On July 20, the Guangzhou City Administration for Industry and Commerce announced on the official website the results of recent random inspections of dairy products and milk-containing foods on the market. The Nanshan milk powder produced by Hunan Changsha Yahua Dairy Co., Ltd. has the most serious problems, and 5 batches of infant milk powder were all found to contain aflatoxin M1. It is worth noting that the well-known brands Bright Cream and the local Shawan ginger juice hit the milk are all unqualified, and Aixin Duoyang milk powder was on the "black list" on February 3rd.
The current methods for detecting aflatoxin are usually immunoaffinity chromatography purification high performance liquid chromatography and enzyme-linked immunosorbent assay (ELISA). The enzyme-linked immunosorbent assay (ELISA) is simple and fast, but the sensitivity is low and false positives will occur. It is necessary to use the immunoaffinity column method for precise determination and quantification. However, the immunoaffinity column has cumbersome, expensive, and storage conditions. Defects such as harshness and short shelf life.
In response to the above problems, Dima Technology has recently developed a new, fast and low-cost ProElutTM solid phase extraction method. This method can achieve high-precision recovery results comparable to immunoaffinity column method, but the cost of use is greatly reduced. ProElutTM solid phase extraction method costs 1/4 of a single sample for immunoaffinity column method and 1/2 for enzyme-linked immunoassay method. At the same time, ProElutTM solid phase extraction method is simple and easy to operate, and does not require special large-scale equipment. The requirements are not high, especially suitable for various food production enterprises and testing institutions, which will greatly reduce the testing cost of aflatoxin.
The following is the detection scheme of aflatoxin M1 developed using ProElutTM solid phase extraction column for your reference!
1 Scope of application
It is suitable for the detection of aflatoxin M1 in dairy products such as milk, milk powder and cheese.
2 Sample preparation / extraction
2.1 Liquid milk products such as milk and raw milk
Weigh 5g sample, add 5mL acetonitrile, vortex to mix for 1min;
Then add 10mL of acetonitrile, vortex to mix for 1 min, 4000rpm, and centrifuge for 5min;
Take 5mL of supernatant and use it as the sample to be purified.
2.2 Solid milk products such as milk powder and cheese
Weigh 2g sample, add 5mL water, vortex to mix for 2min, the sample and water are mixed well;
Add 5mL acetonitrile, vortex to mix for 1 min;
Then add 10mL of acetonitrile, vortex to mix for 1min, 4000rpm, and centrifuge for 5min;
Take 5mL of supernatant and use it as the sample to be purified.
3 SPE column purification-ProElutTM AFT aflatoxin detection special column 1500mg / 12mL (Cat # 65904)
(1) Activation: 10mL of acetonitrile, the effluent is discarded;
(2) Loading: add the loading liquid to the column and receive the effluent;
(3) Elution: elute with 10 mL of acetonitrile, and collect the effluent. Combine step (2), (3) effluent;
(4) Re-dissolve: concentrate the effluent to about 2mL by vacuum distillation at 40 ℃, add 5mL of absolute ethanol to the rotary flask, continue the distillation under reduced pressure to near dryness, and make the volume to 0.5mL with 10% acetonitrile water For HPLC analysis.
4 Analysis conditions
Column: Diamonsil C18 (2), 250 mm × 4.6 mm, 5 μm (Cat # 99603)
Flow rate: 1.0mL / min
Detector: * Fluorescence detector, Ex: 365 nm; Em: 435 nm
Column temperature: 30 ℃
Injection volume: 20 μL
Mobile phase: acetonitrile: water = 25: 75
5 Add recycling results
5.1 Adding and recovering results of aflatoxin M1 in milk
Analyte addition level (μg / kg) Recovery /% RSD (n * = 4) /% Aflatoxin M1 0.4 90.13 3.42 Aflatoxin M1 2 92.61 4.595.2 Adding and recovering results of aflatoxin M1 in milk powder
Analyte addition level (μg / kg) Recovery /% RSD (n * = 4) /% Aflatoxin M1 1 90.33 3.75 Aflatoxin M1 5 87.61 4.165.3 Recovery results of aflatoxin M1 in cheese
Analyte addition level (μg / kg) Recovery /% RSD (n * = 4) /% Aflatoxin M1 1 92.92 2.75 Aflatoxin M1 5 85.16 3.94
Product information related to aflatoxin testing (spot):
(Refer to GB 5413.37-2010 Determination of aflatoxin M1 in milk and dairy products, GB / T 5009.23-2006 Determination of aflatoxin B1, B2, G1, G2 in food and other standards)
Item No. Name Spec Sample Pretreatment 65904 Dedicated solid phase extraction column for aflatoxin detectionProElutTM AFT
(Can be used for the determination of total aflatoxin and aflatoxin M1) 1500mg / 12mL, 20 / pk 82O-COIAC1005 Aflatoxin M1 immunoaffinity column 3mL, 25 / pk 82O-COIAC1001 total aflatoxin (B1 B2, G1, G2)
Immune affinity column 1mL, 25 / pk 82O-COIAC1004 Total aflatoxin (B1, B2, G1, G2)
Immune affinity column 3mL, 25 / pk 244358 12 tubes anti-cross contamination vacuum SPE extraction device 12 positions 4803 1,3,6mL column tube universal connector 15 / pk 4806 Cork (control flow) 15 / pk 99011 vacuum / positive pressure Dual-purpose pump, oil-free 1 / pk 99013 suction filter bottle set
(Including silicone rubber tube 2 meters, 2L suction filter bottle and rubber stopper) 1 / pk 37177 syringe filter Nylon 13mm, 0.22μm 100 / pk 37180 syringe filter Nylon 13mm, 0.45μm 100 / pk standard 51-46304 -U-1EA Aflatoxin mixed standard (B1, B2, G1, G2) 5 × 1mL in Methanol
Aflatoxin B1, 1μg / mL
Aflatoxin B2, 0.3μg / mL
Aflatoxin G1, 1μg / mL
Aflatoxin G2, 0.3μg / mL 51-46319-U-1EA Aflatoxin M1 [6795-23-9] 1mL, 10μg / mL in acetonitrile 51-46323-U-1EA Aflatoxin B1 [1162-65-8] 1mL
3μg / mL in benzene: acetonitrile (98: 2) 51-46324-U-1EA Aflatoxin B2 [7220-81-7] 1mL
3μg / mL in benzene: acetonitrile (98: 2) 51-46325-U-1EA Aflatoxin G1 [1165-39-5] 1mL
3μg / mL in benzene: acetonitrile (98: 2) 51-46326-U-1EA Aflatoxin G2 [7241-98-7] 1mL
3μg / mL in benzene: acetonitrile (98: 2) column and guard column 99603 RP-HPLC column
Diamonsil C18 (2) 250 × 4.6mm, 5μm 6201 EasyGuard C18 guard column 10 × 4.0mm 1 / pk
2 columns + 1 column sleeve 87003 UPLC special chromatographic column
Endeavorsil C18 100 × 2.1mm, 1.8μm HPLC solvent buffer salt ion pair reagent 50102 methanol HPLC grade 4L 50101 acetonitrile HPLC grade 4L 50144 formic acid HPLC grade 50mL 50122 isopropanol HPLC grade 4L 50106 acetone HPLC grade 4L 50115 n-hexane HPLC grade 4L 50134 Trifluoroacetic acid HPLC grade 50mL General chromatography product 52401B bottle rack / blue (spot) 50-well 52401A bottle rack / white (spot) 50-well 5323 vial (brown / thread) 2mL, 100 / pk 5325 vial cap / With pad (assembled) 100 / pk H80465 HPLC syringe 25μL
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