ABSTRACT
Highly sensitive and rapid detection of ethylene, the smallest alkene of great significance in human physiological metabolism remains a great challenge. In this study, we developed a new photoionization-induced substitution reaction chemical ionization time-of-flight mass spectrometry (PSCI-TOFMS) for trace exhaled ethylene detection. An intriguing ionization phenomenon involving a substitution reaction between the CH2Br2+ reactant ion and ethylene molecule was discovered and studied for the first time. The formation of readily identifiable [CH2Br·C2H4]+ product ion greatly enhanced the ionization efficiency of ethylene, which led to approximately 800-fold improvement of signal intensity over that in single photon ionization mode. The CH2Br2+ reactant ion intensity and ion-molecule reaction time were optimized, and a Nafion tube was employed to eliminate the influence of humidity on the ionization of ethylene. Consequently, a limit of detection (LOD) as low as 0.1 ppbv for ethylene was attained within 30 s at 100 % relative humidity. The application of PSCI-TOFMS on the rapid detection of trace amounts of exhaled ethylene from healthy smoker and non-smoker volunteers demonstrated the satisfactory performance and potential of this system for trace ethylene measurement in clinical diagnosis, atmospheric measurement, and process monitoring.
Subject(s)
Ethylenes , Ethylenes/chemistry , Ethylenes/analysis , Humans , Limit of Detection , Breath Tests/methods , Photochemical Processes , Exhalation , Mass Spectrometry/methodsABSTRACT
RATIONALE: Ethylene oxide (EO) sterilization is commonly employed for the sterilization of medical devices and has a very high market share. However, EO and its metabolite ethylene chlorohydrin (ECH) are toxic to humans. In compliance with the classification and residue limits of medical devices defined by ISO 10993-7, our study established two extraction methods for the testing of EO and ECH. METHODS: The first method involves simulated-use extraction using water as the extraction solvent. While the second, exhaustive extraction, directly extracts sample through headspace sampling analysis. Gas chromatography-tandem mass spectrometry in multiple reaction monitoring mode was utilized, requiring only 16 min. Then, the developed method was applied to assess 10 commercially available medical devices sterilized by EO. RESULTS: In simulated-use extraction, calibration curves were evaluated in the range of 1-100 and 5-500 µg for EO and ECH, respectively (r > 0.999). Inter-day recoveries ranged from 85.0% to 95.2% and from 94.8% to 102.4%. In exhaustive extraction, calibration curves spanned 0.5-50 and 2-200 µg for EO and ECH, respectively (r > 0.999). Inter-day recoveries ranged from 101.6% to 102.1% for EO and from 98.1% to 102.2% for ECH. After analysis of the 10 commercially available medical devices, two cotton swabs were found to have ECH of 35.1 and 28.4 µg per device, and four medical devices were found to have EO with concentration below the limit of quantification. Meanwhile, we found that the EO internal standard (propylene oxide) recommended by ISO 10993-7 had interference problems with other similar substances and was not suitable as an internal standard for EO. CONCLUSIONS: This study offers a sensitive and straightforward analytical approach to EO and ECH residues in a variety of medical devices. In addition, the results show that the EO or ECH content of these types of medical devices in our study falls below the regulatory limits, therefore instilling confidence among consumers regarding their safe use.
Subject(s)
Ethylene Oxide , Gas Chromatography-Mass Spectrometry , Tandem Mass Spectrometry , Ethylene Oxide/analysis , Ethylene Oxide/chemistry , Tandem Mass Spectrometry/methods , Gas Chromatography-Mass Spectrometry/methods , Equipment and Supplies , Limit of Detection , Ethylenes/analysis , Ethylenes/chemistry , Reproducibility of Results , Equipment Contamination , Sterilization/methodsABSTRACT
O presente trabalho teve como objetivo avaliar a qualidade pós-colheita de frutos de cubiu (Solanum sessiliflorum) durante o amadurecimento após o tratamento com Etefon. Frutos das variedades Santa Luzia e Thais no estádio verde-maduro foram coletados, lavados e pulverizados até o completo molhamento com 1000 mg L-1 de Etefon e o controle com água. A cada três dias, durante 12 dias foram realizadas análises da firmeza do pericarpo, pH, teor de sólidos solúveis totais, acidez total titulável (ATT), umidade e cinzas. Foi avaliada a liberação de C0(2) e etileno diariamente durante 12 dias, conjuntamente com a perda de matéria fresca e evolução da cor, a cada três dias, sempre no mesmo grupo de frutos. Foi empregado o delineamento experimental inteiramente casualizado. Os dados foram submetidos à análise de variância e análise de regressão. Ocorreu perda de firmeza do pericarpo dos frutos com o tempo de armazenamento pós-colheita, com diminuição do pH, aumento da ATT e perda da matéria fresca. A aplicação de Etefon promoveu poucas mudanças na qualidade interna dos frutos, porém foi eficiente no desverdecimento da casca, o que pode ser verificado pelos menores valores do ângulo de cor e maiores da cromaticidade e luminosidade. O comportamento da respiração e produção de etileno aponta para um modelo de amadurecimento não climatérico.
The objective of the present work was to evaluate postharvest quality of cubiu (Solanum sessiliflorum) fruits during ripening after Ethephon treatment. Fruits from the varieties Santa Luzia and Thais were harvested at green-mature stage, washed and sprayed until run off with Ethephon (0 e 1000 mg L-1). At every three days, during 12 days, the following analyses were performed: pericarp firmness, pH, total soluble solid content, total titratable acidity (ATT), water content and ashes. CO2 and ethylene production were evaluated daily for 12 days, together with the loss of fresh matter and color evolution, at every three days, always the same fruit group. The experiment was arranged in a complete randomized design. Data were examined by analysis of variance and regression analysis. There was loss of pericarp firmness with time of postharvest storage, with decrease in pH, increase in ATT and loss of fresh matter. Ethephon promoted small changes in the internal quality of fruits, whereas it was efficient to induce degreening of fruit peel, which can be verified by the lower color angles and higher chromaticity and brightness. Respiration rates and ethylene production of the fruit suggest that cubiu has non-climateric behavior.