Improved Extraction Technique Research Articles

STANDARDISATION AND OPTIMIZATION OF MERCURY EXTRACTION FROM CINNABAR (HINGULA) USING THE NADA YANTRA METHOD IN AYURVEDIC PRACTICE

The extraction of mercury (Parada) from cinnabar (Hingula) is a critical process in Ayurvedic medicine, particu-larly for use in metallic and mineral formulations known as Rasayoga. Traditional methods for mercury extrac-tion, such as Urdhva Patana (upward sublimation), Adhah Patana (downward sublimation), and Tiryanka Pat-ana (transverse sublimation), face challenges in terms of efficiency and environmental concerns. This research addresses contemporary efficiency, safety, and environmental issues while creating a refined and standardised procedure for extracting mercury (Parada) from cinnabar (Hingula) utilising conventional Ayurvedic techniques. This study aims to refine mercury extraction by applying the Nada Yantra method, a specific approach detailed in classical Ayurvedic texts. A series of pharmaceutical trials developed a standard operating procedure (SOP) to optimise mercury yield from Hingula with and without purification (Shodhana). The process involves a series of sublimations following purification steps and a series of sublimations without purification, ensuring effective procurement of mercury for medicinal use. The study successfully standardises and compares mercury extraction from cinnabar with and without purification using the Nada Yantra method, yielding approximately 60% and 45 % purified mercury, respectively. This optimised process is efficient, environmentally considerate, and suitable for modern Ayurvedic practices, ensuring safe and high-quality mercury for medicinal use without additional pu-rification steps for Parada Shodhana. The project aims to create a repeatable standard operating procedure (SOP) for mercury extraction using the Nada Yantra technique, which has its roots in ancient writing but has been up-dated for modern applications. This method offers a reproducible and efficient means of obtaining purified mer-cury, suitable for modern Ayurvedic pharmaceutical practices. Enhancing the quality and yield of mercury for use in Ayurvedic medicinal formulations by improved extraction techniques would ensure that the material is safe, effective, and comply with environmental and regulatory requirements.

Advanced Extraction Techniques and Physicochemical Properties of Carrageenan from a Novel Kappaphycus alvarezii Cultivar.

Carrageenans are valuable marine polysaccharides derived from specific species of red seaweed (Rhodophyta) widely used as thickening and stabilizing agents across various industries. Kappaphycus alvarezii, predominantly cultivated in tropical countries, is the primary source of kappa-carrageenan. Traditional industrial extraction methods involve alkaline treatment for up to three hours followed by heating, which is inefficient and generates substantial waste. Thus, developing improved extraction techniques would be helpful for enhancing efficiency and reducing environmental impacts, solvent costs, energy consumption, and the required processing time. In this study, we explored innovative extraction methods, such as ultrasound-assisted extraction (UAE) and supercritical water extraction (SFE), together with other extraction methods to produce kappa-carrageenan from a new strain of K. alvarezii from the Philippines. FTIR-ATR spectroscopy was employed to characterize the structure of the different carrageenan fractions. We also examined the physicochemical properties of isolated phycocolloids, including viscosity, and the content of fatty acids, proteins, and carbohydrates. For refined carrageenan (RC), both the traditional extraction method and the UAE method used 1 M NaOH. Additionally, UAE (8% KOH) was employed to produce semi-refined carrageenan (SRC). UAE (8% KOH) produced a high yield of carrageenan, in half the extraction time (extraction yield: 76.70 ± 1.44), and improved carrageenan viscosity (658.7 cP), making this technique highly promising for industrial scaling up. On the other hand, SFE also yielded a significant amount of carrageenan, but the resulting product had the lowest viscosity and an acidic pH, posing safety concerns as classified by the EFSA's re-evaluation of carrageenan as a food additive.

Diabetic Retinopathy Features Segmentation without Coding Experience with Computer Vision Models YOLOv8 and YOLOv9.

Computer vision is a powerful tool in medical image analysis, supporting the early detection and classification of eye diseases. Diabetic retinopathy (DR), a severe eye disease secondary to diabetes, accompanies several early signs of eye-threatening conditions, such as microaneurysms (MAs), hemorrhages (HEMOs), and exudates (EXs), which have been widely studied and targeted as objects to be detected by computer vision models. In this work, we tested the performances of the state-of-the-art YOLOv8 and YOLOv9 architectures on DR fundus features segmentation without coding experience or a programming background. We took one hundred DR images from the public MESSIDOR database, manually labelled and prepared them for pixel segmentation, and tested the detection abilities of different model variants. We increased the diversity of the training sample by data augmentation, including tiling, flipping, and rotating the fundus images. The proposed approaches reached an acceptable mean average precision (mAP) in detecting DR lesions such as MA, HEMO, and EX, as well as a hallmark of the posterior pole of the eye, such as the optic disc. We compared our results with related works in the literature involving different neural networks. Our results are promising, but far from being ready for implementation into clinical practice. Accurate lesion detection is mandatory to ensure early and correct diagnoses. Future works will investigate lesion detection further, especially MA segmentation, with improved extraction techniques, image pre-processing, and standardized datasets.

An advanced Bayesian parameter estimation methodology for concrete dams combining an improved extraction technique of hydrostatic component and hybrid response surface method

It is very important to estimate the mechanical parameters based on monitoring data for investigating the operation behavior of concrete dams. In this paper, an advanced Bayesian parameter estimation method for concrete dams is proposed. The Empirical Mode Decomposition (EMD) is adopted to extract the aging component of the observed deformation sequence, and the hydrostatic component is separated from the remaining periodic term through the statistical regression model (SRM). A hybrid response surface method (HRSM) is proposed as a surrogate model for finite element method (FEM) simulation. The likelihood function, which reflects the error between the observed and simulated deformation, is constructed, then the Bayesian formula for parameter estimation is established. The transitional Markov chain Monte Carlo (TMCMC) algorithm is used to obtain the parameter posterior distribution. The proposed method is applied to estimate the elastic modulus of the GD concrete dam, the parameter posterior distribution is obtained through the fusion of monitoring information and parameter prior information. This method can also avoid the issues of multiple solutions and unreasonable parameter combinations, which may exist in traditional deterministic inversion methods. The case study shows that the proposed method has good applicability in the parameter estimation of concrete dams.

A Review on the Usage of Main Secondary Metabolites of Crocus sativus in Cancer Treatments

Saffron is the world’s second most costly spice, with numerous advantages of culinary, cosmetics, pharmaceutical and medical fields. There is an inadequate awareness of how Crocus sativus L. (Family Iridaceae) which produces the spice saffron from the filaments that grow inside the flower, can possibly treat cancer. Since, cancers are regarded as a devastating disease in today's world, anticancer and antioxidant properties of secondary metabolites available in saffron will be highly invaluable. The present review focuses on investigating on the role of crocin, crocetin and safranal in cancer treatments, which are the main secondary metabolites of C. sativus, and evaluating the various methods of extracting, isolating and analysing them. The review conducted using subjective indexed journal articles that were published over the past ten years. Out of the available data, it found that crocin would be quite beneficial in healing cancer without revealing any adverse effects. Crocin showed immense potential in curing a wide range of cancer types, mainly prostate and lung cancers, by eliminating cancer cells through apoptosis and inhibiting tumour invasion. There were a limited number of researches conducted using crocetin and safranal. However, they will approve for cancer treatments shortly. Crocetin was widely employed as a chemo-preventive and anti-inflammatory medication for pancreatic and breast cancer treatments. It has recently been utilized only for treatments of few types of cancers. Only one publication recorded in the recent ten years, as the usage of safranal in cancer treatment, which was against leukaemia. Moreover, secondary metabolite analysis techniques including spectrophotometry and chromatography utilized effectively, whereas predominantly improved extraction techniques including ultrasound-assisted extraction, emulsion liquid membrane, high hydrostatic pressure extraction. The analysis affirmed that, microwave[1]assisted extraction (80±1%) followed by low-pressure liquid chromatography (99.04±0.01%) showed optimum recovery of crocin. Whereas for safranal, microwave-assisted extraction (15.9±0.1%) and ultraviolet (UV) spectrophotometry preferred methods. The analysed data will be useful for future studies that focus on the analysis of saffron secondary metabolites and potentiality in cancer treatments to provide the researchers with a wide range of alternatives for carrying out the processes of curing cancers.
 Keywords: Anticancer, Crocin, Crocetin, Safranal, Saffron

Bio-Mediated Soil Improvement Using Plant Derived Enzyme in Addition to Magnesium Ion

Recently, soil improvement using EICP (Enzyme-Induced Carbonate Precipitation) methods in the geotechnical and geo-environmental field has become a prominent interest worldwide. The objective of this study was to develop an improved extraction technique of crude urease from watermelon seeds in both dry and germinated conditions. Subsequently, this study also analyzed the improvement methodology of crystal polymorphs and soil bonding incorporation of various Mg2+/Ca2+ ratios. The optimization of enzyme-mediated carbonate precipitation was also investigated by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) analysis. Results confirmed that the precipitated crystals are mainly calcite, vaterite and aragonite primarily (depending on the Mg2+/Ca2+ ratios). Therefore, to improve the bonding capacity in between the sand particles a novel improvement methodology was investigated by adding various Mg2+/Ca2+ ratios. The mechanical properties of the treated soil (Mikawa Sand, D50 = 0.870 mm) specimens were tested by unconfined compressive strength (UCS) and this confirmed the effectiveness of adding various Mg2+/Ca2+ ratios. The results of the UCS tests showed that, the lower molar ratios of Mg2+/Ca2+ can significantly improve the UCS of the specimen (up to 50%) which could be considered a significant outcome for different bio-geotechnical applications.

Optimization of ultrasound‐assisted water extraction conditions for the extraction of phenolic compounds from black mulberry leaves (Morus nigra L.)

AbstractMultiple response optimizations of ultrasound‐assisted water extraction (UAWE) conditions for the extraction of phenolic compounds from Morus nigra L. leaves were investigated. The experimental design and optimization of the UAWE were performed using response surface methodology (RSM) coupled with a central composite design (CCD). The optimum conditions of UAWE were determined as extraction time: 15 min, solvent:solid ratio: 85 mL/g and extraction temperature: 55°C. The optimized UAWE was compared with conventional extraction (CE) and it was observed that TPC (21.78 ± 0.50 mg GAE/g dw), TFC (11.70 ± 0.26 mg CAT/g dw), and TAA (66.37 ± 0.66% 1,1‐diphenyl‐2‐picrylhydrazyl [DPPH]) in UAWE were higher than CE. The polyphenolic profile of the extracts obtained from both methods was evaluated and most of the 16 phenolic compounds especially chlorogenic acid (3.47 ± 0.06 mg/g dw), kaempferol (1.39 ± 0.02 mg/g dw) and quarcetin hydrate (1.92 ± 0.01 mg/g dw) were found in higher amounts in UAWE extracts.Practical applicationsBlack mulberry leaf extract, which is an important source for antioxidants and especially phenolic compounds, has a potential to become a supplement and functional food. Herbal infusion or tea prepared from black mulberry leaves can be an alternative to mostly consumed tea. The extraction and purification of natural antioxidant substances from plant sources make it possible to use these substances in the food industry. It is therefore important to optimize the extraction conditions of natural antioxidants and identify the substances in the extracts obtained. In this study, UAWE for high extraction yield at low temperature was also preferred to extract high quantities of phenolic compounds, which are heat sensitive. UAWE for phenolic extraction from black mulberry leaves was optimized by RSM. The optimized and improved extraction technique obtained from this study can contribute to the food industry by being used in large‐scale industrial applications.

Emerging Technologies for Recovery of Value-Added Components from Olive Leaves and Their Applications in Food/Feed Industries

Olive leaves are the most abundant agricultural waste source rich in polyphenolics. Due to the numerous health benefits associated with these compounds, the interest in recovering polyphenols from olive leaves has increased in the scientific community over the last decade. Recent studies have focused on improved extraction techniques and processing methods that are most suited for agro-biological industries involved in the development of nutraceutical and functional products. The major problems in olive leaves processing include bitter taste and the low stability of various phenolic compounds. Oleuropein and hydroxytyrosol are the most important phenolic compounds extracted from olive leaves. The present review highlights the importance of olive leaves, their composition, preparation methods, major phenolic compounds, and commercial applications. This review article focuses on integrating studies on olive leaf extract (OLE) pertinent to nutrition, health, and beauty. The different board categories of delivery systems available for the encapsulation of OLE are given. These novel delivery systems could improve fortification, supplementation, and dietary diversification in food and pharmaceutical products.

Climate Change, Directed Technical Change and Exhaustible Resources

Data shows increasing oil extraction rates accompanied by increasing proven reserves over the last decades. This suggests the existence of research by oil companies aimed at increasing their stocks (e.g. exploration or improved extraction techniques). Increasing oil prices act as an incentive to perform that kind of research and hence potentially postpone the development of clean alternative energies. This has consequences for optimal environmental policies. We propose a model of directed technical change with clean and dirty energy in production which is able to replicate the recent trends in the data on oil production and reserves. Our results show that ignoring research in extraction technologies leads to suboptimal climate policy and in particular carbon taxes that are too high and research subsidies that are too low.

Impact of pre‐analytical factors on the proteomic analysis of formalin‐fixed paraffin‐embedded tissue

Formalin-fixed paraffin-embedded (FFPE) tissue samples represent a tremendous potential resource for biomarker discovery, with large numbers of samples in hospital pathology departments and links to clinical information. However, the cross-linking of proteins and nucleic acids by formalin fixation has hampered analysis and proteomic studies have been restricted to using frozen tissue, which is more limited in availability as it needs to be collected specifically for research. This means that rare disease subtypes cannot be studied easily. Recently, improved extraction techniques have enabled analysis of FFPE tissue by a number of proteomic techniques. As with all clinical samples, pre-analytical factors are likely to impact on the results obtained, although overlooked in many studies. The aim of this review is to discuss the various pre-analytical factors, which include warm and cold ischaemic time, size of sample, fixation duration and temperature, tissue processing conditions, length of storage of archival tissue and storage conditions, and to review the studies that have considered these factors in more detail. In those areas where investigations are few or non-existent, illustrative examples of the possible importance of specific factors have been drawn from studies using frozen tissue or from immunohistochemical studies of FFPE tissue.

Novel coupling of surfactant assisted emulsification dispersive liquid–liquid microextraction with spectrophotometric determination for ultra trace nickel

In this work, dispersive liquid–liquid microextraction (DLLME) was improved and the preconcentration method named as surfactant assisted emulsification dispersive liquid–liquid microextraction (SAE-DLLME) was established for ultra trace nickel preconcentration and spectrophotometric determination. Non-ionic surfactant Triton X-100 (TX-100) was used as emulsifier and Triton X-114 (TX-114) was investigated as comparison. Disperser solvent was substituted by surfactant, which could afford more effective emulsification and make the extraction relatively greener. The extraction was accomplished efficiently in only 1min during manual shaking. Compared to traditional DLLME, the developed SAE-DLLME pretreatment was simple, rapid and effective. The improved extraction technique was firstly coupled with traditional spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The influence factors relevant to SAE-DLLME including extraction parameters and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for nickel was 0.24μgL−1, with sensitivity enhancement factor (EF) of 23.

Design and Optimization of a Semicontinuous Hot–Cold Extraction of Polyphenols from Grape Pomace

Grape pomace contains appreciable amounts of polyphenolic compounds such as anthocyanins and procyanidins which can be recovered for use as food supplements. The extraction of these polyphenols from the pomace is usually accomplished at slightly elevated temperatures, frequently employing hydroethanolic solvents. Due to governmental regulations and the cost involved in using ethanol as a solvent, as well as the loss in polyphenolics due to thermal degradation, improved extraction techniques are required. In this study, a semicontinuous extraction apparatus employing only water was developed to maximize the recovery of anthocyanins and procyanidins from red grape pomace (Vitis vinifera). Water is preheated prior to its entry to the extraction cell containing the grape pomace sample, where it is allowed to then flow continuously through the unheated extraction vessel prior to its collection at ambient conditions. Extraction variables that impacted the polyphenolic recovery included pomace moisture content (crude or dried), sample mass, water flow rate, and extraction temperature. A response surface method was used to analyze the results from the extraction, and the optimal conditions were found to be 140 °C and 9 mL/min water flow rate. These conditions can produce an extract containing 130 mg/100 g DW of anthocyanins and 2077 mg/100 g DW of procyanidins. Higher yields of polyphenolics were observed using crude (wet) rather than dried pomace, hence avoiding the need to dry the pomace prior to extraction. The described semicontinuous extraction method using only water as the extraction solvent under subcritical conditions allowed the efficient extraction of polyphenols from red grape pomace without the attendant loss of polyphenolic content due to having to heat the extraction vessel prior to commencement of extraction.

Investigation of novel rapidly synergistic cloud point extraction pattern for bismuth in water and geological samples coupling with flame atomic absorption spectrometry determination

Rapidly synergistic cloud point extraction (RS-CPE) greatly simplified and accelerated the procedure of traditional cloud point extraction (CPE). In order to expand the application of RS-CPE, this work was carried out after the establishment of the improved extraction technique. The new established extraction method was firstly applied for bismuth extraction and determination coupled with flame atomic absorption spectrometry (FAAS) in this work. The improved RS-CPE was accomplished in the room temperature in 1min. Non-ionic surfactant Triton X-100 (TX-100) was used as extractant. Octanol worked as cloud point revulsant and synergic reagent. TX-100 has a relatively high cloud point temperature (CPT), which limited its application in CPE. In this work, TX-100 accomplished the RS-CPE procedure in room temperature successfully. The factors influencing RS-CPE, such as concentrations of reagents, pH, conditions of phase separation, effect of environmental temperatures, salt effect and instrumental conditions, were studied systematically. Under the optimal conditions, the limit of detection (LOD) for bismuth was 4.0μgL−1, with sensitivity enhancement factor (EF) of 43. The proposed method greatly improved the sensitivity of FAAS for the determination of bismuth and was applied to the determination of trace bismuth in real and certified samples with satisfactory analytical results. The proposed method was rapid, simple, and sensitive.

Investigation of analytical performance for rapidly synergistic cloud point extraction of trace amounts of copper combined with spectrophotometric determination

In this work, an improved preconcentration method named as rapidly synergistic cloud point extraction (RS-CPE) was established for copper preconcentration and determination. Non-ionic surfactant Triton X-100 (TX-100) was used as extractant. Octanol worked as cloud point revulsant and synergic reagent, which successfully decreased the cloud point temperature (CPT) of TX-100 to realize the room temperature (about 20 °C) CPE without heating. The established RS-CPE pretreatment was simple, rapid and effective. Compared with traditional CPE (about 40 min for heating, incubation and cooling), the extraction time of the proposed method was very short (1 min). The improved extraction technique RS-CPE was combined with traditional spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The influence factors relevant to RS-CPE, such as concentrations of TX-100 and octanol, concentration of chelating agent, pH, conditions of phase separation, salt effect, environmental temperature and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for copper was 0.4 μg L −1, with sensitivity enhancement factor (EF) of 18. The proposed method was applied to the determination of trace copper in real samples and certified samples with satisfactory analytical results.

Assay for urinary desmosines in a healthy pre-pubertal population using an improved extraction technique

Current evidence indicates that increased desmosine excretion reflects the active inflammatory status of some connective tissue diseases. Our goal was to establish a reliable method of detection and to investigate the normal distribution of urinary desmosine excretion in a healthy pre-pubertal population. Urine was collected from healthy volunteers aged four weeks to 12 years old. We modified a published high-performance liquid chromatography (HPLC) method by (a) increasing hydrolysis time and temperature and (b) increasing cellulose column size. Our modified method had small inter- and intra-assay variability, with coefficients of variation of <6.4% and 5.3%, respectively. There was positive correlation between isodesmosine and desmosine (r(2) = 0.91). There was no significant diurnal or day-to-day variability in total desmosine levels. A reference range for healthy pre-pubertal children aged four weeks to 12 years was established. The modified HPLC method is reliable with low variability. The technique can now be applied as a non-invasive research or diagnostic tool for children with chronic lung disease.

Towards Quantitative mRNA Analysis in Paraffin-Embedded Tissues Using Real-Time Reverse Transcriptase-Polymerase Chain Reaction: A Methodological Study on Lymph Nodes from Melanoma Patients

Improved extraction techniques combined with sensitive real-time reverse transcriptase-polymerase chain reaction may allow detection of mRNA in formalin-fixed, paraffin-embedded (FFPE) materials, but the factors affecting mRNA quantification in clinical material using these methods have not been systematically analyzed. We designed analyses using real-time reverse transcriptase-polymerase chain reaction for quantification of MART-1, beta-actin, and beta(2)-microglobulin mRNAs. The analytical intra- and interassay imprecision (coefficient of variation) was in the range 10 to 20% for all three genes studied. Using these protocols, we studied the influence of tissue autolysis and length of formalin-fixation on mRNA detection in metastatic melanoma. Delay in freezing reduced detectable mRNA, although this was less than predicted and mostly occurred early in autolysis. MART-1, beta-actin, and beta(2)-microglobulin mRNAs were consistently detected in FFPE metastatic melanoma even after fixation for up to 3 weeks, although the total mRNA detected was markedly reduced in fixed compared with fresh tissues (up to 99%). Quantification of MART-1 was, however, possible if this was expressed relative to a housekeeping gene. The polymerase chain reaction product from FFPE tissues could be increased up to 100-fold amplifying short (<136 bp) compared with long amplicons. Variations in time before tissue processing and in fixation length seem to be less important sources of imprecision than previously assumed. Our findings suggest that quantitative analysis of mRNA in archive and routine diagnostic tissues may be possible.

Advances in Sampling and Analysis for Aflatoxins in Food and Animal Feed

Advances in analytical methods and novel detection systems are reviewed from publications from 1995 onwards. The review covers aflatoxins B1, B2, G1, G2, and their metabolites in food, animal feed and biological matrices such as blood and urine. Improved extraction techniques, new clean‐up methods and optimized methods for specific matrices are summarized. This review highlights methods such as thin layer chromatography (TLC) and high performance‐TLC (HPTLC), which are particularly suited to developing countries, and advances that have been made in TLC quantification through low cost detection and scanning systems. Novel developments in detection of aflatoxins are assessed such as the application of surface plasmon resonance biosensors, flow injection monitoring, fibre optic sensors, capillary electrokinetics, electrochemical transduction, and immunological‐based rapid test kits. Recent advances in confirmatory techniques such as liquid chromatography/mass spectrometry (LC/MS) and tandem mass spectrometry...

Behaviour of Pterotylenchus Cecidogenus (Nematoda) in Soil and On Desmodium Ovalifolium as Related To Infection and Host Resistance

In order to develop a technique for screening accessions of Desmodium ovalifolium for resistance to Pterotylenchus cecidogenus, the stem gall nematode, some aspects of the nematode's behaviour were examined. P. cecidogenus moved more readily from dead than from live plants of D. ovalifolium and more nematodes left galls via gall tissue than through healthy stem tissue. An improved extraction technique yielded 650 nematodes per gram fresh weight of gall during 38 hours. Nematodes moved little either vertically or horizontally in soil. In July 1984, most nematodes in an infested field of D. ovalifolium were found in the 40 cm of stem closest to the base but with another clustering of nematodes between 50 and 80 cm. Nematodes moved 40 cm above the plant base between July and September. Plant resistance to P. cecidogenus was unrelated to key aspects of host-finding behaviour including attraction to stems, vertical movement on stem and penetration into seedling roots or shoots.

Retinal isomer ratio in dark-adapted purple membrane and bacteriorhodopsin monomers.

On the basis of data obtained by spectroscopic analysis and chromatography of retinal extracts, a consensus has been adopted that dark-adapted purple membrane (pm) contains 13-cis- and all-trans-retinal in equal amounts, whereas the light-adapted membrane contains all-trans-retinal only. We have developed an improved extraction technique which extracts up to 70% of the retinal in pm within 4 min. In the extracts from dark-adapted pm at room temperature, we consistently find 66-67% 13-cis-retinal and 33-34% all-trans-retinal, and more than 98.5% all-trans isomer in light-adapted samples. The spectrum obtained by reconstitution of bacterioopsin with 13-cis-retinal at 2 degrees C (to minimize isomerization) shows an absorbance maximum at 554 nm and agrees well with the spectrum for the 13-cis component calculated from the dark-adapted and light-adapted bR spectra with our extraction data. The ratio of 13-cis:all-trans isomer in dark-adapted pm is 2:1 and nearly constant between 0 and 38 degrees C but begins to decrease distinctly above 40 degrees C, and more rapidly near 70 degrees C, reaching 0.75 at 90 degrees C. The van't Hoff plot of the isomer ratio shows a nonlinear temperature dependence above 40 degrees C, indicating a more complex system than a simple thermal 13-cis/all-trans isomer equilibrium. We attribute the broadening, absorbance decrease, and blut shift of the visible absorption band with increasing temperature to the appearance of at least one and possibly two or three new chromophores which contain, mainly or exclusively, the all-trans isomer.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of Furanocoumarins on the Leaf Surface of Ruta graveolens with an Improved Extraction Technique

En plongeant la surface de la feuille de «Ruta graveolens» dans de l'eau proche de l'ebullition, les quantites de furanocoumarine extraites sont 1 a 3 fois plus importantes que par les methodes traditionnelles. La rupture des cuticules entrainant la liberation des coumarines associees en serait responsable