Inductively coupled plasma mass spectrometry method for simultaneous determination of chromium, nickel, arsenic and lead in hot melt adhesive for cigarette

Technical Field

The invention belongs to the technical field of chemical test, in particular relates to tobacco hot-melt adhesive of the heavy metals in the measuring method.

Background Art

Hot-melt adhesive for tobacco cigarette processing technology to meet performance requirements, can be applied in processing the cigarette, conforms to the food hygiene standard hot melt adhesive. Wherein the content of heavy metal as a security health indicators public attention has been increasingly, the world health organization recommends that the chromium, nickel, arsenic, heavy metals such as lead and control them. YC/T   187-2004 arsenic and lead to the cigarette by hot-melt adhesive of the limiting requirements, its detection method are respectively reference GB/T   7686-2008 and GB/T   7532-1987 and visual with the lead content and obviously limited method, and lead examination arsenic according to the above method, step tedious operation, low sensitivity, and limited to measure the concentration, in the sample in batches not suitable for the determination of the heavy metal elements. The xu Aifei microwave digestion-graphite furnace atomic absorption spectrometry As element in the hot-melt adhesive, the method adopts the nitric acid-hydrofluoric acid-hydrochloric acid- nitric acid arrowhead -hydrogen peroxide counteracting system, wide variety of the solvent used, and the graphite furnace atomic absorption spectrometry multielment the simultaneous detection is difficult to realize.

Content of the invention

In order to overcome the deficiency of the prior art, the present invention provides a device utilizing inductively coupled plasma mass spectrometry in the hot-melt adhesive for simultaneous determination of chromium, nickel, arsenic, lead content method. The assay method comprises the following steps:

A.   sample prepared to: the hot-melt adhesive sample is crushed and seal for subsequent use;

B.   pre-reaction: in 0.2g in a sample of the hot-melt adhesive to join 5 ml   65%   HNO₃, sample is then heated to melt the hot melt adhesive, cooling to room temperature;

 Digestion constant c.: the melting is sequentially added in the hot-melt adhesive particle 1mL65%   HNO₃ and 1mL30%   H₂ O₂ rear, for microwave digestion to exert counteracting in accordance with the following steps of : (1) from the room temperature after 5 min heating to 100 the thermal insulation after [...] 5 min ; (2) by the 100 [...] after 5 min heating to 130 the insulation after [...] 5 min ; (3) the utility 130 [...] after 5 min heating to 160 the insulation after [...] 5 min ; (4) is the 160 [...] after 5 min heating to 190 the [...] , then thermal insulation 30 min to the temperature after the 40 [...] , then constant volume to 30 ml is the sample to be measured;

D. working solution   preparing standard series: are respectively accurately move 10 mg/L of chromium, nickel, arsenic, lead heavy metal elements mixed standard solution, using 2% HNO₃ constant volume after dilution, the concentration of respectively 0 subsidence g/l, 0.1 subsidence g/l, 0.2 subsidence g/l, 0.5 subsidence g/l, 1 subsidence g/l, 2 the g/l the, 5 the g/l, 10 subsidence g/l, 20 the and g/l 100 the chromium g/l, nickel, arsenic, lead series mixed standard working solution;

E.   inductively coupled plasma mass spectrometry: the sign enters in the method the sample to be inserted into the 1 the   internal standard solution g/mL, at the same time, the sample tube are orderly inserted into a standard solution for the above-mentioned different concentrations, and the blank solution is measured in the sample to be measured.

The technical progress made in this invention:

1, because the invention uses nitric acid-hydrogen peroxide system microwave digestion pre-processing, the inductively coupled plasma mass spectrometry detection (ICP-MS) in hot-melt adhesive for chromium, nickel, arsenic, lead content, simplifies the pre-processing and detection method is realized at the same time the simultaneous determination of multiple, and has high sensitivity, wide linear range, spectral line is simple, the detection limit is low, and the like;

2, in the present invention, chromium, nickel, arsenic, the linear correlation coefficient of 0.9993-1.000, the linear range is wide, linear better; 6 of the parallel determination of the relative standard deviation (RSD) 2.04%-4.23%, note the method of the invention good repeatability; and the recovery of 95.2%-118.1%, good recovery rate, high accuracy of the method of the invention; the detection limit (3SD) to 0.012   μg/L-0.093   μg/L, loqs (10SD) to 0.039   μg/L-0.309   μg/L, can be realized in hot-melt adhesive to the cigarette chromium, nickel, arsenic, the accurate quantification of the lead, the operation is simple, fast, the result is accurate, reliable, hot-melt adhesive for tobacco in the various heavy metal element chromium, nickel, arsenic, the simultaneous determination of the lead content.

Description of drawings

Figure 1 is of injected in the hot-melt adhesive of chromium, nickel, arsenic, lead content.

Mode of execution

The following specific embodiment with further description of the present invention.

This embodiment adopts the instrument, material and reagent:

1, apparatus: of the United States Company Agilent 7500cX-shaped inductively coupled plasma mass spectrometer; the United States of CEM MarsXpress-type microwave resolution device; Shanghai microwave stands Yao the production of chemical technology Company DKQ-4 type intelligent controlled electric water heater; the production of Mettler   Toledo Company of Switzerland identical 0.0001g the   AB204-S type electronic balance; the United States Company Millipore Milli-Q   Advantage the production of ultra-pure water treatment system.

2, material and the reagent: 8 sample hot-melt adhesive for share smoke (China's tobacco provide standardization research center); 65% concentration of quality HNO₃, 30% quality concentration H₂ O₂; heavy metal elements mixed standard solution (10 mg/L, Agilent); internal standard solution (100 subsidence g/mL the⁶ Li, Sc, Ge, Y, In, Bi mixed internal standard solution, Agilent, before use 2%   HNO₃ diluted to 1 subsidence g/mL); harmonious fluid (10 subsidence g/l   Li, Y, Ce, Tl and Co mixed standard solution, the United States Company Agilent); purity of 99.999% Ar of gas.

Specific determination process is as follows:

A.   sample prepared to: the hot-melt adhesive sample cutting to length of about 2 mm after the particles sealed spare;

B.   pre-reaction: accurate weighing the hot-melt adhesive particle 0.2g, the tetrafluoroethylene-full the fluorine is positive propyl vinyl ether copolymer (PFA) in digestion tank, adding 5 ml   65% concentration of quality HNO₃ on the electric heater for the 100 [...] heated to melt the particles, and then taking out digestion tank cooling to room temperature;

 Digestion constant c.: in the above-mentioned melt is sequentially added in the hot-melt adhesive particle 1mL65% of the   mass concentration HNO₃ and 1mL30% of the   mass concentration H₂ O₂ the rear, is put into the microwave resolution device, in accordance with the following table 1 temperature programming steps digestion, counteracts, wait for the temperature to fall below the 40 taken out after [...] digestion tank, then the digestion tank transfer to the sample of the sample bottle polyethylene terephthalate (PET), ultra-pure water for washing inner tank 3 or more times, fluid is transferred to the sample bottle latter constant volume to 30 ml sample to be measured is, then using the same preparation method of sample blank solution;

D. working solution   preparing standard series: are respectively accurately move 10 mg/L of chromium, nickel, arsenic, lead heavy metal elements mixed standard solution, using 2% HNO₃ constant volume after dilution, the concentration of respectively 0 subsidence g/l, 0.1 subsidence g/l, 0.2 subsidence g/l, 0.5 subsidence g/l, 1 subsidence g/l, 2 the g/l the, 5 the g/l, 10 subsidence g/l, 20 the and g/l 100 the chromium g/l, nickel, arsenic, lead series mixed standard working solution;

Instrument working conditions: in order to 10 the the g/l   Li, Y, Ce, and Tl mixed Co to the instrument standard solution the most optimized and selected working conditions, optimization parameter in table 2:

E.   inductively coupled plasma mass spectrometry: use the standard method is used for correction. After the tuning instrument, is inserted into the sample the sign enters 1 the   internal standard solution g/mL, at the same time, the sample tube are orderly inserted into a standard solution for the above-mentioned different concentrations, and blank solution in the sample to be measured, a sample introduction system through the peristaltic pump to pump internal standard solution with the sample solution in the sample tube is transmitted to the three-way device enters the atomizer in measured after mixing. In order to avoid cross-contamination of the sample, for each data acquisition and 5%   HNO₃ and ultra-pure water are respectively flush line 1 min, then the determination of the next sample.

The hot-melt adhesive in the above-mentioned measured chromium, nickel, arsenic, lead content of the sample can be obtained by the following formula in which chromium, nickel, arsenic, the content of lead:

In the formula:

X- in the sample to chromium, nickel, arsenic, the content of lead, the unit is μg/g;

C- sample liquid concentration, the unit is μg/L;

C₀-sample blank solution concentration, the unit is μg/L;

The volume V- sample solution, the unit is ml;

M- sample quality, the unit is g.

This embodiment the choice of the digestion reagent:

The nitric acid used in the invention is an inductive coupling plasma mass spectrometric analysis of the acid medium is the most good, N the nitric acid, O and H three elements of the plasma are entrained in the gas containing, will not introduce new multiatom ion interference, but also nitric acid is extremely pure form can be obtained of one of a small number of commodity acid, is very suitable for trace elemental analysis. Microwave digestion is the commonly used hydrogen peroxide is an oxidizing reagent, similar to with the water because of its background, will not introduce new multiatom ion interference, usually added to the nitric acid mixed for use, can reduce the generation of nitrogen oxides and increased digestion temperature, therefore can reduce the consumption of the nitrate, to accelerate the digestion of the organic sample.

The choice of the pre-reaction time:

Because the hot-melt adhesive in order to basically resin as the base material, the basic resin is ethylene, polymerized vinyl acetate, and the like, added directly to the nitric acid in the closed environment microwave digestion is easy to generate a large amount of heat and the burst may occur, therefore, the invention firstly adding 5 ml   HNO₃ pre-reaction of the hot-melt adhesive, to be hot-melt adhesive solid melt, yellow smoke had been lost after, adding 1mLHNO₃ and 1mLH₂ O₂ microwave digestion. The 30 min, 60 min and 90 min time point pre-reaction analysis, found pre-response 30 min then, hot-melt adhesive particle has not yet been completely melted, the solution is yellow opacitas shape ; pre-reaction 60 min later, the basic melted hot-melt adhesive particle, to clarify the solution, in accordance with the sample testing requirements; pre-reaction 90 min after the remaining amount of acid is easy to occur the phenomenon of even does the pot too, therefore pre-reaction 60 min, of a burst without the, and the pre-reaction of the sample after digestion more completely.

And since the choice of the volume of volume:

And since the choice of the volume of volume of the element is in two important factors, the sequentially 0.1g, 0.2   g, 0.3g, 0 . 4g, 0.5g this 5 contacting a, are respectively constant volume to 30 ml and 50 ml for analysis, digestion of the solution state as shown in table 3. if constant volume to 30 ml, sampling 0.1g and 0.2g, after digestion volume is colorless clear solution, in accordance with the sample testing requirements; if the constant volume to 50 ml, sampling 0.1g and 0.2g, constant volume of the solution is colorless clarification, sampling 0.3g, constant volume of the solution is clear, can be sees calls the type 0.1g, 0 . 2g, 0.3g in the test sample. Taking into account if sampling 0.1g, since the relatively small, the representation of the sample test will be affected, and because the hot-melt adhesive of the content of the heavy metal elements in low, if the constant volume to 50 ml, sample concentration is low, it is difficult to reach the required sensitivity, therefore selection for the sampling quantity 0.2g, constant volume to 30 ml for testing.

The working curve, the correlation coefficient, the detection limit and loqs:

Are respectively accurately move 10 mg/L of the heavy metal elements mixed standard solution to 50 ml in plastic capacity bottle, using 2% HNO₃ dilution constant volume, respectively, of the obtained 0 subsidence g/l, 0.1 subsidence g/l, 0.2 subsidence g/l, 0.5 subsidence g/l, 1 subsidence g/l, 2 the g/l the, 5 the g/l, 10 subsidence g/l, 20 the and g/l 100 the mixed g/l standard series of working solution, and ICP-MS detection. To the content of the target element to be measured (X, μg/L) of the target element to be measured with the internal standard elements in response to ratio the intensity of the (Y) for linear regression, the chromium, nickel, arsenic, lead the 4 kinds of elements of the standard curve and the correlation coefficient (table 4). From table 4 can be known, the elements of the linear relationship of good working curve, the correlation coefficient is 0.9993-1.000.

Preparing blank solution and analyzed, parallel experiment 11 time, the measured value of to 3 times of a standard deviation (3SD) and 10 times of a standard deviation (10SD) corresponding to the detection limit of the content of the and loqs. The results (table 4) display, 4 elements in the detection limit 100   ng/L the following.

Precision and recovery rate:

A hot-melt adhesive to the processing and testing samples, weighing 6 parts of parallel sample hot-melt adhesive, by microwave digestion measured after 4 heavy metal element content, the relative standard deviation is calculated, the results (table 5) show that, for precision 2.04%-4.23%.

Accurate weighing 3 copy of the hot-melt adhesive used for testing precision parallel sample, microwave digestion tank is, according to the samples by selecting the content of the element in the mixing of the standard solution concentration, for processing and analysis, results (table 6) display, and the recovery rate of the sample 95.2%-118.1%.

Hot-melt adhesive of chromium in the sample, nickel, arsenic, the content of lead:

The 8 parts hot-melt adhesive for testing a sample, the results (table 7) display, the measured 4 elements of the content of the whole trend Cr>Ni>Pb>As, as shown in Figure 1, wherein the" "Wherein said the content of Cr," "Said injected As content," "Injected that the content of Ni," " Trends in that the content of the Pb map. The content of Ni and Pb in the calorimetric melt adhesive has a great difference between, its coefficient of variation are 86.6% and 81.8%.

Note: "-" representative not be detected.