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Results for “Green analytical method”

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At least 19 recordsLinked to original sources

PubMed2026

Vortex-assisted liquid-liquid microextraction based on natural deep eutectic solvents for the determination of pyrethroid pesticides in urine.

A novel, facile, and environmentally friendly analytical method was developed based on vortex-assisted liquid-liquid microextraction and high-performance liquid chromatography with diode-array detection for detecting pyrethroid pesticides (PPs) in urine. Natural deep eutectic solvents (NADESs) were prepared using plant essential oil-derived monoterpenoids (thymol, carvacrol, and menthol) combined with aromatic primary alcohols (benzyl alcohol, phenethyl alcohol, and phenylpropyl alcohol) as hydrogen bond donors and acceptors. These solvents served as environmentally benign extraction media, thereby avoiding the use of conventional volatile, toxic organic solvents. NADESs are naturally derived, easy to prepare, biodegradable, and environmentally friendly solvents. Hydrophobic and π-π interactions between the NADESs and PPs may contribute to enhancing the affinity of PPs toward the NADESs phase. Vortex technology, accelerating mass transfer between the sample and extractant phases, enables fast extraction of PPs. Under optimized conditions, the method achieved a low detection limit (0.002 mg L-1), satisfactory precision with relative standard deviations (0.3%-2.4%), and acceptable recovery (80.7%-86.2%). The method demonstrated excellent performance in urine analysis and was feasible as a facile and green strategy for monitoring the content of PPs in biological matrices and assessing exposure risk.

Liquid Phase Microextraction↗

PubMedDate not supplied

Determination of hepatic blood flow in the rat using sequential infusions of indocyanine green or galactose.

A method was developed for the estimation of hepatic blood flow in the rat using sequential infusions of one of two model substrates, indocyanine green or galactose. Either substrate was infused to steady state (achieved within 6 min of the start of indocyanine green infusion and within 40 min of the start of galactose infusion) through either the femoral or portal vein, and three steady state blood samples were obtained. Following a 30-min washout period, the same substrate was infused a second time through the alternate blood vessel. Using a pharmacokinetic approach, hepatic blood flow was estimated from the mean steady state concentrations during the two infusions and the infusion rate. The present method yielded hepatic blood flow estimates of 2.03 +/- 0.13 ml/min/g of liver (indocyanine green) and 2.28 +/- 0.49 ml/min/g of liver (galactose) in two groups of four adult male rats. A Monte-Carlo simulation experiment was conducted to assess the potential error introduced into the blood flow calculation by the moderate transhepatic extraction ratio of the two model substrates (0.386 +/- 0.049 for indocyanine green; 0.439 +/- 0.139 for galactose). The simulation experiment predicted calculational errors between 7.4% (indocyanine green) and 19.5% (galactose), based on the hepatic extraction ratio and the precision of the analytical method for the two compounds. The predicted errors were in good agreement with the variability in blood flow estimates observed experimentally (6.5% for indocyanine green; 21.4% for galactose). The steady state approach employed appears to be associated with superior reproducibility as compared to previously reported methods utilizing bolus dose administration of marker compounds and calculations based upon AUC estimates.

Animals↗

PubMed1991

Overestimation of albumin in heparinized plasma.

Monochromatic measurement of albumin by the bromcresol green method leads to overestimation of albumin in the presence of heparin. The interference seems to be caused by fibrinogen, which, in the presence of heparin, produces an almost constant increase of the measuring signal over the whole range of suitable wavelengths (550 to 700 nm). The albumin overestimation can be eliminated by using a bichromatic modification. An application of this procedure for the automated analyzer RAXT, RA-1000 (Bayer Diagnostik, Technicon) is presented. We recommend using only bichromatic methods for albumin determination with bromcresol green to avoid unexpected analytical artifacts.

Bromcresol Green↗

PubMed1978

New automated dye-binding method for serum albumin determination with bromcresol purple.

We describe a new automated dye-binding method for serum albumin determination with bromcresol purple (BCP) that has several advantages over an existing bromcresol green (BCG) method. The continuous-flow method is sensitive, linear, and precise, with negligible sample interaction at an analytical rate of 60 samples per hour. Unlike BCG, BCP did not react with an albumin-free serum globulin preparation or pure human transferrin solutions. Reaction with serum was instantaneous; in contrast, BCG exhibits a slow nonspecific reaction with some specimens. The specificity of BCP was demonstrated by good agreement with results of "rocket" immunoelectrophoresis (EIA) where y(BCP) = 0.95X(EIA) + 1.72. The BCG method overestimated serum albumin concentration where y(BCG) = 1.01X(EIA) + 6.77. Precipitation, which affects the BCG method, was not observed with BCP. Blank corrections were negligible, salicylate did not interfere, and bilirubin affected the method only if present in very high concentration. The method offers a solution to the poor accuracy of existing BCG methods while retaining many of their desirable features.

Autoanalysis↗

PubMed2026

Evaluating Substitution of Hazardous Solvents in USP Monograph HPLC Methods.

BACKGROUND: Hazardous solvents, such as dichloromethane (DCM), n-hexane, and acetonitrile (ACN), are widely used in HPLC methods, posing significant health and environmental risks. OBJECTIVE: To evaluate the feasibility and impact of substituting hazardous solvents with greener alternatives in USP monograph methods. METHODS: Six high-impact solvents were identified from USP-NF monographs. Two representative monographs per solvent were selected. Substitution strategies were assessed, and performance was compared using system suitability and sample acceptance criteria. Greenness improvement was evaluated using the Analytical GREEnness (AGREE) metric. RESULTS: Performance remained equivalent across all twelve substitution cases. In almost every instance, only the mobile phase required modification, either by direct substitution or by adjusting the solvent-to-buffer ratio, except for one case that required a minor adjustment in column temperature. The AGREE Greenness metric increased by 18-65% in ten out of twelve cases; for n-hexane, improvements were modest at just 6% when replaced with n-heptane but exceeded 40% when substituted with supercritical CO₂. CONCLUSIONS: Greener solvents are highly likely to replace hazardous solvents used in compendial chromatography methods without loss of performance. HIGHLIGHTS: Demonstrated performance equivalency for greener solvent substitutions; Quantified greenness improvements using AGREE; Discussed strategies to implement greener solvents in USP monograph methods.

HPLC↗

PubMed2026

Unravelling bioanalytical innovations, degradation processes, and impurity landscapes of VEGFR inhibitors.

From pre-formulation studies to clinical trials, VEGFR-targeted small-molecule tyrosine kinase inhibitors (TKIs) require rigorous analytical standards. Bioanalysis, stability-indicating studies, and impurity profiling are used to examine chromatographic advances for VEGFR-targeted TKIs like sunitinib, pazopanib, axitinib, sorafenib, cabozantinib, vandetanib, apatinib, lenvatinib, nintedanib, and regorafenib. An LC-MS/MS and UPLC-MS/MS routinely show sub ng/mL performance, as shown by LLOQs (0.2 ng/mL) for sunitinib and axitinib, 1 ng/mL for pazopanib, 5-7 ng/mL for sorafenib, 0.5-1.5 ng/mL for regorafenib metabolic products, and 0.1-0.5 ng/mL for lenvatinib. These approaches are used for pharmacokinetics and therapeutic drug monitoring due to their good correlation coefficient of 0.1-10,000 ng/mL, accuracy of 95%-108%, and precision of 15% RSD. UPLC-QTOF-MS/MS distinguishes degradants and metabolites during forced degradation studies, enabling structural elucidation following ICH M7 risk evaluation protocol. HPTLC/MLC offers fast, sensitive screenings, while RP-HPLC/DAD or HPLC-UV offer reliable, cost-effective routine quality-control solutions with LOD/LOQ in the μg/mL range and linearity of 10-240 μg/mL. This review lists the structures and CAS numbers of ten VEGFR-2 TKI degradants and metabolites, as well as pharmacopeial impurities in SMILES forms. It will be useful for future method development and regulatory applications. To ensure VEGFR-targeted TKI quality, safety, and therapeutic efficacy, LC-MS/MS for trace quantification and HRMS for structure elucidation provide a robust, future-oriented framework. To improve VEGFR-targeted TKI quality, safety, and regulatory compliance, analytical development should focus on HRMS-based impurity characterization, AI-assisted degradation prediction, green chromatography, and harmonized bioanalytical validation.

Humans↗

PubMed1991

Disposable electrochemical biosensors.

The market for decentralized clinical testing is undergoing expansion. Electrochemical biosensors represent one approach to the different demands of this market. A range of sensing systems are described which use electrochemical techniques for the measurement of various analytes and which have been demonstrated to be applicable to the manufacturing methods required for single-use disposable tests.

Biosensing Techniques↗

PubMed1975

Microwave sanitization of color additives used in cosmetics: feasibility study.

Microwave exposure has been explored as a method of microbiologically sanitizing color additives used in cosmetic products. Selected microbiologically unacceptable cosmetic color additives, D&C red no. 7 Ca lake (certified synthetic organic color), carmine (natural organic color not subject to certification), and chromium hydroxide green (inorganic color not subject to certification), were submitted to microwave exposure. Gram-negative bacteria were eliminated, as verified by enrichment procedures, and levels of gram-positive bacteria were reduced. Generally, analytical and dermal safety studies indicated no significant alterations in physical, chemical, and toxicological properties of the colors. Sanitization was also successfully performed on other colors (D&C red no. 9 Ba lake, D&C red no. 12 Ba lake, D&C green no. 5, and FD&C red no. 4); initial physical and chemical tests were satisfactory. Results indicated that this method of sanitization is feasible and warrants further investigation.

Bacteria↗

PubMed1975

A proposed fluorimetric determination of unsaturated iron-binding capacity.

A completely new method for the analysis of uncombined iron-binding capacity (UIBC) in human serum is proposed. The method is based on the discovery by C. K. Luk that the fluorescence of terbium ion (Tb-3+) is enhanced enormously when it binds to an empty Fe-3+ binding site of transferrin. Tb-3+ cannot displace Fe-3+ from an occupied binding site on transferrin. The analytic procedure is to dilute the serum (in order to lower its ultraviolet absorbance), add a solution of Tb-3+, excite with ultraviolet radiation, and measure the intensity of the resulting green fluorescence. With proper calibration this intensity is a measure of UIBC. Analyses of 65 serum samples previously measured at a hospital laboratory show no obvious difficulty with the method. Its absolute accuracy has not been probed in detail.

Binding Sites↗

PubMed1991

Biomonitoring of human exposure to alkylating agents by measurement of adducts to haemoglobin or DNA.

Recent analytical developments in the determination of adducts of DNA and protein with alkylating carcinogens are described which have considerably extended the number of carcinogens that can be examined. While sensitivity of detection equal to or better than one modified DNA base per 10(8) normal bases is now achievable for many specific alkylating carcinogens, further developments in the analytical methods are still needed for the identification and quantification of adducts derived from unknown and/or mixed exposures to carcinogens.

Alkylating Agents↗

PubMed1975

Collaborative study of the 2,4-dinitrophenyl ether multiresidue method for use in determining four carbamate pesticides.

Eight laboratories tested the 2,4-dinitrophenyl ether method for determining carbamate pesticide residues by gas-liquid chromatography. Propoxur, carbofuran, carbanolate, and carbaryl in apples, corn, green beans, and a leafy vegetable (kale, collards, cabbage, or turnip greens) were determined at the fortification levels of 0.1, 0.2, and 0.5 ppm. Average recoveries of propoxur were 87-95%; carbofuran, 87-100%; carbanolate, 89-102%; and carbaryl, 77-92%. No serious background problems were encountered, other than that from field-incurred carbaryl residues in apples. The study revealed the need for certain precautions in determining carbaryl because of its instability in analytical operations. The method has been adopted as official first action.

Carbamates↗

PubMed1979

Improved detection of coliforms and Escherichia coli in foods by a membrane filter method.

Analytical procedures based on filtration of homogenates through membrane filters, and particularly hydrophobic grid-membrane filters (HGMF), offer definite improvements in the enumeration of Escherichia coli and coliforms in foods. Whereas the counted specimen in pour plates may not usually be greater than 0.1 g, up to 1.0 g of ground beef, green beans, potato, cod, strawberries, or grapes could be filtered and counted on HGMF. Greatly improved limit of detection, reduced interference by noncoliforms, and complete removal of growth inhibitors such as polyphenols were demonstrated for HGMF, using violet red bile and mFC agars. In addition, counting on HGMF eliminated a false-positive reaction caused by sucrose in ice cream.

Escherichia coli↗

PubMed1976

Cancer mortality among rubber workers: an epidemiologic study.

Several previous epidemiologic studies of the rubber industry--an industry that uses many chemicals--have identified excess mortality from certain specific cancers. In this study, four cohorts of active and retired workers, at four major rubber-tire plants, were identified historically and followed for the ten-year period from 1964 to 1973. The cancer mortality of these four population was compared, separately and combined, with that of the general community. For all cancers combined, there was a slight excess above the expected number of deaths, whereas for some specific cancers (stomach, colon, prostate, and neoplasms of the lymphatic and hematopoietic system) there was a marked excess of deaths. Proportional mortality analysis at other small plants revealed similar excesses for these cancers, and some excess for lung, bladder, and CNS cancers. Analysis of detailed individual work histories reveals an association of certain cancers with specific job exposures; in particular, lymphatic leukemia and solvent exposure, and lung cancer and curing-room exposure. For both bladder cancer and stomach cancer, preliminary analyses indicate an association with groups of jobs in adjacent production stages (handling and mixing raw ingredients, and processing the "green" precured rubber, respectively). Further analytic studies are currently under way to identify groups of rubber workers at increased risk of other specific cancers.

Adult↗

PubMed1975

[A comparative study of total protein and albumin in man, monkey, dog and rat employing different analytical methods (author's transl)].

In the present study, serum albumin was determined colorimetrically in three animal species and in man with the help of four currently used dye-reagents (protein binding reagents). The results were compared with those obtained from corresponding electrophoretic and biuret determinations, using Versatol as a standard-control throughout. Using 2-(4-hydroxyazobenzene)-benzoic acid and bromocresol purple as reagent for the albumin determinations, species-specific differences from the electrophoretic results were found. No such differences occurred with bromo-cresol green, except in rats. There was no significant difference in albumin concentrations between man, monkeys and rats. Total protein concentration was only similar in man and monkeys.

Animals↗

PubMed1977

The red and green cone visual pigments of deuternomalous trichromacy.

1. Three "simple" deuteranomalous trichromats match with abnormally low "red" tristimulus values throughout the spectrum and abnormally high "green" tristimulus values in the long wave end of the spectrum which become normal (and then low) in the yellow-green. The spectrum locus of this transition differs from one anomalous to the other. Differences in the matches of two of these cannot be due to differences in eye media transmissivities alone. Therefore these two deuteranomalous have different cone visual pigments. 2. The analytical anomaloscope was used in the confrontation of one deuteranomalous with six deuteranopes in turn. In each confrontation the deuteranope set the anomaloscope in his mode and adjusted the intensity of the monochromatic light for a match. Deuteranomalous matches were rejected by four of these six deuteranopes. 3. They were accepted by two of the six. These two rejected each other's matches in a way not attributable to differences in eye media transmissivity. 4. Three different psychophysical techniques were used to measure the action spectra of the long wave cones of these two deuternopes. All three methods reveal small but systematic differences in lambdamax and shape of the curve for the one deuteranope compared with that of the other. 5. In red-green spectral range, these spectra are accurately described by different linear combinations of the color matching functions of the same deuteranomalous whose matches the two deuteranopes accept. Linear combinations of those of a second deuteranomalous, with at least one different kind of cone, fit less well. 6. The wave length discrimination curve of the former deuteranomalous was measured with a new method. The curves of two normals were also obtained for comparison. Wave-length discrimination predictions from the Stiles (1946) line element theory were compared to the anomalous curve. The deuteranopic action spectra were used in the line element to compute this deuteranomalous' discrimination. There is reasonable first order correspondence between prediction and observation, but the prediction is sensitive to small changes in the derivatives of the logarithms of the action spectra. 7. Line element prediction of the deuteranomalous step-by-step luminous efficiency curve is insensitive to such uncertainties. The agreement with expectation from the above assumptions and the measured step-by-step deuteranomalous luminous efficiency curve in the red-green part of the spectrum is therefore good. 8. It is concluded that the erythrolabe in one deuternope's long wave cones has the action spectrum of this deuteranomalous' long and the erythrolabe in the other deuternope's long wave sensitive cones has that of this deuternomalous' medium wave cones. This leads to a general hypothesis about the nature of all forms of red-green colour vision defects transmitted recessively on the X chromosome.

Color Vision Defects↗

PubMed1975

Collaborative study of a spectrophotometric method for determining maleic hydrazide residues in tobacco and vegetables.

A distillation-spectrophotometric method for the determination of maleic hydrazide residues in tobacco and vegetables reported previously was studied collaboratively. Ten laboratories submitted analytical results on 10 samples containing residues resulting either from field treatment or laboratory fortification. The samples were estimated to contain from 0.99 to 16.36 mug maleic hydrazide/0.5 g sample analyzed. The coefficients of variation based on precision standard deviation ranged from 57.7% for the lowest residue content to 32.4% for the highest. The corresponding coefficients of variation based on overall standard deviations were estimated to be at least one-fifth larger. Strong evidence of systematic laboratory differences was found (F-test, significant at 0.1%). Apparent recoveries of 10.0 mug maleic hydrazide added to 0.5 g fluecured tobacco and potato were 97.3 and 89.7%, respectively. Apparent recoveries of 16.0 and 16.5 mug added to 0.5 g green bean were 87.4 and 85.5%, respectively. The precision of the method studied was no better than that of the current official final action method, 29.121--29.127, and its adoption is not recommended.

Pesticide Residues↗

PubMedDate not supplied

A pattern classification system for automated cervical cytologic screening based on flow microfluorometric analysis.

A data analytic technique is described for use in automated cervical cytology. The method entails the application of a two-dimensional Fourier transform to histogram data obtained by flow microfluorometry and the subsequent use of the Fourier coefficients as parameters for pattern classification. Analyses were performed on 186 samples including material from 62 positive and 124 negative cases. Cell suspensions were stained with propidium iodide and fluorescein isothiocyanate, and red and green cytofluoresence were measured simultaneously. The two-dimensional histogram data were normalized, the Fourier transform was applied, and a multivariate classifier based on 30 coefficients was assembled using a training set of half the original series. Performance was then assessed on the remaining cases. Overall accuracy was 79.6%, with a false-positive rate of 14.8% and a false-negative rate of 31.2%. The potential applicability of this approach as the basis of a practical screening system is discussed.

Adolescent↗

PubMed1992

Techniques for obtaining analytical solutions to the multicylinder somatic shunt cable model for passive neurones.

The somatic shunt cable model for neurones is extended to the case in which several equivalent cylinders, not necessarily of the same electrotonic length, emanate from the cell soma. The cable equation is assumed to hold in each cylinder and is solved with sealed end conditions and a lumped soma boundary condition at a common origin. A Green's function (G) is defined, corresponding to the voltage response to an instantaneous current pulse at an arbitrary point along one of the cylinders. An eigenfunction expansion for G is obtained where the coefficients are determined using the calculus of residues and compared with an alternative method of derivation using a modified orthogonality condition. This expansion converges quickly for large time, but, for small time, a more convenient alternative expansion is obtained by Laplace transforms. The voltage response to arbitrary currents injected at arbitrary sites in the dendritic tree (including the soma) may then be expressed as a convolution integral involving G. Illustrative examples are presented for a point charge input.

Animals↗