This work proposes a Flow Injection Analysis (FIA) system to determine neomycin in pharmaceutical formulation, utilizing ninhydrin as chromogenic reagent, with absorbance signal measured at 570 nm. To check the significant flow parameters, a screening with 2⁴ full factorial designs was optimized, and a Doehlert matrix used to obtain the optimum variable values. The method presents two linear responses ranging from 29.8 up to 300 mg L^-1 (r²=0.9933) and 800.0 up to 2500 mg L^-1 (r²=0.9926). The Limits of Detection and Quantifications were 8.94 mg L^-1 and 29.8 mg L^-1, respectively. The readings frequency was of 33 reading h^-1. The method accuracy was checked through comparison with HPLC method and the results found were similar (t-test, 95% confidence level). The method was applied in pharmaceutical samples with very good performance and the precision (RSD) was always below 8.0%. The reagent and sample consumption was very low, what is in agreement with the green chemistry concept.

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Direct detection of immunoglobulin G (IgG) by using a surface plasmon resonance (SPR) sensor through an antigen‒antibody interaction was described. An anti‒IgG antibody was chemically immobilized on a sensor chip through a self‒assembled monolayer (SAM) in order to enhance the recognition of an IgG antigen. By assuming the Langmuir adsorption isotherm, maximum amount of adsorbed anti‒IgG antibody on the sensor chip and an apparent biding constant of the IgG antigen to anti‒IgG antibody were estimated. The amount of the IgG antigen bound to the anti‒IgG antibody, which was immobilized onto the sensor chip through the SAM was three times higher compared with the amount of the IgG antigen bound to the anti‒IgG antibody, which was immobilized directly to the sensor chip through physical adsorption.

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