User:Bbayliss2020/Malachite green

Detection Methods
Although malachite green has almost no fluorescence in aqueous solution (quantum yield 7.9x10−5), several research groups have developed technologies to detect malachite green. For example, Zhao et al., demonstrated the use of malachite green aptamer in microcantilever based sensors to detect low concentration of malachite green. Because MG is less soluble in water, samples must be prepared with organic solvents such as acetonitrile (polar aprotic), ethanol (polar protic/universal), ammonium acetate in methanol (protein precipitation). Matrices used for determination of MG and LMG concentration include tissue, water, or sediment samples. Since extraction techniques and detectors are interchangeable, methodology cannot be arranged according to sample type.

Extraction methods include solid phase extraction (SPE), liquid-liquid extraction (LLE) molecular imprinting molecules (MIPs) or synthetic polymers with a pitted surface that have a high affinity for a certain (conformational specificity) molecule such as MG or LMG, (MMIPS) magnetic molecular imprinting molecules, unlike MIPs, MMIPs can be recuperated with a magnetic field and reused. The molecules have also been used as biomimetic antibodies in ELIZA methodology listed below.

Detectors most commonly used- mass spectrometer (MS), fluorescence (FLD), ultraviolet detector (UV), or diode ray (DA).

High Performance Liquid Chromatography (HPLC)-quantitative analysis of MG and LMG, this technique relies on the structural differences to separate MG from LMG using a solution of acetonitrile for the mobile phase. In order to attain more precise readings, MG within the sample, can be reduced entirely to LMG or LMG can be oxidized to MG via DDQ depending on detection method. HPLC is the standard for MG/LMG separation as the technique can simultaneously detect MG/LMG.

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)- The most commonly employed interface includes rapid extractive electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI).

Surface Enhanced Raman Spectroscopy (SERS)- Determines MG presence by detecting molecular vibrations which are characteristic of the compound's structure. Substrate can be manufactured to increase surface area or affinity and is at current most commonly a roughened metal plates or nano-sized metal particles, typically composed of Au or Ag, only promising for water samples. Only silver coated magnetic nanoparticles (Song et al.) are able to be regenerated. No other SERS substrate at this time is reusable as composite materials forming nanodome arrays, nanorod scaffolds, and silica shells may not be recovered for reuse.

Rapid Extractive Electrospray Ionization (ESI)- A method where an aerosol is formed by exposing a sample to high voltage. This creates ions that can be analyzed via mass spectrometry.

Enzyme-linked Immunosorbent Assays (ELIZA)- An analytical method that relies on the highly specific binding interaction between an antibody and its antigen. Polyclonal or monoclonal antibody manufacturing is key and can be completed via immunization of animal hybridoma cell lines, or through the use of native bovine serum, as the MG/LMG analytes form protein complexes. Multianalyte assays are less accurate as single analyte methods may detect analogues. Immunoassays are ideal on account of there is no need to oxidize/reduce MG/LMG for testing, however the antigen must be synthesized.

Chemiluminescence Enzyme Immunoassay (CLEIA)- A non-competitive immunoassay.

It should be noted that up to 50% of farmed fish loss is attributed to disease and aqua culturists are resorting to the use of Malachite Green and Malachite Green + formalin as either a proactive, or reactive, measure. New detection and analyses methods to determine the presence and amount of MG/LMG are currently being explored.