CN103257199A

CN103257199A - Method of determining residual quantity of methylmercury in aquatic products

Info

Publication number: CN103257199A
Application number: CN201210035620XA
Authority: CN
Inventors: 宋薇
Original assignee: Pony Testing Co ltd
Current assignee: Pony Testing Co ltd
Priority date: 2012-02-17
Filing date: 2012-02-17
Publication date: 2013-08-21

Abstract

The invention relates to a method of determining a residual quantity of methylmercury in aquatic products. The method comprises mixedly extracting samples by a given volume of hydrochloric acid of a certain concentration and a sodium chloride solution, extracting with toluene, stripping with an L-cysteine solution, deriving with a given volume of derivative agents of two concentrations, pre-treating with n-hexane extraction, measuring the methylmercury by using a gas chromatography-mass spectrometry, wherein a temperature of an introduction port of the gas chromatography is set to be 250-300 DEG C, a carrying gas is set as a constant voltage mode, a nonpolar chromatographic column is selected and an interface temperature is 260-300 DEG C, passing the pre-treated sample through the gas chromatography and then into the chromatographic column, then heating, separating the sample in the chromatographic column, then entering into the mass spectrometry, determining nature of the sample according to a retention time of object compounds, characteristic ions and an abundance ratio, and determining an amount of the sample by an external-standard peak-area method. The method provided by the invention has advantages of accurate analysis method, good selectivity, high sensitivity and small interference.

Description

The assay method of methyl mercury residual quantity in a kind of aquatic products

Technical field

The present invention relates to the assay method of methyl mercury residual quantity in a kind of aquatic products, particularly relate to a kind of method of using gas chromatograph-mass spectrometer (GCMS) to measure methyl mercury residual quantity in the aquatic products

Background technology

Methyl mercury is a kind of neurovirulent environmental contaminants that have, the main central nervous system of invading, can cause language and memory capability obstacle etc. the main position of its infringement is occipital lobe and the cerebellum of brain, its neurotoxicity may and cause the neurocyte abnormal gene expression with the reuptake of upsetting glutamic acid, generally speaking, organomercurial toxicity is stronger than inorganic mercury, methyl mercury is one of the strongest mercury compound of organic mercury poisoning, owing to have lipophilicity, biological accumulation effect and biological amplification, its toxicity is the hundred times of inorganic mercury.

The inorganic mercury that discharges in the environment methylates under certain condition and generates the bigger methyl mercury of toxicity, and concentrated also enrichment can be to tens thousand of times from water by fish and shellfish, and for example the methyl mercury concentration in the Japanese Minamata bay fish body reaches 1-20mg/kg.The methyl mercury major part that enters human body absorbs through alimentary canal, skin, lung, the intestinal absorption rate is more than 95%, thereby harm humans health, in today that food security receives much attention, accuracy is strong, highly sensitive, selectivity is good, disturb little detection method significant to set up one.

Existing methyl mercury detection method, sample preparation are with mercapto-cotton enrichment, and the test of gas chromatography packed column ECD detecting device is main.The Sulfhydryl Cotton processing procedure wastes time and energy, and the Sulfhydryl Cotton of handling be difficult for to be preserved, and in the enrichment methyl mercury with impurity also enrichment, contaminating impurity instrument desensitization, and the ECD detecting device has only retention time qualitative.The instruments of mentioning in the common bibliographical information such as GC-AAS, HPLC-AFS are online cumbersome in addition, and the appliance requires special use, the difficult realization detection methyl mercury that routinizes.And the derivative products after most of detection method is derived all exists stable inadequately, and detection sensitivity is low, the shortcoming of selectivity and accurate qualitative difference.

Summary of the invention

The technical problem to be solved in the present invention is, avoid above-mentioned the deficiencies in the prior art part and propose the method for methyl mercury residual quantity in a kind of, gauge water product can be accurately qualitative by gas chromatograph-mass spectrometer (GCMS): this analytical approach derivant is stable, selectivity is good, adopt hydrochloric acid, sodium chloride solution to extract, tetraphenylboron sodium derivation process GCMS method for measuring, operation is simple in pre-treatment, do not need complicated enrichment to handle, sample is after the reextraction derivation process, the simple background of matrix disturbs little, does not pollute instrument.GCMS employing characteristic ion and retention time are dual qualitative, qualitative more accurate, and highly sensitive.

The technical scheme that the present invention solve the technical problem employing is:

Propose the assay method of methyl mercury residual quantity in a kind of aquatic products, may further comprise the steps:

1. utilize finite concentration hydrochloric acid and the sodium chloride solution of deciding volume to mix extraction, the toluene extraction, L-halfcystine solution is stripped, the pre-treatment of n-hexane extraction again after the derivating agent of two kinds of concentration of certain volume is derived;

2. will detect with gas chromatograph-mass spectrometer (GCMS) through the sample solution of pre-treatment.

The concrete steps of step in 1. are: take by weighing preparation sample 1g in the 50ml centrifuge tube, add 6mol/L hydrochloric acid solution 5mL, ultrasonic extraction 30min.After the extract cooling, add 10% sodium-chloride water solution 10mL, add 5ml toluene behind the vortex 3min, with the centrifugal 5min of the rotating speed of 4000r/min, shift toluene layer, repeating 5ml toluene extracts twice, use 5mL after merging three toluene layers, be transferred in the 15ml centrifuge tube behind the 1%L-halfcystine aqueous solution reextraction toluene layer, wherein add 1mL, 0.1% sulfuric acid solution acidifying, make and add 1ml copper/saturated copper sulphate solution and 0.2mL under the condition of its PH=3,0.1% sodium tetraphenylborate solution is derived, and adds 1ml normal hexane vibration 30min extraction again, gets extract.

Step 2. in, GC conditions is: DB-5MS 15m * 0.25mm * 0.1um chromatographic column, injector temperature is 280 ℃, injection port pressure 25.1kpa, the sample introduction pattern is split sampling, and temperature programme keeps from 50 ℃ that the speed with 10 ℃ of per minutes is warmed up to 150 ℃ behind the 1min, speed with 30 ℃ of per minutes is warmed up to 280 ℃, 10: 1 split ratio then.The mass spectrum condition adopts 280 ℃ of interface temperature, the EI ion gun, and 230 ℃ of temperature, detector voltage is 1.1Kv, selects 279,292,294 to be characteristic ion, wherein 294 is quota ion.

Compare with prior art, beneficial effect of the present invention is:

1, adopting 6mol/L hydrochloric acid solution of the present invention and 10% sodium chloride solution ratio is that 2: 1 15mL extract carries out pre-treatment, and extraction efficiency height, background disturb little.

2, adopt 1ml copper/saturated copper sulphate solution of the present invention and 0.2mL0.1% sodium tetraphenylborate solution to derive, derivative compound is stable, and is highly sensitive on mass detector.

3, adopt the gas chromatograph-mass spectrometer (GCMS) under the appropraite condition of the present invention to detect, compare existing single gas chromatographic technique that adopts, method selectivity height is qualitative accurate.

Description of drawings

The methyl mercury total ion current journey chromatogram of Fig. 1 for detecting in the embodiment of the invention 1, ordinate represents the intensity of total ion current, and horizontal ordinate represents retention time, and unit is minute;

Fig. 2 by in the embodiment of the invention 1 the chromatography of ions peak of 279,292,294 3 ions of detection methyl mercury, ordinate represents the ionic strength of its corresponding ion, horizontal ordinate represents retention time, unit is minute;

The methyl mercury canonical plotting of Fig. 3 for detecting in the embodiment of the invention 1, ordinate represents the quota ion chromatographic peak area in this typical curve, the concentration of horizontal ordinate represent methylidene mercury, unit is ng/mL;

Embodiment

Below in conjunction with accompanying drawing the present invention is described in further details.

Experiment condition: the model of using the production of Tianjin, island company detects for the 2010Plus gas chromatograph-mass spectrometer (GCMS), used organic reagent is chromatographically pure, inorganic reagent is that top grade is pure, the gas chromatograph condition of gas chromatograph-mass spectrometer (GCMS) is: the DB-5MS that chromatographic column selects for use Agilent company to produce, 15m * 0.25mm * 0.1um capillary column, injector temperature is 280 ℃, injection port pressure 25.1kpa, the sample introduction pattern is split sampling, temperature programme, keep being warmed up to 150 ℃ with 10 ℃ of per minutes behind the 1min from 50 ℃, be warmed up to 280 ℃ with 30 ℃ of per minutes then, 10: 1 split ratio.The mass spectrum condition adopts 280 ℃ of interface temperature, the EI ion gun, and 230 ℃ of ion source temperatures, detector voltage is 1.1Kv, selecting characteristic ion 294 is quota ion, 279 and 292 qualitative ions.Computer system record mass spectrum figure.

It is as follows to use the specific embodiment that above-mentioned test condition does:

Embodiment 1

Be solvent with toluene, press table 1 preparation methyl mercury series standard solution, carry out pre-treatment by above-mentioned experiment condition, gas chromatograph-mass spectrometer (GCMS) carries out analyzing and testing, Fig. 1 by the total ion current journey chromatogram of detection methyl mercury, Fig. 2 is corresponding selectivity ion process flow diagram, ordinate represents ionic strength among two figure, and horizontal ordinate represents retention time, known to Fig. 1, the object appearance time is suitable, and retention time is 5.198min.With peak area concentration is mapped, according to 3 horizontal survey results of each standard point, set up the typical curve of methyl mercury, as shown in Figure 3, the ordinate in this canonical plotting represents quasi-molecular ions area analog value, and horizontal ordinate represents concentration.Be Y=12736.24X+0.0 referring to Fig. 3 gained typical curve funtcional relationship, its linear relationship number is R ²=0.9996, this shows that this typical curve has the favorable linearity correlativity, and the instrument detection limit that utilizes this gas chromatograph-mass spectrometer (GCMS) to detect reaches 0.1 μ g/kg.

Table 1 series standard solution concentration

Embodiment 2

Accurately take by weighing preparation sample 1g in the 50ml centrifuge tube, add 6mol/L hydrochloric acid solution 5mL, ultrasonic extraction 30min.After the extract cooling, add 10% sodium-chloride water solution 10mL, add 5ml toluene behind the vortex 3min, with the centrifugal 5min of the rotating speed of 4000r/min, shift toluene layer, repeating 5ml toluene extracts twice, use 5mL after merging three toluene layers, shift extract behind the 1%L-halfcystine aqueous solution reextraction toluene layer to the 15ml centrifuge tube, wherein add 1mL, 0.1% sulfuric acid solution acidifying (PH=3), 1ml copper/saturated copper sulphate solution and 0.2mL, 0.1% sodium tetraphenylborate solution is derived, and adds 1ml normal hexane vibration 30min extraction again, and gas chromatograph-mass spectrometer (GCMS) carries out analyzing and testing.This sample has been made 3 parallel sample, and test number is respectively A, B, C, and analysis result sees Table 2, and to test number A replication 6 times, analysis result sees Table 3.Known that by table 2 relative standard deviation of parallel sample is.Known that by table 3 relative standard deviation of repeated test is.

The residual quantity of methyl mercury in the table 2 aquatic products tissue

This aquatic products of table 3 is organized reperformance test

Embodiment 3

With the standard solution among the embodiment 1, decide in the aquatic products organized processing sample that is added to embodiment 2 of concentration, test according to above-mentioned sample pretreatment process and instrument test condition, this sample is done six mark-on content, and the sample replication of each mark-on content is averaged for three times, according to actual addition and measured value, calculate the recovery of standard addition of this sample, experimental result sees Table 4, and as shown in Table 4, the recovery of standard addition of sample is between 89.9%-109%.

The recovery of standard addition of this sample of table 4

Addition/ng	1	2	3	4
					Mean value/the ng of actual measurement	50	100	200	500
The recovery, %	89.9	90.4	90.2	109

Embodiment 4:

Carry out dependence test with above-mentioned methyl mercury method of testing, its series standard solution coefficient R ²＞0.999, the relative standard deviation of parallel sample＜5%, the relative standard deviation of repeated test＜2%, the recovery of standard addition of sample reaches between the 80%-120%, shows that described method is applicable to the mensuration of the residual quantity of methyl mercury in the aquatic products.

The above embodiment has only expressed preferred implementation of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention; Should be pointed out that for the person of ordinary skill of the art without departing from the inventive concept of the premise, can also make some improvement, these all belong to protection scope of the present invention; Therefore, all equalizations of doing with claim scope of the present invention change and modify, and all should belong to the covering scope of claim of the present invention.

Claims

1. the assay method of methyl mercury residual quantity in the aquatic products is characterized in that: comprises the steps,

(1) utilize finite concentration hydrochloric acid and the sodium chloride solution of deciding volume to mix extraction, the toluene extraction, L-halfcystine solution is stripped, the pre-treatment of n-hexane extraction again after the derivating agent of two kinds of concentration of certain volume is derived;

(2) measure residual methyl mercury in the aquatic products with gas chromatograph-mass spectrometer (GCMS), used instrument injector temperature is set at 250 ℃-300 ℃, carrier gas is constant voltage mode, is set at 25.1Kpa, and chromatographic column is selected non-polar column, 260 ℃-300 ℃ of interface temperature;

(3) make treated described sample enter in the described chromatographic column by the gas chromatograph injection port, carry out temperature programme, keep from 50 ℃ that the speed with 10 ℃ of per minutes is warmed up to 150 ℃ behind the 1min, speed with 30 ℃ of per minutes is warmed up to 280 ℃ then, and the target compound in the described sample separates from described chromatographic column;

(4) the described sample that is separated by chromatographic column, interface by described chromatograph-mas spectrometer enters mass detector and detects, ion gun adopts the EI source, carries out qualitatively with the retention time of target compound and characteristic ion and abundance ratio, and the external standard peak area method is quantitative.

2. the assay method of methyl mercury residual quantity in a kind of aquatic products according to claim 1, it is characterized in that: described step 1. in, decide the finite concentration hydrochloric acid of volume and sodium chloride solution and mix and be extracted as: the 6mol/L hydrochloric acid solution of 5mL and 10% sodium chloride solution of 10mL.

3. the assay method of methyl mercury residual quantity in a kind of aquatic products according to claim 1 is characterized in that: described step 1. in, the derivating agent of two kinds of concentration of certain volume is: 0.1% sodium tetraphenylborate solution of 1ml copper/saturated copper sulphate solution and 0.2ml.

4. the assay method of methyl mercury residual quantity in a kind of aquatic products according to claim 1, it is characterized in that: described step 3. in, the best mode of described temperature programme is: keep from 50 ℃ that the speed with 10 ℃ of per minutes is warmed up to 150 ℃ behind the 1min, the speed with 30 ℃ of per minutes is warmed up to 280 ℃ then.

5. the assay method of methyl mercury residual quantity in a kind of aquatic products according to claim 1 is characterized in that: described step 4. in, the ion gun voltage of mass detector is 1.1Kv, ion source temperature is set at 230 ℃.