A comprehensive LC-UHPLC-MS/MS method for the monitoring of N-nitrosamines in lipophilic drugs: A case study with rifampicin.

In the last five years, the presence of N-nitrosamines in commonly used medicines has become a significant concern for patients, physicians, and the pharmaceutical industry, due to their carcinogenic properties, even at low concentrations. Analytical methods that enable the unequivocal monitoring of these compounds, with low detection limits and covering a range of drugs, are indispensable. The present work proposes a bidimensional liquid chromatography-tandem mass spectrometry method capable of quantifying eleven N-nitrosamines in lipophilic active pharmaceutical ingredients (APIs). The API is retained in the first chromatographic dimension, while the fraction containing the N-nitrosamines is transferred to the second chromatographic dimension and, after separation, to the mass spectrometer. The logP values for the APIs and N-nitrosamines enabled prediction of the APIs that could be separated from the target analytes. The method was validated and successfully applied for the quantification of 1-methyl-4-nitroso piperazine (MNP) and N-nitrosodimethylamine (NDMA) in rifampicin, a drug used to treat tuberculosis. Although NDMA was not detected in two pharmaceutical analyzed, MNP was found at concentrations of 0.44 ± 0.05 and 2.1 ± 0.3 µg g-1. Given the ability to apply the method to various APIs, together with its reliance solely on logP values for determining suitability, the proposed technique could be extended to the determination of N-nitrosamines in other drugs besides rifampicin.

On-line solid phase extraction-ultra-high performance liquid chromatography coupled to tandem mass spectrometry for the determination of N-nitrosodiethanolamine in baby shampoo.

N-nitrosodiethanolamine (NDELA) is a carcinogenic contaminant of concern in the cosmetics industry. Contaminated raw material, degradation, reactions of ingredients of the formulation, or migration of packaging material can be responsible for the presence of NDELA in the final product. Liquid chromatography coupled to tandem mass spectrometry is the most widely accepted technique for the quantitation of NDELA in cosmetic products. Still, there is no consensus regarding the sample preparation procedure. The aim of this work was to evaluate the performance of two-dimensional liquid chromatography coupled with tandem mass spectrometry for the determination of NDELA in shampoo. In the first dimension an Oasis HLB SPE-column was used and in the second dimension a CSH C18 column. NDELA-d8 was used as an internal standard. The 2D-LC parameters were optimized by a central composite multivariate design. However, before quantitation, a sample preparation step using solid-phase extraction was necessary to eliminate compounds present in the formulation, especially surfactants that were not compatible with the chromatographic columns. Moreover, the complex matrices and singular compositions of shampoo from different manufacturers required adjustments of the sample preparation procedure for each sample. The limit of quantitation of the method for the determination of NDELA in shampoo was in the range of 5-10 ng g-1. The accuracy of the method at the LOQ (10 ng g-1) was 114 % and the inter-day precision of 15.3 % (n = 9). One sample out of 12 presented an NDELA concentration of 54 ng g-1.

Development of an analytical method for the quantification of pfaffic acid in Brazilian ginseng (Hebanthe eriantha).

Hebanthe eriantha (Poir.) Pedersen (Amaranthaceae), which is known as Brazilian ginseng is widely used in folk medicine as an aphrodisiac and antidiabetic tonic. The anti-tumor activity, attributed to the pfaffic acid present in roots of H. eriantha, is responsible for the great interest in the commercialization of this species. In Brazil, the species H. eriantha is mainly used in commercial preparations, although other plants of the genus Pfaffia and Hebanthe have been marketed as Pfaffia paniculata or Brazilian ginseng. The pfaffic acid present in the roots is mainly conjugated with sugars (pfaffosides) and can be used as an active marker of H. eriantha, which helps to differentiate this species from others marketed as Brazilian ginseng. The main objective of this study was to develop and validate a liquid chromatographic method to quantify pfaffic acid in the roots of H. eriantha. The extraction and hydrolysis conditions were optimized using an univariate and experimental design, respectively, and the quantification of pfaffic acid by high performance liquid chromatography with diode-array detection (HPLC-DAD) was validated. This method was used to evaluate the pfaffic acid content in 30 different genotypes of the species from a germplasm collection. The content of pfaffic acid ranged from 0.97 to 4.29% (w/w) on a dry weight basis.

QuEChERS-HPLC-DAD method for sulphonamides in chicken breast

The development of a QuEChERS-HPLC-DAD method using a Lichrospher 60 RP-Select B column (250 x 4.6 mm x 5 µm) at 40ºC, mobile phase constituted by phosphate buffer:acetonitrile (75:25, v/v) at a initial flow rate of 0.5 mL min-1, increased by 1.2 mL min-1 and at 265 nm is presented for simultaneous determination of sulphadiazine, sulphametoxipiridazine and sulphamethoxazole in chicken breast samples. QuEchERS is inexpensive, fast and easy, and the extraction of the analytes of the matrix was successfully employed. In addition, the method presented linearity, in the range of 25, 50, 100, 150, 175, and 200 µg kg-1, precision, selectivity and sensitivity. The intraday precision (RSD %) for QuEChERS method was between 3.6-10.8 (SDZ), 6.9-14.1 (SPZ) and 1.9-10.9 (SMX) and interday precision (RSD%) was between 1.5-9.7, 1.7-4.1 and 2.1-10.2, respectively. Results of accuracy (bias) were in the range of -8.6 to +11.9 %. Therefore, the validated method is clearly useful for the practical residue monitoring of the drugs evaluated in chicken samples, as all the values were within the acceptable criteria used for food safety. Of 6 samples analyzed, none of them showed contamination of the sulphonamides studied at detectable levels.

O desenvolvimento de um método QuEChERS-HPLC-DAD usando uma coluna Lichrospher RP-60 Select B (250 x 4,6 mm x 5 µm) a 40 ºC, fase móvel constituída por tampão de fosfato: acetonitrila (75:25, v/v) a uma vazão inicial de 0,5 mL min-1, aumentando 1,2 mL min-1 e a 265 nm é apresentado para a determinação simultânea de sulfadiazina, sulfametoxipiridazina e sulfametoxazol em amostras de peito de frango. O QuEChERS é barato, rápido e fácil, e a extração dos analitos da matriz foi empregada com sucesso. Além disso, o método apresentou linearidade, na faixa de 25, 50, 100, 150, 175 e 200 µg kg-1, precisão, seletividade e sensibilidade. A precisão intradia (RSD %) para o método QuEChERS foi entre 3,6-10,8 (SDZ), 6,9-14,1 (SPZ) e 1,9-10,9 (SMX) e a precisão interdias (RSD%) foi entre 1,5-9,7, 1,7-4,1 e 2,1-10,1, respectivamente. Resultados de exatidão (tendenciosidade) foram na faixa de -8,6 a +11,9%. Portanto, o método validado é útil para a monitorização de resíduos de medicamentos avaliados em amostras de frangos, bem como todos os valores estavam dentro dos critérios aceitáveis utilizados para a segurança dos alimentos. De seis amostras analisadas, nenhuma apresentou contaminação de sulfonamidas nos níveis detectáveis estudados.

Simultaneous determination of cadmium and lead in medicinal plants by anodic stripping voltammetry.

A simple method for the simultaneous determination of Cd and Pb in medicinal plants by differential pulse anodic stripping voltammetry, using a hanging mercury drop electrode, was developed. The pre-concentration of the metals was performed in 0.8 mol L(-1) HCl at -0.73V for 180s. The sample preparation was carried out by dry-ashing 1.0g of finely pulverized plant samples for 2.5h at 500 degrees C. The determination limit of the method was 0.12 and 0.010 mg kg(-1) for Pb and Cd, respectively. The method was applied to the quantification of cadmium and lead in samples of Hypericum perforatum, Mikania guaco, Mikania glomerata and Peamus boldus. The voltammetric method was shown to be useful for the control of contaminants in medicinal plants.

Considerações sobre a presença de ivermectina em alimentos de origem animal / Considerations about the presence of ivermectin in foods of animal origin

Ivermectina, princípio farmacológico de um medicamento de uso veterinário que possui efeito antiparasitário contra endo e ectoparasitos, é amplamente utilizada na prática veterinária. A ivermectina age no sistema nervoso dos parasitas e interage com receptores do ácido gama amino-butírico (GABA) no sistema nervoso central de mamíferos. Assim, é de se esperar que seus efeitos tóxicos estejam relacionados às células que sofrem mediação do GABA. Resíduos de ivermectina podem ser encontrados na musculatura, nas vísceras, na gordura e no leite dos animais tratados, sendo importante avaliar a sua veiculação para o homem através desses produtos, uma vez que esses resíduos poderão provocar efeitos indesejáveis à saúde do consumidor. Este artigo objetiva abordar as características químicas e físico-químicas do fármaco, seus aspectos toxicológicos e a incidência de resíduos em alimentos de origem animal, assim como a legislação vigente sobre a ivermectina

Targeting Leishmania (L.) chagasi amastigotes through macrophage scavenger receptors: the use of drugs entrapped in liposomes containing phosphatidylserine.

OBJECTIVES: We devised liposome-entrapped antimony with the negatively charged lipid phosphatidylserine-liposome-entrapped antimony (Sb-LP)-in order to improve their targeting to infected macrophages through the interaction with scavenger receptors (SRs). METHODS: SR production was indirectly evaluated by its mRNA synthesis in infected and uninfected peritoneal macrophages using RT-PCR. The interaction and cytotoxicity of Sb-LP with SRs and their metabolism were determined by incubation with macrophages in the presence of cytochalasin B, chloroquine or different competitive ligands, with determination of the 50% inhibitory concentration (IC50) in vitro in infected macrophages. The intracellular trafficking of Sb-LP was evaluated by confocal microscopy using trapped fluorescent dyes. RESULTS: Our results showed an up-regulation of macrophage SR mRNA during the initial steps of Leishmania (L.) chagasi infection. By competitive ligand assays, we demonstrated the preferential uptake of Sb-LP by macrophage SRs. Sb-LP was 16-fold more effective (IC50=14.11 microM) than the free drug (IC50=225.9 microM) against L. (L.) chagasi-infected macrophages. The binding and uptake of Sb-LP in macrophages were shown to be energy-dependent and were reduced in the presence of cytochalasin B, showing the dependency of the cell microfilament system. Confocal analysis using trapped fluorescent dyes showed fluorescence of parasites or in their close proximity, compatible with the localized delivery of the liposomes. CONCLUSIONS: The uptake of Sb-LP was reduced in infected macrophages, despite their effectiveness and targeting ability, suggesting a low metabolic rate in infected macrophages that could be overcome by the higher efficiency of the liposomal formulation. These in vitro results suggest that liposomes could improve the therapeutic index of old drugs, such as pentavalent antimony, via targeted delivery to Leishmania-infected cells.

Consideraçöes sobre a presença de carbamato de etila em alimentos e bebidas alcoólicas: uma revisäo / Considerations about the presence of ethyl carbamate in foods and alcoholic beverages: a review

A contaminação de alimentos e bebidas alcoólicas por carbamato de etila (CE), bem como seu mecanismo de formação são discutidos neste artigo de revisão. O CE induz efeitos mutagênicos, teratogênicos e carcinogênicos em animais de experimentação, sendo considerado substância potencialmente carcinogênica para o homem. Com o propósito de alertar para os riscos à saúde decorrentes da exposição ao CE, este artigo trata da ocorrência deste contaminante em alimentos e bebidas, bem como de suas propriedades físico-químicas e aspectos analíticos e toxicológicos.

Teor de nitrato e nitrito em vegetais cultivados no Distrito Federal: um estudo preliminar / Nitrate and nitrit in vegetable cultived at Distrito Federal: preliminary study

Amostras de alface, couve e espinafre cultivadas no Distrito Federal foram analisadas quanto ao teor de nitrato e nitrito. A determinacao do nitrito foi baseada no metodo de Follett e Ratcliff, reacao com acido sulfanilico e 1-naftol e determinacao espectrofotometrica, em 474 nm, do azo composto formado. O nitrato foi determinado de maneira semelhante apos reducao a nitrito em coluna de cadmio. De 26 amostras analisadas, 84 por cento apresentaram um teor de nitrito acima de 500mg/kg e 58 por cento acima de 1000mg/kg. O maior valor encontrado foi de 2881 mg de nitrato de sodio/kg em uma amostra de couve. Nitrito nao foi detectado em nenhuma das amostras analisadas. O limite de determinacao do metodo foi de 20 e 16 mg/kg de amostra para nitrato de sodio e nitrito de sodio, respectivamente