CN102095815A - Method for determining musk xylene in washing products - Google Patents

Abstract

The invention relates to a method for determining musk xylene in washing products by gas chromatography-mass spectrometry or mass spectrometry. The method is accurate and reliable, and the detection limit, the recovery rate and the precision meet the requirement. The method has good reproducibility in detecting the washing products. The method established by the invention is convenient in operation, has accurate result, and can be used for determining musk xylene in the washing products.

Description

The assay method of musk xylene in a kind of articles for washing

Technical field

The present invention relates to the assay method of musk xylene in a kind of articles for washing.

Background technology

Musk xylene:

English name: 5-tert-butyl-2,4,6-trinitro-m-xylene (musk xylene)

CAS：81-15-2

Molecular formula: C ₁₂H ₁₅N ₃O ₆

Molecular weight: 297.3

Structural formula:

Musk xylene (Musk xylene) chemical name 2,4,6-trinitro--1,3-dimethyl-5-tert-butyl benzene is the nitroaromatic Moschus compound of synthetic, is commonly used for the fixastive of cosmetics and fragrance for detergents.Musk xylene is as high persistence, high biological accumulation material, by chemicals management administration of European Union (European Chemicals Agency, ECHA) classify as high pay close attention to material (Substances of Very High Concern, SVHC).The regulation musk xylene is to limit the use of material (must not be used for dental care product) in the components of cosmetics in China's cosmetics health standard and the European Union's cosmetics rules (CouncilDirective 76/768/EEC), and limiting the quantity of in essence, floral water and other products is respectively 1.0%, 0.4% and 0.03%.(International Fragrance Association IFRA) plans to recommend in the 44th revised draft of IFRA standard musk xylene should not use as the daily use chemicals fragrance component to international daily use chemicals fragrance association.(Research Institute for Fragrance Materials RIFM) advises that also musk xylene must not be used for lip with product or dental care product in international daily use chemicals spices research institute.

The research report that detects about musk xylene mainly concentrates on aspects such as cosmetic sample, biological sample, environmental sample, and the method that relates to mainly comprises thin-layered chromatography (TLC), capillary electrophoresis (CE), gas chromatography-electron capture detection method (GC-ECD), gas chromatography-mass spectrography (GC-MS), gas chromatograph-high resolved mass spectroscopy (GC-HRMS), gas chromatography-tandem mass spectrometry (GC-MS-MS), nuclear magnetic resonance method (NMR) etc.

Summary of the invention

Technical matters solved by the invention provide a kind of accurately, reliable, the method for the micro-musk xylene in all higher fast measuring articles for washing of detectability, the recovery and precision is beneficial to the quality monitoring of Related product.

For achieving the above object, the technical solution used in the present invention is as follows: the assay method of musk xylene in a kind of articles for washing may further comprise the steps:

(1) sample is handled: accurately take by weighing articles for washing sample 0.500g in the 10mL color-comparison tube, accurately add the 1mg/L deuterium for musk xylene inner mark solution 0.1mL, add methyl alcohol again to 10mL, behind the vortex vibration 2min, get the 2mL supernatant, after slowly drying up with nitrogen, add 2mL methylene chloride dissolved residue, be transferred to solid-phase extraction column, discard direct effluent, use 2mL methylene chloride wash-out again; Collect eluent, after slowly drying up with nitrogen, accurately add 1mL n-hexane dissolution residue, excessively behind the miillpore filter, for measuring;

(2) measure: adopt gas chromatography-mass spectrum/mass spectroscopy; Chromatogram column temperature wherein:

Injector temperature: 250 ℃; Chromatography-mass spectroscopy interface temperature: 250 ℃; Ion source temperature: 100 ℃; Carrier gas: helium, purity 〉=99.999%; Flow velocity: 1.0mL/min; Sample size: 1 μ L;

(3) drawing standard working curve: accurately draw a certain amount of musk xylene standard solution and deuterium respectively and be mixed with the hybrid standard working solution of a series of variable concentrations for the musk xylene inner mark solution, wherein deuterium is 100 μ g/L for musk xylene concentration; Accurately draw 1 μ L injection gas chromatography-series connection quadrupole mass spectrometer respectively, according to detecting under the above-mentioned analysis condition, ratio with standard substance and the peak area of interior target quota ion is an ordinate, and the concentration corresponding with it is horizontal ordinate, the drawing standard working curve.

The inventive method adopts the musk xylene in gas chromatography-mass spectrum/mass spectrometric determination articles for washing, and method is accurate, reliable, and detectability, the recovery and precision all meet the requirements.Method is applied to the articles for washing sample detection, and reappearance is good.The method of inspection that the present invention sets up is easy and simple to handle, the result is accurate, can be used for the check of musk xylene in the articles for washing.

Description of drawings

Fig. 1 is the cleavage of mass spectrum mode of musk xylene;

Fig. 2 is the MRM chromatogram of musk xylene.

Embodiment

For further specifying the present invention, specify with the following Examples:

1, reagent and material: except as otherwise noted, it is pure that agents useful for same is analysis.

1.1 methylene chloride.

1.2 methyl alcohol.

1.3 normal hexane.

1.4 musk xylene standard substance: purity 99.5%.

1.5 deuterium is for marking standard substance in the musk xylene: purity 97.5%.

1.6 musk xylene standard reserving solution: accurately take by weighing 10mg (being accurate to 0.0001g) musk xylene standard items in the 100mL volumetric flask, be diluted to scale with normal hexane, mixing, the concentration of this solution is 100mg/L.

1.7 deuterium is for marking storing solution in the musk xylene: accurately measure the 1mL deuterium for the musk xylene standard solution in the 10mL volumetric flask, be diluted to scale with normal hexane, mixing, the concentration of this solution is 10mg/L.

1.8 solid-phase extraction column: matrix is silica gel, 500mg, 6mL, or suitable person.Activate with 5mL methyl alcohol, 5mL methylene chloride successively before the use.

2, instrument and equipment

2.1 gas chromatography-series connection quadrupole mass spectrometer (GC-MS/MS): be furnished with chemical ionization source (CI).

2.2 analytical balance: sensibility reciprocal is 0.0001g and 0.001g.

2.3 solid-phase extraction device.

2.4 turbine mixer.

2.5 filter membrane: 0.45 μ m, organic phase.

3, determination step

3.1 sample is handled

Accurately take by weighing articles for washing sample 0.500g in the 10mL color-comparison tube, accurately add the 1mg/L deuterium for musk xylene inner mark solution 0.1mL, add methyl alcohol again to 10mL, behind the vortex vibration 2min, get the 2mL supernatant, after slowly drying up with nitrogen, add 2mL methylene chloride dissolved residue, be transferred to solid-phase extraction column (3.6), discard direct effluent, use 2mL methylene chloride wash-out again.Collect eluent, after slowly drying up with nitrogen, accurately add 1mL n-hexane dissolution residue, behind the miillpore filter (4.5), measure excessively for GC-MS/MS.

3.2 measure

3.2.1 gas chromatography-mass spectrum/mass spectrum condition

Because test result depends on employed instrument, therefore can not provide the general parameter of stratographic analysis.It is suitable adopting following operating conditions to be proved to be test.

A) chromatographic column: DB-5MS quartz capillary column, 30m * 0.25mm (i.d.) * 0.25 μ m, or suitable person;

B) chromatogram column temperature:

C) injector temperature: 250 ℃;

D) chromatography-mass spectroscopy interface temperature: 250 ℃;

E) ion source temperature: 100 ℃;

F) carrier gas: helium, purity 〉=99.999%; Flow velocity: 1.0mL/min;

G) sample size: 1 μ L;

H) input mode: split sampling not, drive valve behind the 0.5min;

I) ionization mode: negative chemical ionization source (CI-);

J) mass scanning scope: (50～1000) amu;

K) ionizing energy: 60eV;

L) trap electric current: 200 μ A;

M) solvent delay: 3min;

N) monitoring mode: multiple-reaction monitoring (MRM).

3.2.2 the drafting of standard working curve

Accurately draw a certain amount of musk xylene standard solution and deuterium respectively and be mixed with the hybrid standard working solution of a series of variable concentrations for the musk xylene inner mark solution, wherein deuterium is 100 μ g/L for musk xylene concentration.Accurately draw 1 μ L injection gas chromatography-series connection quadrupole mass spectrometer respectively, according to experimentizing under the above-mentioned analysis condition, ratio with standard substance and the peak area of interior target quota ion is an ordinate, and the concentration corresponding with it is horizontal ordinate, the drawing standard working curve.

3.3 blank test

Except that not adding the sample, all undertaken by above-mentioned steps.

4, the result calculates

The relative correction factor of musk xylene and internal standard compound, calculate by formula (1):

$R=\frac{A_n\×c_1}{A_1\×c_1}...\left(1\right)$

In the formula:

Target relative correction factor in R---musk xylene and its isotope;

A _n---the peak area of musk xylene standard specimen;

A ₁---the peak area of musk xylene internal standard compound;

C _n---the concentration of musk xylene standard specimen, unit is every liter (mg/L) of milligram;

C ₁---target concentration in the musk xylene isotope, unit is every liter (mg/L) of milligram

The content of musk xylene in the sample, calculate by formula (2):

$X=\frac{A_{\mathrm{sn}}\×m_{s1}}{A_{s1}\×R\×m}...\left(2\right)$

In the formula:

X---musk xylene content in the sample, unit are every kilogram (mg/kg) of milligram;

The relative correction factor of R---musk xylene and internal standard compound;

A _Sn---the peak area of musk xylene in the sample;

A _S1---target peak area in musk xylene during mensuration;

m _S1---target quality in musk xylene during mensuration, unit is a milligram (mg);

The quality of m---sample, unit is a kilogram (kg).

5, the linear relationship of method and detection limit

5.1 linear relationship

Inner mark method ration is selected ion 267.0＞174.9, and 282.1＞190.1 is quantitative.Prepare the series of standards working solution respectively, measure under selected chromatographic condition and mass spectrum condition, in standard items concentration was 5～200ng/mL scope, the linear equation of musk xylene was: Y=0.2047X+0.448, r=0.9993.

5.2 the detection limit of method

Through the laboratory experiment to the method for inspection, the result shows that the mensuration lower bound of method is 0.05mg/kg.

6, the recovery of method and precision

The experiment of the inventive method recovery is by the interpolation situation in the common articles for washing, set three and added concentration, by the determined experiment condition of this method of inspection, each is added concentration carry out 6 tests, musk xylene content is in 0.05～0.5mg/kg scope, and the recovery is 81.6%～92.4%; Indoor precision test (n=6) records relative standard deviation 2.33%～3.89%.

Table 1 recovery and precision experimental result

7, conclusion

Comprehensive above-mentioned situation, the recovery of the method for inspection of the present invention, every technical indicators such as detectability and precision all meet the requirements, and method is applied to the articles for washing sample detection, and reappearance is good.The method of inspection that this standard is set up is easy and simple to handle, the result is accurate, can be used for the check of musk xylene in the articles for washing.

Emphasis of the present invention is optimized above-mentioned chromatographic separation condition:

1, investigated the gas chromatographic column of different fixing liquid, opposed polarity respectively: non-polar column (DB-1MS, 100% dimethyl polysiloxane immobile liquid; DB-5MS, 5% phenyl-95% methyl polysiloxane immobile liquid), middle polarity post (DB-1701,14% cyanogen propyl group-phenyl-86% methyl polysiloxane immobile liquid), the chromatographic resolution effect of strong polar column (HP-INNOWax, polyglycol immobile liquid) P-xylene Moschus.N-octyl alcohol/the water partition coefficient of musk xylene (Kow) is 4.9, belong to the low pole compound, usually contain more nonpolarity element in the cosmetic formulations simultaneously, as grease, wax, fatty acid, alcohol, ester etc., according to " similar mixing " principle, select for use the nonpolar capillary gas chromatographic column of DB-5MS to have selectivity preferably, can effectively eliminate or reduce the inhibition of sample substrate analysans ionization for the chromatographic resolution of interfering material in musk xylene and the matrix.For forming complicated cosmetic sample analysis, need higher post to imitate, so adopt the thin liquid film of lower little bore of 0.25mm of column capacity and 0.25 μ m, run off to reduce chromatographic column, improve post and imitate.The present invention also optimizes parameters such as column temperature program, injector temperature, flow rate of carrier gas, split ratios, finally determines the chromatographic condition of above-mentioned the best.

The selection of 2, ionization mode

Chemical ionization source (CI) and electron bombardment ionization source (EI) all are useful on the bibliographical information that musk xylene detects.The present invention has investigated the ionization effect of musk xylene under CI and EI respectively, the result shows, owing to have electronegative atom (N and O) in the musk xylene molecular structure, it has higher sensitivity at negative chemical ionization source (NCI) than EI and positive chemical ionization source (PCI).CI is as a kind of soft ionization pattern, and background signal is low, and in conjunction with the characteristics of the qualitative pin-point accuracy of second order ms, CI embodies the lower background interference than EI, and does not reduce the advantage of detection sensitivity.Utilize the NCI characteristics strong simultaneously, help to eliminate the target compound chromatogram and be total to the interference that does not contain electronegativity group material that may exist in the eluting peak, so the present invention selects NCI as the ionization mode to the electronegativity group selectivity.

3, the selection of mass spectroscopy condition

The cleavage of mass spectrum mode of musk xylene under NCI ionization mode has the cracking characteristics of nitro-aromatic compound, easily lose a part NO and obtain the base peak ion m/z 267.0 ([M-NO]-) that abundance is higher than molecular ion peak, be to obtain higher detection sensitivity, with it as parent ion.Instruction stipulates must reach for the mass spectrum confirmation method requirements of 4 conclusive evidence points according to the 2002/657/EC of European Union, and the low gas chromatograph-mass spectrometer (GCMS) of differentiating should be selected plural daughter ion on the basis of definite parent ion.Behind the parent ion of determining musk xylene, adopt the daughter ion scan mode to carry out the second order ms analysis, choose the stronger main fragmention m/z 174.9 ([M-NO-2NO2]-) of abundance as quantitatively daughter ion and m/z 146.9 ([M-NO-2NO2-CO]-) are as auxiliary qualitative daughter ion, the cleavage of mass spectrum mode of musk xylene is seen Fig. 1.By optimizing mass spectrum parameters such as collision energy, ion energy, mass resolution, methane gas flow, make the base peak ion of musk xylene and the ion pair intensity of feature fragmention generation reach maximum.Musk xylene and deuterium thereof are seen Fig. 2 for target MRM chromatogram in the isotope.

4, the optimization of sample pre-treatments condition

Musk xylene is insoluble in water, in polarity or middle polarity organic solvent solubleness is preferably arranged, and therefore selecting methyl alcohol is to extract solvent.Investigated the clean-up effect of dissimilar solid-phase extraction column P-xylene Moschus respectively: C18 post (SupelcleanLC-C18, Sep-Pak C18), hydrophilic lipophilic post (Oasis HLB), ketjenblack EC post (Supelclean Envi-Carb) and silicagel column (Sep-Pak Silica).The result shows.The clean-up effect of silicagel column and recovery optimum.The employing silicagel column is a solid-phase extraction column, activates stationary phase with 5mL methyl alcohol earlier, and removes the impurity in the stationary phase, uses 5mL methylene chloride balance again, creates the environment that is fit to go up sample.Test discovery, the last sample liquor capacity of 0～2mL when the sample liquor capacity is gone up in the continuation increase, begins to have musk xylene to flow out not obviously influence of sample recovery rate.Investigated the elute effect of the methyl alcohol-methylene chloride mixed liquor elution circuit (consumption is 2mL) of different proportionings.According to elution curve, with methylene chloride during as leacheate, musk xylene can be by complete wash-out, and the most of impurity in the sample substrate will be retained on the solid-phase extraction column, can not eluted, thus with it as eluent.Further the elution volume of eluent is investigated, the result shows that the 2mL eluent can obtain the best recovery with the complete wash-out of musk xylene.

Above-described embodiment is described preferred implementation of the present invention; be not that scope of the present invention is limited; design under the prerequisite of spirit not breaking away from the present invention; various distortion and improvement that the common engineering technical personnel in this area make technical scheme of the present invention all should fall in the definite protection domain of claims of the present invention.

Claims (1)

1. the assay method of musk xylene in the articles for washing is characterized in that: may further comprise the steps:

(1) sample is handled: accurately take by weighing articles for washing sample 0.500g in the 10mL color-comparison tube, accurately add the 1mg/L deuterium for musk xylene inner mark solution 0.1mL, add methyl alcohol again to 10mL, behind the vortex vibration 2min, get the 2mL supernatant, after slowly drying up with nitrogen, add 2mL methylene chloride dissolved residue, be transferred to solid-phase extraction column, discard direct effluent, use 2mL methylene chloride wash-out again; Collect eluent, after slowly drying up with nitrogen, accurately add 1mL n-hexane dissolution residue, excessively behind the miillpore filter, for measuring;

(2) measure: adopt gas chromatography-mass spectrum/mass spectrometry method; Wherein chromatogram column temperature is warming up to 300 ℃ with the programming rate of 20 ℃/min; Injector temperature: 250 ℃; Chromatography-mass spectroscopy interface temperature: 250 ℃; Ion source temperature: 100 ℃; Carrier gas: helium, purity 〉=99.999%; Flow velocity: 1.0mL/min; Sample size: 1 μ L;

(3) drawing standard working curve: accurately draw a certain amount of musk xylene standard solution and deuterium respectively and be mixed with the hybrid standard working solution of a series of variable concentrations for the musk xylene inner mark solution, wherein deuterium is 100 μ g/L for musk xylene concentration; Accurately draw 1 μ L injection gas chromatography-series connection quadrupole mass spectrometer respectively, according to detecting under the above-mentioned analysis condition, ratio with standard substance and the peak area of interior target quota ion is an ordinate, and the concentration corresponding with it is horizontal ordinate, the drawing standard working curve.

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