Analytical Methods Blog

Olive oil/nanoparticle degradation by lipase activity

Researchers in Mexico present a new rapid and cost effective spectrophotometric method to determine lipase activity in olive oil.

Lipases are a group of enzymes which catalyse reaction of hydrolysis of triacylglycerols to give free fatty acids, monoacylglycerol and glycerol. Measuring their activity is important in medicine and diagnostics as well as in pharmaceutical, cosmetic and paper industry. Unfortunately, the conventional assays currently available still rely on time-consuming procedures and employ radioactive materials and expensive reagents. In this work, the researchers used a layer of triglyceride coated with  Fe₂O₃  nanoparticles which are released when the substrate is degraded. A consequent change in light absorbance is observed following substrate degradation.
The new spectrophotometric method introduced by Margarita Stoytcheva and her group represents a promising analytical approach to reduce cost and increase effciency.

To read the full article, please access the link below. The paper will be free to read until March 18th.

A spectrophotometric lipase assay based on substrate–nanoparticle assembly degradation
Margarita Stoytcheva ,  Roumen Zlatev ,  Samuel Behar and Jean-Jacques Bois
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C3AY00044C

Trace lead analysis performed using ID-CP-MS

A toxin or heavy metal in a mother’s body can transfer to her baby, and even though lead is primarily stored in bones, trace amounts have the potential to enter breast milk and create a dangerous health risk.

Although multiple testing procedures are available, they have demonstrated a wide range of sensitivities arising from sample contamination and preparation issues. Adrienne Ettinger and researchers at Harvard School of Public Health, USA,  evaluated three digestion procedures for lead analysis using isotope dilution inductively coupled mass spectrometry (ID-ICP-MS).  The primary goal was to see if they could achieve 100% efficiency in any of the digestion processes in the complex media of breast milk, which contains high levels of contaminants such as fat and calcium, and trace levels of lead. Of these, the high pressure asher demonstrated complete sample digestion and had the most consistent lead concentration measurement. By removing analyte contaminants and maximizing the preparation efficiency, they detected trace levels of lead down to 0.2 ng mL^-1.

To read more about this research, please access the link below. This paper will be free to read until March 8th.

Comparison of digestion procedures and methods for quantification of trace lead in breast milk by isotope dilution inductively coupled plasma mass spectrometry
Chitra J. Amarasiriwardena ,  Innocent Jayawardene ,  Nicola Lupoli ,  Ramon M. Barnes ,  Mauricio Hernandez-Avila ,  Howard Hu and Adrienne S. Ettinger
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C3AY26321E

Picture of 5 interconnecting microfluidic components

A new and fast microchip-inspired analytical device based on standard Plexiglas tubes has been developed by researchers in Brazil.
The team, led by Carlos Garcia from the University of Sao Paulo, propose a device based on 5 plastic microfluidic components that serve as both the injector and the reservoir. The plastic components are connected with standard capillary tubes that easily enable the in-channel detection of analytes by a variety of techniques including electrophoresis. To demonstrate the applicability of this design, the researchers performed efficient analysis of inorganic cations by capillary electrophoresis on soil samples.
The microchip-capillary electrophoresis devices commercially available at the moment are still expensive and do not always offer the best analytical performances. This new microfluidic device developed using cheap and simple fabrication materials is an attractive approach for portable and rapid analytical instrumentation.

To read the full article, free to read until March 6th, please access the link below:

Microfab-less microfluidic capillary electrophoresis devices
Thiago P. Segato ,  Samir A. Bhakta ,  Matthew T. Gordon ,  Emanuel Carrilho ,  Peter A. Willis ,  Hong Jiao and Carlos D. Garcia
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C3AY26392D

Antibiotics provide vital treatment in fighting bacterial infection, but over time some have become phased out or even toxic to humans.

Miniaturized device for detection of chloramphenicol in water

One of these is chloramphenicol. Although banned in the European Union, chloramphenicol continues to be used as a cheap remedy in veterinary medicine and can lead to contaminated water and food for our consumption. One technique to test for this contaminant, solid phase extraction (SPE), purifies samples effectively, but requires a pump and a laboratory setting.

Alternatively, Sheng Liu, from the Chinese Academy of Sciences, and colleagues developed a simple yet portable miniaturized SPE (MSPE) device capable of detecting chloramphenicol in water, which has been difficult to test using other methods. A macroporous resin captures and concentrates the chloramphenicol before it passes through an HPLC, all within a 1.5 kg mass instrument. This new technique directly detects low concentrations of chloramphenicol in water, and demonstrates the capacity to function at contaminated locations.

To know more about the study, please click on the link below. This paper will be free to read for the next two weeks.

On-site solid phase extraction and HPLC determination of chloramphenicol in surface water and sewage
Sheng Liu ,  Xian-Zheng Wu ,  Zi-Hui Gao and Fang Jiao
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C2AY26162F

Take a look at this great list of selected HOT articles recently published in Analytical Methods! Topics include nanoparticle-based colorimetric anticancer drug detection methods and ultra performance liquid chromatography-tandem mass spectrometry for multiple bile acids detection.

Check out also the new review by Edward Randviir and Craig Banks on electrochemical impedance spectroscopy. All these papers will be free for you to read until February 18th. 

Electrochemical Impedance Spectroscopy: An Overview of Bioanalytical Applications
Edward P Randviir and Craig E Banks
Anal. Methods, 2013, Accepted Manuscript
DOI: 10.1039/C3AY26476A

Application of an electronic tongue towards the analysis of brandies
Xavier Cetó ,  Matias Llobet ,  Joan Marco and Manel del Valle
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C2AY26066B

Potential of solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry to monitor the Ag body burden in individual Daphnia magna specimens exposed to Ag nanoparticles
Martín Resano ,  Ana C. Lapeña and Miguel A. Belarra
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C2AY26456K

Self-powered herbicide biosensor utilizing thylakoid membranes
Michelle Rasmussen and Shelley D. Minteer
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C3AY26488B

Quantification of Multiple Bile Acids in Uninephrectomized Rats Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry
Carlos A Penno ,  Denis Arsenijevic ,  Thierry Da Cunha ,  Gerd A Kullak-Ublick ,  Jean-Pierre Montani and A Odermatt
Anal. Methods, 2013, Accepted Manuscript
DOI: 10.1039/C3AY26520J

Colorimetric anticancer drug detection by gold nanoparticle-based DNA interstrand cross-linking
Xiaoji Xie ,  Renren Deng ,  Feng Liu ,  Wei Xu ,  Sam Fong Yau Li and Xiaogang Liu
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C3AY26422J

Trace concentrations of cadmium in water, soil and industrial settings can have devastating health effects if not detected. Furthermore, measuring accurate cadmium levels in these complex samples is hindered by signal interference from other metals such as tin, molybdenum, and zirconium.

Robert Thompson and Steven Christopher in the United States developed a four-step separation methodology to remove these metals, and then used inductively coupled plasma mass spectrometry to measure cadmium concentrations. For this procedure, commercially available solid phase extraction cartridges isolate most of cadmium and strong ion exchange chromatography removes tin and molybdenum. This unique sample preparation facilitates the detection of low cadmium concentrations in marine sediment and rice flour which contain high levels of tin and molybdenum respectively.

Determination of cadmium in samples containing molybdenum and tin

To know more about this study, please access the link below. This paper will be free to read until February 18th.

Novel separation for the determination of cadmium by isotope dilution ICP-MS in samples containing high concentrations of molybdenum and tin
Robert Q. Thompson and Steven J. Christopher
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C2AY26212F

Detection of selenium using graphite-based sensors

Researchers from the Manchester Metropolitan University reported the first example of graphite-based sensors to detect selenium in drinking water.
Selenium is a trace mineral nutrient essential as for all animals, but it is extremely toxic if the intake dose exceeds 400 µg per day. Both the European Union and United States Environmental Protection Agency (EPA) have set the limits for selenium in drinking water to of 10 µg/L and 50 µg/L respectively.

Today, the gold-based electrodes which are traditionally used to detect selenium are very expensive. With this work, Craig Banks and his group address the problem proposing a graphite based sensor to detect selenium in water. They fabricated special screen-printed graphite electrodes and detected low concentrations of selenium in their laboratory tap water, with a limit of detection which fell below those set by the EPA. According to the authors, this new graphite-based sensor could represent an appealing alternative to the gold based electrodes currently used.

To know more about this work, click on the link below. This paper will be free to read until January 24th.

Electroanalytical sensing of selenium(IV) utilising screen printed graphite macro electrodes
Athanasios V. Kolliopoulos ,  Jonathan P. Metters and Craig E. Banks
Anal. Methods, 2013, Advance Article
DOI: 10.1039/C2AY26041G