Disposable Pipette Extraction Research Articles

Development of a reliable method for determination of N-nitrosamines in medicines using disposable pipette extraction and HPLC-MS analysis.

This study outlines the development and optimization of an analytical method using Disposable Pipette Extraction (DPX) followed by high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis to determine NAs in medicines. HPLC-MS analysis utilized a reversed-phase and positive mode electrospray ion source. DPX parameters were optimized through univariate and multivariate analyses, including extraction phase, desorption solvent, sample pH, equilibrium time, and extraction/desorption cycles. The optimized conditions included a C18 extraction phase, methanol desorption solvent, pH at 7, an equilibrium time of 30 seconds, 2 extraction cycles, and 5 desorption cycles. Considering this method, it was possible to achieve a sample preparation step for the analysis of NAs in medicines using a minimal amount of extraction phase, sample, and desorption solvent. Furthermore, the total extraction procedure enables the extraction of NAs in around 4 minutes with NA recovery up to 98%. Analytical performance demonstrated precision and accuracy below 15% and a quantification limit of 1 ng mL-1, meeting validation requirements set by regulations worldwide. Thus, the DPX/HPLC-MS technique offers a faster and cost-effective method for analyzing NAs in medicines compared to traditional approaches. Besides, this method reduces solvent consumption and residue generation, enhancing environmental sustainability according to green chemistry principles.

Quality control of psychoactive substances in human breastmilk samples from a human milk bank by disposable pipette extraction-gas chromatography-mass spectrometry.

The lack of data regarding infant exposure to drugs of abuse consumed by lactating mothers has become a major health concern. Investigating psychoactive substances and their metabolites in breastmilk is an analytical approach to estimate the rate at which drugs of abuse are excreted and how much infants are exposed to them. In this study, we have developed and validated a GC-MS method using disposable pipette tips for simultaneously extracting ten analytes from breastmilk samples obtained from a milk bank in the city of Ribeirão Preto, Brazil. All the 67 analyzed samples tested negative for all the analytes. This is the first study that has applied disposable pipette extraction to analyze drugs of abuse in breastmilk samples.

Application of Disposable Pipette Extraction for Determination of Yb by High‑Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry Using Lanthanum as a Chemical Modifier

The use of extraction technique with disposable tips (DPX) was applied for the first time for the extraction and preconcentration of Yb in samples of liquid waste from the petrochemical industry and environmental water using bioabsorbent cork. The use of cork as an extracting phase in the determination of Yb by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) was evaluated. The pyrolysis and atomization temperatures were optimized at 1400 and 2400 ºC, respectively. H2SO4, HNO3 and HCl acids were compared in the steps of cleaning the extraction phase and desorption of the analyte by DPX. The best extraction in the selected conditions was obtained with pH 8.0 and 5% v/v HCl. The recoveries were close to 100% for residual water and drinking water, 33 to 77% for produced water and 64 to 93% for river water. Tests with interfering ions in different concentrations were performed. The relative limit of quantification (LOQ) and limit of detection (LOD) were estimated at 0.03 and 0.01 µg L-1, respectively. The total time for the preparation of the samples by DPX was close to 1 min per sample. Extraction and pre-concentration were observed using DPX with a preenrichment factor of approximately 4 times.

Determination of selected herbicides in sugarcane-derived foods by graphene-oxide based disposable pipette extraction followed by liquid chromatography-tandem mass spectrometry

Sugarcane is widely cultivated in Brazil. Although there are Maximum Residue Limits of pesticides determined for this plant, there is no legislation covering alimentary products from sugarcane. In this study, Disposable Pipette Tip Extraction (DPX) technique was evaluated as a sample preparation technique for simultaneous determination of eleven herbicides followed by LC-MS/MS analysis in three sugarcane-derived food matrices: juice, candy, and syrup. First, graphene oxide anchored to silica functionalized with octadecyl silane and endcapped was synthesized, which was evaluated as a sorbent in DPX. Then, after evaluating the parameters involved in DPX extraction, the method was validated following the ICH guide. As a result, the method showed acceptable linearity (r ≥ 0.99), limits of quantification (1.0 – 5.0 ng mL−1 for juice and 5.0 – 25.0 ng g − 1 for candy and syrup, varying according to the pesticide), precision, and accuracy within the limits of the literature, and recoveries ranging from 48 – 69% (juice), 34 – 89% (candy), and 28 – 76% (syrup). Finally, the developed method was successfully applied in actual samples of the three studied matrices.

Determination of Cyclaniliprole in Fruits and Vegetables Using Disposable Pipette Extraction Cleanup and Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Despite an outstanding agent for control of Lepidoptera, the diamide insecticide cyclaniliprole (CYCP) is a suspected carcinogen. In the present study, an analytical method was developed for the determination of CYCP in six fruits and vegetables (apple, grape, peach, bell pepper, lettuce, and tomato) using ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry. Sample preparation was carried out by the acetonitrile-salting-out extraction followed by simple and fast cleanup of disposable pipette extraction tip containing styrene divinyl benzene and/or graphitized carbon black. Satisfactory linearity (r > 0.99) was obtained in the calibration range of 0.001–1 µg mL−1. Matrix effects decreased from −9.9–−17.9% to −1.0–−7.6% after the cleanup. The recoveries of CYCP at three spike levels (0.01, 0.1, and 1 mg kg−1) from different matrices were between 75.7% and 111.5%, with the intra-day (n = 5) and inter-day (n = 15) relative standard deviations lower than 12.1%. The limit of quantification was 0.01 mg kg−1. The developed method provides a good reference for routine monitoring of CYCP in these fruits and vegetables.

Molecularly imprinted polymer as sorbent phase for disposable pipette extraction: A potential approach for creatinine analysis in human urine samples

Traditionally, creatinine determination is made by a spectrophotometric method; however, some compounds present in biological samples can interfere with creatinine determination, decreasing the sensitivity of the method in urine samples. Consequently, we report the development of a new molecularly imprinted polymer as a sorbent phase for disposable pipette extraction to determine creatinine in urine samples by high-performance liquid chromatography with UV detection. The synthesized polymer showed a high superficial area and presented a first-order kinetic reaction and a high selectivity for creatinine extraction compared to the non-molecularly imprinted polymer. The main disposable pipette extraction variables evaluated included the number of draw/eject cycles, the pH of the solution and desorption solvent type. The developed method showed an inter and intra-day precision from 1.3% to 2.0% and 0.8–1.6% respectively, accuracy values ranging from 82.3% to 102.1% respectively and recovery values ranging between 96.5% and 101.3%, with a limit of quantification of 0.302 g L−1. The application of the developed method in real urine samples showed creatinine concentrations ranging from 0.55 to 6.61 g L−1. Thus, the developed method was revealed to be an efficient strategy for creatinine determination, reducing analysis time (3 min) and solvent use, and increasing selectivity compared with DPX commercial sorbents.

Determination of Selected Herbicides in Sugarcane-Derived Foods by Graphene-Oxide-Based Disposable Pipette Extraction (DPX) Followed by LC-MS/MS

Determination of Selected Herbicides in Sugarcane-Derived Foods by Graphene-Oxide-Based Disposable Pipette Extraction (DPX) Followed by LC-MS/MS

Development of a Disposable Pipette Extraction Method Using Coffee Silverskin as an Adsorbent for Chromium Determination in Wastewater Samples by Solid Phase Extraction

A procedure using disposable pipette tips adapted for solid-phase extraction, known as DPX‑SPE, was used as an alternative way for the chromium determination in wastewater samples. DPX-SPE consists of a device which allows a dynamic contact between the sample and the solidphase. A residue obtained from the processing of coffee beans, denominate coffee silverskin, was used as a new adsorbent. Characterization techniques revealed properties of lignocellulosic materials with potential application for chromium adsorption. The parameters including adsorbent mass (25.00 mg), elution solvent (0.1 mol L−1 HCl, 200 μL) and pH (2.0) were optimized. Thus, 1.00 mL of deionized water for conditioning, 4.00 mL of sample, 2 extraction cycles and 1 elution cycle were the employed conditions. Enrichment factor of 12, limit of detection of 6.00 μg L−1 and relative standard deviation (RSD) 1.3% (n = 3) were obtained. The method proved to be fast, cheap, environmentally friendly, and simple, providing good recoveries (104-113%), and it was satisfactorily applied in real samples.

Analysis of Stimulants in Sweat and Urine Using Disposable Pipette Extraction and Gas Chromatography Coupled to Mass Spectrometry in the Context of Doping Control.

Urine is initially collected from athletes to screen for the presence of illicit drugs. Sweat is an alternative sample matrix that provides advantages over urine including reduced opportunity for sample adulteration, longer detection-time window and non-invasive collection. Sweat is suitable for analysis of the parent drug and metabolites. In this study, a method was developed and validated to determine the presence of 13 amphetamine- and cocaine-related substances and their metabolites in sweat and urine using disposable pipette extraction (DPX) by gas chromatography coupled to mass spectrometry. The DPX extraction was performed using 0.1 M HCl and dichloromethane:isopropanol:ammonium hydroxide (78:20:2, v/v/v) followed by derivatization with N-methyl-N-(trimethylsilyl) trifluoroacetamide at 90°C for 20 min. DPX extraction efficiencies ranged between 65.0% and 96.0% in urine and 68.0% and 101.0% in sweat. Method accuracy was from 90.0% to 104.0% in urine and from 89.0% to 105.0% in sweat. Intra-assay precision in urine and in sweat were <15.6% and <17.8%, respectively, and inter-assay precision ranged from 4.70% to 15.3% in urine and from 4.05% to 15.4% in sweat. Calibration curves presented a correlation coefficient -0.99 for all analytes in both matrices. The validated method was applied to urine and sweat samples collected from 40 professional athletes who knowingly took one or more of the target illicit drugs. Thirteen of 40 athletes were positive for at least one drug. All the drugs detected in the urine were also detected in sweat samples indicating that sweat is a viable matrix for screening or confirmatory drug testing.

VERIFIKASI METODE ANALISIS METAMFETAMINA DAN AMFETAMINA DALAM MATRIKS URIN SECARA AUTOMATISASI DENGAN GERSTEL® DISPOSABLE PIPETTE EXTRACTION (DPX) MULTIPURPOSE SAMPLER (MPS)

&#x0D; &#x0D; &#x0D; &#x0D; Method analytical validation and verification is crucial in routine qualitative and quantitative analysis. Analysis laboratory need objective evidences about specific parameters in their drugs/analytes or drugs metabolites in matrices biology. Urine is the most preferable matrix biology for determining drugs metabolites especially in drug abuses cases because urine’s sampling process is not invasive. There are many methods extracting drugs in urine, especially methamphetamine and amphetamine as those two analytes are excreted via urine. This study presented method verification for determination of methamphetamine and amphetamine in urine using Gerstel® automated Disposable Pipette Extraction (DPX) Multipurpose Sampler (MPS). Result of this study showed that retention time of methamphetamine is in minute 6.21, and amphetamine is in minute 3.15. Methampethamine’s curve displayed a coefficient of determination r2=0,9999 with the equation y=170,19x+33183. The equation of amphetamine showed y=44390x – 17513 with coefficient of determination r2= 0,9974. Limit of detection (LOD) of methamphetamine in urine is 59,73 ppb, and LOD of amphetamine is 36 ppb.&#x0D; &#x0D; &#x0D; &#x0D;

A Rapid Analytical Approach for Monitoring Pharmaceuticals in Hospital Wastewater—A DPX-Based Procedure with Environmentally-Friendly Extraction Phase Coupled to High Performance Liquid Chromatography–Diode Array/Fluorescence Detectors

In this study, a novel analytical methodology based on disposable pipette extraction (DPX) was developed using an alternative extraction phase for the extraction/determination of six pharmaceutical compounds, including carbamazepine, diclofenac, naproxen, fluoxetine, losartan and 17α-ethinylestradiol, in samples of hospital wastewater by high-performance liquid chromatography coupled to diode array and fluorescence detectors. The performance of three extraction phases was examined, including 3-n-propyl (3-methylpyridinium) silsesquioxane chloride (Si3Py+Cl−), the conductive polymer polypyrrole (PPy), and polypyrrole modified with cetyltrimethylammonium bromide (PPy.CTAB). The optimization of the experimental parameters was performed through univariate and multivariate approaches. The optimized condition was obtained with the use of 20 mg of Si3Py+Cl− as extraction phase; six extraction cycles with 700 μL of sample in each cycle and 15 s of extraction time; three desorption cycles with 100 μL of ACN (same aliquot) and 15 s of desorption time; and sample pH adjusted at 3.5 and addition of 15% (w/v) of NaCl in the sample. The methodology proposed exhibited environmentally-friendly aspects with a significantly reduced volume of organic solvent (only 100 µL) and a small amount of extraction phase (20 mg). In addition, the extraction phase employed exhibits a simple synthetic procedure, low cost, and high stability in organic solvent. Moreover, the method developed exhibits high throughput (extraction time of 6.5 min per sample), and robustness. The analytical figures of merit were obtained using hospital wastewater, and the values were very satisfactory. The correlation coefficients were higher than 0.9710. LODs and LOQs ranged from 0.030 µg L−1 to 1.510 µg L−1 and 0.10 µg L−1 to 5.00 µg L−1, respectively. Relative recoveries varied from 80 to 127%, and intra-day (n = 3) and inter-day (n = 9) precision was lower than 19%.

Polypyrrole monolithic extraction phase: From conventional to miniaturized sample preparation techniques

Monolithic polymers are described as continuous and highly porous materials. They have been gaining popularity as an effective extracting phase for some sample preparation methods, due to their variety of functionalities, such as wide pH range tolerance, good permeability, and its ability to allow changes into their surface. Polypyrrole represents an interesting alternative for the modification in extraction phases due to its well related ability to perform multiple interactions, such as acid-base, π - π, ion exchange, interactions with hydrophobic affinities or polar functional groups. Among the different sample preparation techniques, solid-phase extraction (SPE) is one of the most popular and used; a miniaturized version of SPE is the disposable pipette extraction (DPX). DPX is a recent miniaturized extraction technique that usually employing silica-based sorbents inside a pipette tip (5 or 1 mL). The present study proposes the development of a monolithic extraction phase composed by styrene divinylbenzene (1:1) modified with polypyrrole for SPE and DPX techniques. The efficiency of the material was evaluated in face of the extraction of different samples and analytes, triazine herbicides in water and dexamethasone in synthetic synovial liquid by conventional and miniaturized solid-phase extraction techniques. The extractions performed by SPE and DPX presented absolute recovery values ranging from 74.8 to 105.0%, inter-day precision ranging from 0.6 to 14.0%, and limit of quantification of 0.5 and 5.0 ng.mL−1, respectively. The DPX miniaturized method exhibited results equivalent to the methods reported in the literature for extraction of dexamethasone in synovial fluid samples. Moreover, this technique proved to be quicker and cheaper than SPE, and produced fewer residual volumes, supporting the preference for green chemistry. Monolithic polymers modified with polypyrrole presented to be a feasible alternative extraction phase for miniaturized sample preparation techniques.

Assessment of a natural extraction phase in disposable pipette extraction coupled with the sub-minute determination of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in human urine by fast-GC-FID

The compound 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) consists of the major metabolite of tetrahydrocannabinol (THC) in human urine. Analysis of this compound exhibits an important role in forensic scenario; therefore, several analytical methods have been developed for this purpose. In this study, for the first time, a biosorbent-based disposable pipette extraction was developed for the determination of THC-COOH, using a simple and high-throughput sample preparation technique. In addition, a rapid instrumental analysis was achieved by fast-gas chromatography coupled with flame ionization detection (fast-GC-FID). Different biosorbents were examined, including cork, moringa and bract. The method was optimized through univariate and multivariate designs with the conditions comprised of 15 mg of cork as the extraction phase, pH maintained at 2.5 with 8 cycles of extraction of 60 s each, and 1 cycle of 5 s for the desorption step with a mixture of acetonitrile:methanol (ACN/MeOH). Limit of detection was 0.21 ng mL−1 and the limit of quantification was 0.73 ng mL−1, with a linear range from 5 to 100 ng mL−1 and coefficient of determination (R2) 0.9905. The relative recoveries ranged from 96 to 108%, intraday and interday precisions were lower than 13%. Different samples were subjected to the extractions using the method developed with four positive samples for the analyte.

A Green Procedure Using Disposable Pipette Extraction to Determine Polycyclic Aromatic Sulfur Heterocycles in Water Samples and Solid Petrochemical Residues

A simple and efficient method using reduced amounts of solvents for the determination of polycyclic aromatic sulfur heterocycles (PASHs) in aqueous matrices from a lagoon and leachate solid waste from a petrochemical industry is proposed. The target analytes were previously concentrated using the disposable pipette extraction (DPX) technique applying gas chromatography-mass spectrometry (GC-MS) for analysis. In this innovative approach, the DPX was modified with 8-hydroxyquinoline silica gel immobilized with PdII for the pre-concentration of 4-methyldibenzothiophene, 4,6-dimethyldibenzothiophene, 1,2-naphtobenzothiophene, 2-methylbenzothiophene and 3-methylbenzothiophene. To improve the extraction efficiency, parameters such as desorption solvent, ionic strength, extraction and desorption cycles were optimized. The values obtained for the limits of detection (LOD) and quantification (LOQ) are adequate for the determination of PASHs in aqueous and leachate solid waste samples. Precision and accuracy parameters showed satisfactory results, providing relative recoveries of 74.6-131.2% for PASHs from lagoon water samples and 72.7-118.0% for leachate of solid waste samples. In the lagoon samples the relative standard deviation (RSD) values for the five PASHs ranged from 0.3 to 9.2% and 3.8 to 19.4% for the leachate of the solid waste. These results demonstrate that the proposed method represents a promising alternative for the determination of PASHs in aqueous and leachate solid waste samples.

Molecularly Imprinted Polymer as Sorbent Phase for Disposable Pipette Extraction: A Potential Approach for Creatinine Analysis in Human Urine Samples

The traditional creatinine determination is made by a spectrophotometric method. However, some interferents present in biological samples can decrease the sensitivity in the determination of creatinine in urine samples with this spectrophotometric method. Due to this, this study developed a new molecularly imprinted polymer (MIP) as a sorbent phase to disposable pipette extraction (DPX) for the creatinine determination in urine samples by high-performance liquid chromatography with UV detection (HPLC/UV). The synthesized polymer showed a high superficial area presenting a first-order kinetic reaction and a high selectivity for creatinine compared to the non-molecularly imprinted polymer. The main DPX variables were evaluated: number of draw/eject cycles, pH solution, and type of the desorption solvent. The developed methodology showed an inter and intra-day precision of 1.3 to 2.0% and 0.8 to 1.6% respectively, the accuracy values ranging from 82.3% to 102.1% respectively, and recovery values between 96.5 to 101.3% with the limit of quantification of 0,339 g L-1. The developed methodology was applied to real urine samples which showed creatinine concentrations ranging from 0.55 to 6.61 g L-1. Thus, the developed DPX-MIP-HPLC/UV methodology showed to be efficient for creatinine determination, reducing the time of analysis (3 min), solvent uses, and increasing the selectivity.

Novel Method for the Extraction of Cocaine from Oral Fluid by Means of Disposable Pipette Modified with Restricted Access Material

This study proposes a new, efficient, and selective method for the analysis of cocaine in oral fluid. For this purpose, an extractive phase with restricted access materials (RAM) capable of extract and pre-concentrate low molecular weight analytes and simultaneously exclude macromolecules was developed for disposable pipette extraction (DPX) followed by liquid chromatography coupled to mass spectrometry (LC-MS) analyses. The proposed method was optimized using a 24 factorial design which pointed higher extraction efficiency under the following conditions: pH 9, 10 cycles of extraction (aspirate/dispense), 3 cycles of desorption (aspirate/dispense) and acetonitrile as desorption solvent. The DPX-RAM/LC-MS method showed linearity range from 10 to 100 ng mL-1 with determination coefficient (R2) = 0.999, accuracy values ranged from -0.9 to 4.3%, precision values ranged from 1.7 to 9.1% and recovery values ranged from 97.9 to 101.1%. The benefits of this method are that it can be performed in few minutes and that the analytical performances, including the limit of detection (3.13 ng mL-1), limit of quantitation (10 ng mL-1) and linear range were found to be in agreement with other methods used for similar analysis.

Miniaturized Salting-Out Assisted Liquid-Liquid Extraction Combined with Disposable Pipette Extraction for Fast Sample Preparation of Neonicotinoid Pesticides in Bee Pollen.

As the main source of nutrients for the important pollinator honeybee, bee pollen is crucial for the health of the honeybee and the agro-ecosystem. In the present study, a new sample preparation procedure has been developed for the determination of neonicotinoid pesticides in bee pollen. The neonicotinoid pesticides were extracted using miniaturized salting-out assisted liquid-liquid extraction (mini-SALLE), followed by disposable pipette extraction (DPX) for the clean-up of analytes. Effects of DPX parameters on the clean-up performance were systematically investigated, including sorbent types (PSA, C18, and silica gel), mass of sorbent, loading modes, and elution conditions. In addition, the clean-up effect of classical dispersive solid-phase extraction (d-SPE) was compared with that of the DPX method. Results indicated that PSA-based DPX showed excellent clean-up ability for the high performance liquid chromatography (HPLC) analysis of neonicotinoid pesticides in bee pollen. The proposed DPX method was fully validated and demonstrated to provide the advantage of simple and rapid clean-up with low consumption of solvent. This is the first report of DPX method applied in bee pollen matrix, and would be valuable for the development of a fast sample preparation method for this challenging and important matrix.

Highly sensitive determination of Cu(II) ions in hemodialysis water by F AAS after disposable pipette extraction (DPX) using Moringa oleifera as solid phase

Clinical samples, such as hemodialysis water, require constant monitoring, since inappropriate processing can lead to copper intoxication even at low concentrations. Sensitive, inexpensive and environmental friendly sample preparation procedures are desirable. For this proposal, an extraction and preconcentration procedure by Disposable Pipette Extraction (DPX) was developed using an homemade device with Moringa oleifera seeds powder as a solid phase for the determination of Cu(II) ions in hemodialysis water at levels of µg L−1 by flame atomic absorption spectrometry (F AAS). The proposed DPX device consists of a conventional micropipette tip, syringe, adapter and glass wool as a filter, being easy to operate, simple and low cost. The optimized extraction and preconcentration conditions allowed the use of 10 mg solid phase with particle size of 250 µm, 6 extraction cycles of sample aliquots at pH 6 and elution with 0.5 mol L−1 hydrochloric acid solution (250 µL). The working concentration range showed satisfactory linearity between 10 and 100 µg L−1 (r2 = 0.9992), assessed by the Mandel test (DS2/Sy22 < F). The preconcentration factor, detection limit and recovery were 50, 0.64 µg L−1 and 96.8–100.4%, respectively. The precision (RSD) was 6.2% (80.0 µg L−1; n = 6). The performance results showed that the extraction and preconcentration procedure with the adapted DPX device is promising for Cu(II) determination in hemodialysis water.

Ultrasound-assisted and disposable pipette extraction for the determination of faecal contaminants in sediment samples by GC-MS

ABSTRACT Given the amount of untreated sewage released into the environment and possible consequences, new methodologies are required for the detection and quantification of potential pollutants found in sediment samples, including faecal contamination. Solid matrix extraction methodologies (e.g. Soxhlet extraction) are generally laborious and require the use of large amounts of solvents, which is inconsistent with the principles of green chemistry. In this study,a simple, robust and efficient analytical method for the determination of faecal sterols in sediment samples using ultrasound-assisted extraction (UAE) followed by pre-concentration with disposable pipette extraction (DPX) was developed. Multivariate experimental designs were used for the optimisation of the extraction parameters for the UAE and DPX procedures. The separation and detection of the analytes were conducted by GC-MS. Dichloromethane was used as the extraction solvent in the UAE. The DPX procedure was conducted applying 5 cycles of extraction with 700 µL of sample (10 s each) and 2 cycles of desorption with 200 µL of solvent (20 s each). The optimised desorption solvent was a mixture composed of ethyl acetate:acetonitrile (60:40 v/v). The limits of detection were 7.6 µg kg−1 for cholesterol and 75 µg kg−1 for cholestanol, coprostanol and stigmasterol and the limits of quantification were 25 µg kg−1 for cholesterol and 250 µg kg−1 for the other analytes. Relative recovery was evaluated for 3 levels of concentration and the results ranged from 78% to 114%. The precision was evaluated through intra-day (n = 3) and inter-day (n = 9) tests, and the ranges observed were 0.5–10%and 2–16%, respectively. The results demonstrate that this effective and fast method shows potential for the determination of faecal contaminants in sediments.

Novel strategy for disposable pipette extraction (DPX): Low-cost Parallel-DPX for determination of phthalate migration from common plastic materials to saliva simulant with GC-MS

In widespread use in commercial products as plasticizers, phthalic acid esters (phthalates) have worried researchers and society in general, given the negative impacts on living organisms, especially human health. Since they are not chemically linked to the polymeric matrix, their migration is evident for samples that come into contact with plastics that contain them, such as water, food and saliva. In this work, a new strategy is described, named parallel-disposable pipette extraction (Pa-DPX), in a fast, efficient and robust analytical method using five simultaneous extractions for the determination of migration of 6 phthalates from common plastic materials (children's toys, school supplies, dog toys and oral contact items) to saliva simulant, using gas chromatography-mass spectrometry (GC-MS). The optimized conditions were 5 extraction cycles with 1600 μL of saliva simulant and desorption with 200 μL of ethyl acetate using 5 cycles with the same aliquot. The calibration curves resulted in determination coefficients higher than 0.9915, limits of detection at 1.5 μg L−1, and the quantification limits were 5.0 μg L−1. Excellent results were obtained for repeatability (relative standard deviation ranging from 8.7% to 20.1% for 5 μg L−1) and intermediate precision, varying the day of analyses (7.9%–16.2%). The analyte recovery ranged from 75% to 114% for two different samples, in four different levels of concentration. The Pa-DPX-GC-MS method was successfully applied to determine the migration of PAE from 21 samples. At least one PAE was detected in 81% of samples, and di-n-octyl phthalate was found in higher concentration, achieving the migration of almost 30 μg per g of sample.