1
|
Passive Sampling with Active Carbon Fibres in the Determination of Organic Pollutants in Groundwater. WATER 2022. [DOI: 10.3390/w14040585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Legislation addressing the quality of groundwater and increasing concerns over public health calls for the development of analytical methods that can produce accurate and precise results at the ppt level. Passive sampling has been recognised as a helpful tool in identifying various organic pollutants in groundwater, even when their presence had not yet been identified through conventional groundwater quality monitoring. The article presents an analytical method involving a simple and cost-effective passive sampling device using Zorflex® activated carbon fibres (ACFs) for the qualitative monitoring of a broad range of organic pollutants in water in a single run. The applicability of the method developed was tested in three hydrogeological studies. In the first case, we present a non-targeted qualitative screening and a list of 892 different contaminants detected in the groundwater in Slovenia. In the second case, we discuss the presence and origin of organic compounds in the groundwater from a pilot area of the urban aquifer, Ljubljansko polje. The third case presents a comparison of results between passive and grab sampling. Passive sampling with ACFs confirmed the presence of a pollutant, even when it had not been previously detected through a quantitative method.
Collapse
|
2
|
Pomerantsev AL, Rodionova OY. New trends in qualitative analysis: Performance, optimization, and validation of multi-class and soft models. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116372] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
3
|
Jiménez-Carvelo AM, Cuadros-Rodríguez L. The occurrence: A meaningful parameter to be considered in the validation of multivariate classification-based screening methods - Application for authenticating virgin olive oil. Talanta 2020; 208:120467. [PMID: 31816736 DOI: 10.1016/j.talanta.2019.120467] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 10/05/2019] [Accepted: 10/10/2019] [Indexed: 11/17/2022]
Abstract
The development of multivariate screening analytical methods in the analytical chemistry field focused particularly on food authentication is growing in recent years, which is evidenced by the increase of scientific publications. Currently there are several guides and technical reports about how -univariate qualitative methods should be properly validated to produce reliable and accurate (fitted-for-purpose) results. Nevertheless, this is not the case when multivariate methods are considered. Aimed at redressing this untenable disadvantage, this paper proposes some guidelines for the validation of multivariate classification-based screening methods. As an application example, the detection of adulteration of virgin olive oil with any other edible vegetal oils is showed. The analytical techniques employed are liquid chromatography coupled to diode array detector (LC-DAD) and gas chromatography coupled to flame ionization detector (GC-FID). For the correct validation of the multivariate screening method a new parameter which never considered before, named occurrence, is accounted. Also, it has been developed two new applicability indicators of the multivariate screening methods: the assignation error index (IERROR) and the index saving (ISAVING) to establish the validation requirements. Then the validation parameters of the methods: precision (or target predictive value), sensitivity, non-target predictive value, specificity and accuracy were estimated. The main conclusion of the work has been the need to take accounts the occurrence value to establish the specific validation requirements to apply the multivariate screening method in a particular scenario.
Collapse
Affiliation(s)
- Ana M Jiménez-Carvelo
- Chemical Metrology and Qualimetrics (CMQ), Department of Analytical Chemistry, Faculty of Sciences, University of Granada, C/ Fuentenueva s/n, E-18071, Granada, Spain.
| | - Luis Cuadros-Rodríguez
- Chemical Metrology and Qualimetrics (CMQ), Department of Analytical Chemistry, Faculty of Sciences, University of Granada, C/ Fuentenueva s/n, E-18071, Granada, Spain
| |
Collapse
|
4
|
López-Sanz S, Guzmán Bernardo FJ, Rodríguez Martín-Doimeadios RC, Ríos Á. Analytical metrology for nanomaterials: Present achievements and future challenges. Anal Chim Acta 2019; 1059:1-15. [DOI: 10.1016/j.aca.2019.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 02/05/2019] [Accepted: 02/07/2019] [Indexed: 02/01/2023]
|
5
|
Test for arsenic speciation in waters based on a paper-based analytical device with scanometric detection. Anal Chim Acta 2018; 1011:1-10. [DOI: 10.1016/j.aca.2018.01.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Accepted: 01/03/2018] [Indexed: 12/31/2022]
|
6
|
Determining performance parameters in qualitative multivariate methods using probability of detection (POD) curves. Case study: Two common milk adulterants. Talanta 2017; 168:23-30. [DOI: 10.1016/j.talanta.2016.12.065] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/20/2016] [Accepted: 12/23/2016] [Indexed: 12/15/2022]
|
7
|
Quality performance metrics in multivariate classification methods for qualitative analysis. Trends Analyt Chem 2016. [DOI: 10.1016/j.trac.2016.04.021] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
8
|
Determination of the total content of some sulfonamides in milk using solid-phase extraction coupled with off-line derivatization and spectrophotometric detection. Food Chem 2015; 188:51-6. [DOI: 10.1016/j.foodchem.2015.04.123] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 04/16/2015] [Accepted: 04/25/2015] [Indexed: 11/23/2022]
|
9
|
Prieto-Blanco MC, Jornet-Martínez N, Moliner-Martínez Y, Molins-Legua C, Herráez-Hernández R, Verdú Andrés J, Campins-Falcó P. Development of a polydimethylsiloxane-thymol/nitroprusside composite based sensor involving thymol derivatization for ammonium monitoring in water samples. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 503-504:105-112. [PMID: 25113949 DOI: 10.1016/j.scitotenv.2014.07.077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 06/20/2014] [Accepted: 07/20/2014] [Indexed: 06/03/2023]
Abstract
This report describes a polydimethylsiloxane (PDMS)-thymol/nitroprusside delivery composite sensor for direct monitoring of ammonium in environmental water samples. The sensor is based on a PDMS support that contains the Berthelot's reaction reagents. To prepare the PDMS-thymol/nitroprusside composite discs, thymol and nitroprusside have been encapsulated in the PDMS matrix, forming a reagent release support which significantly simplifies the analytical measurements, since it avoids the need to prepare derivatizing reagents and sample handling is reduced to the sampling step. When, the PDMS-thymol/nitroprusside composite was introduced in water samples spontaneous release of the chromophore and catalyst was produced, and the derivatization reaction took place to form the indothymol blue. Thus, qualitative analysis of NH4(+) could be carried out by visual inspection, but also, it can be quantified by measuring the absorbance at 690 nm. These portable devices provided good sensitivity (LOD<0.4 mg L(-1)) and reproducibility (RSD <10%) for the rapid detection of ammonium. The PDMS-NH4(+) sensor has been successfully applied to determine ammonium in water samples and in the aqueous extracts of particulate matter PM10 samples. Moreover, the reliability of the method for qualitative analysis has been demonstrated. Finally, the advantages of the PDMS-NH4(+) sensor have been examined by comparing some analytical and complementary characteristics with the properties of well-established ammonium determination methods.
Collapse
Affiliation(s)
- M C Prieto-Blanco
- Grupo QANAP, Departamento de Química Analítica, Facultade de Ciencias, Universidade da Coruña, Campus de A Coruña, 15071 A Coruña, Spain
| | - N Jornet-Martínez
- Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
| | - Y Moliner-Martínez
- Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
| | - C Molins-Legua
- Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
| | - R Herráez-Hernández
- Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
| | - J Verdú Andrés
- Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
| | - P Campins-Falcó
- Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
| |
Collapse
|
10
|
Dantas HV, Barbosa MF, Nascimento EC, Moreira PN, Galvão RK, Araújo MC. Screening analysis of natural gas with respect to methane content by near-infrared spectrometry. Microchem J 2014. [DOI: 10.1016/j.microc.2014.01.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
11
|
Gondim CDS, Coelho OAM, Alvarenga RL, Junqueira RG, de Souza SVC. An appropriate and systematized procedure for validating qualitative methods: its application in the detection of sulfonamide residues in raw milk. Anal Chim Acta 2014; 830:11-22. [PMID: 24856507 DOI: 10.1016/j.aca.2014.04.050] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 04/11/2014] [Accepted: 04/24/2014] [Indexed: 11/29/2022]
Abstract
The lack of well-established references for the validation of qualitative analyses and the increasing demand for reliable binary responses were the main motivating factors for this study. A detailed procedure for single-laboratory validation of qualitative methods is proposed. The experimental design and the tools for data analysis were based on the theoretical background, as well as the aspects of efficiency, convenience and simplicity. Four experimental steps were defined, as follows: (i) preliminary tests for the determination of the concentration range, (ii) a study of the rates, unreliability region, detection limit, and the accordance and concordance values, (iii) a study of the selectivity in the presence of known interferences, and (iv) a study of robustness. The applicability of the procedure was demonstrated by the validation of a qualitative commercial kit for detecting sulfonamide residues in raw milk using both the visual and instrumental reading techniques. Reliability rates of 100% were obtained for the blank samples. For the samples spiked with sulfamethazine at 10.8 and 108 μg L(-1) and with sulfadimethoxine or sulfathiazole at 10 and 100 μg L(-1), the reliability rates ranged from 93.3 to 100%. Selectivity was demonstrated using trimethoprim as a potential interferent. The method was considered robust for the factors of the temperature (54 and 58°C) and time (6 and 10 min) for incubating the test strips. The estimated detection limits and unreliability regions confirmed the suitability of the kit for this purpose, based on the legislated residue limits.
Collapse
Affiliation(s)
- Carina de Souza Gondim
- Federal University of Minas Gerais (UFMG), Faculty of Pharmacy (FAFAR), Department of Food Science, Avenue Antônio Carlos, 6627, Campus da UFMG, Pampulha, Belo Horizonte, MG 31270-010, Brazil
| | - Otávio Augusto Mazzoni Coelho
- Federal University of Minas Gerais (UFMG), Faculty of Pharmacy (FAFAR), Department of Food Science, Avenue Antônio Carlos, 6627, Campus da UFMG, Pampulha, Belo Horizonte, MG 31270-010, Brazil
| | - Ronália Leite Alvarenga
- Federal University of Minas Gerais (UFMG), Faculty of Pharmacy (FAFAR), Department of Food Science, Avenue Antônio Carlos, 6627, Campus da UFMG, Pampulha, Belo Horizonte, MG 31270-010, Brazil
| | - Roberto Gonçalves Junqueira
- Federal University of Minas Gerais (UFMG), Faculty of Pharmacy (FAFAR), Department of Food Science, Avenue Antônio Carlos, 6627, Campus da UFMG, Pampulha, Belo Horizonte, MG 31270-010, Brazil
| | - Scheilla Vitorino Carvalho de Souza
- Federal University of Minas Gerais (UFMG), Faculty of Pharmacy (FAFAR), Department of Food Science, Avenue Antônio Carlos, 6627, Campus da UFMG, Pampulha, Belo Horizonte, MG 31270-010, Brazil.
| |
Collapse
|
12
|
García-Fernández J, Trapiella-Alfonso L, Costa-Fernández JM, Pereiro R, Sanz-Medel A. A quantum dot-based immunoassay for screening of tetracyclines in bovine muscle. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:1733-40. [PMID: 24437360 DOI: 10.1021/jf500118x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A reliable and robust direct screening methodology based on a quantum dot (QD) fluorescent immunoassay has been developed to detect trace levels of different antibiotic species from the family of the tetracyclines (e.g., oxytetracycline, tetracycline, chlortetracycline, and doxycycline) in contaminated bovine muscle tissues. First, the synthesis and characterization of a new immunoprobe (oxytetracycline-bovine serum albumin-QD) has been carried out for its further application in the development of a competitive fluorescent QD-immunoassay. The developed fluoroimmunoassay provides sensitive and binary "yes/no" responses being appropriate for the screening of this family of antibiotics above or below a preset concentration threshold. The detection limit achieved with this strategy, 1 μg/L in aqueous media and 10 μg/kg in bovine muscle samples, is 10-fold lower than the maximum level concentration allowed by International Legislation in muscle tissue, enabling suitable and efficient screening of the antibiotics.
Collapse
Affiliation(s)
- Jenifer García-Fernández
- Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo , 33006 Oviedo, Spain
| | | | | | | | | |
Collapse
|
13
|
Armenta S, de la Guardia M, Alcalà M, Blanco M. Noninvasive double confirmation of cocaine abuse. Anal Chem 2013; 85:11382-90. [PMID: 24171548 DOI: 10.1021/ac4023583] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A double confirmation procedure, based on the combined application of Ion Mobility Spectrometry (IMS) and Infrared Spectroscopy (IR), has been developed for the noninvasive unambiguous identification of cocaine consume. The use of nasal mucus as a biological specimen for cocaine abuse confirmation has been proposed as an alternative to the use of blood and urine due to its noninvasive character and the presence of the parent compound instead of its metabolites. Sampling conditions, interferences caused by cutting agents and other substances, and limits of identification (LOI) and confirmation (LOC) have been deeply evaluated. The procedure combines the high sensitivity of the IMS to identify positive samples with the high selectivity of the IR procedure to confirm positive results. Thus, the proposed two tier method has been applied to the detection and identification of cocaine in the nasal mucus of different individuals, consumers, and nonconsumers, providing results comparable with those obtained by a reference procedure.
Collapse
Affiliation(s)
- Sergio Armenta
- Department of Analytical Chemistry, Research Building, University of Valencia , 50th Dr. Moliner St., E-46100 Burjassot, Valencia, Spain
| | | | | | | |
Collapse
|
14
|
Pena-Pereira F, Costas-Mora I, Lavilla I, Bendicho C. Rapid screening of polycyclic aromatic hydrocarbons (PAHs) in waters by directly suspended droplet microextraction-microvolume fluorospectrometry. Talanta 2011; 89:217-22. [PMID: 22284483 DOI: 10.1016/j.talanta.2011.11.084] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Revised: 11/22/2011] [Accepted: 11/27/2011] [Indexed: 11/17/2022]
Abstract
A rapid and simple screening method for polycyclic aromatic hydrocarbons (PAHs) in water samples is proposed. The method is based on the combination of a miniaturized sample preparation approach, namely, directly suspended droplet microextraction (DSDME), and microvolume fluorospectrometry. Benzo[a]pyrene (BaP) was used as the model compound for screening purposes. Under optimal conditions, a detection limit of 0.024 μg L(-1) and an enrichment factor of 159 were obtained for BaP in 5 min. The repeatability, expressed as relative standard deviation (RSD), was 4.9% (n=8). The unreliability region of the screening method was 0.54-0.67 μg L(-1), by using a cut-off value of 0.6 μg L(-1) of BaP. Finally, the proposed method was applied to the in situ achievement of the binary "yes/no" response for PAHs in different water samples and recovery studies were performed at three different levels, with BaP recoveries in the range of 93-104%.
Collapse
Affiliation(s)
- Francisco Pena-Pereira
- Departamento de Química Analítica y Alimentaria, Área de Química Analítica, Facultad de Química, Universidad de Vigo, Campus As Lagoas-Marcosende s/n, 36310 Vigo, Spain
| | | | | | | |
Collapse
|
15
|
Evaluating the reliability of analytical results using a probability criterion: a Bayesian perspective. Anal Chim Acta 2011; 705:193-206. [PMID: 21962362 DOI: 10.1016/j.aca.2011.05.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 05/05/2011] [Accepted: 05/16/2011] [Indexed: 11/22/2022]
Abstract
Methods validation is mandatory in order to assess the fitness of purpose of the developed analytical method. Of core importance at the end of the validation is the evaluation of the reliability of the individual results that will be generated during the routine application of the method. Regulatory guidelines provide a general framework to assess the validity of a method, but none address the issue of results reliability. In this study, a Bayesian approach is proposed to address this concern. Results reliability is defined here as "the probability (π) of an analytical method to provide analytical results (X) within predefined acceptance limits (±λ) around their reference or conventional true concentration values (μ(T)) over a defined concentration range and under given environmental and operating conditions." By providing the minimum reliability probability (π(min)) needed for the subsequent routine application of the method, as well as specifications or acceptance limits (±λ), the proposed Bayesian approach provides the effective probability of obtaining reliable future analytical results over the whole concentration range investigated. This is summarised in a single graph: the reliability profile. This Bayesian reliability profile is also compared to two frequentist approaches, the first one derived from the work of Dewé et al. [W. Dewé, B. Govaerts, B. Boulanger, E. Rozet, P. Chiap, Ph. Hubert, Chemometr. Intell. Lab. Syst. 85 (2007) 262-268] and the second proposed by Govaerts et al. [B. Govaerts, W. Dewé, M. Maumy, B. Boulanger, Qual. Reliab. Eng. Int. 24 (2008) 667-680]. Furthermore, to illustrate the applicability of the Bayesian reliability profile, this approach is also applied here to a bioanalytical method dedicated to the determination of ketoglutaric acid (KG) and hydroxymethylfurfural (HMF) in human plasma by SPE-HPLC-UV.
Collapse
|
16
|
Development of fast screening methods for the analysis of veterinary drug residues in milk by liquid chromatography-triple quadrupole mass spectrometry. Anal Bioanal Chem 2010; 397:2777-90. [DOI: 10.1007/s00216-009-3425-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 12/16/2009] [Accepted: 12/17/2009] [Indexed: 10/19/2022]
|
17
|
Rodríguez N, Ortiz M, Sarabia L, Herrero A. A multivariate multianalyte screening method for sulfonamides in milk based on front-face fluorescence spectroscopy. Anal Chim Acta 2010; 657:136-46. [DOI: 10.1016/j.aca.2009.10.048] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 09/29/2009] [Accepted: 10/21/2009] [Indexed: 11/30/2022]
|
18
|
Ávila M, Zougagh M, Escarpa A, Ríos Á. Fast single run of vanilla fingerprint markers on microfluidic-electrochemistry chip for confirmation of common frauds. Electrophoresis 2009; 30:3413-8. [DOI: 10.1002/elps.200900238] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
19
|
Vázquez AS, Costa-Fernandez JM, Encinar JR, Pereiro R, Sanz-Medel A. Bromine determination in polymers by inductively coupled plasma-mass spectrometry and its potential for fast first screening of brominated flame retardants in polymers and paintings. Anal Chim Acta 2008; 623:140-5. [DOI: 10.1016/j.aca.2008.06.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 06/11/2008] [Accepted: 06/19/2008] [Indexed: 10/21/2022]
|
20
|
Traviesa-Alvarez JM, Costa-Fernández JM, Pereiro R, Sanz-Medel A. Direct screening of tetracyclines in water and bovine milk using room temperature phosphorescence detection. Anal Chim Acta 2007; 589:51-8. [PMID: 17397652 DOI: 10.1016/j.aca.2007.02.063] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 02/12/2007] [Accepted: 02/15/2007] [Indexed: 11/21/2022]
Abstract
A fast and simple flow-through optosensor was designed and characterized for the direct screening of four tetracycline (TCC) antibiotics (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in water and bovine milk samples. The proposed optosensor provides rapid binary yes/no overall responses, being appropriate for the screening of this family of antibiotics above or below a pre-set concentration threshold. The experimental set-up is based on a flow-injection manifold coupled on-line to a phosphorescence detector. Aliquots of the samples are pretreated with Eu(III) to form room temperature phosphorescent metal chelates and injected in the flow manifold. Those chelates are then on-line retained on a conventional flow-cell (packed with polymeric Amberlite XAD-4 particles) which is placed inside the cell holder of the phosphorimeter. After the emission is registered, the antibiotic-metal complexes are eluted from the packed resin with 1M HCl (for milk samples a second regeneration step, using methanol, should be performed). A sample throughput of about 20 samples per hour was obtained. Optimum experimental conditions include a pH 9, a Eu(III) concentration of 2 x 10(-4) M and 8 mM sodium sulphite as chemical deoxygenant. The phosphorescence emitted by the europium-TCC complexes was measured at 394 and 617 nm for excitation and emission wavelengths, respectively. The unreliability region, given by the probability of false positives and false negatives, respectively (set at 5% in both cases) was in the range between 0.2 and 11.6 nM for detection of tetracyclines in water samples (at a cut-off level of 4 nM) and in the range between 165 and 238 nM for detection of tetracyclines in milk (cut-off level fixed at the normative EU level of 200 nM). Finally, the applicability of the proposed screening optosensor was tested for the reliable control of tetracyclines in contaminated and uncontaminated water and milk samples.
Collapse
Affiliation(s)
- J M Traviesa-Alvarez
- Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain
| | | | | | | |
Collapse
|
21
|
Statistical Evaluation of Analytical Results. Anal Chem 2007. [DOI: 10.1007/978-3-540-35990-6_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
22
|
Aguilera E, Lucena R, Cárdenas S, Valcárcel M, Trullols E, Ruisánchez I. Robustness in qualitative analysis: a practical approach. Trends Analyt Chem 2006. [DOI: 10.1016/j.trac.2006.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
23
|
A guide for selecting the most appropriate method for ammonium determination in water analysis. Trends Analyt Chem 2006. [DOI: 10.1016/j.trac.2005.12.002] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
24
|
|
25
|
|
26
|
|
27
|
León-Ruiz V, Vera S, San Andrés MP. Validation of a screening method for the simultaneous identification of fat-soluble and water-soluble vitamins (A, E, B1, B2 and B6) in an aqueous micellar medium of hexadecyltrimethylammonium chloride. Anal Bioanal Chem 2005; 381:1568-75. [PMID: 15827721 DOI: 10.1007/s00216-005-3137-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Revised: 01/25/2005] [Accepted: 01/31/2005] [Indexed: 10/25/2022]
Abstract
Simultaneous determination of the fat-soluble vitamins A and E and the water-soluble vitamins B1, B2 and B6 has been carried using a screening method from fluorescence contour graphs. These graphs show different colour zones in relation to the fluorescence intensity measured for the pair of excitation/emission wavelengths. The identification of the corresponding excitation/emission wavelength zones allows the detection of different vitamins in an aqueous medium regardless of the fat or water solubility of each vitamin, owing to the presence of a surfactant which forms micelles in water at the used concentration (over the critical micelle concentration). The micelles dissolve very water insoluble compounds, such as fat-soluble vitamins, inside the aggregates. This approach avoids the use of organic solvents in determining these vitamins and offers the possibility of analysing fat- and water-soluble vitamins simultaneously. The method has been validated in terms of detection limit, cut-off limit, sensitivity, number of false positives, number of false negatives and uncertainty range. The detection limit is about microg L(-1). The screening method was applied to different samples such as pharmaceuticals, juices and isotonic drinks.
Collapse
Affiliation(s)
- V León-Ruiz
- Dpto. Química Analítica, Facultad de Química, Universidad de Alcalá, Ctra. Madrid-Barcelona, Km. 33.6, 28871, Alcalá de Henares (Madrid), Spain
| | | | | |
Collapse
|
28
|
Development and validation strategies for qualitative spot tests: application to nitrite control in waters. Anal Chim Acta 2005. [DOI: 10.1016/j.aca.2005.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
29
|
Santos B, Lista A, Simonet BM, Ríos A, Valcárcel M. Screening and analytical confirmation of sulfonamide residues in milk by capillary electrophoresis-mass spectrometry. Electrophoresis 2005; 26:1567-75. [PMID: 15765476 DOI: 10.1002/elps.200410267] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new methodology is proposed to automate the monitoring of sulfonamide residues in milk samples. It combines a screening unit for the total amount of sulfonamide with capillary electrophoresis-mass spectrometry (CE-MS) equipment for processing the samples containing a detectable level of sulfonamide. The screening unit consists of continuous-flow system (CFS) to precipitate the proteins connected on-line to the CE-MS equipment, in which a common characteristic ion of all sulfonamides was monitored with the MS detector by flushing the sample through the capillary. The confirmatory method is based on the purification and preconcentration of sulfonamides in a CFS unit and posterior analysis by CE-MS. The sample treatment unit was also on-line connected to the CE-MS equipment. In order to increase sensitivity, the flow rate of the sheath liquid was diminished from 0.5 to 0.2 microL.min(-1) by increasing the content in water from 0 to 50% and the formic acid from 0.5 to 1.5% in this liquid and by applying an overimposed pressure of 5 mbar during the electrophoretic separation. The method allowed the analysis of 30 samples per hour.
Collapse
Affiliation(s)
- Bricio Santos
- Department of Analytical Chemistry, University of Córdoba, Córdoba, Spain
| | | | | | | | | |
Collapse
|