RESUMEN
Endogenous aldehydes (EAs) formed by the free-radical-mediated reaction are regarded as potential biological markers of several diseases. In this work, an automated and solvent-free analytical method was developed for quantitative analysis of seven EAs (C1-C7) in human blood by using gas chromatography-mass spectrometry coupled with a headspace generator sampler (HS-GC-MS). A 1:4 (blood:water) dilution and the 1,2dibromopropane internal standard were introduced to reduce the influence of the matrix effect from complex biological fluids. The sample preparation steps were simplified. Various experimental parameters for derivatization and extraction conditions were studied such as HS extraction temperature and time, the amount of derivatization reagent, pH and the salt effect. Under these optimum conditions, seven low-mass aldehydes were separated and analyzed within 10â¯min. Additionally, this method achieved limits of detection in the range of 0.0692-0.864⯵g/L, an excellent linearity with correlation coefficients higher than 0.9996 and appropriate repeatability and reproducibility values (RSDâ¯<â¯12% at low, middle and high levels). The HS-GC-MS method was applied to measure the concentrations of the seven aldehydes in blood from bladder cancer patients (nâ¯=â¯15) and control subjects (nâ¯=â¯15). Compared with the control subjects, the levels of butanal (pâ¯<â¯0.01), formaldehyde, acetaldehyde, propanal, pentanal, hexanal and heptanal (all pâ¯<â¯0.001) were increased significantly, indicating that EAs may be useful as biomarkers in the early diagnosis of bladder cancer.
Asunto(s)
Aldehídos/sangre , Cromatografía de Gases y Espectrometría de Masas/métodos , Aldehídos/química , Aldehídos/aislamiento & purificación , Biomarcadores de Tumor/sangre , Biomarcadores de Tumor/química , Biomarcadores de Tumor/aislamiento & purificación , Estudios de Casos y Controles , Humanos , Límite de Detección , Modelos Lineales , Reproducibilidad de los Resultados , Neoplasias de la Vejiga Urinaria/sangreRESUMEN
Volatile aldehydes appear in canned vegetables as constituents and some of them can also be present as disinfection by-products (DBPs) because of the contact between vegetables and treated water. This paper describes two static headspace-gas chromatography-mass spectrometry (SHS-GC-MS) methods to determine 15 aldehydes in both the solid and the liquid phases of canned vegetables. The treatment for both phases of samples was carried out simultaneously into an SHS unit, including the leaching of the aldehydes (from the vegetable), their derivatization and volatilization of the oximes formed. Detection limits were obtained within the range of 15-400µg/kg and 3-40µg/L for aldehydes in the solid and the liquid phases of the food, respectively. The relative standard deviation was lower than 7% -for the whole array of the target analytes-, the trueness evaluated by recovery experiments provided %recoveries between 89 and 99% and short- and long-term stability studies indicated there was no significant variation in relative peak areas of all aldehydes in both phases of canned vegetables after their storing at 4°C for two weeks. The study of the origin of the 15 aldehydes detected between both phases of canned vegetables showed that: i) the presence of 13 aldehydes -at average concentrations of 2.2-39µg/kg and 0.25-71µg/L for the solid and the liquid phases, respectively- is because they are natural constituents of vegetables; and ii) the presence of glyoxal and methylglyoxal -which are mainly found in the liquid phase (average values, 1.4-4.1µg/L)- is ascribed to the use of treated water, thereby being DBPs.
Asunto(s)
Aldehídos/análisis , Tecnología de Alimentos/métodos , Cromatografía de Gases y Espectrometría de Masas , Verduras/química , Desinfección , Contaminación de Alimentos/análisis , Límite de DetecciónRESUMEN
Canned vegetables appear to be a possible exposure pathway for hazardous disinfection by-products due to the use of sanitizers and treated water by the canning industry in the preparation of these foods. This work reports on two static headspace-gas chromatography-mass spectrometry methods for the simultaneous determination of 10 trihalomethanes (THMs) and 13 haloacetic acids (HAAs) in both solid and liquid phases of the canned vegetables. Both methods carry out the whole process (including the leaching of target analytes from the vegetable), derivatization of HAAs and volatilization of THMs and HAA esters, in a single step within a static headspace unit. The methods proposed provide an efficient and simple tool for the determination of regulated disinfection by-products in canned vegetables. Average limits of detection for THMs and HAAs were 0.19 and 0.45µg/kg, respectively, in the solid phase of canned vegetables, and 0.05 and 0.09µg/L, respectively, in the liquid phase. Satisfactory recoveries (90-99%) and precision, calculated as relative standard deviations (RSD≤10%), were obtained in both phases of canned vegetables. The methods proposed were applied for the analysis of frequently-used canned vegetables and confirmed the presence of up to 3 THMs and 5 HAAs at microgram per kilogram or liter levels in both phases of the samples.
Asunto(s)
Acetatos/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Trihalometanos/análisis , Verduras/química , Acetatos/química , Límite de Detección , Reproducibilidad de los Resultados , Trihalometanos/químicaRESUMEN
Endogenous aldehydes (EAs) generated during oxidative stress and cell processes are associated with many pathogenic and toxicogenic processes. The aim of this research was to develop a solvent-free and automated analytical method for the determination of EAs in human urine using a static headspace generator sampler coupled with gas chromatography-mass spectrometry (HS-GC-MS). Twelve significant EAs used as markers of different biochemical and physiological processes, namely short- and medium-chain alkanals, α,ß-unsaturated aldehydes and dicarbonyl aldehydes have been selected as target analytes. Human urine samples (no dilution is required) were derivatized with O-2,3,4,5,6-pentafluorobenzylhydroxylamine in alkaline medium (hydrogen carbonate-carbonate buffer, pH 10.3). The HS-GC-MS method developed renders an efficient tool for the sensitive and precise determination of EAs in human urine with limits of detection from 1 to 15ng/L and relative standard deviations, (RSDs) from 6.0 to 7.9%. Average recoveries by enriching urine samples ranged between 92 and 95%. Aldehydes were readily determined at 0.005-50µg/L levels in human urine from healthy subjects, smokers and diabetic adults.
Asunto(s)
Aldehídos/análisis , Cromatografía de Gases y Espectrometría de Masas , Urinálisis/instrumentación , Urinálisis/métodos , Adulto , Humanos , Sensibilidad y Especificidad , Solventes/análisisRESUMEN
Volatile organic sulfur compounds (VOSCs) are important sources of unpleasant odor in wastewater systems. However, the study of VOSCs is usually hindered by their complicated measurement method and highly reactive nature. In this work, a static headspace method utilising gas chromatography (GC) with a sulfur chemiluminescence detector (SCD) was developed to quantitatively analyze VOSCs in wastewater matrices. The method has low detection limits and requires no pre-concentration treatment. Three typical VOSCs, namely methanethiol (MT), dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), were chosen as examples for this study. The calibration curves of all three compounds covering a wide range from 0.5 ppb to 500 ppb showed good linearity (R(2) > 0.999). The method detection limits (MDL) were 0.08, 0.12 and 0.21 ppb for MT, DMS and DMDS, respectively. The reproducibility (relative standard deviation) was approximately 2%. The recovery ratio of MT, DMS and DMDS in spiked wastewater samples were 83 ± 4%, 103 ± 4% and 102 ± 3%, respectively. Sample preservation tests showed that VOSCs in wastewater samples could be preserved in vials without headspace under acidified conditions (pH â¼1.1) for at least 24 h without significant changes (<1.8 ppb). The analysis of real wastewater samples from both a laboratory-scale sewer system and a full-scale sewer pipe demonstrated the suitability of this method for routine wastewater VOSC measurement.
Asunto(s)
Cromatografía de Gases/métodos , Compuestos de Azufre/análisis , Compuestos Orgánicos Volátiles/análisis , Aguas Residuales/análisis , Calibración , Disulfuros/análisis , Límite de Detección , Luminiscencia , Queensland , Reproducibilidad de los Resultados , Compuestos de Sulfhidrilo/análisis , Sulfuros/análisis , Compuestos de Azufre/química , Aguas Residuales/químicaRESUMEN
Low-molecular-mass aldehydes (LMMAs) are water disinfection by-products formed by the reaction of ozone and/or chlorine with natural organic matter in water. LMMAs are mutagenic and carcinogenic compounds, which are detected at ng/L levels in water. An analytical method that allows simultaneous derivatisation and extraction of LMMAs in water has been developed using the classical static headspace technique coupled with gas chromatography-mass spectrometry (HS-GC-MS). Important parameters controlling the derivatisation of LMMAs with o-2,3,4,5,6-pentafluorobenzylhydroxylamine, oxime-products extraction and headspace generation were optimised to obtain the highest sensitivity, completing the entire process in 20min. For the first time the derivatisation reaction was carried out at alkaline pH adjusted with sodium hydrogen carbonate which exerts a significant enhancement effect on the derivatisation efficiency of the aldehydes; up to 20-fold with respect to those obtained in weak acid media as recommended by EPA Method 556.1. The addition of 200µL of n-hexane, as a chemical modifier, favoured the volatilisation of oxime-products, increasing the sensitivity of the method. The proposed method allows the achieving of detection limits from 2 to 80ng/L and has excellent precision (RSD average value of 6.4%) and accuracy (recovery ranging from 97% to 99%) for LMMA quantifications in drinking water samples. Finally, the HS-GC-MS method was validated relative to EPA Method 556.1 for the analysis of drinking water samples subjected to several disinfection treatments.