Pipette Tip Research Articles

Simple and sensitive determination of radium-226 in river water by single column-chromatographic separation coupled to SF-ICP-MS analysis in medium resolution mode

This article describes a novel and simple method to measure ultra-trace 226Ra in river water samples at fg L−1 (mBq L−1) levels as a means for surveying 226Ra in an unintended contamination in river water. To simplify the procedure, a single column was used for separation and purification; 10 mL of AG 50W-X8 resin was packed into a 10 mL Eppendorf pipette tip, which was used as a separation column. A 500 mL sample solution was loaded, and interfering elements were removed with 80 mL 4 M HCl in 20% ethanol. Subsequently, Ra together with Ba was eluted by 20 mL 5 M HNO3 prior to SF-ICP-MS analysis; this allows the naturally existing Ba in water samples to be employed as a yield tracer for 226Ra analysis. Using the medium mode of SF-ICP-MS, the instrumental detection limit of 380 fg L−1 (10 mBq L−1) was obtained. An extremely low method detection limit of 0.46 fg L−1 (0.02 mBq L−1) was achieved with 500-fold pre-concentration. Finally, the developed technique was applied to analyze natural water samples collected from Japanese rivers, in which the 226Ra concentrations varied in the range of 0.7–49.6 fg L−1 (0.03–1.82 mBq L−1).

First Report of Colletotrichum siamense Causing Stem Tip Dieback of Sacha Inchi (Plukenetia volubilis) in China

Sacha inchi (Plukenetia volubilis L.), which belongs to the Euphorbiaceae family, was introduced into China in 2006. It is considered one of the most promising economic oilseed crops in China. A high content of polyunsaturated fatty acid, phytosterols, tocopherols, total carotenoids, and hydrophilic and lipophilic antioxidant capacities was found in the seeds of this plant with disease prevention potential (Chirinos et al. 2013). In 2018 to 2019, dieback characterized by progressive death of branches from tip was observed on the sacha inchi at the Danzhou campus of Hainan University. The disease incidence was nearly 100% in adult plants. In July 2018, six infected branches covered with Parafilm at both ends to reduce desiccation were collected, and 5-mm-long branch fragments were cut from the diseased and healthy borders. The branch fragments were surface disinfected in 2% sodium hypochlorite for 2 min, rinsed with sterile double distilled water for five to seven times, plated on potato dextrose agar (PDA) medium amended with 100 μg/ml of streptomycin, and incubated at 28°C for 5 days. Three pure isolates were obtained by transferring mycelial fragments from the margin of fungal colonies onto fresh PDA, and a representative isolate was DZJ-10. Colonies produced by isolates were dense, white to greyish aerial mycelium on PDA at 28°C for 7 days. The morphology of conidia was cylindrical, aseptate, with the average size 8.3 ± 1.1 × 2.7 ± 0.4 μm (50 conidia). To do molecular identification, three genes/genetic regions were amplified: the rDNA regions of the inner internal transcribed spacer (ITS) regions (primers ITS1/ITS4) (White et al. 1990), the actin gene (ACT; primers ACT-512F/ACT-783R) (Carbone and Kohn 1999), and the glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH; primers GDF/GDR) (Weir et al. 2012). The sequences were deposited in GenBank (accession nos. MT020423, MT029317, and MT029318). The sequences were blasted in GenBank. The sequence of ITS revealed 100% identity with Colletotrichum siamense ITS of KP703372 and KP703373 in GenBank, respectively. The ACT showed 100% similarity with C. siamense LC412418 and MK568557 accessions. And the GAPDH showed 99.59% identity with MK457189 and MH681394. The phylogenetic analysis of combined GAPDH, ITS, and ACT sequences performed in MEGA 6.0 using neighbor joining revealed that the isolates were C. siamense. The isolates are C. siamense based on morphological characters and multigene phylogeny (Ling et al. 2019; Prihastuti et al. 2009). For the pathogenicity test, the cut-stem inoculation technique was performed (Wang et al. 2020). The stem apex of each 2-month-old sacha inchi plant was cut above the node with a sharp scalpel. The open end of a 10- to 200-μl pipette tip was pushed into the margin of the 7-day-old C. siamense culture growing on PDA, and a mycelium plug was removed. The pipette tip containing the mycelium plug was immediately transferred onto the cut stem and pushed down to embed the stem into the medium and to secure the tip onto the stem. Nine plants were used for each isolate and the control, and the plants inoculated by PDA plugs were used as a control. All plants were placed in the greenhouse at 28°C and 80% relative humidity. Typical symptoms of plants infected by isolates were photographed after 18 days. C. siamense was reisolated from inoculated plants but not from the control plants. The experiment was repeated with similar results. To the authors’ knowledge, this report is the first to identify the pathogen of sacha inchi stem tip dieback as C. siamense in China. Our findings enriched the pathogen library of sacha inchi and paved the way for developing effective strategies to control the disease.

Rapid Analysis of Four Amphetamines in Urine by Self-Made Pipette-Tip Solid-Phase Extraction Followed by GC-MS/MS.

A simple and rapid pipette-tip solid-phase extraction (PT-SPE) procedure with derivatization prior to gas chromatography triple quadrupole mass spectrometry analysis is developed for the simultaneous determination of amphetamine (AMP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA) in urine samples. The PT-SPE procedure using self-made sorbent could extract drugs within 6min from 100-μL urine samples, requiring low solvent-consumption (<2.0mL). Besides, the self-made pipette tip could be reused at least five times. Under optimized conditions, the recoveries of four amphetamines at spiked levels (low, medium and high) ranged from 87.7 to 110.4%, with relative standard deviations<9.5%. The limit of detections and limit of quantifications for AMP, MA, MDA and MDMA were in the range of 2.52-8.25ng⋅mL-1 and 8.4-27.5ng⋅mL-1, respectively. Validation results show that the proposed method is suitable for the quantitation of amphetamines and has been successfully applied in the urine samples of suspected drug abusers.

One pot green synthesis of m-aminophenol–urea–glyoxal resin as pipette tip solid-phase extraction adsorbent for simultaneous determination of four plant hormones in watermelon juice

Plant hormones (PHs) are a type of pesticide that can potentially affect human health. Therefore, their quantitative detection is particularly important. In this study, a green and economic method for the simultaneous extraction and determination of four PHs, namely thidiazuron, forchlorfenuron, 1-naphthylacetic acid, and 2-naphthoxyacetic acid, in watermelon juice was developed by using m-aminophenol–urea–glyoxal resin as the adsorbent for pipette tip solid phase extraction (PT-SPE) coupled with liquid chromatography. The resin was synthesized via a simple (one pot hydrothermal synthesis) and green (ethanol as the solvent and glyoxal as crosslinking agent) process. The synthesized resin possesses multiple functional groups (hydroxyl, amino, and imino, among others), high adsorption capacity, larger specific surface area than the urea–glyoxal resin and m-aminophenol–glyoxal resin, and can be regenerated easily. The PT-SPE device is simple, cheap, and easy to obtain, and the adsorbent dosage is only 5.0 mg. The proposed method has a wide linear detection range, high recovery, good precision, and high sensitivity, and satisfies the measurement requirements for detecting trace levels of PHs in fruits and vegetables.

Electrospinning fabrication of covalent organic framework composite nanofibers for pipette tip solid phase extraction of tetracycline antibiotics in grass carp and duck

In the current study, a novel covalent organic frameworks COF-SCU1 incorporated electrospun nanofibers (PAN@COF-SCU1 nanofibers) was fabricated via a facile electrospinning method and utilized as adsorbent in pipette tip solid-phase extraction (PT-SPE) of tetracycline antibiotics (TCs) from foods. The prepared PAN@COF-SCU1 nanofibers possessed both of the unique characteristics of electrospun nanofibers and COFS-CU1, and thus improving the adsorption capacity of the electrospun nanofibers and preventing the problems of leakage and high pressure caused by directly using the nanosize COFs as adsorbent in PT-SPE. The experiments affected the adsorption and desorption efficiencies, such as the loading ratios of COFS-CU1 in nanofibers, the amount of nanofibers, the matrix pH and desorption solvent, were studied in detail. Eventually, a new pipette tip solid-phase extraction-high performance liquid chromatography (PT-SPE/HPLC) method was proposed for the analysis of three TCs from food. Satisfied linearity for TCs was obtained in the range of 4–70 ng mL−1. The limits of detection and quantification were ranged from 0.6 to 3 ng mL−1 and from 2 to 10 ng mL−1, respectively. The interday and intraday precisions (RSD) were all lower than 9%. The proposed PT-SPE/HPLC method was used to determine TCs residues in grass carp and duck samples for the first time. The results could not only explore the availability of PT-SPE in the extraction of TCs in food samples, but also broadened the potential applications of COFs in sample preparation.

Dilution of digestive fish proteases with protein-free blocking reagents prevents loss of catalytic activity during microquantification

The activity of proteases may be lost during microquantification because of their nonspecific binding to tubes and pipette tips. In this study, the effects of blocking reagents (blockers) in dilutions of digestive proteases of yellowtail, Seriola quinqueradiata, were compared. EzBlock Chemi (EBC; protein free), Western BLoT Blocking Buffer (WBB; protein free), casein-based blocker, and bovine serum albumin were evaluated by the measurement of trypsin, chymotrypsin, and aminopeptidase activities using fluorogenic substrates. Protease activities were linear in extracts of pyloric caeca at dilution rates of up to at least 1/6400 with the four blockers. However, the activities of pancreatic enzymes differed, and the highest levels were observed with EBC and WBB. Extracts diluted with EBC and WBB were incubated for up to 24 h at 25 °C. Pancreatic enzyme activities increased with time in extracts diluted with EBC, but for those diluted with WBB there was no clear trend. The activities of chymotrypsin and aminopeptidase in whole-body extracts of individual yellowtail larvae extracted with EBC were significantly higher than in those extracted with 150 mM NaCl, suggesting that EBC inhibits the loss of enzyme activity that may otherwise occur during extraction. Thus, EBC is considered to be the most effective diluent for the microquantification of proteases amongst the four blockers tested.

An efficient low-cost xylem sap isolation method for bacterial wilt assays in tomato.

PremiseA portable, simple, yet efficient method was developed for the rapid extraction of xylem sap from the stems and petioles of tomato plants for diagnostic and quantification assays of the xylem‐colonizing wilt bacterium Ralstonia solanacearum.Methods and ResultsXylem saps were extracted from tomato stem sections using negative pressure generated from handheld needleless syringes. The samples were collected from plants grown under different soil moisture levels at four days after inoculation with the pathogen. Pipette tips were modified to serve as adapters for the stem sections. The quantification of the bacterial load in the extracted sap was performed by plating sap dilutions in Kelman's triphenyltetrazolium chloride (TTC) medium. Pathogen identity was further confirmed by performing a PCR using R. solanacearum‐specific primers.ConclusionsDue to its simplicity, portability, and thoroughness of extraction from predetermined tissue sizes, the method can potentially facilitate high‐throughput onsite sampling from a large number of samples in a short time, which cannot be achieved with other available techniques.

Deciphering the role of Notch1 in ulcerative colitis

BackgroundUlcerative colitis (UC) is an inflammatory bowel disease, that causes ofchronic inflammation and ulcers affecting the innermost layer of the colon. UC patients have an increased risk of colitis associated cancer. Notch1 signaling is a conserved intracellular signaling pathway. It regulates cell fate, cell proliferation, differentiation, and cell death. However, Notch1 can act as a mediator or suppressor depending on the cellular context and disease stage.AimAim of this study is to understand the mechanistic role of Notch1 in colitis.MethodsFor our in vivo model, epithelial cell‐specific deletion of Notch1 was done using the Cre/Lox system. Villin‐cre+/−/Notch1flox/flox (Ncre‐C57/B6) mice were generated, which cannot express Notch1 in epithelium. We used 2% DSS as inflammation inducer. Biopsy tissues‐ 3 normal and 6 UC patients (Emory University bio‐repository).ResultsAcute colitis was induced among 8 weeks old both male and female wild type (WT‐ C57/B6) and Ncre mice by giving 2%DSS for 5 days. After the colitis phase mice were allowed to recover for 10 days and were sacrificed. Ncre mice had significant loss of body weight compared to WT mice at the end of the recovery phase . Colonoscopy indicated severe inflammation and mucosal thickening among Ncre mice. Histology exhibited significant loss of crypt architecture and infiltration of neutrophils among Ncre mice compared to WTs. Active Notch1 (NICD/Notch1 inter cellular domain) was overexpressed in HCT116 cells by transient transfection. Wound healing assay was performed by scratching with a pipet tip. HCT116 cells overexpressing NICD exhibited faster wound closure at 24 and 48 hours . Quantification of wound closure was done by calculating the wound area using the ImageJ program. To assess the role of Notch1 in chronic inflammation, 10 weeks old both male and female Ncre and WT mice were given 2 cycles of 2% DSS followed by a 21 days recovery cycle. Mice were sacrificed on day 56. Ncre mice were more susceptible to chronic inflammation as indicated by colonoscopy, significant body weight loss, shorter colon length, and lower histological score compared to WT mice in chronic colitis. Barrier function was assessed by using 4kD FITC‐dextran tracer showing leaky epithelium among Ncre mice compared to WT mice. QPCR analysis showed a significant decrease in the mRNA levels of 16SrRNA (universal RNA for microbial population) among Ncre mice . QPCR analysis of human biopsies indicated a significant decrease in mRNA levels of TGFβ and MMP7 (wound healing markers) among UC biopsy tissues compared to healthy biopsy tissues.ConclusionThese results together suggest a novel protective role of Notch1 during the recovery (after acute colitis) as well as in the chronic colitis. Notch1 mediates preferential differentiation of epithelial cells, therefore is necessary to maintain epithelial integrity. It mediates its wound healing role by promoting the expression of wound healing markers such as TGFβ and MMP7. It maintains the microbial population by recruiting healthy epithelial cells to maintain epithelial homeostasis in chronic colitis. Therefore, as long‐term cure the beneficial role of Notch1 in wound healing and in chronic colitis could be translated as an efficient targeted therapy for UC patients.

Molybdenum disulfide-hypercrosslinked polymer composite as an adsorbent for determination of polycyclic aromatic hydrocarbons in environmental water coupled with HPLC-FLD.

A composite was synthesized from two-dimensional molybdenum disulfide (MoS2) nanosheets and hypercrosslinked polymers (HCP), and the composite was characterized by infrared spectroscopy, scanning electron microscopy, and specific surface area. The fluffy and porous structure and multiple adsorption sites (π-interaction, static electricity, hydrogen bonding) make it ideal for use as an adsorbent. A pipette tip solid-phase extraction with the composite as the adsorbent combined with HPLC-FLD was developed to determine trace amounts of polycyclic aromatic hydrocarbons (phenanthrene, anthracene, fluoranthene, pyrene, benzo(α)anthracene) in environmental water. Under optimal extraction conditions, the method has a wide linear range (0.5-100ngmL-1) and low limit of detection (0.024-0.099ngmL-1), and the recoveries of PAHs from spiked environmental water were 73.8% to 123.6% (relative standard deviation ≤ 6.7%, n= 3). Graphical abstract Schematic representation of a three-dimensional molybdenum disulfide-ethylenediamine-hypercrosslinked polymer composite (MoS2-EDA-HCP) using pipette tip solid-phase extraction adsorbent for extracting trace levels of polycyclic aromatic hydrocarbons (PAHs) prior to HPLC-FLD. HCP, hypercrosslinked polymer; MoS2, molybdenum disulfide; EDA, ethylenediamine.

Impedance-Based Single-Cell Pipetting.

Many biological methods are based on single-cell isolation. In single-cell line development, the gold standard involves the dilution of cells by means of a pipet. This process is time-consuming as it is repeated over several weeks to ensure clonality. Here, we report the modeling, designing, and testing of a disposable pipet tip integrating a cell sensor based on the Coulter principle. We investigate, test, and discuss the effects of design parameters on the sensor performances with an analytical model. We also describe a system that enables the dispensing of single cells using an instrumented pipet coupled with the sensing tip. Most importantly, this system allows the recording of an impedance trace to be used as proof of single-cell isolation. We assess the performances of the system with beads and cells. Finally, we show that the electrical detection has no effect on cell viability.

Application of 3D printed tools for customized open port probe-electrospray mass spectrometry

Three dimensional printed open port probe (3DP-OPP) and air displacement based liquid handler, were designed and optimized using fused deposition modeling (FDM) and stereolitography (SLA) 3D printing. The performance of the devices were investigated for the analysis of solid and liquid samples with electrospray ionization mass spectrometry (ESI-MS). Direct analysis in less than 1 min and without any sample preparation, enabled detection of pesticides (azoxtystrobin/imazalil) on fruits peel surface and illegal substances (MDMA/MDEA) in home-made pills. Conjunction of OPP in the overspill mode with a customized autosampler, equipped with disposable pipette tips, enables direct quantitative analysis of drugs of abuse in urine and plasma, with minimized carry-over and reduced matrix effect compared to flow injection analysis.

A Benchtop Automated Sputum-to-Genotype System Using a Lab-on-a-Film Assembly for Detection of Multidrug-Resistant Mycobacterium tuberculosis.

Automated genotyping of drug-resistant Mycobacterium tuberculosis (MTB) directly from sputum is challenging for three primary reasons. First, the sample matrix, sputum, is highly viscous and heterogeneous, posing a challenge for sample processing. Second, acid-fast MTB bacilli are difficult to lyse. And third, there are hundreds of MTB mutations that confer drug resistance. An additional constraint is that MTB is most prevalent where test affordability is paramount. We address the challenge of sample homogenization and cell lysis using magnetic rotation of an external magnet, at high (5000) rpm, to induce the rotation of a disposable stir disc that causes chaotic mixing of glass beads ("MagVor"). Nucleic acid is purified using a pipet tip with an embedded matrix that isolates nucleic acid ("TruTip"). We address the challenge of cost and genotyping multiple mutations using 203 porous three-dimensional gel elements printed on a film substrate and enclosed in a microfluidic laminate assembly ("Lab-on-a-Film"). This Lab-on-a-Film assembly (LFA) serves as a platform for amplification, hybridization, washing, and fluorescent imaging, while maintaining a closed format to prevent amplicon contamination of the workspace. We integrated and automated MagVor homogenization, TruTip purification, and LFA amplification in a multisample, sputum-to-genotype system. Using this system, we report detection down to 43 cfu/mL of MTB bacilli from raw sputum.

A Flexible, Low-Cost Hydroponic Co-Cultivation System for Studying Arbuscular Mycorrhiza Symbiosis.

Arbuscular mycorrhiza (AM) is a widespread symbiosis between plant roots and fungi of the Glomeromycotina, which improves nutrient uptake by plants. The molecular mechanisms underlying development and function of the symbiosis are subject to increasing research activity. Since AM occurs in the soil, most studies targeting a molecular understanding of AM development and function, use solid substrates for co-cultivating plants and AM fungi. However, for some experiments very clean roots, highly controlled nutrient conditions or applications of defined concentrations of signaling molecules (such as hormones) or other small chemicals (such as synthetic inhibitors or signaling agonists) are needed. To this end, hydroponics has been widely used in research on mechanisms of plant nutrition and some hydroponic systems were developed for AM fungal spore amplification. Here, we present a hydroponics set-up, which can be successfully utilized for experimental root colonization assays. We established a “tip-wick” system based on pipette tips and rock wool wicks for co-cultivation of AM fungi with small model plants such as Lotus japonicus. A larger “Falcon-wick” system using Falcon tubes and rockwool wicks was developed for larger model plants such as rice. The hydroponic system can also be employed for growing L. japonicus hairy roots after transformation by Agrobacterium rhizogenes, thus circumventing the laborious cultivation on agar medium-containing Petri dishes during hairy root development. The tip-wick and Falcon-wick systems are easy to use and can be built with low cost, conventional and reusable lab plastic ware and a simple aquarium pump.

Trace Analysis of Heavy Metals (Cd, Pb, Hg) Using Native and Modified 3D Printed Graphene/Poly(Lactic Acid) Composite Electrodes

AbstractHere we investigate the use of 3D printed graphene/poly(lactic acid) (PLA) electrodes for quantifying trace amounts of Hg, Pb, and Cd. We prepared cylindrical electrodes by sealing a 600 μm diameter graphene/PLA filament in a pipette tip filled with epoxy. We characterized the electrodes using scanning electron microscopy, Raman spectroscopy, and cyclic voltammetry in ferrocene methanol. The physical characterization showed a significant amount of disorder in the carbon structure and the electrochemical characterization showed quasi‐reversible behavior without any electrode pretreatment. We then used unmodified graphene/PLA electrode to quantify Hg, and Pb and Cd in 0.01 M HCl and 0.1 M acetate buffer using square wave anodic stripping voltammetry. We were able to quantify Hg with a limit of detection (LOD) of 6.1 nM (1.2 ppb), but Pb and Cd did not present measurable peaks at concentrations below ∼400 nM. We improved the LODs for Pb and Cd by depositing Bi microparticles on the graphene/PLA and, after optimization, achieved clear stripping peaks at the 20 nM level for both ions (4.1 and 2.2 ppb for Pb2+ and Cd2+, respectively). The results obtained for all three metals allowed quantification below the US Environmental Protection Agency action limits in drinking water.

Parallel sample processing using dispersive INtip micro-purification on programmable multichannel pipettes.

Automation gives researchers the ability to process and screen orders of magnitude higher numbers of samples than manual experimentation. Current biomacromolecule separation methodologies suffer from necessary manual intervention, making their translation to high-throughput automation difficult. Herein, we present the first characterization of biomacromolecule affinity purification via dispersive solid-phase extraction in a pipette tip (INtip). We use commercially available resin and compare efficiency with batch and spin column methodologies. Moreover, we measure the kinetics of binding and evaluate resin binding capacities. INtip technology is effective on, and scalable for, an automated platform (INTEGRA ASSIST). The results suggest that high-throughput biomolecular workflows will benefit from the integration of INtip separations.

Selective extraction and detection of β-agonists in swine urine for monitoring illegal use in livestock breeding

The illegal use of β-agonists often endangers animal-derived food safety. In this study, a selective detection method for β-agonists in swine urine was established via the combination of polymeric ionic liquid-molecularly imprinted graphene oxide-miniaturized pipette tip solid-phase extraction and high-performance liquid chromatography. It is worth noting that this method relied mainly on the designed adsorbent, which presented a rich adsorption mechanism, fast mass transfer rate, and high selectivity, and was successfully utilized in the selective extraction of β-agonists from swine urine samples. The proposed method has low LOD (0.20–0.56 ng/mL), high recovery (94.9–107.9%), and high reusability (4 times, 91.9–108.8%), which indicates its high potential as a selective, sensitive, accurate, and nonfatal method for monitoring the illegal use of β-agonists in the livestock breeding stage.

A molecularly imprinted polymer based monolith pipette tip for solid-phase extraction of 2,4-dichlorophenoxyacetic acid in an aqueous sample.

This paper presents a simple approach for fabrication of a pipette tip solid-phase extraction (PT-SPE) device, which possesses a monolith structure with low back pressure and has high selectivity to 2,4-dichlorophenoxyacetic acid (2,4-D). Pipette tips were packed with molecularly imprinted polymers (MIPs) as a selective adsorbent and high-density polyethylene (HDPE) as a co-sintering agent, and then heated to form a monolith extraction device. The key factors including the particle size and amount of packing material, and the type and volume of elution solvent, which influence PT-SPE device performance were optimized. A packing material of 40 mg/0.20 mL in a ratio of 4/6 (MIPs/HDPE) and treatment temperature of 150 °C was selected. By the determination with high-performance liquid chromatography (HPLC-SPD), the extraction device was found to have a good extraction recovery for a 2,4-D lake water sample at a low concentration (0.006 mg L-1) with an enrichment factor about 50. The proposed method provided a simple approach for the fabrication of a PT-SPE monolith device with reduced back pressure and wall effect, which are very important for improving the extraction efficiency. And the device will have promising application in the extraction of a variety of analytes in complex samples.

Exploring Polypyrrole as Extraction Phase for Disposable Pipette Extraction Method for Multiclass Organic Micro-Pollutant Determination in River and Tap Water Using Gas Chromatography-Mass Spectrometry

The use of a polypyrrole (PPy) is described as an efficient extraction phase for disposable pipette extraction (DPX), in a fast and ruggedized analytical method for simultaneous determination of 18 organic micro-pollutants in water using gas chromatography-mass spectrometry (GC-MS). The DPX-blank pipettes were filled with PPy, a material produced through the chemical polymerization of PPy using iron(III) chloride hexahydrate. The optimized conditions were 5 extraction cycles with 600 µL of sample, adjusted to pH 9, and desorption with 150 µL of ethyl acetate using 7 cycles with the same aliquot. The calibration curves resulted in determination coefficient (R2) higher than 0.9963, the limit of detection (LOD) ranged from 0.4 to 1.5 µg L−1, and the limit of quantification (LOQ) were from 1.4 to 5.0 µg L−1. Excellent results were obtained for repeatability (2.3 to 15%, for 5 µg L−1) and intermediate precision, varying the day of analyses (3.9 to 15.5%) and the pipette tip (3.4 to 22.4%). The analyte recovery ranged from 75.4 to 115.0% for river water, and from 74.9 to 116.2% for tap water, in three different levels of concentration. The DPX-GC-MS method with PPy was successfully applied to determine the 18 analytes in river and tap water from the cities of Joinville and Florianopolis, Santa Catarina, Brazil.

A novel hybrid micro extraction for the sensitive determination of 17β-estradiol in water samples.

A novel and green hybrid of pipette tip micro solid-phase extraction (PT-μSPE) and supported liquid extraction (SLE) was tailored and established for efficient and sensitive determination of 17β-estradiol (E2) in water samples. The hybrid design used chitin as a solid phase in PT-μSPE and applies the SLE principle on it for micro extraction. The analytical setup was termed as chitin-supported pipette tip-micro liquid extraction (CPT-μLE). E2 is a highly active environmental endocrine disruptor, widely spread in the water environment, and thus it is relevant to develop a novel and noble method for its monitoring at trace concentrations in water. The detection and quantification of E2 were performed via HPLC-UV. Under the optimal conditions, E2 showed excellent linearity in the lower scale range of 0.02-20 ng mL-1, and the correlation coefficient (R2) value was 0.9958. The limit of quantitation (LOQ) and limit of detection (LOD) were 0.01 ng mL-1 and 0.008 ng mL-1, respectively, with inter-day and intra-day precision in the range of 3.2-5.1% and 3.6-4.8%, respectively. The method was successfully applied for the sensitive determination of E2 in real water samples. Overall, the method is simple, rapid, technically innovative, cost-effective, highly sensitive, environment friendly, and highly efficient. Furthermore, this method should allow easy expansion to pharmaceutical and biological samples. Finally, this novel hybrid analytical approach proposes a new direction in sample pre-treatment advancements and should act as a reference for other noble analytical advancements in the trace analysis of various emerging contaminants in environmental and biological matrices.

Peristaltic pump-assisted zirconium nanoparticle-based pipette-tip solid phase extraction for the determination of cobalt by slotted quartz tube-flame atomic absorption spectrophotometry

In this work, a novel, efficient, simple and green solid phase extraction method based on a pipette tip filled with zirconium nanoparticles was developed for the sensitive determination of cobalt in soil samples via slotted quartz tube-flame atomic absorption spectrophotometry.