Optofluidics, understood as the synergistic combination between microfluidics and photonics, has been at the forefront of the scientific research due to its outmatching properties: on the one hand, microfluidics allows the handling of minute amounts of liquid samples at the microscale. On the other hand, photonics has proved to outmatch other detection methods (e.g. electrochemistry) in terms of sensitivity and selectivity. From the initial single analyte or spiked samples, currently the technology is mature enough for selective detection of a variety of analytes in raw, complex liquid samples. This will pave the way for the applicability of optofluidic devices for applications in the field or at the point of care. Here, we will revisit the current state of the art of optofluidic and photonic lab-on-a-chip systems for the analysis of real and biologically relevant samples: body fluids and water.

In recent years, environmental concerns over ultra-trace levels of steroid estrogens concentrations in water samples have increased because of their adverse effects on human and animal life. Special attention to the analytical techniques used to quantify steroid estrogens in water samples is therefore increasingly important. The objective of this review was to present an overview of both instrumental and non-instrumental analytical techniques available for the determination of steroid estrogens in water samples, evidencing their respective potential advantages and limitations using the Need, Approach, Benefit, and Competition (NABC) approach. The analytical techniques highlighted in this review were instrumental and non-instrumental analytical techniques namely gas chromatography mass spectrometry (GC-MS), liquid chromatography mass spectrometry (LC-MS), enzyme-linked immuno sorbent assay (ELISA), radio immuno assay (RIA), yeast estrogen screen (YES) assay, and human breast cancer cell line proliferation (E-screen) assay. The complexity of water samples and their low estrogenic concentrations necessitates the use of highly sensitive instrumental analytical techniques (GC-MS and LC-MS) and non-instrumental analytical techniques (ELISA, RIA, YES assay and E-screen assay) to quantify steroid estrogens. Both instrumental and non-instrumental analytical techniques have their own advantages and limitations. However, the non-instrumental ELISA analytical techniques, thanks to its lower detection limit and simplicity, its rapidity and cost-effectiveness, currently appears to be the most reliable for determining steroid estrogens in water samples.

Chromium holds a special position among living organisms because depending on its species it can be either essential or toxic. Cr(VI) even at very low concentrations is harmful and carcinogenic, while Cr(III) is a necessary microelement for cellular metabolism. Therefore, a simple analysis of Cr concentration in collected samples will not be able to distinguish these differences effectively: for a proper chemical analysis we need to perform a reliable detection and quantification of Cr species. Separation and detection of chromium can be accomplished with high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-MS) in a one-step. Our review assembles articles published since 2000 regarding chromium speciation in water samples with the use of HPLC/ICP-MS. It addresses the following issues: chromium chemistry, the possibilities of dealing with interferences, metrological aspects, analytical performance and speciated isotope dilution mass spectrometry (SIDMS) which is a definitive measurement method. The authors would like to advocate this hyphenated advanced technique as well as the metrological approach in speciation analysis of chromium.