Pheromones are essential for colony organization in honeybees. The pheromones 9-ODA ((E)-9-oxodec-2-enoic acid) and 9-HDA ((E)-9-hydroxydec-2-enoic acid), produced by the mandibular gland of the queen, have various functions within the colony, including inhibition of ovarian development of workers, attraction of swarms, and stabilization of the cluster group. An example of reaction of the colony to adverse conditions is absconding, which is defined as mass exit of all of the adult individuals, leaving even brood and food. In this study, the pheromones 9-ODA and 9-HDA were determined in virgin and normal mated, egg-laying European Carniolan and Africanized queens, as well as in mated queens that were in absconding colonies, using liquid chromatography with UV detection developed methodology. Absconding was induced by maintaining free-flying five-standard-Langstroth-frame colonies in a chamber artificially heated to 45 ºC. The obtained results showed that the amount of 9-ODA in Africanized queens (6.56 µg bee-1) is very low compared with European queens. However, large amounts of 9-HDA were found in the queens of absconding Africanized swarms (107.4 µg bee-1). According to our results, the quantities of 9-ODA and 9-HDA in Africanized honeybees in Brazil may be contributing to the high rates of absconding, promoting low effect of stabilizing agent, and high effect of attraction of dispersers cluster.

Paper spray ionization (PSI) is a promising analytical tool for direct analysis in mass spectrometry (MS). However, this technique usually uses chromatographic paper, which rarely accomplishes a stable MS signal and could vary with the sample matrix effect. In the present study, the application of graphene oxides (GO) was scrutinized as modifier paper substrate for PSI-MS methods. The developed substrate efficiency was evaluated towards creatinine determination in urine samples. The GO-PSI-MS developed method for creatinine in urine samples showed linearity in the range of 0.1 to 3.4 ppm with R2 = 0.9991. The precision was evaluated and the values were between 1.1 to 6.8% and the accuracy above 96.8%. The limit of quantification (LOQ) and limit of detection (LOD) were 0.05 and 0.17 ppm, respectively. The GO-PSI developed was compared to conventional chromatographic paper for PSI-MS methods, and the results showed that the modified paper with GO bolsters method linearity, precision, and LOQ values.

A method based on disposable pipette extraction (DPX) was successfully applied to creatinine determination in urine samples analysis using liquid chromatography with ultraviolet spectrophotometric detection (DPX/LC-UV). DPX variables, number of draw/eject cycles, sample pH, and type of the desorption solvent, were employed in a factorial experimental design to optimize the sorption equilibrium and time analysis. Among the evaluated DPX variables, the highest extraction efficiency was obtained with 500 µL of urine sample mixed with 1 mL of borate solution (pH 9) with one draw/eject cycle followed by liquid desorption of 1 mL of methanol in seven draw/eject cycles. The developed DPX/LC-UV method showed a linear response from the limit of quantification of 0.317 to 3.390 g L-1 with r2 = 0.996 and inter-day precision with a coefficient of variation below 8.8%. Based on these results, the proposed method can be a useful tool for determining the creatinine levels in urine samples.

A fase extratora de politiofeno (PTh), desenvolvida por eletropolimerização em haste de aço inox, foi avaliada para microextração em fase sólida (SPME) e análise por cromatografia líquida com detecção espectrofotométrica (LC-UV) de antidepressivos inibidores seletivos da recaptação de serotonina (citalopram, paroxetina, fluoxetina e sertralina) em amostras de plasma. A influência das variáveis da eletropolimerização (velocidade de varredura de potencial, potencial e ciclos de varredura) foi avaliada no desempenho SPME. As variáveis SPME (tempo de extração, temperatura, pH da matriz, força iônica e procedimento de dessorção), assim como a influência das proteínas do plasma no mecanismo de sorção, foram também avaliadas. O método SPME-PTh/LC-UV desenvolvido para a determinação de antidepressivos em amostras de plasma apresentou faixa linear de resposta do limite de quantificação (LOQ, 200-250 ng mL-1) a 4000 ng mL-1 e precisão interensaio com coeficiente de variação no intervalo de 11 a 15%. O método proposto poderá ser utilizado para a determinação de antidepressivos em amostras de plasma humano para análises toxicológicas de urgência, após a ingestão acidental ou suicida de doses altas de medicamentos.

Polythiophene (PTh) phase electropolymerized on the stainless steel wire was evaluated as solid-phase microextraction (SPME), and analysis by liquid chromatography with spectrophotometric detection (LC-UV) for determination of new-generation antidepressants, selective serotonin reuptake inhibitors (SSRIs) (citalopram, paroxetine, fluoxetine and sertraline), in plasma samples. The influence of electropolymerization variables (scan rate, potential range and scan cycles) was evaluated on SPME performance. The SPME variables (extraction time, temperature, matrix pH, ionic strength and desorption procedure), as well as the influence of plasma proteins on sorption mechanisms were also evaluated. The SPME/LC-UV method developed for determination of antidepressants in plasma sample presented a linear range between the limit of quantification (LOQ, 200-250 ng mL-1) to 4000 ng mL-1, and interday precision with coefficient of variation (CV) ranged from 11 to 15%. The proposed method can be a useful tool for the determination of antidepressants in human plasma samples in urgent toxicological analysis after the accidental or suicidal intake of higher doses of medications.