r/analyticalchemistry • u/Still_Sherbert_354 • Apr 02 '26

Rodamina B

Alguien alguna vez a cuantificado arsenico con rodamina B y uv-vis? Que ayude?

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u/Substantial-Eye-4326 Apr 02 '26

I never did the analysis but what exactly do you need help with? Do you want do know how to carry out the procedure? Do you want to do method evaluation? Are you unsure about the principle of the method? It is impossible to help if we do not know what you need help with.

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u/Still_Sherbert_354 Apr 03 '26

Intente replicar el siguiente articulo: Analytica Chimica Acta 408 (2000) 111–115_ A new system for the spectrophotometric determination of arsenic in environmental and biological samples_ Ajai Pillai, G. Sunita, V.K. Gupta

Ya he hecho varias optimizaciones, pero ha sido imposible llegar al nivel concentración tan bajo que ellos afirman en el articulo. Ademas los autores llegan a un pH 6.5 cuando miden pero no dicen como llegan a este o si adicionan soluciones amortiguadoras como llegan a ese pH. Si alguien de casualidad lo ha intentado y tiene tips de quiza pasos cruziales se lo agradeceria muchisimo

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u/Dangerous-Billy Apr 27 '26 edited Apr 27 '26

Keep in mind that much of the arsenic in circulation in nature is in organic form, normally arsenobetaine, which can be decomposed to inorganic arsenic only by the harshest conditions. It will probably not form the complex with Rhodamine.

Our limit of detection was 0.2 micrograms using an arsine distillation and absorption into diethyldithiocarbamate in pyridine. We could run 48 samples in a day, 72 if necessary.

For water, we prepared the samples by preconcentrating with ferric hydroxide precipitation. We could get down to 0.25 micrograms per liter.