References 1. Kamizake, N. K.; Gonçalves, M. M.; Zaia, C. T; Zaia, D. A. Determination of total proteins in cow milk powder samples: a comparative study between the Kjeldahl method and spectrophotometric methods. J. Food Comp. Anal. 2003 , 16 , 507-516. 2. Laporte, M. F.; Paquin, P. Near-infrared analysis of fat, protein, and casein in cow's milk. J. Agric. Food Chem. 1999 , 47 , 2600-2605. 3. Lüthi-Peng, Q.; Puhan, Z. Determination of protein and casein in milk by fourth derivative UV spectrophotometry. Anal. Chim. Acta 1999 , 393 , 227-234. 4. Nakai
Objective: Letrozole is a highly potent oral nonsteroidal aromatase inhibitor triazole derivative. The aim of this study was to quantify letrozole from bulk, pharmaceutical formulation, and spiked urine samples by developing a simple, rapid and cost effective capillary electrophoresis method. Methods: A capillary zone electrophoresis method was optimized and validated. Additionally, an UV spectrophotometry method was used for comparing results. Results:The capillary zone electrophoresis method using a 90 mM sodium tetraborate background electrolyte proved to be an efficient method for determination of letrozole in a very short time, less than 2 minutes, using 20 kV voltage, 50 mbar/2 seconds pressure and 50°C temperature as optimum parameters. Additionally, the UV spectrophotometry method proved to be simple and efficient to quantify letrozole from bulk material and pharmaceutical formulation with linearity of response between 5 to 20 μg·mL-1 concentrations. For both methods, validation parameters, including linearity, detection and quantification limits were determined. Also we proved that our electrophoretic method has potential in analyzing letrozole from biological samples, obtaining encouraging results on estimation of letrozole from spiked urine samples without any special treatment. Conclusions: To quantify letrozole from bulk material, pharmaceutical preparations, and spiked urine samples the capillary zone electrophoresis method using a tetraborate sodium background electrolyte has proven to be simple and appropriate. Also a simple UV spectrophotometric method has been developed and validated for the same purposes.
, Russian J. General Chem. 74 (2004) 957-959; DOI:10.1023/B:RUGC.0000042436.62526.80. M. Balcerzak, A. Kosiorek and E. Święcicka, Morin as a spectrophotometric reagent for gold, J. Anal. Chem. 61 (2006) 119-123; DOI:10.1134/S1061934806020055. A. Kosiorek-Rupińska, E. Święcicka-Füchsel and M. Balcerzak, Speciation analysis of osmium (VIII) and osmium(IV) by UV-VIS spectrophotometry using quercetin as the reagent, Anal. Lett. 39 (2006) 589-602; DOI: 10.1080/00032710500535881. International Conference on Harmonisation of Technical Requirements for Registration of
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Melamine is an organic-based chemical material widely used in the production of tableware. Given the adverse effects of melamine on human health, melamine tableware can be a source for its introduction into the human body. The aim of this study was to use a simple method for monitoring the rate of melamine migration from the tableware to food and the effect of time and tableware on this migration. To measure the migration, spectrophotometry was used. The limit of detection (LOD) of the method was 0.2 (μg/ml), which is functional for measuring the rate of migration. The investigation of sample migration of melamine tableware revealed that migration has occurred across all samples. The rate of migration in all samples was less than the standard level of the European Union (30 μg/ml). Statistical analysis indicated that time is an important factor in melamine migration, which significantly increased (p<0.05) in 93% of cases with lengthening the contact time from 30 minutes to 90 minutes. The type of tableware (new or old) and production conditions (standard or non-standard) were found to significantly affect (p<0.001) the rate of migration. Statistical analysis of the results suggested that old tableware increased melamine migration in 41% of cases (p<0.05). Non-standard tableware significantly (p<0.001) increased the rate of migration and thus the effect of non-standard production on melamine tableware was more significant than the age of the tableware.
and K. Mądra-Gackowska, Determination of lormetazepam in tablets using high-performance liquid chromatography, and derivative spectrophotometry methods, J. Planar Chromatogr. - Mod. TLC 31 (2018) 235–242; https://doi.org/10.1556/1006.2018.31.3.9 11. M. Gackowski, M. Koba and S. Kruszewski, Comparison of UV- and derivative-spectrophotometric and HPTLC UV-densitometric methods for the determination of amrinone and milrinone in bulk drugs, Curr. Pharm. Anal. 14 (2018) 1–8; https://doi.org/10.2174/1573412914666180627141659 12. AOAC International, Guidelines for