Origami paper analytical assay based on metal complex sensor for rapid determination of blood cyanide concentration in fire survivors

Cyanide-based blood poisoning can seriously damage fire victims and cause death if not detected quickly. Previous conventional methods require laboratory equipment, which are expensive and increase the duration of the analysis. Here, a simple origami based microfluidic device was introduced for point of need detection of blood cyanide concentration in people involved in fire. The device is made of four layers of paper. Each layer was in the size of 1 × 1 cm folded on each other. In this work, the blood sample was acidified by trichloroacetic acid to separate cyanide from methaemoglobin in the form of HCN gas. The produced gas released into borate buffer to recover free cyanide ions which interacted with the Pt complex ([Pt(p-MeC6H4)2(phen)]) used as a receptor in this study. Optimized conditions were applied to have a suitable interaction causing the color of the receptor to change from yellow to colorless. The color changes were recorded by a smartphone, and the sensor response was calculated by the routine image analysis software. The assay was capable of determining cyanide ions at different concentrations in the range of 1.0 to 100.0 µmol L−1. The detection limit of these determination was equal to 0.4 µmol L−1. The assay responses were not affected by the interfering species. As a practical analysis, the proposed sensor was applied to determine cyanide ions in the blood sample of 20 studied fire survivors and 10 controls with high accuracy.

Ground Flaxseed – How Safe is it for Companion Animals and for Us?

EFSA released the 89-page Scientific Opinion “Evaluation of the health risks related to the presence of cyanogenic glycosides in foods other than raw apricot kernels”. This opinion, and the ensuring media coverage, has left uncertainty in the minds of consumers, feed and supplement manufacturers and flaxseed producers of how much ground flaxseed can safely be consumed without crossing the threshold of cyanide toxicity. This editorial updates the science and tries to bring clarity to the question “how much flaxseed can I safely feed my dog, cat, horse on a daily basis?” and “how much can I safely eat?” The great majority of ground flaxseed products have a cyanogenic glycoside content of less than 200 mg / kg seed. For people, consuming 30 grams of such flaxseed the average peak blood cyanide concentration will be about 5 µmole / L, much less than the toxic threshold value of 20 to 40 µmole / L favoured by EFSA. Thus, as much as 120 grams of crushed / ground flaxseed can be consumed by a 70 kg adult person before a toxic threshold of 40 µmole / L is reached (up to 1.7 grams ground flaxseed / kg body weight). The toxic threshold of cyanide for dogs is 2 to 4-fold greater than for humans, and unknown for cats and horses. The daily serving amounts for dogs and cats are about 0.23 grams / kg body mass per day, which will result in blood cyanide well below the toxic threshold. The highest recommended daily serving amount for horses is 454 grams per day, or 0.8 to 2 grams per kg / body mass depending on mass of the horse. This amount for horses should not be exceeded.

Comment on “Rapid visual detection of blood cyanide” by C. Männel-Croisé and F. Zelder, Analytical Methods, 2012,4, 2632

We discuss evidence suggesting that the approach described in the manuscript of Männel-Croisé and Zelder may not be a practically usable procedure regardless of the exact chromogenic reagent used.

Reply to the ‘Comment on “Rapid visual detection of blood cyanide”’ by A. F. Kadjo, P. K. Dasgupta and G. R. Boss, Analytical Methods, 2015, 7, DOI: 10.1039/C4AY00190G

It is now experimentally demonstrated that the two step protocol for visual detection of blood cyanide detects ‘free’, but not transition metal bound cyanide.