RESUMEN
Immune checkpoint blockade (ICB) therapy has been approved for colorectal cancer (CRC). However, response rates are variable and often <50%. The low tumor immunogenicity and immunosuppressive tumor microenvironment (TME) jointly contribute to this suboptimal response rate. This study confirmed the potential of combining immunogenic cell death (ICD) inducer irinotecan (IRI) and transforming growth factor-ß (TGF-ß) inhibitor galunisertib (GAL) to improve tumor immunogenicity and remodel the immunosuppressive TME. Moreover, to ameliorate the in vivo delivery barriers associated with small molecules, neutrophil micropharmacies (NOG) were developed for the codelivery of IRI and GAL, which loaded the commercial liposome formulation of IRI (ONIVYDE, ONI) intracellularly and conjugated the pH-responsive GAL liposome (GLP) on the cell surface. This neutrophil-based formulation resulted in a >4-fold increase in the ratios of the amount of both IRI and GAL accumulated in tumors to the dosage administration, effectively achieving multiple mechanism-mediated sensitization of CRC to ICB therapy.
RESUMEN
Limited intratumoral T-cell infiltration in pancreatic ductal adenocarcinoma (PDAC) is an obstacle to immunotherapy, yet the efficient approach to enhance tumor-infiltrating T cells is not fully established. Here, we show that tumor-specific knockdown of carbohydrate sulfotransferase 15 (CHST15), a tumor stromal proteoglycan-synthetic enzyme, suppresses tumor growth in a T-cell-dependent manner in a murine model of PDAC. Silencing of tumoral CHST15 unexpectedly expanded CD4+ and CD8+ T cells in tumor draining LN (TDLN), leading to accelerated accumulation of EdU+ proliferating CD4+ and CD8+ T cells and granzyme B+ CD8+ T cells in the tumor. RNA expression analysis indicated that tumoral CHST15 knockdown (KD) downregulated matrix remodeling-related genes, while upregulated anti-tumor T-cell activity-related genes in both tumor and TDLN. CHST15 KD significantly diminished intratumoral and TDLN Ly6C/G+ myeloid-derived suppressor cells prior to TDLN T-cell expansion, suggesting that tumoral CHST15 remotely regulated myeloid-derived suppressor cell mediated T-cell suppression in the TDLN. Our findings illustrate a novel immunotherapeutic potential of tumoral CHST15 blockage by reactivating T cells in immune suppressive TDLN of PDAC.
Asunto(s)
Carcinoma Ductal Pancreático , Linfoma , Neoplasias Pancreáticas , Animales , Ratones , Linfocitos T CD8-positivos , Neoplasias Pancreáticas/genética , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/metabolismo , Ganglios Linfáticos , Ratones Endogámicos C57BL , Carbohidrato Sulfotransferasas , Neoplasias PancreáticasRESUMEN
Recent evidence indicates that RNA-dependent RNA polymerase (RdRP) activity of human telomerase reverse transcriptase (hTERT) regulates expression of target genes and is directly involved in tumor formation in a telomere-independent manner. Non-canonical function of hTERT has been considered as a therapeutic target for cancer therapy. We have previously shown that hTERT phosphorylation at threonine 249 (p-hTERT), which promotes RdRP activity, is an indicator of an aggressive phenotype and poor prognosis in liver and pancreatic cancers, using two cohorts with small sample sizes with polyclonal p-hTERT antibody. To clarify the clinical relevance of p-hTERT, we developed a specific monoclonal antibody and determined the diagnostic and prognostic value of p-hTERT in cancer specimens using a large cohort. A monoclonal antibody for phosphorylated hTERT (p-hTERT) at threonine 249 was developed and validated. The antibody was used for the immunohistochemical staining of formalin-fixed, paraffin-embedded specimens from 1523 cases of lung, colon, stomach, pancreatic, liver, breast, and kidney cancers. We detected elevated p-hTERT expression levels in cases with a high mitotic activity, high pathological grade, and high nuclear pleomorphism. Elevated p-hTERT expression was an independent prognostic factor for lung, pancreatic, and liver cancers. Furthermore, p-hTERT expression was associated with immature and aggressive features, such as adenosquamous carcinoma (lung and pancreas), invasive type of cancer (lung), high serum alpha-fetoprotein level (liver), and triple-negative status (breast). In conclusion, RdRP activity indicated by p-hTERT expression predicts aggressive cancer phenotypes in various types of cancer. Thus, p-hTERT is a novel biomarker for the diagnosis of aggressive cancers with a poor prognosis. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
Asunto(s)
Neoplasias , Telomerasa , Anticuerpos Monoclonales , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Humanos , Neoplasias/genética , Neoplasias/patología , Fosforilación , Pronóstico , ARN Polimerasa Dependiente del ARN , Telomerasa/genética , Treonina/metabolismoRESUMEN
BACKGROUND: The pathologic assessments of tumor response after neoadjuvant chemoradiotherapy (NACRT) are critical to improving the prognostic stratification for patients with pancreatic ductal adenocarcinoma (PDAC). Here we clarified the utility of our new grading system based on the area of residual tumor (ART) as compared to existing systems, such as the College of American Pathologists (CAP) and MD Anderson (MDA) score. METHODS: Eight reviewers individually evaluated the tumor regression grade of 30 patients with PDAC based on three types of grading systems. The interobserver concordance and clinicopathological characteristics were compared between the three systems. RESULTS: The interobserver concordance (kappa value) of the ART, CAP, and MDA score were 0.61, 0.48, and 0.53, respectively. Discrepant cases, which were 27% of the cases, exhibited smaller tumor and tumor bed sizes than concordant cases. The reduction in tumor size evaluated by microscopy showed a correlation with the rate of change in carcinoembryonic antigen (CEA) level, CA19-9 level, and tumor size on computed tomography (CT). The ART score was correlated with the tumor size on CT before and after NACRT and disease-free survival. The CAP and MDA scores were not associated with prognosis. CONCLUSION: The ART grading system may be the most practical system to assess the tumor response in post-NACRT resections of PDAC.
Asunto(s)
Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Carcinoma Ductal Pancreático/cirugía , Humanos , Terapia Neoadyuvante , Neoplasia Residual , Neoplasias Pancreáticas/cirugía , Pronóstico , Reproducibilidad de los Resultados , Estudios Retrospectivos , Neoplasias PancreáticasRESUMEN
BACKGROUND: The relationship between Helicobacter pylori (H pylori) and body mass index (BMI) is still inconclusive. Not only the high rate of H pylori infection but also the increasing higher BMI levels are endangering Chinese today. METHODS: The aim of this research was to evaluate the association between different situations of H pylori infection and BMI values or levels in Chinese healthy population. A total of 39 091 individuals aged from 18 years to 80 years, performed healthy examination including a 13 C/14 C urease breath test (13 C/14 C-UBT), were included. Among them, 30 224 individuals only had one time of health examination, and 8867 had two or more times. A case-cohort data of 8752 with an interval time more than 6 months, collected by the first and the last time, were established from the latter. BMI groups are classified according to the China recommendation: low weight (<18.5 kg/m2 ), normal weight (18.5 ~ 23.9 kg/m2 ), overweight (24.0 ~ 27.9 kg/m2 ), and obesity (≥28.0 kg/m2 ). RESULTS: The rate of H pylori infection among low weight, normal weight, overweight, and obesity was 43.2%, 44.7%, 46.4%, and 48.0%, respectively (P = .000). H pylori infection increased the risk of higher level of BMI (OR = 1.077, 95% confidence interval = 1.036-1.119, χ2 = 14.048, P = .000) with adjustments for sex and age. In the case-control study, the rate of persistent negative, persistent infection, new infection, and eradicated infection was 39.5%, 25.8%, 15.8%, and 18.9%, respectively, with a median interval time of 13 months. The mean obesity BMI descend values in the persistent negative subgroup were lower than those in the persistent infection subgroup (-0.21 ± 1.19 kg/m2 vs -0.003 ± 1.01 kg/m2 , P = .021). But the change of BMI classifications had no difference between the subgroups of H pylori infection in different BMI levels. CONCLUSIONS: H pylori infection was positively correlated with higher BMI levels. And H pylori persistent infection had a negative effect on the fall of BMI values in Chinese obese population.
Asunto(s)
Pueblo Asiatico/estadística & datos numéricos , Infecciones por Helicobacter/patología , Helicobacter pylori/aislamiento & purificación , Obesidad/patología , Adulto , Anciano , Índice de Masa Corporal , Pruebas Respiratorias , Estudios de Casos y Controles , China/epidemiología , Estudios de Cohortes , Femenino , Infecciones por Helicobacter/diagnóstico , Infecciones por Helicobacter/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Obesidad/diagnóstico , Obesidad/epidemiología , Riesgo , Pérdida de PesoAsunto(s)
Fibroblastos/patología , Neoplasias , Cráneo/patología , Anciano de 80 o más Años , Autopsia , Diagnóstico Diferencial , Femenino , Humanos , Inmunohistoquímica , Queratinas/metabolismo , Ganglios Linfáticos/patología , Neoplasias/diagnóstico , Neoplasias/metabolismo , Neoplasias/patología , Neoplasias de Tejido Óseo/diagnóstico , Neoplasias de Tejido Óseo/metabolismo , Neoplasias de Tejido Óseo/patologíaRESUMEN
The dense stroma is one cause of poor efficacy of T cell-mediated immunotherapy in pancreatic ductal adenocarcinoma (PDAC). Carbohydrate sulfotransferase 15 (CHST15) is a proteoglycan-synthetic enzyme responsible for remodeling tumor stroma. Intra-tumoral injection of CHST15 small interfering RNA (siRNA) has been shown to increase the tumor-infiltrating T cells (TILs) in patients with unresectable PDAC. However, the mechanism underlying the enhanced accumulation of TILs is not fully explored. Here, we demonstrate that intra-tumoral injection of CHST15 siRNA locally and remotely diminishes myeloid-derived suppressor cells (MDSCs) and enhances TILs in mice. CHST15 was expressed by tumor cells and MDSCs in both tumor and tumor-draining lymph nodes (TDLNs), and CHST15 siRNA repressed stromal density, neutrophil extracellular traps, and Ly6C/G+ MDSCs in vivo. Remarkably, tumor growth inhibition was only observed in the immunocompetent KPC model, which is associated with enhanced TILs. In vitro, CHST15 siRNA significantly downregulated the levels of CHST15 and indoleamine 2,3-dioxygenase mRNA in CD33+ MDSCs derived from human peripheral blood mononuclear cells. These results suggest a dual role for intra-tumorally injected CHST15 siRNA on modulating the tumor immune microenvironment for T cell entry and remotely diminishing CHST15+ MDSCs, decreasing T cell suppression and expanding T cells in the TDLN, ultimately leading to an enhanced accumulation of TILs.
RESUMEN
BACKGROUND/AIM: Immunohistochemical (IHC) staining has been routinely used to distinguish adenocarcinoma (ADC) and squamous cell carcinoma (SCC) of the lungs; however, it is challenging to obtain an accurate diagnosis, especially for cases with discrepancies between IHC and hematoxylin and eosin (H&E) staining results. This study aimed to clarify the clinicopathological characteristics of these discrepant cases. PATIENTS AND METHODS: Tissue microarray specimens from 321 patients with ADC and SCC were used for H&E and IHC staining of thyroid transcription factor 1 (TTF-1), Napsin A, cytokeratin 5/6 (CK5/6), p40, and p63. The pathological diagnosis was made based on (1) H&E, (2) IHC, and (3) both H&E and IHC results. Discrepant cases were defined as those with different diagnoses based on the H&E and IHC results. RESULTS: A total of 32 (10%) discrepant cases were identified. ADC (3.9%) showed fewer discrepant cases than SCC (51%). Discrepant cases of ADC had a significantly higher proportion of poorly differentiated tumors and subtypes of solid and invasive mucinous ADC, and they also had shorter overall and disease-free survival than concordant cases. Solid and invasive mucinous ADC cases showed low positivity for TTF-1 (84% and 40%, respectively) and Napsin A (88% and 80%, respectively), and invasive mucinous ADC cases showed high positivity for CK5/6 (80%). The sensitivity and specificity of TTF-1+Napsin A for ADC were 91% and 83%, respectively, whereas those of CK5/6+p40 for SCC cases were 90% and 96%, respectively. CONCLUSION: Discrepant cases of ADC are associated with solid and invasive mucinous subtypes and shorter survival.
Asunto(s)
Adenocarcinoma , Carcinoma de Pulmón de Células no Pequeñas , Carcinoma de Células Escamosas , Neoplasias Pulmonares , Humanos , Neoplasias Pulmonares/patología , Carcinoma de Pulmón de Células no Pequeñas/patología , Factores de Transcripción , Inmunohistoquímica , Biomarcadores de Tumor , Adenocarcinoma/patología , Carcinoma de Células Escamosas/patología , PronósticoRESUMEN
Monolithic materials were synthesized in capillaries by in situ polymerization with N-isopropylacrylamide, glycidyl methacrylate, and ethylene dimethacrylate as the monomers, and methanol and PEG as the porogens. With γ-alumina nanoparticles attached to the surface of the porous monolithic column via epoxide groups, a novel polymer monolith microextraction (PMME) material was prepared with a good mechanical stability and a high extraction capacity. SEM and X-ray photoelectron spectroscopy were employed to characterize the modified monolithic column, demonstrating that γ-alumina nanoparticles were effectively functionalized onto the monolithic column. In addition, a new method was developed for the analysis of Sudan I-IV dyes using PMME coupled with HPLC. In order to obtain the optimum extraction efficiency, the PMME conditions including desorption solvent type, sample pH, sample volume, sample flow rate, and eluent flow rate were investigated. Under the optimum conditions, we obtained acceptable linearities, low LODs, and good intra- and interday RDSs. When applied to the determination of Sudan I-IV dyes in red wine samples, satisfactory recoveries were obtained in the range of 84.0-115.9%.
Asunto(s)
Compuestos Azo/aislamiento & purificación , Colorantes/aislamiento & purificación , Contaminación de Alimentos/análisis , Polímeros/química , Microextracción en Fase Sólida/métodos , Vino/análisis , Compuestos Azo/química , Cromatografía Líquida de Alta Presión/métodos , Colorantes/química , Nanopartículas/química , Porosidad , Microextracción en Fase Sólida/instrumentaciónRESUMEN
Recent studies have shown that D-allose, a rare sugar, elicits antitumor effects on different types of solid cancers, such as hepatocellular carcinoma, non-small-cell lung cancer, and squamous cell carcinoma of the head and neck. In this study, we examined the effects of D-allose on the proliferation of human glioblastoma (GBM) cell lines (i.e., U251MG and U87MG) in vitro and in vivo and the underlying mechanisms. D-allose treatment inhibited the proliferation of U251MG and U87MG cells in a dose-dependent manner (3-50 mM). However, D-allose treatment did not affect cell cycles or apoptosis in these cells but significantly decreased the cell division frequency in both GBM cell lines. In a subcutaneous U87MG cell xenograft model, intraperitoneal injection of D-allose (100 mg/kg/day) significantly reduced the tumor volume in 28 days. These data indicate that D-allose-induced reduction in cell proliferation is associated with a subsequent decrease in the number of cell divisions, independent of cell-cycle arrest and apoptosis. Thus, D-allose could be an attractive additive to therapeutic strategies for GBM.
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas , Glioblastoma , Neoplasias Hepáticas , Neoplasias Pulmonares , Humanos , Glioblastoma/tratamiento farmacológico , Proliferación Celular , Glucosa/metabolismo , División Celular , Apoptosis , Línea Celular TumoralRESUMEN
BACKGROUND: Telomere dysfunction has been reported to be directly involved in carcinogenesis owing to chromosomal instability and immortalization; however, the clinicopathological significance of telomeres remains controversial. We have shown that telomere shortening occurs in normal-appearing duct cells at initiation and then continues during the progression of pancreatic cancer. In this study, we determined the clinicopathological and prognostic value of telomere length (TL) in cancer progression. METHODS: TL in both cancer cells and cancer-associated fibroblasts (CAFs) was analyzed by high-throughput quantitative fluorescence in situ hybridization using a previously reported cohort comprising 1434 cases of adenocarcinoma (ADC), squamous cell carcinoma (SCC), adenosquamous carcinoma, hepatocellular carcinoma, and renal cell carcinoma (RCC), which are known cancers with a statistically significantly low incidence of alternative lengthening of telomeres. Cases were divided into 2 groups as follows: longer and shorter telomeres, according to the median TL of cancer cells and CAFs. The statistical significance of TL in cancer cells and CAFs on clinicopathological characteristics and prognosis was analyzed. RESULTS: There was a close association between TL in cancer cells and CAFs. Longer telomeres in cancer cells and CAFs were associated with aggressive features such as advanced stage, high mitosis score and nuclear score, poorly differentiated cancer, and desmoplastic stroma in ADC. Furthermore, a longer TL was an independent prognostic factor for ADC, SCC, and RCC. CONCLUSIONS: Longer telomeres are associated with worse prognosis in ADC, SCC, and RCC. Thus, TL is a novel biomarker for the diagnosis of aggressive cancers with poor prognoses.
Asunto(s)
Fibroblastos Asociados al Cáncer , Carcinoma de Células Renales , Carcinoma de Células Escamosas , Neoplasias Renales , Neoplasias Hepáticas , Humanos , Fibroblastos Asociados al Cáncer/patología , Hibridación Fluorescente in Situ , Pronóstico , Acortamiento del Telómero , Telómero , Carcinoma de Células Escamosas/patología , Neoplasias Hepáticas/patología , Homeostasis del TelómeroRESUMEN
Telomeres are tandem repeats of the TTAGGG sequence at chromosomal ends and afford protection against chromosomal instability. To investigate the contribution of telomere dysfunction in meningiomas, here we estimate the associations between telomere length, tumor grade, and proliferation index in a series of 14 archived samples, using quantitative-fluorescence in situ hybridization, Ki67 immunostaining, and pathological analysis. The number of mitoses per 10 high-power fields (HPF) and Ki67 index was higher in grade III cases than in grade I or grade II cases. Telomere length was negatively associated with both the number of mitoses/10HPF and Ki67 index. Meningioma cases with atypical mitosis, a morphological marker of chromosomal instability, exhibited shortened telomeres. Among telomere-shortened meningioma cases, 40% were grade I, 20% were grade II, and 100% were grade III. In grade I or II meningiomas, shortened telomeres lacked high proliferation activity and atypical mitosis. In conclusion, telomere shortening might be pivotal in the development of high-grade meningioma. Analysis of telomere length might be a selective marker for meningiomas with high-grade malignant potential.
Asunto(s)
Neoplasias Meníngeas , Meningioma , Inestabilidad Cromosómica , Humanos , Hibridación Fluorescente in Situ , Antígeno Ki-67/genética , Neoplasias Meníngeas/genética , Neoplasias Meníngeas/patología , Meningioma/genética , Meningioma/patología , Telómero/genética , Telómero/patologíaRESUMEN
Despite advances in diagnostics and therapeutics, the prognosis of pancreatic cancer remains dismal. Because of a lack of early diagnostic methods, aggressive local progression, and high incidence of distant metastasis, most pancreatic cancers are inoperable; therefore, the characteristics of early pancreatic cancer have not been well understood. Autopsy studies revealed the characteristics of prediagnostic pancreatic malignancies, including precancerous lesions, early stage pancreatic cancer, and pancreatic cancer without clinical symptoms (occult cancers). Animal models using hamsters and genetically engineered mice have focused on mechanisms of carcinogenesis, thereby providing insights into risk factors and prevention and serving as a preclinical test for the development of novel diagnostic and treatment modalities. In this review, we have summarized pathological changes in the pancreas of humans and experimental animals during carcinogenesis.
RESUMEN
Lung cancer remains the leading cause of cancer-related deaths, with an estimated 1.76 million deaths reported in 2018. Numerous studies have focused on the prevention and treatment of lung cancer using rodent models. Various chemicals, including tobacco-derived agents induce lung cancer and pre-cancerous lesions in rodents. In recent years, transgenic engineered rodents, in particular, those generated with a focus on the well-known gene mutations in human lung cancer (KRAS, EGFR, and p53 mutations) have been widely studied. Animal studies have revealed that chronic inflammation significantly enhances lung carcinogenesis, and inhibition of inflammation suppresses cancer progression. Moreover, the reduction in tumor size by suppression of inflammation in animal experiments suggests that chronic inflammation influences the promotion of tumorigenesis. Here, we review rodent lung tumor models induced by various chemical carcinogens, including tobacco-related carcinogens, and transgenics, and discuss the roles of chronic inflammation in lung carcinogenesis.
RESUMEN
Standardized pathological evaluation of the regression assessment of neoadjuvant pancreatic cancer is necessary to improve prognostication and compare treatment outcomes in clinical trials. However, appropriate tissue sampling from surgically resected pancreatic cancer after neoadjuvant therapy has not been elucidated. We compared the tumor regression scores in the largest cancer slide determined macroscopically or histologically. We reviewed all slides and macroscopic photos of cut surfaces from resected pancreas of patients treated with neoadjuvant chemotherapy (n = 137; chemoradiotherapy or chemotherapy). The tumor regression scores (the Evans, College of American Pathologists, Japanese Pancreas Society grading systems, and Area of Residual Tumor [ART] score) were evaluated for the largest tumor slide determined by macroscopy or histologically as well as all slides from the resected pancreas. The largest cancer slides determined macroscopically and histologically were discrepant in 26% of the cases. Cancer cells were not detected in the largest macroscopically defined cut slides in 3%. Only ART scores assessed in the largest histological slides displayed significant difference in overall survival. We recommend obtaining the largest histological slides to provide adequate assessment for regression of neoadjuvant-treated pancreatic cancer. Sufficient sampling to detect the largest histological slides would be mandatory.
Asunto(s)
Neoplasias Pancreáticas/diagnóstico , Anciano , Anciano de 80 o más Años , Biopsia , Toma de Decisiones Clínicas , Manejo de la Enfermedad , Progresión de la Enfermedad , Femenino , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Clasificación del Tumor , Estadificación de Neoplasias , Neoplasias Pancreáticas/etiología , Neoplasias Pancreáticas/mortalidad , Neoplasias Pancreáticas/terapia , Pronóstico , Factores de TiempoRESUMEN
BACKGROUND: Pancreatoblastoma is a rare malignant epithelial neoplasm of the pancreas that mainly occurs in children and involves abnormalities in the WNT/ß-catenin pathway, such as CTNNB1 mutation. However, the molecular abnormalities in adult pancreatoblastoma are not well known. CASE PRESENTATION: An elderly man, who underwent elective distal pancreatectomy and splenectomy, was referred to our hospital with a mass in the tail of the pancreas. Histologically, the lesion revealed proliferation of clear, basophilic, and cartilaginous tumor cells with lymphatic metastasis. Each of the morphologically distinct tumor components showed different immunohistochemical patterns, indicating heterogeneous differentiation, including epithelial (both acinar and ductal), mesenchymal, and neuroendocrine differentiation. All tumor components showed nuclear expression of ß-catenin and cyclin D1. Per next-generation sequencing (NGS), the clear and basophilic tumor cells shared mutations in APC, GRM8, LAMP1, and AKA9. Among the mutations, APC, c.1816_1817insA showed the highest frequency in both cell types, indicating that APC mutation was a driver mutation of the tumor. A diagnosis of PB was rendered. SUMMARY: In conclusion, the clear and basophilic cells of the tumor were supposedly derived from the same clone and subsequently acquired additional mutations. This is the first report of clonal evolution in pancreatoblastoma.
RESUMEN
A new ionic liquid (IL)-calixarene coated solid-phase microextraction (SPME) fibre has been synthesized on the surface of quartz fibre by the sol-gel method. The coated fibre has been coupled with gas chromatography-flame ionisation detector (GC-FID) for the determination of triazines in fruit and vegetable samples. The operation parameters including sample volume, extraction time, extraction temperature, desorption time, and sample pH have been investigated and optimised. Under the optimum conditions, the limits of detection of atrazine, simazine, ametryn, and cyanazine based on three times of standard deviations of blank by seven replications are 3.3, 4.4, 8.8, and 13.0 µg kg(-1), respectively. The intra-day and inter-day relative standard deviations are less than 7.2% and 9.9%. The proposed method has been successfully applied to the determination of the four triazines in fruit and vegetable samples and the accuracy is assessed through recovery experiments.
Asunto(s)
Calixarenos/química , Frutas/química , Líquidos Iónicos/química , Microextracción en Fase Sólida/métodos , Triazinas/análisis , Verduras/química , Cromatografía de Gases , Ionización de LlamaRESUMEN
A simple and highly selective procedure for on-line determination of trace levels of Au, Pd, and Pt in mine samples has been developed using flow injection-column adsorption preconcentration coupled with graphite furnace atomic absorption spectrophotometry (FI-column-GFAAS). The precious metals were adsorbed on the as-synthesized magnetic nanoparticles functionalized with 4'-aminobenzo-15-crown-5-ether packed into a micro-column and then eluted with 2% thiourea + 0.1 mol L(-1) HCl solution prior to the determination by GFAAS. The properties of the magnetic adsorbents were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Various experimental parameters affecting the preconcentration of Au, Pd, and Pt were investigated and optimized. Under the optimal experimental conditions, the detection limits of the developed technique were 0.16 ng mL(-1) for Au, 0.28 ng mL(-1) for Pd, and 1.01 ng mL(-1) for Pt, with enrichment factors of 24.3, 13.9, and 17.8, respectively. Precisions, evaluated as repeatability of results, were 1.1%, 3.9%, and 4.4% respectively for Au, Pd, and Pt. The developed method was validated by the analysis of Au, Pd, and Pt in certified reference materials and mine samples with satisfactory results.