A kind of liquid chromatography-tandem mass of toxoflavin
Technical field
The present invention relates to a kind of liquid chromatography-tandem mass of toxoflavin, belong to instrument detection technique field.
Background technology
Coconut palm poison Burkholderia (Burkholderiacocovenans) is called for short coconut palm ferment uncle Salmonella, it is a kind of new food poisoning bacteria that China finds, it is present in cereal fermented product (comprising fermented maize face, Zea mayssinesis Kulesh dumpling flour, cornstarch etc.), rotten white fungus, sorghum rice vermicelli goods, potato based article (as potato vermicelli, sweet potato starch, sweet potato starch etc.) and surrounding environment, and it is the pathogen of fermented flour and deteriorated tremella poisoning.The toxin that this bacterium produces, has toxic action to humans and animals cell.General cooking method can not destroy, and absorbed by alimentary canal and spread to whole body, latent period is short, is 20min ~ 24h, and patient starts to feel to have a stomach upset, general weakness, and diarrhoea appears in small number of patients, but gastrointestinal symptoms is slight; Vomitus mostly is coffee-like, and the symptoms such as severe patient occurs jaundice, stupor, delirious speech, tic of limbs, blood urine, has blood in stool, hepatomegaly, liver function has obvious change.Acute poisoning person falls ill urgency, and present toxic shock, average case fatality rate is up to 41.80%.
Coconut palm ferment uncle Salmonella produces two kinds of toxin: bongkrekic aicd and toxoflavin are its pathogenesis.Toxoflavin (Toxflavin, TXF) is soluble small molecular fatty acid toxin, and toxicity is extremely strong, and its chemical toxicity reaches and poisons by force product standard.The molecular formula of toxoflavin is C
7h
7n
5o
2, molecular mass is 193.17, and structure is 1,6-dimethyl one 5,7-dioxy-1,5,6,7-tetrahydro-pyrimidine base (5,4e) asymmetric triazine.Pure toxoflavin is glassy yellow flaky crystal, 172-173 DEG C of decomposition, and ultraviolet absorption peak is in 256.7nm and 394nm (ε=16400,2500).Mouse LD
50l.7mg/kg intravenous injection is, oral is 8.4mg/kg.
At present, the research about toxoflavin mainly concentrates on physio-biochemical characteristics and poisoning detoxication mechanisms.About the research of the extraction of toxoflavin in food and detection method still belongs to blank, therefore the detection method of toxoflavin in a kind of fermented flour of fast and reliable is set up, to the security ensureing cereal rice and flour food, promote the technological innovation of manufacturing enterprise, improve food quality and class, ensure that the people's is healthy significant.
Summary of the invention
Technical matters to be solved by this invention is: the liquid chromatography-tandem mass providing a kind of easy and simple to handle, toxoflavin that qualitative, quantitative ability is stronger.
For solving the problems of the technologies described above, the technical solution used in the present invention is:
The liquid chromatography-tandem mass of toxoflavin provided by the invention, comprises the following steps:
(1) sample pre-treatments
Accurately take through the fermented flour 1.0g pulverized, homogeneous is crossed, with the ultrapure extraction with aqueous solution toxin of 5mL, 200rpm shaking table concussion 30min, less than the 20 DEG C centrifugal 10min of 8000rpm, get supernatant, regulate supernatant pH value to 6 ~ 7 with 2mol/L formic acid; Repeat to extract once with 5mL ultrapure water, merge twice supernatant, be settled to 10mL with ultrapure water.Now obtain comparatively pure crude extract.
(2) enrichment and purification
Enrichment purification uses solid-phase extraction column, and solid-phase extraction column is weak cation exchange post, with the polymer absorbant of weak cation exchange mechanism of action, and can at high and low pH condition wash-out.Particle diameter 33 μm, 85 μm, aperture, surface area 800m
2/ g, ion capacity 1.0meq/g.
First with 1mL methyl alcohol and 1mL ultrapure water activating ion exchange column, reactivation process flow control is at 1-2 drop/sec, get 2mL crude extract injection ion exchange column and carry out purification enrichment, flow control, at 1 drop/sec, then uses 1mL ultrapure water eluent ion exchange column, to remove impurity, last with 1.0mL methanol solution wash-out toxoflavin at twice, nitrogen blows near dry, is settled to 0.4mL, treats that liquid chromatography-tandem mass spectrometry (LC-MS/MS) detects with 50% acetonitrile solution;
(3) LC-MS/MS detects
Liquid-phase condition PhenomenexGeminiC18 chromatographic column (3.0mm × 150mm, 5 μm), column temperature 30 DEG C; Sample size 20 μ L; Mobile phase A is water (containing 0.1% formic acid, 5mmol/L ammonium formate), and B is 95% acetonitrile (containing 0.1% formic acid, 5mmol/L ammonium formate); Condition of gradient elution is in table 1:
Table 1 condition of gradient elution
Time/min |
Flow velocity/μ Lmin
-1 |
A/% |
B/% |
0.0 |
250 |
90 |
10 |
3.0 |
250 |
40 |
60 |
3.01 |
500 |
40 |
60 |
5.0 |
500 |
40 |
60 |
5.01 |
250 |
90 |
10 |
10.0 |
250 |
90 |
10 |
Mass Spectrometry Conditions Ionization mode is electro-spray ionization negative mode (ESI-); Multiple-reaction monitoring pattern (MRM); Collision atmospheric pressure (CAD): 6; Gas curtain atmospheric pressure (CUR): 10; Electron spray voltage (IS) :-4500V; Ion source temperature (TEM): 600 DEG C.
Multiple-reaction monitoring ion pair and the mass spectrum correlation parameter of compound are as shown in table 2.
The multiple-reaction monitoring ion pair of table 2 compound and mass spectrum correlation parameter table
* be quota ion
When liquid chromatography-mass spectrography detects, due to the impact of matrix effect, cause the effect of target compound generation ion enhancer or inhibitor, adopt and do not obtain matrix blank solution preparation gradient hybrid standard product solution (0.1,0.2,0.5 containing target determinand, 1.0,2.0mg/kg).Condition measures according to the above analysis, with peak area to concentration linear regression.Redeterminate after exceeding the sample needs dilution of the range of linearity.Typical curve is shown in Fig. 5,6.
Table 3 typical curve and linear relationship
In sample, the retention time of toxoflavin chromatographic peak is compared with the retention time of respective standard chromatographic peak, and variation range should within ± 2.5%.The signal to noise ratio (S/N ratio) at the reconstructed ion chromatogram peak of the qualitative ion of toxoflavin should be more than or equal to 3 (S/N >=3), and the signal to noise ratio (S/N ratio) at the reconstructed ion chromatogram peak of quota ion should be more than or equal to 10 (S/N >=10).The detect and track of toxoflavin is 0.2mg/kg.
Beneficial effect:
Method of the present invention is easy and simple to handle, qualitative, quantitative ability is comparatively strong, can make the reliable method detecting fermented flour quality and assessment food safety risk.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.
Fig. 1 is [M-H] of toxoflavin
-parent ion mass spectrogram.
Fig. 2 is [M-H] of toxoflavin
-for the feature daughter fragment ion spectrogram that parent ion produces.
Fig. 3 is the total ion current figure of toxoflavin.
Fig. 4 is the chooser ion flow graph of toxoflavin.
The typical curve of Fig. 5 ion pair 192.1/107.8.
The typical curve of Fig. 6 ion pair 192.1/163.7.
Embodiment
The selection of embodiment 1 parent ion
Detection method about toxoflavin still belongs to blank, and the present invention compares [M-H] of toxoflavin
-with [M-2H]
2-the response of secondary fragment ion, result shows [M-H] of toxoflavin
-the secondary ion fragment that ion can meet with a response stronger as parent ion, the present invention finally selects [M-H]
-ion is as toxoflavin parent ion, and its Mass Spectrometer Method sensitivity is apparently higher than existing detection method.[M-H] of a parent ion select tape negative charge of toxoflavin
-ion.
Fig. 1 is [M-H] of toxoflavin
-parent ion mass spectrogram.Fig. 2 is [M-H] of toxoflavin
-for the feature daughter fragment ion spectrogram that parent ion produces.After mass spectrometry parameters is optimized, carries out secondary fragment scanning, finds [M-H] of toxoflavin
-the secondary ion fragment that ion can meet with a response stronger as parent ion.Toxoflavin is with [M-H]
-ion, as in parent ion situation, determines two pairs of ion pairs, 192.1/163.7 and 192.1/107.8; After MRM optimization and ion gun optimization are carried out respectively to above two class ion pairs, under respective optimal conditions, liquid chromatography-tandem mass spectrometry detection is carried out to the MC-LR standard items of same concentrations, by the comparative analysis to mass spectrogram, find that toxoflavin is with [M-H]
-ion has stronger response as the two pairs of ion pairs determined in parent ion situation, and sensitivity is higher.
Embodiment 2 sample pre-treatments condition
Sample pre-treatments
The present invention is based on fermented flour, the matrix more complicated of fermented flour, and enrichment purification pre-treatment requires higher.
Accurately take through the fermented flour 1.0g pulverized, homogeneous is crossed, with the ultrapure extraction with aqueous solution toxin of 5mL, 200rpm shaking table concussion 30min, less than the 20 DEG C centrifugal 10min of 8000rpm, get supernatant, regulate supernatant pH value to 6 ~ 7 with 2mol/L formic acid; Repeat to extract once with 5mL ultrapure water, merge twice supernatant, be settled to 10mL with ultrapure water.Now obtain comparatively pure crude extract.
Enrichment and purification
First with 1mL methyl alcohol and 1mL ultrapure water activating ion exchange column, reactivation process flow control is at 1-2 drop/sec, get 2mL crude extract injection ion exchange column and carry out purification enrichment, flow control, at 1 drop/sec, then uses 1mL ultrapure water eluent ion exchange column, to remove impurity, last with 1.0mL methanol solution wash-out toxoflavin at twice, nitrogen blows near dry, is settled to 0.4mL, treats that liquid chromatography-tandem mass spectrometry (LC-MS/MS) detects with 50% acetonitrile solution.
The determination of embodiment 3LC-MS/MS testing conditions
According to relevant regulations in No. 657/2002/EECth, CAC and EU resolution, select two pairs of ions to carry out MRM monitoring can meet, the simultaneously selection of daughter ion mainly considers that wherein parent ion and daughter ion are chosen according to the mass spectrogram of often kind of compound and architectural characteristic, and it is less to analyze mesostroma interference at actual sample.Determine the molion of various material, then respectively with the molion of various compound for parent ion, full scan is carried out to its daughter ion and chooses that abundance is comparatively strong, two pairs of less daughter ions of interference are qualitative ion, as shown in Figure 2, the Selective ion mode flow graph of the two pairs of ions finally determined as shown in Figure 4 for toxoflavin second order ms figure.Finally optimize various mass spectrometry parameters with multiple-reaction monitoring (MRM) positive ion mode.
LC-MS/MS testing conditions:
Liquid-phase condition PhenomenexGeminiC18 chromatographic column (3.0mm × 150mm, 5 μm), column temperature 30 DEG C; Sample size 20 μ L; Mobile phase A is water (containing 0.1% formic acid, 5mmol/L ammonium formate), and B is 95% acetonitrile (containing 0.1% formic acid, 5mmol/L ammonium formate); Condition of gradient elution is in table 1:
Table 1 condition of gradient elution
Time/min |
Flow velocity/μ Lmin
-1 |
A/% |
B/% |
0.0 |
250 |
90 |
10 |
3.0 |
250 |
40 |
60 |
3.01 |
500 |
40 |
60 |
5.0 |
500 |
40 |
60 |
5.01 |
250 |
90 |
10 |
10.0 |
250 |
90 |
10 |
Mass Spectrometry Conditions Ionization mode is electro-spray ionization negative mode (ESI-); Multiple-reaction monitoring pattern (MRM); Collision atmospheric pressure (CAD): 6; Gas curtain atmospheric pressure (CUR): 10; Electron spray voltage (IS) :-4500V; Ion source temperature (TEM): 600 DEG C.
Multiple-reaction monitoring ion pair and the mass spectrum correlation parameter of compound are as shown in table 2.
The multiple-reaction monitoring ion pair of table 2 compound and mass spectrum correlation parameter table
Embodiment 4 recovery is tested
(1) sample adds:
Get the interpolation that blank fermented flour sample carries out three levels, the Pitch-based sphere of toxoflavin is 0.2mg/kg, 0.5mg/kg, 1.0mg/kg, each level do 6 parallel.
(2) sample pre-treatments
Accurately take the fermented flour 1.0g having added toxin, with the ultrapure extraction with aqueous solution toxin of 5mL, 200rpm shaking table concussion 30min, less than the 20 DEG C centrifugal 10min of 8000rpm, get supernatant, regulate supernatant pH value to 6 ~ 7 with 2mol/L formic acid; Repeat to extract once with 5mL ultrapure water, merge twice supernatant, be settled to 10mL with ultrapure water.Now obtain comparatively pure crude extract.
(3) enrichment and purification
First with 1mL methyl alcohol and 1mL ultrapure water activating ion exchange column, reactivation process flow control is at 1-2 drop/sec, get 2mL crude extract injection ion exchange column and carry out purification enrichment, flow control, at 1 drop/sec, then uses 1mL ultrapure water eluent ion exchange column, to remove impurity, last with 1.0mL methanol solution wash-out toxoflavin at twice, nitrogen blows near dry, is settled to 0.4mL, treats that liquid chromatography-tandem mass spectrometry (LC-MS/MS) detects with 50% acetonitrile solution;
(4) LC-MS/MS detects
Liquid-phase condition PhenomenexGeminiC18 chromatographic column (3.0mm × 150mm, 5 μm), column temperature 30 DEG C; Sample size 20 μ L; Mobile phase A is water (containing 0.1% formic acid, 5mmol/L ammonium formate), and B is 95% acetonitrile (containing 0.1% formic acid, 5mmol/L ammonium formate); Condition of gradient elution is in table 1:
Table 1 condition of gradient elution
Time/min |
Flow velocity/μ Lmin
-1 |
A/% |
B/% |
0.0 |
250 |
90 |
10 |
3.0 |
250 |
40 |
60 |
3.01 |
500 |
40 |
60 |
5.0 |
500 |
40 |
60 |
5.01 |
250 |
90 |
10 |
10.0 |
250 |
90 |
10 |
Mass Spectrometry Conditions Ionization mode is electro-spray ionization negative mode (ESI-); Multiple-reaction monitoring pattern (MRM); Collision atmospheric pressure (CAD): 6; Gas curtain atmospheric pressure (CUR): 10; Electron spray voltage (IS) :-4500V; Ion source temperature (TEM): 600 DEG C.
Multiple-reaction monitoring ion pair and the mass spectrum correlation parameter of compound are as shown in table 2.
The multiple-reaction monitoring ion pair of table 2 compound and mass spectrum correlation parameter table
* be quota ion
Experimental result shows, and the recovery of this experimental technique is 92.0% ~ 94.5%, and the coefficient of variation is 1.2% ~ 6.3%.
Embodiment 5
At market stochastic buying 2 parts of fermented flour samples.This method is utilized to carry out the detection of toxoflavin to 2 kinds of products.
(1) sample pre-treatments
Accurately take fermented flour 1.0g, with the ultrapure extraction with aqueous solution toxin of 5mL, 200rpm shaking table concussion 30min, less than the 20 DEG C centrifugal 10min of 8000rpm, get supernatant, regulate supernatant pH value to 6 ~ 7 with 2mol/L formic acid; Repeat to extract once with 5mL ultrapure water, merge twice supernatant, be settled to 10mL with ultrapure water.
Get blank fermented flour and carry out interpolation recovery experiment, toxoflavin Pitch-based sphere is 0.5mg/kg, and pre-treating method is identical with sample method.
(2) enrichment and purification
First with 1mL methyl alcohol and 1mL ultrapure water activating ion exchange column, reactivation process flow control is at 1-2 drop/sec, get 2mL crude extract injection ion exchange column and carry out purification enrichment, flow control, at 1 drop/sec, then uses 1mL ultrapure water eluent ion exchange column, to remove impurity, last with 1.0mL methanol solution wash-out toxoflavin at twice, nitrogen blows near dry, is settled to 0.4mL, treats that liquid chromatography-tandem mass spectrometry (LC-MS/MS) detects with 50% acetonitrile solution;
(3) LC-MS/MS detects
Liquid-phase condition PhenomenexGeminiC18 chromatographic column (3.0mm × 150mm, 5 μm), column temperature 30 DEG C; Sample size 20 μ L; Mobile phase A is water (containing 0.1% formic acid, 5mmol/L ammonium formate), and B is 95% acetonitrile (containing 0.1% formic acid, 5mmol/L ammonium formate); Condition of gradient elution is in table 1:
Table 1 condition of gradient elution
Time/min |
Flow velocity/μ Lmin
-1 |
A/% |
B/% |
0.0 |
250 |
90 |
10 |
3.0 |
250 |
40 |
60 |
3.01 |
500 |
40 |
60 |
5.0 |
500 |
40 |
60 |
5.01 |
250 |
90 |
10 |
10.0 |
250 |
90 |
10 |
Mass Spectrometry Conditions Ionization mode is electro-spray ionization negative mode (ESI-); Multiple-reaction monitoring pattern (MRM); Collision atmospheric pressure (CAD): 6; Gas curtain atmospheric pressure (CUR): 10; Electron spray voltage (IS) :-4500V; Ion source temperature (TEM): 600 DEG C.
Multiple-reaction monitoring ion pair and the mass spectrum correlation parameter of compound are as shown in table 2.
The multiple-reaction monitoring ion pair of table 2 compound and mass spectrum correlation parameter table
* be quota ion
(4) testing result
The recovery of method is 92.5%.
After the testing result of sample is corrected by the recovery, obtain final testing result: in fermented flour No. 1 sample, toxoflavin content is 0.32mg/kg, in fermented flour No. 2 samples, toxoflavin content is not for detect.