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Iorgulescu E, Voicu VA, Sârbu C, Tache F, Albu F, Medvedovici A. Experimental variability and data pre-processing as factors affecting the discrimination power of some chemometric approaches (PCA, CA and a new algorithm based on linear regression) applied to (+/-)ESI/MS and RPLC/UV data: Application on green tea extracts. Talanta 2016; 155:133-44. [PMID: 27216666 DOI: 10.1016/j.talanta.2016.04.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 04/15/2016] [Accepted: 04/19/2016] [Indexed: 12/28/2022]
Abstract
The influence of the experimental variability (instrumental repeatability, instrumental intermediate precision and sample preparation variability) and data pre-processing (normalization, peak alignment, background subtraction) on the discrimination power of multivariate data analysis methods (Principal Component Analysis -PCA- and Cluster Analysis -CA-) as well as a new algorithm based on linear regression was studied. Data used in the study were obtained through positive or negative ion monitoring electrospray mass spectrometry (+/-ESI/MS) and reversed phase liquid chromatography/UV spectrometric detection (RPLC/UV) applied to green tea extracts. Extractions in ethanol and heated water infusion were used as sample preparation procedures. The multivariate methods were directly applied to mass spectra and chromatograms, involving strictly a holistic comparison of shapes, without assignment of any structural identity to compounds. An alternative data interpretation based on linear regression analysis mutually applied to data series is also discussed. Slopes, intercepts and correlation coefficients produced by the linear regression analysis applied on pairs of very large experimental data series successfully retain information resulting from high frequency instrumental acquisition rates, obviously better defining the profiles being compared. Consequently, each type of sample or comparison between samples produces in the Cartesian space an ellipsoidal volume defined by the normal variation intervals of the slope, intercept and correlation coefficient. Distances between volumes graphically illustrates (dis)similarities between compared data. The instrumental intermediate precision had the major effect on the discrimination power of the multivariate data analysis methods. Mass spectra produced through ionization from liquid state in atmospheric pressure conditions of bulk complex mixtures resulting from extracted materials of natural origins provided an excellent data basis for multivariate analysis methods, equivalent to data resulting from chromatographic separations. The alternative evaluation of very large data series based on linear regression analysis produced information equivalent to results obtained through application of PCA an CA.
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Affiliation(s)
- E Iorgulescu
- University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, Panduri Ave., no. 90, Bucharest 050663, Romania
| | - V A Voicu
- Romanian Academy, Medical Science Section, Calea Victoriei no. 125, Bucharest 010071, Romania; University of Medicine and Pharmacy "Carol Davila", Department of Pharmacology, Toxicology and Clinical Psychopharmacology, #8 Floreasca St., Bucharest 014461, Romania
| | - C Sârbu
- Babeş-Bolyai University, Faculty of Chemistry and Chemical Engineering, Department of Chemistry, Arany Janos Street, no. 11, Cluj-Napoca 400028, Romania
| | - F Tache
- University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, Panduri Ave., no. 90, Bucharest 050663, Romania
| | - F Albu
- Analytical Application Laboratory, Agilrom, # 40S Th. Pallady Ave., Bucharest 032266, Romania
| | - A Medvedovici
- University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, Panduri Ave., no. 90, Bucharest 050663, Romania.
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Medvedovici A, David F, Sandra P. Determination of the rodenticides warfarin, diphenadione and chlorophacinone in soil samples by HPLC-DAD. Talanta 2012; 44:1633-40. [PMID: 18966902 DOI: 10.1016/s0039-9140(97)00068-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/1996] [Revised: 10/28/1996] [Accepted: 11/21/1996] [Indexed: 10/17/2022]
Abstract
A HPLC-DAD method is described for the analysis of the rodenticides warfarin, diphenadione and chlorophacinone, together with the phenylurea herbicides isoproturon and diuron, in soil samples. The HPLC parameters have been optimised to provide baseline separation with symmetrical peakshapes in short analysis times. The sample preparation consists of Soxhlet extraction followed by SPE clean-up on cyanopropyl silica.
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Affiliation(s)
- A Medvedovici
- Department of Organic Chemistry, University of Gent, Krijgslaan 281 (S4), B-9000, Gent, Belgium
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Magureanu M, Piroi D, Mandache NB, David V, Medvedovici A, Bradu C, Parvulescu VI. Degradation of antibiotics in water by non-thermal plasma treatment. Water Res 2011; 45:3407-3416. [PMID: 21514950 DOI: 10.1016/j.watres.2011.03.057] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 03/23/2011] [Accepted: 03/30/2011] [Indexed: 05/30/2023]
Abstract
The decomposition of three β-lactam antibiotics (amoxicillin, oxacillin and ampicillin) in aqueous solution was investigated using a dielectric barrier discharge (DBD) in coaxial configuration. Solutions of concentration 100 mg/L were made to flow as a film over the surface of the inner electrode of the plasma reactor, so the discharge was generated at the gas-liquid interface. The electrical discharge was operated in pulsed regime, at room temperature and atmospheric pressure, in oxygen. Amoxicillin was degraded after 10 min plasma treatment, while the other two antibiotics required about 30 min for decomposition. The evolution of the degradation process was continuously followed using liquid chromatography-mass spectrometry (LC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analyses.
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Affiliation(s)
- M Magureanu
- National Institute for Lasers, Plasma and Radiation Physics, Department for Plasma Physics and Nuclear Fusion, Atomistilor Str. 409, Magurele-Bucharest 077125, Romania.
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Sandra P, Medvedovici A, Zhao Y, David F. Characterization of triglycerides in vegetable oils by silver-ion packed-column supercritical fluid chromatography coupled to mass spectroscopy with atmospheric pressure chemical ionization and coordination ion spray. J Chromatogr A 2002; 974:231-41. [PMID: 12458940 DOI: 10.1016/s0021-9673(02)01311-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Characterization of triglycerides in vegetable oils was achieved by silver-ion packed-column supercritical fluid chromatography (SI-pSFC) with mass spectrometric detection. Hyphenation was made using commercially available liquid chromatography-mass spectrometry (LC-MS) interfaces without any modification. A make-up fluid was delivered through a T-piece placed before or after the SFC restrictor by means of a high pressure pump. Atmospheric pressure chemical ionization (APCI) and coordination ion spray (CIS) with silver ions were used as ionization modes. Compared to UV detection, the sensitivity was increased by a factor of 100. Both ionization modes are generating similar structural information. Molecular ions [M-H]+ or [M-Ag(-)] are observed in the mass spectra with exception of the saturated triglycerides for which only CIS gives intense molecular ions. The position at which the fatty acids are esterified to the glycerol backbone can be elucidated by pSFC-APCI although it remains speculative whether this is valid for highly unsaturated triglycerides because reference compounds are not available to proof this.
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Affiliation(s)
- P Sandra
- Department of Chemistry, University of Stellenbosch, CENSSUS, Private Bag X1, Matieland 7602, South Africa.
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Medvedovici A, David V, Tache F, David F, Sandra P. SPE-HPLC-DAD DETERMINATION OF TRITON X-100 IN PERFUSABLE SOLUTIONS. ANAL LETT 2001. [DOI: 10.1081/al-100104921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Medvedovici A, Mircioiu C, David V, Miron DS. Liquid extraction and HPLC-DAD assay of hydrochlorothiazide from plasma for a bioequivalence study at the lowest therapeutic dose. Eur J Drug Metab Pharmacokinet 2000; 25:91-6. [PMID: 11112088 DOI: 10.1007/bf03190073] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The main parameters considered in optimizing the liquid extraction and quantitative assay were the yield, precision, limit of quantification, time required for extraction and concentration, and quantity of solvent. The influence on these parameters of the following factors was examined: nature of the extracting solvent, quantity of solvent, co-extraction solvent, and duration of stirring. Instead of equilibrium parameters of the involved thermodynamic system, a kinetic approach was preferred in terms of the effective partition 'constant', which is not really constant but a function of time and extraction conditions. The final selected method, considered to be rapid and simple, was applied to determine the pharmacokinetics of hydrochlorotiazide (HCT) after administration of Capozide (Bristol-Myers Squibb) tablets containing 50 mg Captopril and 25 mg HCT, to 4 healthy volunteers. The results obtained were in accordance with the pharmacokinetic parameters of HCT reported in the literature.
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Affiliation(s)
- A Medvedovici
- Department of Analytical Chemistry, University of Bucharest, Romania
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Medvedovici A, David V, Miron D, Mircioiu C. Comparison of Two Sample Preparation Methods for a HPLC-DAD Assay of Tolbutamide from Human Plasma. ANAL LETT 2000. [DOI: 10.1080/00032710008543184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Dermaux A, Medvedovici A, Ksir M, Van Hove E, Talbi M, Sandra P. Elucidation of the triglycerides in fish oil by packed-column supercritical fluid chromatography fractionation followed by capillary electrochromatography and electrospray mass spectrometry. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1520-667x(1999)11:6<451::aid-mcs7>3.0.co;2-h] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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