Multi-energy calibration to circumvent matrix effects in the determination of biodiesel quality parameters by UV–Vis spectrophotometry

Talanta ◽  
2020 ◽  
Vol 209 ◽  
pp. 120584
Author(s):  
Samara Soares ◽  
Fábio R.P. Rocha
Keyword(s):  
Matrix Effects ◽  
Quality Parameters ◽  
Energy Calibration ◽  
Biodiesel Quality

Determination of musks and other fragrance compounds at ng/L levels using CLSA (closed loop stripping analysis) and GC/MS detection

2004 ◽  
Vol 50 (5) ◽  
pp. 119-123 ◽  
Author(s):  
D. Mitjans ◽  
F. Ventura
Keyword(s):  
Closed Loop ◽  
Matrix Effects ◽  
Limit Of Detection ◽  
Tap Water ◽  
Quality Parameters ◽  
Stripping Analysis ◽  
Polycyclic Musks ◽  
Relative Standard ◽  
High Resolution Gas Chromatography

Closed loop stripping analysis (CLSA), a suitable tool for the determination of volatile and semivolatile compounds at low trace levels (ng/l), has been used to determine and quantify seven selected musks and two fragrances (Acetyl cedrene and Amberonne). The obtained extracts are analyzed by high resolution gas chromatography coupled to mass spectrometry (GC/MS) operating in the SIM mode. Quality parameters such as limit of detection; matrix effects; precision expressed as repeatability and reproducibility relative standard deviations of the method and an estimation of the uncertainty have been evaluated. The method has been applied to the analysis of wastewater effluents, surface water and tap water from different places in Europe. All samples contained differents musks at ng/l levels with the polycyclic musks Galaxolide and Tonalide and both fragrances, Amberonne and Acetyl cedrene, being the most abundant. These results suggest the importance of studying and controlling the presence of these ubiquitous environmental compounds in water systems.

scholarly journals Determination of Fungicide Residues in White Grapes for Winemaking by Gas Chromatography with Mass Spectrometric Detection and Assessment of Matrix Effects

2003 ◽  
Vol 86 (5) ◽  
pp. 1008-1014 ◽  
Author(s):  
Carlos Fernández González ◽  
Raquel Rial Otero ◽  
Beatriz Cancho Grande ◽  
Jesús Simal Gándara
Keyword(s):  
Gas Chromatography ◽  
Matrix Effects ◽  
Quality Parameters ◽  
Mass Spectrometric ◽  
Mass Spectrometric Detection ◽  
Good Precision ◽  
Fungicide Residues ◽  
Relative Standard ◽  
Rías Baixas

Abstract A new analytical method, based on organic solvent extraction with dichloromethane–acetone (75 + 25, v/v) followed by gas chromatography with mass spectrometric detection, is presented for the determination of residues of 10 fungicides in white grapes for vinification. Some of them (cyprodinil, fludioxonil, and pyrimethanil) have been used for only 2–3 years and, therefore, no methods are available in the scientific literature for such a screening. Quality parameters yielded good precision (relative standard deviation of <10%) and detection limits (ranging between 1 and 18 μg/kg) that are lower than the maximum residue limits (MRLs) set by the 76/895/European Economic Community (EEC) and 90/642/EEC Directives. The applicability of the method was evaluated by analysis of 5 different white grapes produced in the Rías Baixas area in Galicia (northwestern Spain) for vinification. The method showed good performance in analyses of real samples to determine whether the concentrations of the fungicides used exceeded their MRLs. The method of standard additions was found to be necessary to avoid matrix effects in the quantification of fungicide residues. Results showed that concentrations of the fungicides identified in grapes were lower than the MRLs established by the European legislation.

The Frequency of Occurrence of Handwriting Performance Features Used to Predict Whether Questioned Signatures are Simulated

2018 ◽  
Vol 28 ◽  
pp. 35-42
Author(s):  
David Black ◽  
Bryan Found ◽  
Doug Rogers
Keyword(s):  
Large Population ◽  
Quality Parameters ◽  
Frequency Of Occurrence ◽  
Relative Speed ◽  
Simulation Process ◽  
Spatial Features ◽  
And Performance ◽  
Document Examiners ◽  
Line Trace

Forensic Document Examiners (FDEs) examine the physical morphology and performance attributes of a line trace when comparing questioned to specimen handwriting samples for the purpose of determining authorship. Along with spatial features, the elements of execution of the handwriting are thought to provide information as to whether or not a questioned sample is the product of a disguise or simulation process. Line features such as tremor, pen-lifts, blunt beginning and terminating strokes, indicators of relative speed, splicing and touch ups, are subjectively assessed and used in comparisons by FDEs and can contribute to the formation of an opinion as to the validity of a questioned sample of handwriting or signatures. In spite of the routine use of features such as these, there is little information available regarding the relative frequency of occurrence of these features in populations of disguised and simulated samples when compared to a large population of a single individual’s signature. This study describes a survey of the occurrence of these features in 46 disguised signatures, 620 simulated signatures (produced by 31 different amateur forgers) and 177 genuine signatures. It was found that the presence of splices and touch-ups were particularly good predictors of the simulation process and that all line quality parameters were potentially useful contributors in the determination of the authenticity of questioned signatures. Purchase Article - $10

scholarly journals Application of Bar Adsorptive Microextraction for the Determination of Levels of Tricyclic Antidepressants in Urine Samples

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3101
Author(s):  
Mariana N. Oliveira ◽  
Oriana C. Gonçalves ◽  
Samir M. Ahmad ◽  
Jaderson K. Schneider ◽  
Laiza C. Krause ◽  
...  
Keyword(s):  
Tricyclic Antidepressants ◽  
Matrix Effects ◽  
Activated Carbons ◽  
Process Efficiency ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Experimental Conditions ◽  
Analytical Methodology ◽  
Low Efficiency

This work entailed the development, optimization, validation, and application of a novel analytical approach, using the bar adsorptive microextraction technique (BAμE), for the determination of the six most common tricyclic antidepressants (TCAs; amitriptyline, mianserin, trimipramine, imipramine, mirtazapine and dosulepin) in urine matrices. To achieve this goal, we employed, for the first time, new generation microextraction devices coated with convenient sorbent phases, polymers and novel activated carbons prepared from biomaterial waste, in combination with large-volume-injection gas chromatography-mass spectrometry operating in selected-ion monitoring mode (LVI-GC-MS(SIM)). Preliminary assays on sorbent coatings, showed that the polymeric phases present a much more effective performance, as the tested biosorbents exhibited low efficiency for application in microextraction techniques. By using BAμE coated with C18 polymer, under optimized experimental conditions, the detection limits achieved for the six TCAs ranged from 0.2 to 1.6 μg L−1 and, weighted linear regressions resulted in remarkable linearity (r2 > 0.9960) between 10.0 and 1000.0 μg L−1. The developed analytical methodology (BAμE(C18)/LVI-GC-MS(SIM)) provided suitable matrix effects (90.2–112.9%, RSD ≤ 13.9%), high recovery yields (92.3–111.5%, RSD ≤ 12.3%) and a remarkable overall process efficiency (ranging from 84.9% to 124.3%, RSD ≤ 13.9%). The developed and validated methodology was successfully applied for screening the six TCAs in real urine matrices. The proposed analytical methodology proved to be an eco-user-friendly approach to monitor trace levels of TCAs in complex urine matrices and an outstanding analytical alternative in comparison with other microextraction-based techniques.

scholarly journals Multi-residue analytical methods for the determination of pesticides and PPCPs in water by LC-MS/MS: a review

2012 ◽  
Vol 10 (3) ◽  
pp. 876-899 ◽  
Author(s):  
Ednei Primel ◽  
Sergiane Caldas ◽  
Ana Escarrone
Keyword(s):  
Mass Spectrometry ◽  
Analytical Methods ◽  
Environmental Samples ◽  
World Wide ◽  
Matrix Effects ◽  
Tandem Mass ◽  
Selective Determination ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

AbstractResidues of pesticides, pharmaceutical and personal care products (PPCPs) are contaminants of world-wide concern. Consequently, there is a growing need to develop reliable analytical methods, which enable rapid, sensitive and selective determination of these pollutants in environmental samples, at trace levels. In this paper, a review of the liquid chromatography-tandem mass spectrometry (LC-MS/MS) based methods for the determination of pesticides and PPCPs in the environment is presented. Advanced aspects of current LC-MS/MS methodology, including sample preparation and matrix effects, are discussed.

Determination of Carbon Content in Steel Using Laser-Induced Breakdown Spectroscopy

1992 ◽  
Vol 46 (9) ◽  
pp. 1382-1387 ◽  
Author(s):  
J. A. Aguilera ◽  
C. Aragón ◽  
J. Campos
Keyword(s):  
Carbon Content ◽  
Matrix Effects ◽  
Sample Surface ◽  
Nitrogen Atmosphere ◽  
Laser Induced Breakdown Spectroscopy ◽  
Time Resolved ◽  
Breakdown Spectroscopy ◽  
Use Of Time ◽  
Laser Induced Breakdown

Laser-induced breakdown spectroscopy has been used to determine carbon content in steel. The plasma was formed by focusing a Nd:YAG laser on the sample surface. With the use of time-resolved spectroscopy and generation of the plasma in nitrogen atmosphere, a precision of 1.6% and a detection limit of 65 ppm have been obtained. These values are similar to those of other accurate conventional techniques. Matrix effects for the studied steels are reduced to a small slope difference between the calibration curves for stainless and nonstainless steels.

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