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1.
Artículo en Inglés | MEDLINE | ID: mdl-38335086

RESUMEN

The domain of machine learning is confronted with a crucial research area known as class imbalance (CI) learning, which presents considerable hurdles in the precise classification of minority classes. This issue can result in biased models where the majority class takes precedence in the training process, leading to the underrepresentation of the minority class. The random vector functional link (RVFL) network is a widely used and effective learning model for classification due to its good generalization performance and efficiency. However, it suffers when dealing with imbalanced datasets. To overcome this limitation, we propose a novel graph-embedded intuitionistic fuzzy RVFL for CI learning (GE-IFRVFL-CIL) model incorporating a weighting mechanism to handle imbalanced datasets. The proposed GE-IFRVFL-CIL model offers a plethora of benefits: 1) leveraging graph embedding (GE) to preserve the inherent topological structure of the datasets; 2) employing intuitionistic fuzzy (IF) theory to handle uncertainty and imprecision in the data; and 3) the most important, it tackles CI learning. The amalgamation of a weighting scheme, GE, and IF sets leads to the superior performance of the proposed models on KEEL benchmark imbalanced datasets with and without Gaussian noise. Furthermore, we implemented the proposed GE-IFRVFL-CIL on the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset and achieved promising results, demonstrating the model's effectiveness in real-world applications. The proposed GE-IFRVFL-CIL model offers a promising solution to address the CI issue, mitigates the detrimental effect of noise and outliers, and preserves the inherent geometrical structures of the dataset.

2.
Ann R Coll Surg Engl ; 106(3): 245-248, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37489513

RESUMEN

INTRODUCTION: Iliac lymphadenectomy is performed to provide anastomotic access during the vascular implantation procedure in renal transplantation. Iliac lymph nodes (LNs) are often enlarged, but there are no standardised guidelines for the management of incidentally enlarged LNs during transplantation. We aimed to evaluate histological findings of LNs sent for examination at our unit. METHODS: Patients were evaluated in two distinct date cycles. In the first cycle, lymphadenectomy and histological assessment were performed at the discretion of the transplanting surgeon. In the second cycle, all incidentally enlarged LNs were sent for histological assessment, regardless of size. RESULTS: In the first cycle (n = 76), 11 patients (14.47%) had incidentally enlarged iliac LNs on lymphadenectomy and histology showed only reactive changes. In the second cycle (n = 165), eight patients (4.85%) had incidentally enlarged LNs on lymphadenectomy. One patient was found to have mature B cell chronic lymphocytic leukaemia. The patient was referred to haematology and a "watch and wait" approach was taken, with the patient still alive at last follow-up (511 days post-transplantation). DISCUSSION: There are currently no published guidelines on the management of incidentally enlarged iliac LNs during transplantation. Current literature suggests that clinically significant lymphadenopathy needs to be investigated in all patients. Based on our centre's experience of a 5.26% (1 in 19) positive pathological LN sampling, we recommend that all incidental LNs with suspicious features and/or that are greater than 10mm in diameter should be considered for histological, microbiological and molecular assessment as appropriate.


Asunto(s)
Trasplante de Riñón , Linfadenopatía , Humanos , Trasplante de Riñón/efectos adversos , Linfadenopatía/etiología , Ganglios Linfáticos/cirugía , Escisión del Ganglio Linfático , Anastomosis Quirúrgica
3.
Artículo en Inglés | MEDLINE | ID: mdl-36112566

RESUMEN

Randomized shallow/deep neural networks with closed form solution avoid the shortcomings that exist in the back propagation (BP) based trained neural networks. Ensemble deep random vector functional link (edRVFL) network utilize the strength of two growing fields, i.e., deep learning and ensemble learning. However, edRVFL model doesn't consider the geometrical relationship of the data while calculating the final output parameters corresponding to each layer considered as base model. In the literature, graph embedded frameworks have been successfully used to describe the geometrical relationship within data. In this paper, we propose an extended graph embedded RVFL (EGERVFL) model that, unlike standard RVFL, employs both intrinsic and penalty subspace learning (SL) criteria under the graph embedded framework in its optimization process to calculate the model's output parameters. The proposed shallow EGERVFL model has only single hidden layer and hence, has less representation learning. Therefore, we further develop an ensemble deep EGERVFL (edEGERVFL) model that can be considered a variant of edRVFL model. Unlike edRVFL, the proposed edEGERVFL model solves graph embedded based optimization problem in each layer and hence, has better generalization performance than edRVFL model. We evaluated the proposed approaches for the diagnosis of Alzheimer's disease and furthermore on UCI datasets. The experimental results demonstrate that the proposed models perform better than baseline models. The source code of the proposed models is available at https://github.com/mtanveer1/.

4.
Eur J Surg Oncol ; 45(2): 249-253, 2019 02.
Artículo en Inglés | MEDLINE | ID: mdl-30082178

RESUMEN

BACKGROUND AND AIM: The retroperitoneal tumor (RPT) service in the North West costal region of England was centralized in May 2011 by the merger of the Merseyside, Cheshire and Lancashire, Cumbria sarcoma networks. Our aim was to analyze the impact of centralization of services on patient outcomes. METHODS: An analysis from 01/12/2004 to 30/11/2017 was undertaken from prospectively maintained database and electronic patient records; follow-up was until 30/04/2018. This time period encompassed 6.5 years before and after centralization of services took place. Survival analysis was done for Retroperitoneal Sarcomas (RPS) and also compared the impact of centralization. RESULTS: 72 patients (27 men), median age 69 (21-90) years) underwent 95 operations with an intention to excise RPS. Overall there were 52 (54.7%) multi-visceral resections (MVR). 91/95 (95.8%) patients with primary tumors had surgery with a curative (R0/1) intent. 30-day and 90-day operative mortality was 3.2% (n = 3) and 4.2% (n = 4) respectively. The 5-year survival for patients undergoing resection for RPTs was 51.3%. 79 (83.1%) of the resections in this series occurred in the 6.5-years post-centralization with an increase in MVR between the two time points (p < 0.0006). Despite the more radical nature of surgery post-centralization, there was no difference in 5-year survival for RPS patients when compared to pre-centralization, p = 0.575. However the 5-yr survival post-centralization compared favorability to national outcomes. CONCLUSION: Centralization in the management of RPS has resulted in an increase in resection rates and more complex MVRs, without compromising R0/1 resection rates; peri-operative mortality or overall survival.


Asunto(s)
Atención a la Salud/organización & administración , Neoplasias Retroperitoneales/cirugía , Sarcoma/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Inglaterra , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Sistema de Registros , Neoplasias Retroperitoneales/mortalidad , Sarcoma/mortalidad , Análisis de Supervivencia , Resultado del Tratamiento
5.
Ann R Coll Surg Engl ; 100(4): e81-e84, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29543047

RESUMEN

Angiomyxomas are uncommon myxoid tumours arising most commonly from the pelvis. A 46-year-old woman with a history of polycystic kidney disease presented asymptomatically for surveillance ultrasonography; changes were noted in the size and morphology of her liver cysts. Subsequent radiological assessment displayed features suspicious of malignancy and a right hemihepatectomy was performed with curative intent. Pathological examination of the resected specimen found histology consistent with an angiomyxoma arising primarily from the liver parenchyma. Follow-up review of the patient has been uneventful with annual imaging showing no evidence of recurrence. Angiomyxomas do not characteristically invade other tissues. However, any liver lesion displaying suspicious features of malignancy should be resected in the absence of disseminated disease.


Asunto(s)
Quistes/cirugía , Hallazgos Incidentales , Hepatopatías/cirugía , Neoplasias Hepáticas/cirugía , Mixoma/cirugía , Neoplasias del Sistema Biliar/sangre , Neoplasias del Sistema Biliar/diagnóstico , Biomarcadores de Tumor/sangre , Cistadenocarcinoma/sangre , Cistadenocarcinoma/diagnóstico , Quistes/diagnóstico por imagen , Diagnóstico Diferencial , Femenino , Hepatectomía , Humanos , Hígado/patología , Hígado/cirugía , Hepatopatías/diagnóstico por imagen , Neoplasias Hepáticas/sangre , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/patología , Imagen por Resonancia Magnética , Persona de Mediana Edad , Mixoma/sangre , Mixoma/diagnóstico , Mixoma/patología , Neoplasias Ováricas/sangre , Neoplasias Ováricas/diagnóstico , Neoplasias Ováricas/patología , Tomografía Computarizada por Rayos X , Ultrasonografía
6.
Pediatr Neurosurg ; 43(6): 492-7, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17992038

RESUMEN

Ossified cephalhematoma is a rare clinical entity and a pathological curiosity. Even though cephalhematoma is frequently encountered, ossified cephalhematoma is seen only sporadically and is restricted to only few case reports in the literature. Its pathogenesis is unclear, and the clinical course is different in neonates and juveniles. The risk factors are known, but why it gets ossified in some cases is not understood. We report a case of ossified cephalhematoma which developed in a 10-week-old male child in the right parietal region and discuss its possible pathogenesis.


Asunto(s)
Hemorragia Intracraneal Traumática/diagnóstico , Osificación Heterotópica/diagnóstico , Traumatismos del Nacimiento/complicaciones , Traumatismos del Nacimiento/diagnóstico , Traumatismos del Nacimiento/cirugía , Humanos , Lactante , Hemorragia Intracraneal Traumática/etiología , Hemorragia Intracraneal Traumática/cirugía , Masculino , Osificación Heterotópica/etiología , Osificación Heterotópica/cirugía
8.
Drugs ; 46(6): 986-1008, 1993 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-7510615

RESUMEN

Epidemiological and clinical studies suggest that low dietary potassium intake may have an important role in determining the development of diseases such as hypertension, and perhaps even stomach cancer, and that increased potassium intake may have beneficial effects in several other conditions. Dietary adjustment or active potassium supplementation has been suggested as a natural, less costly and safe method of increasing potassium levels, although active supplementation with tablets or solutions is not recommended in healthy people with normal serum potassium levels. However, increasing dietary potassium intake in the elderly and in patients with renal impairment must be considered with caution. Diuretics have a long established role in the management of hypertension and heart failure. There is no convincing evidence to suggest that the small reduction in plasma potassium levels associated with low dose thiazide and loop diuretic therapy needs to be routinely prevented by the use of potassium-sparing drugs. In non-digitalised patients little association has been found between mild diuretic-induced hypokalaemia and arrhythmias. Thus, the routine prophylactic use of potassium-sparing diuretics in combination with non-potassium-retaining diuretics for the treatment of hypertension and oedematous states is not justified. Based on current evidence, treating all patients whose serum potassium level decreases below 3 mmol/L is recommended, although for certain patients at particular risk of hypokalaemia, levels may need to be maintained above 3.5 mmol/L. In overt hypokalaemia, several therapeutic options are available to the clinician. These include increased consumption of potassium-rich foods, the use of salt substitutes, medicinal potassium supplementation or distal tubular (potassium-sparing) diuretics.


Asunto(s)
Diuréticos/efectos adversos , Potasio/uso terapéutico , Administración Oral , Dieta , Diuréticos/administración & dosificación , Relación Dosis-Respuesta a Droga , Homeostasis , Humanos , Hipopotasemia/etiología , Antagonistas de Receptores de Mineralocorticoides/efectos adversos , Antagonistas de Receptores de Mineralocorticoides/uso terapéutico , Potasio/administración & dosificación , Potasio/efectos adversos
9.
Clin Chim Acta ; 275(1): 9-18, 1998 Jul 06.
Artículo en Inglés | MEDLINE | ID: mdl-9706839

RESUMEN

This study has examined the association between circulating atrial natriuretic peptide (ANP), plasma cyclic GMP and urinary cyclic GMP in relation to hypertension and reduced renal function in 30 normotensives, in 30 patients with essential hypertension and in 22 patients with stable dialysis-independent chronic renal failure (CRF). Plasma ANP was significantly raised (about two-three-fold) in the CRF group compared with the hypertensive and normal groups; plasma cyclic GMP was also significantly raised in the CRF group (median group values: 4.6, 5.8 and 11.0 pmol/ml, respectively, for the normal, hypertensive and CRF groups). There were no significant differences in urinary cyclic GMP between the normotensives and hypertensives but urinary cyclic GMP was significantly reduced in the patients with CRF (median group values: 407.1, 450.9 and 247.8 pmol/min for the normal, hypertensive and CRF groups, respectively, P < 0.001). In the subjects with CRF, the clearance of cyclic GMP was reduced in proportion to the clearance of creatinine, but there was no significant difference in the fractional excretion of cyclic GMP (median group values: 78.1% in the normal group, 78.9% in the hypertensive group and 70.2% in the CRF group). In all groups, there was no association between circulating ANP and urinary cyclic GMP: By contrast, there was a positive association between plasma ANP and plasma cyclic GMP (r = 0.39 P < 0.001) that was independent of blood pressure or renal function. These results demonstrate that while a substantial amount of urinary cyclic GMP originates from the glomerular filtrate, to some extent, raised plasma ANP also contributes to the circulating levels of cyclic GMP. However, plasma cyclic GMP cannot be taken as a direct substitute for plasma ANP.


Asunto(s)
Factor Natriurético Atrial/sangre , GMP Cíclico/sangre , Hipertensión/sangre , Fallo Renal Crónico/sangre , Adulto , Anciano , Anciano de 80 o más Años , GMP Cíclico/orina , Femenino , Humanos , Masculino , Persona de Mediana Edad
10.
J Hum Hypertens ; 13(1): 37-40, 1999 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-9928750

RESUMEN

Hypertension is common in West Africa and likely to become more common as urbanisation increases. There are at present few facilities for the detection and management of hypertension so the influence it has on overall morbidity and mortality in the population is not clear. The objectives of the study were to assess: (a) renal disease and blood pressure related admissions and deaths among acute medical admissions to Komfo Anokye Teaching Hospital, Kumasi, during an 8-month period; and (b) the burden of renal disease among out-patient hypertensives at the same hospital. Ward admission books were examined in the four acute medical wards to ascertain admission diagnosis and cause of death (two 4-month periods in 1995 and 1996). Clinical assessment (blood pressure, plasma creatinine, proteinuria) was also made of 448 consecutive out-patient hypertensives seen between March 1995 and April 1996. Five hundred and ninety-three (17.9%) of 3317 acute medical admissions were ascribable to a cardiovascular cause (hypertension, heart failure, stroke); 171 (28.8%) of these died. One hundred and sixty-six (5.0%) had renal disease of whom 45 (27.1%) died, usually of end-stage renal disease. Among the 448 hypertensive out-patients, 30.2% (110 out of 365) had a plasma creatinine >140 micromol/l (48 > or = 400 micromol/l) and 25.5% (96 out of 376) had proteinuria. Eighty-nine of the 448 had a diastolic blood pressure > or =115 mm Hg; in this group 38 (42.7%) had a plasma creatinine of >140 micromol/l (and 18 or 20.2% > or =400 micromol/l). In conclusion, cardiovascular and renal disease are important contributors to morbidity and mortality among acute medical admissions to a large city hospital in Ghana. Among out-patient hypertensives renal disease is an important complication, especially in those with the more severe hypertension.


Asunto(s)
Hipertensión/complicaciones , Adulto , Creatinina/sangre , Femenino , Ghana , Hospitalización , Humanos , Hipertensión/sangre , Hipertensión/epidemiología , Hipertensión/mortalidad , Fallo Renal Crónico/etiología , Fallo Renal Crónico/mortalidad , Masculino , Persona de Mediana Edad , Morbilidad
11.
J Chromatogr A ; 857(1-2): 365-8, 1999 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-10536858

RESUMEN

A simple and sensitive capillary electrophoretic method with UV detection has been developed for the determination of Ferbam (ferric dimethyldithiocarbamate) in boric acid buffer after its acidic decomposition and complexation with EDTA as Fe-EDTA- complex. The determination is dependent on the pH and the nature of the buffer solutions. In this method the detection limit (S/N = 3) is 1.8 x 10(-6) mol/L (0.7 mg/kg) of Ferbam. The relative standard deviation for the analysis of 50 microg/ml was found to be 2.9%. The method was successfully applied for the analysis of wheat grain samples spiked with Ferbam. The applicability of capillary electrophoresis as a useful tool for the analysis of Ferbam is demonstrated.


Asunto(s)
Dimetilditiocarbamato/análisis , Ácido Edético/química , Electroforesis Capilar/métodos , Quelantes del Hierro/análisis , Calibración , Espectrofotometría Ultravioleta
12.
Genet Test ; 3(4): 375-7, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-10627947

RESUMEN

Mutations in the HFE gene on chromosome 6 are believed to cause the iron overload disorder hemochromatosis, the most common single gene disorder in northern Europeans. Two mutations have been described previously: C282Y, with an allele frequency of between 3% and 10% in the caucasian population, and H63D, which has an allele frequency of 16%. Published data shows that C282Y appears to be causative in the homozygous state, while the frequency of H63D/C282Y compound heterozygotes is much greater than expected in patient groups. There also appears to be a slightly elevated risk for H63D homozygotes. Hemochromatosis has been thought to be primarily a caucasian disorder. We have studied 97 healthy, black Ghanaian subjects, whose parents and grandparents were also African, to find the frequency of the two mutations. C282Y was absent, while H63D occurred in 2 individuals. These differences are significant at the 0.05 and 0.001 levels, respectively. The prevalence of H63D homozygotes in this population at 1 in 10,000 is clearly of no use in studying the effect of this genotype on phenotype. However, this study suggests an absence of the C282Y mutation in African populations, and the possibility that other populations might provide different genotypes and hence an analysis of H63D risk. A possible heterozygote advantage for the mutation is discussed.


Asunto(s)
Población Negra/genética , Antígenos HLA/genética , Hemocromatosis/genética , Antígenos de Histocompatibilidad Clase I/genética , Proteínas de la Membrana , Adulto , África/etnología , Femenino , Genética de Población , Ghana , Hemocromatosis/epidemiología , Proteína de la Hemocromatosis , Humanos , Masculino , Persona de Mediana Edad , Mutación , Población Blanca/genética
13.
Genet Test ; 4(3): 299-303, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-11142763

RESUMEN

ACE polymorphisms have recently been shown to associate with worse renal and or cardiovascular outcome, with the D allele widely reported as a risk factor for cardiovascular disease. In autosomal dominant polycystic kidney disease (ADPKD), there are conflicting reports of an association between ACE polymorphisms and disease phenotype. There are no previous reports of any association between angiotensinogen polymorphisms and clinical phenotype in ADPKD. We examined the ACE I/D and angiotensinogen M235T polymorphisms in 176 patients with ADPKD. Patients are categorized into three groups according to the reason for initial investigation. Clinical history and examination findings were recorded at the time of first referral. A cohort of 17 patients had progressive renal impairment observed after 3 or more years of follow-up. Reciprocal creatinine against time was plotted in this group. From the patient population of 176, a total of 33 patients reached end-stage renal failure (ESRF) or a serum creatinine greater than 500 microm/liter. ACE genotype and M235T polymorphism frequencies were compared across groups. Serum creatinine and presence of hypertension and onset of ESRF were taken as outcome variables; age and source of referral were taken as confounding variables. There was no association of any genotype or allele with either creatinine, inverse creatinine, hypertension, or age at end-stage renal failure. These findings do not support the proposition that ACE genotype or angiotensinogen polymorphisms are associated with a worse prognosis in patients with ADPKD.


Asunto(s)
Angiotensinógeno/genética , Angiotensinas/genética , Riñón/fisiopatología , Enfermedades Renales Poliquísticas/genética , Creatinina/sangre , Genotipo , Humanos , Hipertensión/complicaciones , Pruebas de Función Renal , Enfermedades Renales Poliquísticas/complicaciones , Enfermedades Renales Poliquísticas/fisiopatología , Polimorfismo Genético
14.
Genet Test ; 6(1): 63-5, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-12180079

RESUMEN

We have tested 186 individuals from Ghana, 95 indigenous and 91 who have settled in the United Kingdom, for the presence of the T594M mutation in the beta-subunit of the epithelial sodium channel, which is associated with hypertension in black populations. The group living in Ghana had a mean age of 27 years and were normotensive, but had an increased frequency of the T allele compared to the London-based population. If this is reflected in larger studies, and the link with hypertension is maintained in the Ghanaian population, this mutation could be a significant cause of hypertension in Ghana.


Asunto(s)
Mutación Missense , Canales de Sodio/genética , Adulto , Sustitución de Aminoácidos , Población Negra/genética , Epitelio/metabolismo , Femenino , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Ghana , Humanos , Hipertensión/genética , Londres/etnología , Masculino
15.
J Periodontol ; 58(4): 231-5, 1987 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-3295181

RESUMEN

A group of 162 maintenance patients, previously studied for compliance to suggested maintenance schedules, were surveyed for tooth loss over a 5-year period. The group was divided into those who complied to suggested maintenance schedules and those whose compliance was erratic. It was found that none of the patients who had complied to suggested maintenance schedules lost any teeth. In the erratic group, where all tooth loss occurred, it was found that the more often a patient presented for maintenance, the less likely he was to lose teeth. These findings are discussed in relation to current studies on efficacy of various therapies for periodontal diseases.


Asunto(s)
Arcada Parcialmente Edéntula/etiología , Cooperación del Paciente , Periodontitis/prevención & control , Raspado Dental , Humanos , Periodontitis/complicaciones , Pronóstico , Raíz del Diente/cirugía
16.
J Agric Food Chem ; 48(12): 5808-11, 2000 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11141253

RESUMEN

A procedure has been developed for the determination of iron(III) dimethyldithiocarbamate by converting it into the iron(II)-bathophenanthroline complex, which is then dissolved in acetone-water (1:1), and the absorbance is measured at 534 nm against a reagent blank. Beer's law is obeyed over the concentration range 0.5-20 microg x mL(-1) in the final solution. The method is sensitive and highly selective and is used for the direct determination of ferbam in a commercial sample and in mixtures with various dithiocarbamates (ziram, zineb, maneb, etc.) and from wheat grains.


Asunto(s)
Dimetilditiocarbamato/análisis , Fungicidas Industriales/análisis , Fenantrolinas , Triticum/química , Espectrofotometría/métodos
17.
J Agric Food Chem ; 48(9): 4044-7, 2000 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10995311

RESUMEN

A procedure has been developed for the determination of iron(III) dimethyldithiocarbamate by converting it into a iron(III)-bathophenanthroline-tetraphenylborate complex, which was then extracted into molten naphthalene, and the absorbance was measured at 534 nm against a reagent blank. Beer's law is obeyed over the concentration range 0.4-20 microg mL(-)(1) in final solution. The method is sensitive and highly selective and is applied for the determination of ferbam in a commercial sample, in mixtures with various dithiocarbamates (ziram, zineb, maneb, etc.), and from wheat grains.


Asunto(s)
Dimetilditiocarbamato/análisis , Fungicidas Industriales/análisis , Naftalenos/química , Fenantrolinas/química , Triticum/química
18.
Talanta ; 38(8): 941-4, 1991 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18965241

RESUMEN

A procedure has been developed for the determination of ziram (zinc dimethyldithiocarbamate), ferbam (ferric dimethyldithiocarbamate) and zineb (zinc ethylenebisdithiocarbamate) after their decomposition and extraction of the diphenylcarbazone complexes of the zinc or iron into isobutyl methyl ketone. These complexes absorb strongly at 520 nm. The method is rapid, sensitive and selective and can be used for the determination of these dithiocarbamates in commercial and synthetic mixtures.

19.
Talanta ; 44(2): 177-83, 1997 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18966732

RESUMEN

A spectrophotometric method was developed for the determination of ferbam (iron(III) dimethyldithiocarbamate) by converting it into an iron-phenanthroline complex, which was then absorbed on microcystalline naphthalene in the presence of tetraphenylborate, and the absorbance was measured at 515 nm against a reagent blank. The molar absorptivity of the complex was 1.2 x 10(4)l mol(-1)cm(-1). Ten replicate analyses of a sample solution containing 150 mug of ferbam gave a relative standard deviation of 0.84%. Beer's law was obeyed over the concentration range 22.4-372.9 mug of ferbam. The effects of various factors such as reagent concentration and naphthalene, shaking time and diverse ions were studied in detail. The method is sensitive and selective and can be applied to the direct determination of ferbam in commercial samples and in mixtures containing various other dithiocarbamates (e.g. ziram, zineb and maneb) in foodstuffs.

20.
Talanta ; 37(12): 1205-7, 1990 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18965097

RESUMEN

A procedure has been developed for the determination of six dithiocarbamates [sodium dimethyldithiocarbamate (dibam), sodium diethyldithiocarbamate (NaDDC), tetramethylthiuram disulphide (thiram), zinc dimethyldithiocarbamate (ziram), sodium N-methylpiperazinecarbodithioate and potassium morpholine-4-carbodithioate] in microgram quantities by converting them into selenium dithiocarbamate complexes, which are then extracted into chloroform and measured at 430 nm against a reagent blank. The method is sensitive and can be used for the determination of dithiocarbamates in commercial samples and synthetic mixtures.

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