A new suppressor design for low noise performance with carbonate eluents for Ion Chromatography

Publication date: 1 October 2018
Source:Talanta, Volume 188
Author(s): Kannan Srinivasan, Brittany K. Omphroy, Rong Lin, Christopher A. Pohl
Carbonate and bicarbonate based eluents have been applied for ion analysis from the inception of ion chromatography. The product of suppression with carbonate and/or bicarbonate eluent is carbonic acid which is weakly dissociated and tends to outgas. While the act of suppression enhanced the signal for fully dissociated ions and lowered the background to a weakly dissociated level, the overall noise performance, however, varied depending on the suppression mechanism. Chemical suppression with a membrane suppressor yielded low noise performance with carbonate and/or bicarbonate eluents. Electrolytic suppression, on the other hand, resulted in a relatively higher noise with carbonate based eluents when compared to chemical suppression. In this work, we investigated the root cause of noise with electrolytic suppressors and carbonate based eluents. Further, a new electrolytic suppressor design based on a three-electrode design is discussed in this paper and provided low noise performance with carbonate and/or bicarbonate eluents.



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β-Cyclodextrin functionalization of metal-organic framework MOF-235 with excellent chemiluminescence activity for sensitive glucose biosensing

Publication date: 1 October 2018
Source:Talanta, Volume 188
Author(s): Xuanxiang Mao, Yuwan Lu, Xiaodan Zhang, Yuming Huang
Herein, we developed a new CL method for the detection of glucose, exhibiting high sensitivity, low limit of detection, good stability and reliability for analysis of real biological samples. The MOF-235/β-cyclodextrin (β-CD) hybrids were facilely prepared by a simple method, and characterized by XRD, TGA, FT-IR and SEM. The as-prepared hybrids exhibited highly catalytic activity for the hydrogen peroxide-luminol system, and gave more than 30-fold enhancement in CL response as compared with that of hydrogen peroxide-luminol system, thus could be used for sensitive detection of H2O2 and glucose. The excellent catalytic performance of the MOF-235/β-CD hybrids is ascribed to the large surface area of MOF-235 as well as the synergistic effect between β-CD and MOF-235. The proposed sensing strategy coupled with CL detection method showed low detection limits of 5 nM and 10 nM for H2O2 and glucose, respectively. Successful application of the MOF-235/β-CD hybrid in CL assay of glucose in real human serum samples is demonstrated as an efficient catalyst for sensitive chemiluminescence-based analyses. The success of this work favors to facilitate the future development in CL catalysts via MOF functionalization.

Graphical abstract

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Temporal decomposition sampling and chemical characterization of eucalyptus harvest residues using NIR spectroscopy and chemometric methods

Publication date: 1 October 2018
Source:Talanta, Volume 188
Author(s): Gabriel W.D. Ferreira, Jussara V. Roque, Emanuelle M.B. Soares, Ivo R. Silva, Eulene F. Silva, Aline A. Vasconcelos, Reinaldo F. Teófilo
Near-infrared (NIR) spectroscopy and chemometric methods were used to predict the chemical properties of decomposing eucalyptus harvest residues to better understand the decomposition process of these materials. Leaves, twigs, branches, and bark from a decomposition experimental set up in commercial plantations were sampled for one year. The contents of carbon (C), nitrogen (N), extractives (EX), acid-soluble lignin (SL), Klason insoluble lignin (KL) and holocellulose (HC) were determined by the reference method in the collected samples. Principal component analysis (PCA) was employed to distinguish the types of harvest residues throughout the decomposition period. Multi-residue regression models were built from the NIR spectra using partial least squares regression (PLS). Two feature selection methods, i.e., ordered predictors selection (OPS) and genetic algorithm (GA), were applied and compared. The OPS and GA did not differ statistically; however, compared with the GA, OPS was more computationally efficient and selected fewer variables. Using the PLS-OPS models, the root mean square errors of prediction (RMSEP) for C, N, EX, SL, KL and HC were 19.70, 0.08, 0.74, 0.39, 28.13 and 33.99, respectively, and the prediction correlations (Rp) for these properties were 0.94, 0.99, 0.99, 0.99, 0.96 and 0.98, respectively. PLS-discriminant analysis (PLS-DA) was used to classify the samples over the decomposition time and provided a good separation. Some mismatches obtained in the modeled classes were explained by the differences in the decomposition rate and changes in the chemical composition of the different harvest residue components that were evaluated. The results showed the feasibility of NIR spectroscopy and chemometric methods to evaluate the chemistry of decomposing eucalyptus harvest residues, indicating that these methods can be used as rapid and inexpensive alternatives to conventional methods to help understand the decomposition process.

Graphical abstract

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Front Matter 1 - Full Title Page (regular issues)/Special Issue Title page (special issues)

Publication date: 1 September 2018
Source:Talanta, Volume 187





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Editorial Board

Publication date: 1 September 2018
Source:Talanta, Volume 187





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Reducing the exposure of the tonsillar fossa does not impact postoperative pain levels in children undergoing tonsillectomy: A double-blind randomized controlled trial

Publication date: August 2018
Source:International Journal of Pediatric Otorhinolaryngology, Volume 111
Author(s): Marco Aurélio Fornazieri, Edson Satoshi Miyazato, Henrique Massamiti Yamamoto, Paulo de Lima Navarro, Fábio de Rezende Pinna, Richard Louis Voegels
BackgroundIt is not established whether reducing the exposure of the tonsillar fossa would be an effective strategy for postoperative pain relief among the pediatric population submitted to tonsillectomy. We assessed the impact of closing this region using absorbable sutures on pain, on the resumption of normal diet and on the healing process until seven days after surgery.MethodsRandomized, double-blind, controlled trial comparing postoperative pain in 132 children between the ages of 5 and 12 years undergoing tonsillectomy having bilateral closure, unilateral closure or non-closure of the tonsillar fossa.ResultsNo differences in pain levels were reported both at discharge and on postoperative day 7. The day of resumption of normal diet was similar in all patients. Less granuloma and edema of the uvula were noted in patients with non-closure of the tonsillar fossa.ConclusionThese results showed that reducing the exposure of the tonsillar fossa after the removal of the palatine tonsils was not an effective method for postoperative pain relief in children. Moreover, its closure was associated with slower healing.



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Infection of the spheno-occipital synchondrosis: A morbid complication following adenoidectomy

Publication date: August 2018
Source:International Journal of Pediatric Otorhinolaryngology, Volume 111
Author(s): Amy E. Wagenaar, David M. Mirsky, Nicholas V. Stence, Todd M. Wine, Kenny H. Chan
Two 2-year-old males presented post-operatively following adenoidectomy with persistent fever and neck stiffness. After multiple office visits, both patients were admitted and found to have a widened spheno-occipital synchondrosis and other imaging findings indicative of skull base osteomyelitis. Treatment with antibiotics allowed for recovery with good long-term outcomes. Infection involving the spheno-occiptal synchondrosis is rare and its circuitous presentation of these two children no doubt led to delayed diagnosis.



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