| Launch：2023-09-05 |
In May this year, the Jiangxi Provincial Market Supervision and Administration organized food safety supervision. After random inspection, it was found that the malachite green sold by Fangwang Aquatic products Company in Xunyang District, Jiujiang City, did not meet the provisions of the national food safety standards.
In 2020, the Beijing Market Regulatory Administration found that the malachite green content of mantis shrimp operated by Beijing Blue Sea Zhongding Tower Restaurant Co., Ltd. Shijingshan Branch (that is, Blue Sea Zhongding Tower Restaurant Shijingshan Store) exceeded the standard.
In October 2019, the Loach sold by Xiamen Shanglu supermarket Co., Ltd. was exposed that malachite green exceeded the standard.
In May 2018, the Public Security Detachment of Changzhou City Public Security Bureau in Jiangsu Province and the Municipal Food and Drug Administration inspected the management stalls of Lingjiatang Agricultural and sideline products Wholesale Market in Zhonglou District and found that 240 kilograms of malachite green exceeded the standard.
2. What is malachite green？
Malachite green is a water-soluble triphenylmethane chemical whose aqueous solution is blue-green. Malachite green is not only a dye, but also a fungicidal, bactericidal and parasitic drug. Long-term overuse can cause cancer, and it is explicitly prohibited by the state in the field of pollution-free aquaculture.
3.How to distinguish？
When distinguishing whether there is malachite green in aquatic fish, you can look at two parts: gills and fins. Normal fins are cyan, those using malachite green are blue-green; normal fish gills are purplish red, and those using malachite green are bright red.
4. What are the detection techniques of malachite green at present?
At present, the detection methods of malachite green and crystal violet related to aquatic products have been very mature, and the common detection methods are liquid chromatography, liquid chromatography-tandem mass spectrometry and so on. These methods have accurate results and high sensitivity, but they are limited by the conditions of the instrument. there are defects such as high detection cost and long inspection period. In order to meet the needs of breeding farms and on-site supervision, the rapid inspection method is a new way to solve these defects. Oceanhood Instruments based on the industry pain point, combined with its own Raman spectrum detection technology, developed a malachite green speed test kit in aquatic products, the lowest detection concentration is 1ppb, the detection time can be completed in about 30min.
1. Experimental object
Detection substrate: grass carp, base shrimp.
Test item: malachite green.
Note: grass carp and prawns have been tested free of malachite green and Leucomalachite green according to "Determination of Malachite Green and Crystal Violet residues in GB/T19857-2005 Aquatic products".
2.Instruments and consumables
Productions | Model | Quantity |
Box type Raman spectrometer | IRS1000 | 1 |
Pre-treatment integrated box | RFSC-1000 | 1 |
Colorimetric dish | CVT-721 | 6 |
Malachite Green Raman Rapid Detection Kit | / | 1 |
3.Experimental scheme
Before the beginning of this experiment, grass carp and prawns were detected by liquid phase-mass spectrometry, and it was confirmed that there were no malachite green and Leucomalachite green residues in the two matrix samples. Carry on the positive standard treatment to the experimental sample after the test, and the specific information of the sample is shown in the table below.
Experiment number | Experimental sample | Addition of drugs | Concentration（μg/kg） |
1 | Grass carp
| Not added | -- |
2 | Malachite green（MG） | 1 | |
3 | Leucomalachite green（LMG） | 1 | |
4 | MG+LMG | 1 | |
5 | Base shrimp | Not added | -- |
6 | MG+LMG | 1 |
* Note: no malachite green and Leucomalachite green residues have been confirmed in the two substrates.
4.Testing method
The experimental scheme and the reagents used in this test are provided by such as malachite green Raman rapid detection kit, the two kinds of matrix pre-processing are completed by Oceanhood self-developed pre-processing machine, and the spectral data are collected by box-type Raman spectrometer after the end of pre-processing. Intelligence test E+ software for identification. For the detailed testing process of the sample, please refer to the instructions for the rapid detection kit of malachite green Raman.
This experiment is divided into 6 groups. The matrix of grass carp was detected in experiment 1, 2, 3 and 4. The test spectra of 1-4 groups were as follows. Experiment 1 was a sample of grass carp without adding malachite green and Leucomalachite green. no Raman characteristic shift of malachite green was found, indicating that malachite green and Leucomalachite green were not detected in grass carp. In experiment 2, the samples of grass carp with 1ppb malachite green were detected, and the obvious Raman characteristic shifts of malachite green (800,1174, 1224, 1619cm-1) were observed in the Raman spectra of grass carp, indicating that the added malachite green in grass carp has been detected.
Because malachite green can be transformed into Leucomalachite green under certain conditions, the Leucomalachite green addition experiment of grass carp was carried out in experiment 3, and the experimental results showed that the Leucomalachite green added in grass carp could also be detected. In experiment 4 and 6, malachite green and Leucomalachite green were added to grass carp and prawn substrates at the same time, and the detection results were similar to those of experiment 2 and 3. Malachite green and Leucomalachite green could be detected in both substrates. The specific experimental results are shown in the table below.
Experiment number | Experimental sample | Addition of drugs | Concentration（μg/kg） | Whether to check out |
1 | Grass carp
| Not added | -- | No |
2 | Malachite green（MG） | 1 | Yes | |
3 | Leucomalachite green（LMG） | 1 | Yes | |
4 | MG+LMG | 1 | Yes | |
5 | Base shrimp | Not added | -- | No |
