Dichloromethane Research Articles

Twisted BiOCl Moiré Superlattices for Photocatalytic Chloride Reforming of Methane.

Solar-driven conversion of CH4 into value-added methyl chlorides and H2 with abundant chloride ions offers a sustainable CH4 reforming strategy but suffers from inefficient Cl- activation and severe e--h+ recombination in traditional photocatalysts. Herein, we demonstrate that BiOCl moiré superlattices with a 11.1° twist angle are highly efficient for photocatalytic CH4 reforming into CH3Cl and H2 with NaCl. These moiré superlattices, featuring misalignment-induced tensile strains, destabilize surface Bi-Cl bonds, facilitating a hole-mediated MvK-analogous process to activate lattice Cl into reactive •Cl for CH4 chlorination. Meanwhile, their twisted stacking configurations reinforce interlayer electronic coupling and thus accelerate out-of-plane carrier transfer. Along with surface anchoring of single-atom Pt sites for H2 evolution, the resulting Pt1/BiOCl moiré superlattices deliver a CH3Cl yield of 53.4 μmol g-1 h-1 with an impressive selectivity of 96% under visible light. This study highlights the potential of lattice engineering in two-dimensional photocatalysts to regulate structural strains and carrier dynamics for the decentralized reforming of CH4.

A Mixed-Pure Planar Heterojunction Structure of Active Layers for Efficient Sequential Blade-Coating Organic Solar Cells.

Precise modulating the vertical structure of active layers to boost charge transfer is an effective way to achieve high power conversion efficiencies (PCEs) in organic solar cells (OSCs). Herein, efficient OSCs with a well-controlled vertical structure are realized by a rapid film-forming method combining low boiling point solvent and the sequential blade-coating (SBC) technology. The results of grazing incident wide-angle X-ray scattering measurement show that the vertical component distribution is varied by changing the processing solvent. Novel characterization technique such as tilt resonant soft X-ray scattering is used to test the vertical structure of the films, demonstrating the dichloromethane (DCM)-processed film is truly planar heterojunction. The devices with chloroform (CF) processed upper layer show an increased mixed phase region compared to these devices with toluene (TL) or -DCM-, which is beneficial for improving charge generation and achieving a superior PCE of 17.36%. Despite significant morphological varies, the DCM-processed devices perform slightly lower PCE of 16.66%, which is the highest value in truly planar heterojunction devices, demonstrating higher morphological tolerance. This work proposes a solvent-regulating method to optimize the vertical structure of active layers through SBC technology, and provides a practical guidance for the optimization of the active-layer microstructure.

Application of nucleophilic substitution reaction for sensitive determination of heptaminol hydrochloride in pharmaceuticals

A straightforward and sensitive spectrofluorimetric approach was established for the determination of heptaminol hydrochloride (HTM-HCl) based on the derivatization of the drug through its reaction with 5-dimethylaminonaphthalene-1-sulfonyl chloride (Dansyl chloride). The reagent underwent a nucleophilic substitution of its chlorine atom with HTM to give N-(5-dimethylaminonaphthalene-1-sulfonyl)-6-amino-2-methylheptan-2-ol. The highly luminescent derivative was extracted using methylene chloride and subjected to analysis at an excitation wavelength of 345 nm and an emission wavelength of 490 nm. The chemical reaction occurred within an aqueous environment buffered with a 0.1 M borate buffer solution adjusted to pH 10.5. Experimental findings indicate that the proposed method displays sensitivity and linearity across a concentration range from 0.03 to 2 µg mL− 1. The method achieves lower detection and quantification limits of 0.016 and 0.048 µg mL− 1, respectively. The analytical validation of this method followed the guidelines outlined by the International Council of Harmonization (ICH). This approach was applied effectively for quantifying the medication in both tablet and oral drops formulations available on the market, demonstrating excellent recovery of 98.95 ± 0.45 for tablets and 99.37 ± 0.24 for oral drops with no interference from excipients.

ASSESSMENT OF TOTAL PHENOLIC CONTENT (TPC), TOTAL FLAVONOID CONTENT (TFC) AND ANTIDIARRHEAL AND ANTIOXIDANT ACTIVITIES OF DIOSCOREA BULBIFERA TUBER EXTRACT

Objective: This study aims to conduct a comprehensive phytochemical screening of the tuber of Dioscorea bulbifera extract, evaluate its antioxidant capacity, and assess its anti-diarrheal activity. Methods: In this research, we reported the phytochemical screening, antidiarrheal and antioxidant activity of methanol, acetone, and dichloromethane (DCM) extracts. The qualitative phytochemical assessment of the bioactive extracts of the tuber of Dioscorea bulbifera was done. Quantitative analysis of total phenolic contents (TPC) and total flavonoid contents (TFC) were also determined. The scavenging activity of D. bulbifera was determined by DPPH assay. The antidiarrheal activity was experimented by the castor oil-induced diarrhea method. Results: TPC of Acetone, Methanol & DCM extract of D. bulbifera was 537.2, 352.7, and 79.12 μgGAE/ml, respectively, and TFC of those extracts were 2.96, 1.08, and 0.35 mgQE/g, respectively. The Acetone extract of D. bulbifera (IC50 27.99 μg/ml) showed the highest antioxidant activity. Antidiarrheal properties of the three extracts were tested at 150 mg/kg, 300 mg/kg, and 600 mg/kg per body weight (bw) in mice. The methanol and DCM extracts showed an important antidiarrheal activity by curbing 69.56% and 86.95% of diarrheal faces at the doses of 600 and 300 mg/kg/bw, respectively. Conclusion: Since the current study implies that the plant extracts gave significant results for Antidiarrheal, Antioxidant, and Phytochemical analysis, the tuber of D. bulbifera may contain therapeutic potential compounds, such as flavonoids, terpenoids, alkaloids, tannins, and saponins. These results moderate more investigation for the potential discovery of new natural bioactive compounds from this medicinal plant.

Solvent Dictated Organic Transformations.

Solvent plays an important role in many chemical reactions. The C-H activation has been one of the most powerful tools in organic synthesis. These reactions are often assisted by solvents which not only provide a medium for the chemical reactions but also facilitate reaching to the product stage. The solvent helps the reaction profile both chemically and energetically to reach the targeted product. Organic transformations via C-H activation from the solvent assistance perspective has been discussed in this review. Various solvents such as tetrahydrofuran (THF), MeCN, dichloromethane (DCM), dimethoxyethane (DME), 1,2-dichloroethane (1,2-DCE), dimethylformamide (DMF), dimethylsulfoxide (DMSO), isopropyl nitrile (iPrCN), 1,4-dioxane, AcOH, trifluoroacetic acid (TFA), Ac2O, PhCF3, chloroform (CHCl3), H2O, N-methylpyrrolidone (NMP), acetone, methyl tert-butyl ether (MTBE), toluene, p-xylene, alcohols, MeOH, 1,1,1-trifluoroethanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), tert-amyl alcohol and their roles are discussed. The exclusive role of the solvent in various transformations has been deliberated by highlighting the substrate scope, along with the proposed mechanisms. For easy classification, the review has been divided into three parts: (i) solvent-switched divergent C-H activation; (ii) C-H bond activation with solvent as the coupling reagent, and (iii) C-H activation with solvent caging and solvent-assisted electron donor acceptor (EDA) complex formation and autocatalysis.

Cellulose nanocrystal dispersion-ability in polylactides with various molecular weights prepared in dichloromethane/dimethyl sulfoxide solvents for electrospinning applications

In this study, effects of polylactide molecular weight, i.e., high (HPLA), medium (MPLA), low (LPLA), and dichloromethane (DCM)/dimethyl sulfoxide (DMSO) blend ratio on cellulose nanocrystal (CNC) dispersion quality in solution casted PLA/CNC nanocomposites were investigated via small amplitude oscillatory shear rheological analysis, while crystallization behavior, thermal degradation, morphological structure of the nanocomposites were also reported. Due to its low dielectric constant, none of the nanocomposites with 100DCM indicated a change in their complex viscosity as a result of poor CNC dispersion. This is while the increase in DMSO content (50%vv−1) improved CNC dispersion. The superior CNC dispersion-ability in PLAs with lower molecular weight was confirmed. The poorer CNC dispersion in HPLA attributes to hindering effect of higher molecular weight on solvent and nanoparticle diffusion. The better dispersed CNCs influenced crystal nucleation behavior of PLAs and increased crystallinity degree. In addition, the impact of well-dispersed CNCs on fiber formation quality of nanocomposites was reported. Introducing finely dispersed CNCs (1 wt%) in LPLA refined fiber diameters around 1200 nm with more homogenous structure. Besides, the use of 100DCM and the use of DMSO at high contents (50%vv−1) deteriorated fiber formation, respectively, due to low conductivity of DCM and high boiling temperature of DMSO.

Phytochemical composition and therapeutic potential of Caralluma edulis a cholistani plant

This study explores C. edulis, a plant indigenous to the Cholistan desert, locally known as Pimpa or Seetu, traditionally consumed as a vegetable. Our research aimed to comprehensively analyze its phytochemical constituents, and evaluate its antibacterial, antioxidant, antiviral, anti-inflammatory, antidiabetic, and antipyretic potentials. Utilizing a range of extracts including methanol (MtOH), ethanol (EtOH), ethyl acetate (EA), n-hexane (n-hex), dichloromethane (DCM), and aqueous (Aq), for effective extraction of phytochemicals from C. edulis. Standard biochemical assays and High-Performance Liquid Chromatography-Photodiode Array (HPLC-PDA) were used for analysis of phenolic compounds. Antibacterial effect(s) were confirmed through disc diffusion method and min inhibitory concentrations (MICs). The antioxidant activity was assessed through the Ferric Reducing Antioxidant Power (FRAP) assay and the DPPH radical scavenging method. In vivo antiviral potential was assessed through Hemagglutination (HA) test. Anti-inflammatory, antidiabetic, and antipyretic activities were performed on female albino rats using carrageenan, alloxan monohydrate and yeast-induced methods, respectively. Statistical analysis was done using standard one way ANOVA.Our findings revealed a rich diversity of phenolic compounds and the presence of proteins, alkaloids, and carbohydrates in C. edulis. MtOH and n-hex extracts demonstrated deep antiviral activity against various viral strains. In vivo toxicology studies indicated no significant toxicity at doses up to 5 g/kg. The DCM extract has shown notable anti-inflammatory effects, and EA extract was leading in antipyretic activity. All extracts, except MtOH, exhibited antidiabetic properties.In conclusion, C. edulis emerges not only as a valuable nutritional source but also as a potent alternative medicinal resource, offering wide range of therapeutic benefits.

Synthesis, structure, photo- and electroluminescent properties of methyl- and alkoxy-substituted 4-methyl-N-[2-(phenyliminomethyl)phenyl]benzenesulfamides and their zinc(II) complexes

A series of novel Zn(II) bischelate complexes based on azomethines of 2-(N-tosylamino)benzaldehyde and aromatic amines (aniline, 4-methylaniline, 4-methoxyaniline, 2-methoxylaniline, and 4-ethoxylanine) were designed and synthesized with the aim of studying their photo- and electro-luminescent properties. The structures of the synthesized azomethines and their complexes were studied by elemental analysis, infrared (IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The structure of the Zn(II)-complexes was determined using X-ray diffraction analysis. In the solid state, azomethines exhibit bright luminescence in the yellow part of the spectrum with high emission efficiency and quantum yields of approximately 50%. Zinc complexes based on them exhibit noticeable luminescence in the solid state and in solutions of methylene chloride. Compared to azomethines, the luminescence maxima of Zn(II) complexes are hypsochromically shifted, and they exhibit pronounced blue-green luminescence. The OLED devices based on zinc(II) complexes emit strong bluish-green light with a peak maximum at 478-490 nm. The device with the best parameters has a maximum luminance of 2103 cd/m2, a current efficiency of 14.0 cd/A, and an overall efficiency of 4.8%, with a turn-on voltage of 3.6 V.

Facile Formation of Metallic Surface with Microroughness via Spray-Coating of Copper Nanoparticles for Enhanced Liquid Metal Wetting.

This paper presents a simple, fast, and cost-effective method for creating metallic microstructured surfaces by spray-coating a dispersion of copper nanoparticles (CuNPs) onto polymethyl methacrylate (PMMA) substrates, enabling the imbibition-induced wetting of liquid metal. The formation of these microstructured patterns is crucial for the spontaneous wetting of gallium-based liquid metals. Traditional techniques for producing such microstructures often involve complex and costly lithography and vacuum deposition methods. In contrast, this study demonstrates that liquid metal wetting can occur with metal microstructures formed through a straightforward spray-coating process. To immobilize the CuNPs on the polymer substrate, an organic solvent that dissolves the polymer surface was employed as the dispersion medium. The effects of various spray-coating parameters, including distance and time, on the uniformity and immobilization of CuNP films were systematically investigated. Under optimal conditions (120 s of spray time and 10 cm spray distance), CuNPs dispersed in dichloromethane (DCM) yielded uniform and stable microstructured surfaces. The spontaneous wetting of gallium-based liquid metal was observed on the fabricated CuNP film. Additionally, liquid metal selectively wet the CuNP patterns formed by stencil techniques, establishing electrical connections between electrodes. These findings underscore the potential of spray-coating for fabricating metallic surfaces to drive the formation of liquid metal patterns in flexible electronics applications.

Highly efficient synthesis of di-substituted allenes via copper-catalyzed SN2′- substitution reaction of organotitanium reagents with propargyl bromides

A simple and mild catalytic SN2′-type displacement of propargyl halides with organotitanium reagents is reported. The SN2′-type displacement of propargyl bromides with organotitanium reagents mediated by CuI (2 mol%)/MePPh2(4 mol%) in dichloro methane afforded multi-substituted allenes in good yields (up to 95 %) at 40 °C for 5 h. The aryls bearing electron-donating or electron-withdrawing groups in aryltitanium reagents gave multi-substituted allenes in good yields. In addition, the di-substituted allenes bearing a naphthyl group was obtained in 54–99 % selectivities with isolated yields of 43–83 %. The process was simple and easily performed, and it provides an efficient method for the synthesis of di-substituted allene derivatives. On the basis of the experimental results, a possible catalytic cycle has been proposed.

Rifampicin-Loaded PLGA/Alginate-Grafted pNVCL-Based Nanoparticles for Wound Healing

The topical therapy with rifampicin (RF)-based formulations is beneficial for treating postoperative wound infections and to accelerate healing. Despite recent research highlighting the antibiotic’s significant anti-inflammatory properties, limited topical wound healing products are currently available. The present study aimed to prove that the newly synthesized nanoparticles based on grafted alginate and poly(N-vinylcaprolactam) (pNVCL) and poly-lactic-co-glycolic acid (PLGA) contribute to the healing process of a wound. The methods used were at first the synthesis of the copolymer of alginate and pNVCL via grafting from technique and radical polymerization followed by water-in-oil-in water (W/O/W) emulsification; as oil phase PLGA dissolved in dichloromethane (DCM) was used. The formed nanoparticles were than characterized. The loaded RF was determined to be 160 µg/mL for a 20 mg formulation and within a four-hour time frame approximately 10% of the total loaded amount was released. The inhibitory concentrations (IC50) were 192.1 µg/mL for the nanoparticle, 208.8 µg/mL for pure rifampicin, and 718.1 µg/mL for the rifampicin-loaded nanoparticles. Considering the double role rifampicin was used for, the result was considered satisfactory in the way that these formulations could be used predominantly for postoperative wound irrigation in order to avoid infections and to improve healing.

Utilization of Neem Seed Oil as Surfactant in the Production of Flexible and Rigid Polyurethane Foam

Extraction and processing of polyether polyols derived from petrochemicals, commonly used as surfactants during polyurethane foam (PUF) production, contribute to carbon emissions and raises the issue of long-term sustainability given that petrochemicals are non-renewable resources. Here, 5 mg and 4 mg of neem seed oil are employed to form flexible and rigid PUF, classified purposefully based on their divergent usage. To find an environmentally friendly replacement, flexible PUF whose mass, volume, density, compression, tensile strength, cream time, foam rise and rising time are 0.0047 kg m3, 16.52 kg/m3, 8.10%, 39.28 kN/m2, 60s, 10s and 60s is formed by mixing 1.25 kg polyol, 5mg silicon oil and 10g calcium carbonate (CaCO3). Likewise, by mixing 1.2 kg polyol, 4mg silicon oil and 8g CaCO3, a rigid PUF with 0.005kg, m3, 16.2 kg/m3, 8.15%, 40.72 kN/m2, 50s, 15 cm and 58s key, physical and mechanical property as respectively listed under the flexible PUF formulation is produced. Both foams were produced using equal amounts of toluene diisocyanate, water, stannous octoate and methylene chloride, resulting in PUF that can be used in insulation, cushioning and construction support applications based on their characteristic height, density, tensile strength and compressive strength. As the surfactant, neem seed oil's potential in the synthesis of PUF cannot be overemphasized. The study of the kinetics of PUF production is limited and should trigger the adoption of biobased surfactants for industrial applications in the future.

DNA profiling, nutritional value and phytochemical investigation of Cissus rotundifolia Lam. growing in Yemen

Cissus rotundifolia Lam. (Vitaceae) is a wild plant that is commonly used as food and medicine. There are limited studies on the phytochemical composition of this plant. So, this study aims to investigate C. rotundifolia growing in Yemen phytochemically. HPLC analysis of C. rotundifolia aerial parts led to the identification and quantification of four compounds (isoorientin, quercetrin, quercetin, and linarin), among which isoorientin and quercetrin were the major. Proximate analysis showed high fibre content and low moisture content, whereas the nutritional values showed a high carbohydrate content which gave rise to higher nutritional value (266.39 Kcal.). Potassium, calcium, iron, magnesium, and vitamin E were present in high concentrations. Investigation of the methylene chloride and n-butanol fractions lead to the isolation of seven compounds: β-sitosterol, magnificol, β-sitosterol-glucoside, quercetin, quercetrin, isoorientin, and linarin. This is the first report on isolating these compounds from the investigated plant.

Impact of PM2.5 filter extraction solvent on oxidative potential and chemical analysis

ABSTRACT Fine particulate matter (PM2.5) is hypothesized to induce oxidative stress, and has been linked to acute and chronic adverse health effects. To better understand the risks and underlying mechanisms following exposure, PM2.5 is collected onto filters but prior to toxicological analysis, particles must be removed from filters. There is no standard method for filter extraction, which creates the possibility that the methods of extraction selected can alter the chemical composition and ultimately the biological implications. In this study, comparisons were made between extraction solvents (methanol (MeOH), dichloromethane (DCM), 0.9% saline, and Milli-Q water) and the results of oxidative potential and elemental concentration analysis of PM2.5 collected across sites in Arkansas, USA. Significant differences were observed between solvents, with DCM having significantly different results compared to all other extraction solvents (p ≤ 0.001). Significant correlations between element, black carbon, and PM2.5 concentrations and oxidative potential were observed. The observed correlations were extraction solvent dependent. For example, in saline extracted samples, oxidative potential had significant negative correlations with: Ba, Cd, Ce, Co, Ga, Mn and significant positive correlations with: Cr, Ni, Th, U. While in MeOH extracted samples, significant positive correlations were only between oxidative potential and Ga, U and significant negative correlations with V. This indicates that PM2.5 samples extracted with different solvents will yield different conclusions about the causal components. This study highlights the importance of filter extraction methods in interpretation of oxidative potential results and comparisons between studies. Implications While there is no standard method for PM2.5 filter extraction, variation of extraction methods impact analytical results. This project identifies that extraction method variation, particularly extraction solvent selection, leads to discrepancies in chemical and toxicological analysis for PM2.5 collected on the same filter. This work highlights the need for methods standardization to support accurate comparisons between PM2.5 research studies, thus providing better understanding of PM2.5 across the globe.

Whole Genome Sequencing Analysis of Model Organisms Elucidates the Association Between Environmental Factors and Human Cancer Development

Determining a novel etiology and mechanism of human cancer requires extraction of characteristic mutational signatures derived from chemical substances. This study explored the mutational signatures of N-nitroso bile acid conjugates using Salmonella strains. Exposing S. typhimurium TA1535 to N-nitroso-glycine/taurine bile acid conjugates induced a predominance of C:G to T:A transitions. Two mutational signatures, B1 and B2, were extracted. Signature B1 is associated with N-nitroso-glycine bile acid conjugates, while Signature B2 is linked to N-nitroso-taurine bile acid conjugates. Signature B1 revealed a strong transcribed strand bias with GCC and GCT contexts, and the mutation pattern of N-nitroso-glycine bile acid conjugates in YG7108, which lacks O6-methylguanine DNA methyltransferases, matched that of the wild-type strain TA1535, suggesting that O6-methyl-deoxyguanosine contributes to mutations in the relevant regions. COSMIC database-based similarity analysis revealed that Signature B1 closely resembled SBS42, which is associated with occupational cholangiocarcinoma caused by overexposure to 1,2-dichlolopropane (1,2-DCP) and/or dichloromethane (DCM). Moreover, the inflammatory response pathway was induced by 1,2-DCP exposure in a human cholangiocyte cell line, and iNOS expression was positive in occupational cholangiocarcinomas. These results suggest that 1,2-DCP triggers an inflammatory response in biliary epithelial cells by upregulating iNOS and N-nitroso-glycine bile acid conjugate production, resulting in cholangiocarcinoma via DNA adduct formation.

Epicatechin Isolated from Litchi chinensis Sonn. (Litchi) Fruit Peel Ethyl Acetate Extract Modulated Glucose Uptake in Chang Cells and Suppressed ROS Production in RAW 264.7 Macrophages.

Bioactive flavonoid epicatechin has been reported in the peel of litchi fruit but isolated from its hydroalcoholic extracts. This study isolated epicatechin with cellular glucose uptake modulatory and ROS production inhibitory properties from the ethyl acetate (EtOAc) extract using a bioassay-guided approach. The fruit peel was defatted with hexane and sequentially extracted using dichloromethane (DCM), EtOAc, methanol (MeOH) and water. In vitro phytochemical models, namely antioxidant (Fe3+ reducing, radical scavenging and anti-linoleic acid peroxidative) and glycaemic control (α-glucosidase and α-amylase inhibitory and glucose uptake modulatory), were employed for the bioassay-guided isolation, while the isolated compound was characterised using NMR and mass spectrometry and assessed for dose-dependent inhibition of α-glucosidase and lipopolysaccharide (LPS)-induced cellular ROS production, as well as modulation of cellular glucose uptake. Relative to the other extracts, the EtOAc extract had appreciable phenol and flavonoid contents, which perhaps influenced its potent anti-lipid peroxidative (65.0%) and α-glucosidase inhibitory (52.4%) effects. The α-glucosidase inhibitory potency of the fractions (1-8) from the EtOAc extracts correlated with their flavonoid contents, with fraction 5 outperforming other fractions. The fraction comprised a pool of fractions obtained from the DCM:MeOH:water (7:3:0.281 v/v/v) solvent system. LC-MS revealed the predominant presence of epicatechin in fraction 5, which was later isolated from one of the sub-fractions (sub-fraction 4) of fraction 5. This sub-fraction had stronger anti-lipid peroxidative (65.5%), α-glucosidase inhibitory (65.8%) and glucose uptake modulatory (38.2%) effects than the other sub-fractions from fraction 5, which could have been influenced by the isolated epicatechin. Moreover, the isolated epicatechin inhibited α-glucosidase (IC50 = 35.3 µM), modulated cellular glucose uptake (EC50 = 78.5 µM) and inhibited LPS-induced ROS production in RAW 264.7 macrophages in a dose-dependent fashion [IC50 = 18.9 µM; statistically comparable (p > 0.05) to ascorbic acid, IC50 = 9.57 µM]. Epicatechin from litchi peel EtOAc extract could potentiate glucose uptake modulatory, α-glucosidase inhibitory and ROS suppressive capacities, which could be influential in the use of litchi fruit peel for managing diabetes and associated oxidative damage.

Overcoming the Strong Sample Solvent Effect for Sustainability Measurement Challenges in Liquid Chromatography. Example for Bisphenol-A.

This paper describes an approach to achieve low parts per billion (ppb) concentration level detection using a reversed-phase ultrahigh-performance liquid chromatographic ultraviolet absorbance detection method with large-volume feed injection (FI) for analytes in dichloromethane (DCM). FI is a novel technology that allows sample injection at a defined speed into the LC mobile phase. We demonstrate this approach for a mixture of bisphenol A and its diglycidyl ether derivatives in DCM. DCM is a very strong injection solvent at reversed-phase LC conditions and is typically immiscible with a starting reversed-phase gradient mobile phase containing a high percentage of water. As a result, reduced separation performance and even peak splitting are seen with classic flow-through injection. The method setup comprised an octyl-bonded core-shell stationary phase (150 × 4.6 mm i.d., 2.7 μm particle size) with a water/acetonitrile mobile phase gradient and an exceptionally high injection volume of 45 μL of DCM solution using FI. Optimization of feed speed (1%) and isocratic hold duration (4 min) was crucial for final separation conditions. FI delivered more than a 20-fold improvement in the limit of detection (LOD) compared to standard flow-through injection while maintaining peak resolution. The LOD of the final method ranged between 1 and 10 ppb in the polymer resin. This methodology has high potential for trace analysis in a large variety of applications that suffer from the "strong solvent effect".

Improved and Novel Methods for Investigating Organophosphate Esters in Particulate Matter

A pressurized liquid extraction (PLE) method for the extraction of 31 organophosphate esters (OPEs) and novel organophosphate esters (NOPEs) has been developed. Unlike previously published methods, this method utilizes the high-throughput nature of PLE (as opposed to Soxhlet or sonication methods) without using potentially harmful organic solvents like methylene chloride. Combinations of hexane and acetone and hexane and ethyl acetate at various temperatures were examined. Extracts were concentrated and analyzed via gas chromatography–mass spectrometry. The final optimized method utilized 1:1 v/v hexane/ethyl acetate at 100 °C for three static cycles (5 min each) at 80% flush volume and a 100 s N2 purge. This provided average surrogate corrected target analyte percent recoveries in spike and recovery experiments (n = 6) for OPEs and NOPEs of 106 ± 13%, with average surrogate recoveries of 88.6 ± 7.3%. The developed method was further validated using standard reference materials and was then applied to atmospheric particulate matter samples collected in the city of Providence, RI. The dataset reflected ambient concentrations of 16 OPEs and NOPEs (reported in pg m−3) for the first time in the greater Providence metropolitan area, including one of the first reports of NOPEs in atmospheric particulate matter in the U.S.

B-178 A Sensitive LC-MS/MS Assay for Total Testosterone Quantification

Abstract Background Total testosterone immunoassay is a commonly ordered test for the diagnosis of gonadal disorders. However, immunoassays suffer from low specificity and sensitivity, which leads to inaccuracy especially in the low concentration range (< 100 ng/dL). As a result, commercial testosterone immunoassays have difficulties to accurately measure total testosterone levels for women, children, and hypogonadal men. LC-MS/MS has emerged as the method of choice for the accurate quantitation of steroid hormones. We presented here a sensitive laboratory-developed total testosterone assay, which was validated on two LC-MS/MS instruments. Methods An internal standard containing [2,3,4-13C3]-testosterone was added to each sample. The spiked serum sample was loaded on a supported liquid extraction (SLE) cartridge and eluted using methylene chloride. The elute was dried down under nitrogen and reconstituted in sample reconstitution buffer. Chromatographic separation was achieved using a Restek Ultra C18, 50 x 2.1 mm, 3µm analytical column and a total run time of each sample was 5 minutes. The assay was validated on two triple quadrupole mass spectrometers, API 6500 and API 4500. Results were compared with those of a reference laboratory. Results The assay was linear in the range of 1 to 1200 ng/dL for total testosterone and the AMR was set at 2-1200 ng/dL. The interday and intraday imprecision were less than 8%. Split sample comparison to a reference laboratory demonstrated acceptable accuracy with the slope of 1.053 and correlation coefficient (R2) of 0.991. The limit of detection (LOD) was 0.2 ng/dL and the limit of quantitation (LOQ) was 0.5 ng/dL. Results obtained from two instruments agreed well with the slope of 0.996 and the R2 of 0.999. No carryover or interferences was observed for this assay. Conclusions A LC-MS/MS based method was developed and validated for measuring total testosterone levels for female and children. This sensitive and specific assay will improve the diagnosis of hypogonadism and monitoring of testosterone-suppressing treatment.

Effect of Cucurbita pepo (Pumpkin) seed extracts on the cyclicity and reproductive hormones of female Wistar rats

Introduction: Despite the traditional use of Cucurbita pepo seed in pregnancy, its effects on female reproduction remain scarce. This study evaluated the impacts of n-hexane, dichloromethane (DCM), and aqueous ethanol extracts of C. pepo seed on the cyclicity and reproductive hormones of female Wistar rats. Methods: Ten groups of four rats received seed extracts or tween 80 orally for 21 days: A (control)= 0.5 mL tween 80 (vehicle); B, C, & D= 142.86, 285.71, and 428.57 mg/kg nHE; E, F, & G= 142.86, 285.71, 428.57 mg/kg of DCM; and H, I, & J= 142.86, 285.71, 428.57 mg/kg of aqueous ethanol extracts, respectively. Vaginal cytology monitored the estrous cycle daily, and blood samples were obtained for follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone at various oestrus cycle phases. Results: Compared to the control, the estrous cycle phases did not change significantly (P>0.05). FSH levels significantly increased (P<0.05) with DCM and aqueous ethanol extracts of C. pepo seed during proestrus and estrus phases compared to the control. A significant (P<0.05) increase in LH was observed with n-hexane, DCM, and aqueous ethanol extracts during all estrous cycle phases compared to the control. All extracts significantly increased estrogen levels (P<0.05) during all phases. DCM and aqueous ethanol extracts reduced substantially the estrus-phase progesterone. Conclusion: Cucurbita pepo may stimulate the hypothalamic-pituitary-gonadal axis in female reproduction. Further studies should be conducted using various phytoestrogen compounds to gain useful knowledge about the effectiveness, safety, and long-term effects of C. pepo seed extracts in regulating hormonal balance.