & Sons, Ltd.

Extraction and preconcentration of formaldehyde in water by polypyrrole-coated magnetic nanoparticles and determination by high-performance liquid chromatography

In this study, a simple and rapid extraction method based on the application of polypyrrole-coated Fe3 O4 nanoparticles as a magnetic solid-phase extraction sorbent was successfully developed for the extraction and preconcentration of trace amounts of formaldehyde after derivatization with 2,4-dinitrophenylhydrazine. The analyses were performed by high-performance liquid chromatography followed by UV detection. Several variables affecting the extraction efficiency of the formaldehyde, i.e., sample pH, amount of sorbent, salt concentration, extraction time and desorption conditions were investigated and optimized. The best working conditions were as follows: sample pH, 5; amount of sorbent, 40 mg; NaCl concentration, 20% w/v; sample volume, 20 mL; extraction time, 12 min; and 100 μL of methanol for desorption of the formaldehyde within 3 min. Under the optimal conditions, the performance of the proposed method was studied in terms of linear dynamic range (10-500 μg/L), correlation coefficient (R(2) ≥ 0.998), precision (RSD% ≤ 5.5) and limit of detection (4 μg/L). Finally, the developed method was successfully applied for extraction and determination of formaldehyde in tap, rain and tomato water samples, and satisfactory results were obtained.

Investigation on formaldehyde release from preservatives in cosmetics

OBJECTIVE

To understand formaldehyde residue in cosmetics, an investigation on formaldehyde release from eight preservatives (methenamine - MA, paraformaldehyde - PF, poly(p-toluenesulfonamide-co-formaldehyde) -PTSAF, quaternium-15 - QU, imidazolidinyl urea - IU, diazolidinyl urea - DU, dimethyloldimethyl hydantoin - DMDM and bronopol - BP) under various conditions was performed.

METHODS

The concentration of released formaldehyde was determined by high-performance liquid chromatography with photodiode array detection after derivatization with 2,4-dinitrophenylhydrazine.

RESULTS

The amounts of formaldehyde release were in the order of PF > DU > DMDM ≈ QU ≈ IU > MA > BP > PTSAF. The releasing amounts of formaldehyde were the highest in the presence of aqueous matrices for the releasers except QU and IU, and the releasing effect was also relative to pH. More formaldehyde was released with longer storage time and higher temperature. Furthermore, all preservatives in cosmetic matrices released fewer amounts of formaldehyde than in pure aqueous or organic matrices, and the formaldehyde-releasing amounts were also cosmetic specific.

CONCLUSION

Formaldehyde release was dependent on the matrix, pH, time and mainly temperature, and the releasing effect was also cosmetic specific.

A review on textile sonoprocessing: a special focus on sonosynthesis of nanomaterials on textile substrates

The chemical and physical effects of ultrasound with a frequency above 16kHz, higher than the audible frequency of the human ear, have proven to be a useful tool for variety of systems ranging from the application of ultrasound in environmental remediation to the cooperation of ultrasound waves with chemical processing regarding as sonochemistry. Ultrasound opened up new advances in textile wet processing including desizing, scouring, bleaching, dyeing, printing and finishing and also nanoprocessing including nanopretreatment, nanodyeing, nanoprinting and nanofinishing. Use of ultrasound appears to be a promising alternative technique to reduce energy, chemicals and time involved in various operations. Over the past years there has been an enormous effort on using sonochemistry for the synthesis of nanomaterials on various textile materials. In situ sonosynthesis of nanoparticles and nanocomposites on different textiles is a pioneering approach driving future investigations. With such wide range of applications and vast ever increasing publications, the objective of this paper is presenting a comprehensive review on ultrasound application in textile from early time to now by the main emphasis on the sonosynthesis of nanomaterials outlining directions toward future research.

Multi-component analysis of bile acids in natural Calculus bovis and its substitutes by ultrasound-assisted solid-liquid extraction and UPLC-ELSD

An ultrasound-assisted solid-liquid extraction (USLE) coupled to ultra-performance liquid chromatography-evaporative light scattering detection (UPLC-ELSD) method has been developed for the simultaneous extraction and determination of six bile acids (BAs) in natural Calculus bovis and its substitutes, collected from different origins. The USLE conditions, UPLC chromatographic and ELSD conditions for BAs were optimized. Under optimum conditions, the six target analytes were efficiently extracted and baseline separated within 10 min. The limits of detection (LODs) and quantification (LOQs) for six BAs were less than 7 ng and 22 ng, respectively. Average recoveries were within the range of 98.8-100.7% with relative standard deviations (RSDs) <2% for the six analytes. This method, due to its convenience, high selectivity, fast analysis efficiency and good reproducibility can be employed for analyzing the content differences of six BAs in 40 batches of natural C. bovis and its existing substitutes. The differences of the content of each BA in natural C. bovis and its substitutes were significant, and the total contents of six BAs in 13 batches of natural C. bovis were in the range of 7.96-160.17 mg g(-1), in 20 natural C. bovis of 0-245.89 mg g(-1), in 2 artificial cultivated C. bovis of 178.48-194.22 mg g(-1), in 3 cultured C. bovis of 41.01-107.3 mg g(-1), and in 2 counterfeit C. bovis of 144.9-340.25 mg g(-1). The significant differences of multi-component contents reflected the various inherent qualities of these samples, so, the use of these substitutes as the replacers of natural source in clinic should be paid more attention. Some substitutes could not be used as the replacers.

Detection of Trace Formaldehyde Gas Based on Quartz Crystal Microbalance Sensor in Living Environment

Using four types of calixarene derivatives (RCT, PCT, MRCT, TBCA) as coating materials, quartz crystal microbalance (QCM) sensors have been examined for detection of toxic formaldehyde gas indoors. The results showed that PCT was the most efficient adsorption coating material for host-guest recognition of formaldehyde molecule, when the coating mass was 43.93 μg. The PCT based QCM sensor possessed a linear response range of 109 ~ 2721 ppm formaldehyde gas. In comparison with gas chromatography method, the QCM sensor had a recovery of 97.98~104.59 % with a good reversibility, stability and reproducibility, showing that the PCT based QCM sensor can be well used for the determination of trace formaldehyde in the living environment.

Terbium (III) chelate complexes as fluorescence energy transfer donor in the determination of formaldehyde in aqueous solutions

The sensitized fluorescence intensity of the terbium (III) ion can be notably enhanced in the presence of sodium hexametaphosphate (SHMP). Based on this, water-soluble Tb-SHMP chelate complexes were synthesized in aqueous solutions, and characterized by spectrofluorometry. 6-Mercapto-5-triazole[4,3-b]-S-tetrazine was generated by the quantitative reaction of HCHO with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole under alkaline conditions at room temperature. The spectral overlap between the emission of Tb-SHMP chelate complexes and absorption of 6-mercapto-5-triazole[4,3-b]-S-tetrazine meets the prerequisite for fluorescence energy transfer. Based on this, a novel efficient fluorescence energy transfer system between Tb-SHMP chelate complexes as donor and 6-mercapto-5-triazole[4,3-b]-S-tetrazine as acceptor was developed for the determination of HCHO in aqueous solutions. Under the optimal experimental conditions, this method is capable of detecting HCHO concentrations from 2.06×10(-5) to 6.18×10(-3) mg mL(-1) and the limit of detection was 7.11×10(-6) mg mL(-1). Compared with other general methods for the determination of HCHO, the proposed method improved the sensitivity and selectivity. Moreover, the proposed method was successfully applied to the determination of HCHO in water samples.

A potentiometric formaldehyde biosensor based on immobilization of alcohol oxidase on acryloxysuccinimide-modified acrylic microspheres

A new alcohol oxidase (AOX) enzyme-based formaldehyde biosensor based on acrylic microspheres has been developed. Hydrophobic poly(n-butyl acrylate-N-acryloxy-succinimide) [poly(nBA-NAS)] microspheres, an enzyme immobilization matrix, was synthesized using photopolymerization in an emulsion form. AOX-poly(nBA-NAS) microspheres were deposited on a pH transducer made from a layer of photocured and self-plasticized polyacrylate membrane with an entrapped pH ionophore coated on a Ag/AgCl screen printed electrode (SPE). Oxidation of formaldehyde by the immobilized AOX resulted in the production of protons, which can be determined via the pH transducer. Effects of buffer concentrations, pH and different amount of immobilization matrix towards the biosensor’s analytical performance were investigated. The formaldehyde biosensor exhibited a dynamic linear response range to formaldehyde from 0.3–316.2 mM and a sensitivity of 59.41 ± 0.66 mV/decade (R² = 0.9776, n = 3). The lower detection limit of the biosensor was 0.3 mM, while reproducibility and repeatability were 3.16% RSD (relative standard deviation) and 1.11% RSD, respectively (n = 3). The use of acrylic microspheres in the potentiometric formaldehyde biosensor improved the biosensor’s performance in terms of response time, linear response range and long term stability when compared with thick film immobilization methods.

Microwave-assisted extraction coupled online with derivatization, restricted access material cleanup, and high-performance liquid chromatography for determination of formaldehyde in aquatic products

A rapid technique based on microwave-assisted extraction (MAE) coupled online with derivatization, restricted access material cleanup, and high-performance liquid chromatography (HPLC) was developed for the determination of formaldehyde in aquatic products. Formaldehyde was first extracted with water under the action of microwaves and then directly introduced into a derivatization reservoir containing 2,4-dinitrophenylhydrazine (DNPH). The formaldehyde-DNPH derivative (100 μL) was loaded into a restricted access material (RAM) precolumn for online cleanup. Subsequently, the analyte was transferred from the precolumn to an analytical column and determined by UV absorption spectrum at 352 nm. The limit of detection (LOD) was 0.27 mg kg(-1). The intraday and interday precisions expressed as RSDs were 3.5% and 5.0%, respectively. This method was applied to determine the presence of formaldehyde in various aquatic products. The results were in agreement with those obtained by the state standard method (steam-distillation and offline HPLC analysis) used in China and higher than those obtained by the online ultrasound-assisted extraction (UAE) method. The recoveries obtained by analyzing 11 spiked aquatic products were in the range of 70.0%-105.0%. The online technique was demonstrated to be rapid with little consumption of samples and reagents.