Eliane Cristina Pires do Rego

The validation of a new high throughput method for determination of chloramphenicol in milk using liquid–liquid extraction with low temperature partitioning (LLE-LTP) and isotope-dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS)

Chloramphenicol (CAP) is an antibiotic banned for treatment of food-producing animals. The minimum required performance limit (MRPL) of 0.3 μg kg−1 for analytical methods was set by the European Community for the detection of its residues in different matrices, including milk. A highly sensitive analytical method using isotope-dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) and liquid–liquid extraction with low temperature partitioning (LLE-LTP) was developed and validated for CAP residues in milk. Selected validation parameters such as selectivity, working range and linearity, trueness (recoveries), precision (repeatability and intermediate precision), limit of detection (LOD) and limit of quantification (LOQ) were evaluated. The validation procedures were based on the new Eurachem Guide and the European Union Commission Decision 2002/657/EC. The matrix effect was evaluated by the ion suppression test and by comparison of the matrix-matched analytical curve and the solvent standard analytical curve. A linear working range between 0.1 and 5.0 μg kg−1 was observed. The homoscedasticity was demonstrated by the Cochran test, the coefficient of determination (R2) was higher than 0.99 and the residual plot was free of trends. The limits of detection and quantification were 0.015 μg kg−1 and 0.05 μg kg−1, respectively. Mean recoveries evaluated at three levels (0.3, 1.0 and 3.0 μg kg−1) ranged from 94% to 114% with RSDs lower than 6.7% (repeatability). For intermediate precision, different analytes were compared and the RSDs were lower than 7.3%. The method was accurate and reproducible, and was successfully applied to the evaluation of CAP residues in milk samples.

Hidrocarbonetos policíclicos aromáticos em resíduos sólidos industriais: uma avaliação preliminar do risco potencial de contaminação ambiental e humana em áreas de disposição de resíduos

Proper solid waste disposal is important to avoid human and environmental contamination. The NBR 10,004 Waste Classification lists several polycyclic aromatic hydrocarbons (PAHs) and indicates that the presence of at least one PAH in a waste sample is enough to classify it as hazardous. The aim of this study was a preliminary evaluation of PAHs in solid waste samples from selected industries to obtain a preliminary overview of their potential for contamination in case of improper disposal. One or more PAHs listed in NBR 10,004 (benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, indene[1,2,3-c,d]pyrene, chrysene, or fluoranthene) were found in all samples, thus leading to their classification as hazardous waste. Our results showed that toxicologically relevant PAHs were found in all the samples, indicating that their final disposal must be performed in appropriate areas in order to minimize human health risks and environmental contamination from waste disposal areas.

Development studies of a new metronidazole certified reference material

This paper presents the results of the studies carried out with the candidate certified reference material (CRM) of metronidazole, first CRM of this active pharmaceutical ingredient (API) available on the market and second Brazilian CRM of an API. The investigation includes the determination of organic impurities, inorganic impurities and volatiles, validation of the HPLC-DAD method, stability studies under transport and storage conditions, homogeneity testing, calculation of metronidazole content by mass balance, confirmation of the certified value by differential scanning calorimetry (DSC), and estimation of measurement uncertainties.

Quantitative nuclear magnetic resonance for purity assessment of polycyclic aromatic hydrocarbons

The application of 1H quantitative nuclear magnetic resonance (1H qNMR) for purity determination of organic compounds is well documented in the literature. The aim of this work is to determine if the 1H qNMR method produces consistent values for the purity of polycyclic aromatic hydrocarbons (PAH) and is sufficiently accurate for the certification of reference materials. For this purpose, 15 different commercial PAH standards had their purity evaluated by 1H qNMR. The purity values and the associated expanded uncertainty of the 15 analyzed PAH ranged from (97.21 ± 0.28)% to (99.52 ± 1.10)%. The expanded measurement uncertainties were acceptable for the certification of reference materials and the purity values were in the expected range, confirming, therefore, that qNMR is appropriate for this type of analysis.

Quantification of benzoic acid in beverages: the evaluation and validation of direct measurement techniques using mass spectrometry

Orange juice is one of the most consumed beverages around the world and one of the most important export products in Brazil. Juice is a perishable good and industrial processing is generally carried out with the aim of increasing the lifetime of the product enabling its distribution worldwide. One extremely common process used for preservation is the addition of chemical preservatives such as benzoic acid. This addition has to be controlled to maintain safe levels and not to give the product a bad taste. Many analytical methods are available for the analysis of this compound in beverages; however, these methods tend to be laborious and long, involving tedious sample preparation steps. In this study, direct methods using mass spectrometry were evaluated for the rapid analysis of this compound. Two rapid methods were then developed are as follows: one using dilute and shoot preparation with flow injection analysis coupled to tandem mass spectrometric detection and another using headspace sampling gas chromatography coupled to mass spectrometry with very little sample preparation; both methods used isotope dilution calibration. Both methods were validated and metrologically evaluated using certified reference materials and applied to real samples of different types of beverages, including orange juice, soft drink, soy drink and orange flavored drink. Both methods present excellent performance in all cases and were rapidly performed, serving as references for laboratories, which might want to implement these methods in their routine analyses.

Using the L/O ratio to determine blend composition in biodiesel by EASI-MS corroborated by GC-FID and GC-MS

Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is applied to the analysis of biodiesel blends prepared from soybean and animal fat biodiesel. A correlation was established between the ratio of abundance of linoleic acid (L) and oleic acid (O) methyl ester ions with the biodiesel blend composition. To compare these results from the EASI-MS technique, the L/O ratio of these blends was also determined using both gas chromatography with flame ionization detection (GC-FID) and gas chromatography with mass spectrometry (GC-MS). Both these classical techniques confirmed that the ratio between the mass fraction of FAME from L and O as measured by EASI-MS is indeed correlated with the blend composition of soybean–animal fat biodiesel.

Evaluation of sampling inhalable PM10 particulate matter (≤ 10 μm) using co-located high volume samplers

This paper presents the results of the determination of the concentrations of atmospheric particulate matter ≤ 10 μm (PM10), collected simultaneously by six PM10 high volume samplers from two different manufacturers installed in the same location. Fifteen samples of 24 h were obtained with each equipment at a selected urban area of Rio de Janeiro city. The concentration of PM10 ranged between 10.73 and 54.04 μg m−3. The samplers were considered comparable to each other, as the adopted methodology presented good repeatability.

Certified reference material for traceability in environmental analysis: PAHs in toluene

Certified reference material (CRM) plays a vital role for quality control assurance in environmental analysis, because the quality of data arising from measurements has crucial importance. This article presents the results from studies carried out for certification of a candidate reference material composed by sixteen polycyclic aromatic hydrocarbons (PAHs) dissolved in toluene (naphthalene, acenaphthylene, acenaphtene, fluorene, anthracene, phenanthrene, fluoranthene, chrysene, benzo[a]anthracene, pyrene, benzo[k]fluoranthene, benzo[b]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthacene, indeno[123-cd]pyrene and benzo[ghi]perylene). This is the first Brazilian PAH CRM developed by Inmetro. The certification procedure includes validation of the GC/IDMS method (isotopic dilution mass spectrometry coupled to gas chromatography), homogeneity study, stability studies under transport and storage conditions and estimation of measurement uncertainties.

Final report of CCQM-K130 nitrogen mass fraction measurements in glycine

Mass fraction of nitrogen is very important pointer because the results of these measurements are often used for determination of protein mass fraction that is an important indicator of the quality ...

Potential of electrospray ionization mass spectrometry (ESI-MS), using direct infusion, to quantify fatty acid methyl esters (FAMEs) in biodiesel

Biodiesel is a very important biofuel obtained from vegetable oil or animal fat by a chemical reaction known as transesterification. It consists mainly of fatty acid methyl esters (FAMEs). In biodiesel quality control, the limits and methodologies for each parameter are well established, and one of them is related to the total amount of FAMEs, which is measured by gas chromatography. However, the development of other analytical methods for such measurements can serve as alternative techniques. In this work, the use of a mass spectrometer with direct infusion into an electrospray ionization source (ESI-MS) is shown as a promising technique to quantify the FAMEs present in biodiesel. Due to the chemical difference and the behaviour of the methyl esters, the ionizations occur at different scales. Thus, to evaluate this behaviour, the concept of relative ionization efficiency (RIE) in the ESI source was used for quantification. Uncertainty estimations of intensity measurement by ESI-MS were also proposed. Four biodiesel samples (canola, coconut, crambe and soy) were synthesized, and their concentrations were determined by the reference methods, GC-MS and GC-FID, and by the proposed method, ESI-MS. Then the efficiency of the method was evaluated by comparing the methods with two approaches, one using the uncertainties and another considering a statistical analysis. In both situations, the methods could be considered as equivalent.