CN104833750A - Method for separating and determining chromium elements with different valences in tobacco and tobacco products - Google Patents

Abstract

The invention discloses a method for separating and determining chromium elements with different valences in tobacco and tobacco products. The method comprises the following steps of 1, selecting apparatuses and equipment, wherein the separation and determination device is a high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) combined device, 2, preparing a reagent and a standard solution, 3, pretreating a sample, 4, determining the sample and calculating and expressing a calculation result. The method utilizes the HPLC-ICP-MS combined technology to realize separation and determination of chromium elements with different valences in tobacco and tobacco products, has good effects of analysis, determination and separation of chromium elements with different valences, a low detecting limit, high sensitivity and good repeatability, can detect chromium elements with different valences in a sub-concentration (microgram/liter) level, and in other word, can detect content of Cr(III) and Cr(VI) in tobacco and tobacco products. The method for separation and determination optimizes a sample pre-treatment process and simplifies separation and determination processes.

Description

The method of separating and assaying of different valence state chromium element in tobacco and tobacco product

Technical field

The invention belongs to the method for separating and assaying technical field of different valence state heavy metal element, particularly one grow tobacco and the method for separating and assaying and preparation method thereof of different valence state chromium element in tobacco product.

Background technology

Chromium is widely distributed at occurring in nature, can form more than-2 to+6 kinds of valence state compounds, and modal is Cr (III) and Cr (VI).Wherein, Cr (III) is the necessary element that human body sustains life, and can promote the utilization of glucose in human body; And Cr (VI) thermodynamically stablizes, there is very strong mobility in vivo, with CrO ₄ ^2-and Cr ₂o ₇ ^2-valence state by electronegative cell membrane, and impel oxidation, thus cause pathology to occur, its toxicity is generally 100 ~ 1000 times of Cr (III) toxicity.The different valence state of chromium has visibly different impact for environment and human body, is therefore necessary to further investigate chromium element valence.

For the Determination of Different Valence States of chromium, classic method is that the methods such as AAS or ICP detect total chrome content, with the content of spectrophotometry Cr (VI), total both differences of chromium and Cr (VI) are exactly the content of Cr (III).During this method operating cost, and degree of accuracy is also difficult to ensure.In up-to-date correlative study, Lu Zhaoling etc. utilize Dynamic Reaction Cell to carry out separation determination and migration research to the Cr (III) in municipal sludge and Cr (VI), but with the addition of TBAH RP-ion pair reagent in mobile phase, method has limitation.Xu Min etc. have carried out compartment analysis to the chromium element that can extract in textile, employ TBAH RP-ion pair reagent equally, and there is very big difference due to the matrix in tobacco actual sample and environmental sample, textile etc., therefore its method set up also is difficult in the research of the different valence state chromium element directly applied in tobacco and tobacco product.

Presently, single instrument or technology have been difficult to carry out original position, online, microcell and instantaneous high sensitivity and high-resolution ultimate analysis related work, and Instrument crosslinking technology progressively occupies critical role in modern analysis science.And develop one of comparatively perfect technology as online technology, high performance liquid chromatography (HPLC) and inductivity coupled plasma mass spectrometry (ICP-MS) coupling technique have the features such as high selectivity, the wide range of linearity and low detection limit, can at the content of sub-concentration (μ g/L) horizontal detection chromium element, because being widely used in the fields such as material, environment and life science.At present in relevant report, not yet there is the different valence state analytical approach research about chromium in the tobacco utilizing HPLC-ICP-MS coupling technique to set up.Therefore one is needed can to carry out quantitative measurement for tobacco business person skilled to different valence state chromium element in tobacco and tobacco product, in comprehensive objective evaluation tobacco and tobacco product, the harmfulness of chromium element provides technical support.

Summary of the invention

The object of the present invention is to provide a kind of method adopting High performance liquid chromatography-inductively coupled plasma mass spectrometry coupling means to measure the chromium constituent content of different valence state in tobacco and tobacco product.

To achieve these goals, the method of separating and assaying of different valence state chromium element in tobacco of the present invention and tobacco product, comprise the following steps: (I) selects instrument and equipment, wherein separation determination equipment adopts HPLC-ICP-MS combined system, (II) reagent preparation and standard solution, (III) sample pre-treatments, (IV) sample determination, (V) sample measurement result calculates, and it is characterized in that, concrete technology step is as follows:

(I) select instrument and equipment, wherein separation determination adopts HPLC-ICP-MS combined system, and described instrument and equipment are selected by following condition:

Described combined instrument is furnished with the chromatographic column guard column that filler is styrene-divinylbenzene polymkeric substance, and surface bond has the styrene-divinylbenzene polymkeric substance of quaternary ammonium salt functional group to be the anion-exchange column (can be used for the ultimate analysis of different valence state chromium) of 250mm × 4.1mm × 10 μm as filler, specification;

(2) ultrapure water instrument;

(3) ultrasonic cleaner;

(4) heavy metal special grinder;

(5) climatic chamber;

(6) supercentrifuge, rotating speed is not less than 3500r/min;

(7) electronic balance, degree of accuracy 0.0001g; ;

(8) pH meter;

(9) 0.45 μm of aqueous phase pin type filters;

(II) reagent preparation and standard solution:

(1) hybrid standard storing solution preparation: using 0.3mmol/L disodium ethylene diamine tetra-acetic acid solution as solvent, preparation Cr (III) and Cr (VI) mixed standard solution, and constant temperature 3h under being placed in 50 DEG C of conditions, obtain Cr (III) that content is 1000.0 μ g/L and Cr (VI) hybrid standard storing solution, store under being placed in 0 DEG C ~ 4 DEG C conditions, the term of validity is 1 month.

(2) preparation of series standard solution: by hybrid standard storing solution stepwise dilution, be formulated as Cr (III) and Cr (VI) standard solution of variable concentrations, described series standard solution concentration is respectively 0 μ g/L, 0.5 μ g/L, 1.0 μ g/L, 2.0 μ g/L, 5.0 μ g/L, 10.0 μ g/L and 20.0 μ g/L, and matching while using.

(3) sample treatment liquid: 20mmol/L disodium ethylene diamine tetra-acetic acid solution;

(4) ultrasonic leaching liquor: distilled water;

(5) mobile phase: 0.10mol/L ammonium nitrate solution, regulates pH to be 7.0 with ammoniacal liquor.

(III) sample pre-treatments: by through heavy metal special grinder levigate to 100 object tobacco samples temperature be (22 ± 1) DEG C, after relative humidity is balance 24h in the climatic chamber of (60 ± 2) %, accurately take 1.0000g sample in 50mL PET bottle, add 30mL 20mmol/L disodium ethylene diamine tetra-acetic acid solution, ultrasonic extraction 60min at 50 DEG C, 10mL is pipetted in centrifuge tube after leaving standstill, centrifugal 20min under 3500r/min condition, get supernatant liquor 0.45 μm of aqueous phase pin type frit, obtain treating sample measuring liquid.Blank test should be done in sample pretreatment process simultaneously.

(IV) sample determination: treat that sample measuring liquid uses HPLC-ICP-MS combined instrument to carry out upper machine analysis described in the described series standard solution of preparation and process being obtained:

(1) instrument service condition:

Described liquid chromatograph HPLC condition: mobile phase be with ammoniacal liquor regulate pH be 7.0 0.10mol/L aqueous ammonium nitrate solution, flow velocity is 1.0mL/min; Sampling volume 50 μ L, auto injection;

Described icp ms ICP-MS condition: RF incident power 1550W, RF matching voltage 1.8V; Concentric circles atomizer, carrier gas is argon gas or the argon gas of purity >=99.99%, plasma gas flow speed 15.0L/min, flow rate of carrier gas 1.02L/min, assist gas flow velocity 0.90L/min; Peristaltic pump rotating speed 0.3rps; Sampling depth 8mm; Detection job number m/z=52 (Cr), the residence time is 0.5s (m/z=52);

(2) sample separation measures:

Arrange by described instrument service condition after (i) start, after stable, first use the series standard solution production standard curve prepared, regretional analysis is carried out respectively with the concentration of Cr (III) and Cr (VI) and respective peaks area, obtain respective typical curve, typical curve linearly dependent coefficient (R ²) be all greater than 0.999;

(ii) described in handling well, treat that sample measuring liquid measures to HPLC-ICP-MS combined instrument sample introduction 50 μ L, treat Cr (III) in sample measuring liquid and Cr (VI) chromatographic peak carries out integration, obtain respective peak area respectively, substitute into typical curve, calculate corresponding concentration value, and then try to achieve the content of Cr in sample (III) and Cr (VI).

(iii) result calculates and expresses:

Cr (III) in sample and Cr (VI) content, calculate by formula (1):

$X=\frac{(C-C_0)\×V}{m}...\left(1\right)$

In formula:

The content of Cr (III), Cr (VI) in X-sample, μ g/kg;

The concentration measurement of C-treat Cr in sample measuring liquid (III), Cr (VI), μ g/L;

C ₀the concentration measurement of Cr (III), Cr (VI) in-solvent blank, μ g/L;

The cumulative volume of V-treat sample measuring liquid, mL;

M-sample quality, g.

Represent the content of Cr in sample (III), Cr (VI) with the mean value of the measured value being no less than twice parallel experiment, be accurate to 0.01 μ g/kg.

(4) detection limit of method of separating and assaying of the present invention and quantitative limit:

To the object response signal in standard solution, least concentration standard specimen is adopted to repeat sample introduction 10 times, get that its 3 times of standard deviations are detection limit, 10 times of standard deviations are quantitative limit, as shown in table 2, the detection limit obtaining Cr (III) and Cr (VI) is respectively 0.048 μ g/L, 0.054 μ g/L, and quantitative limit is respectively 0.160 μ g/L, 0.180 μ g/L.

Table 2 the inventive method detection limit and quantitative limit:

Valence state	Typical curve	Related coefficient (R 2)	Detection limit (μ g/L)	Quantitative limit (μ g/L)
					Cr(Ⅲ)	y＝168422x-29.23	0.9999	0.048	0.160
Cr(Ⅵ)	y＝170394x-39.275	0.9998	0.054	0.180

(5) precision of method of separating and assaying of the present invention is with repeated:

Same batch sample is taken 1 part, sample measuring liquid is treated through sample pre-treatments preparation, continuous sample introduction is analyzed for 10 times, calculate the content of Cr (III) and Cr (VI) respectively, the RSD value of 10 experimental results is respectively: 1.05%, 1.28%, all be less than 2%, show that instrument performance is stablized, precision is good.

Same batch sample is parallel takes 10 parts, sample measuring liquid is treated through sample pre-treatments preparation, sample introduction analysis successively, calculate the content of Cr (III) and Cr (VI) respectively, the RSD value of 10 experimental results is respectively: 4.03%, 3.28%, all be less than 5%, show that method repeatability is good.

Compared with prior art, in this tobacco and tobacco product, the method for separating and assaying of different valence state chromium element adopts high performance liquid chromatography (HPLC) and inductivity coupled plasma mass spectrometry (ICP-MS) coupling technique, good separating effect is measured to different valence state chromium element sepatation, detection limit is low, highly sensitive, reproducible, can at sub-concentration (μ g/L) horizontal detection different valence state chromium element, i.e. Cr (III) and Cr (VI) content in tobacco and tobacco product; And this method of separating and assaying optimizes the pre-treatment operation steps of sample, simplifies separation determination process.

Accompanying drawing explanation

Fig. 1 is the method for separating and assaying process flow diagram of different valence state chromium element in tobacco of the present invention and tobacco product;

Fig. 2 is the Cr (III) of embodiment 1 and the chromatogram of Cr (VI) standard solution;

Fig. 3 is the chromatogram that the Cr (III) of embodiment 1 and Cr (VI) tobacco sample treat sample measuring liquid.

Embodiment

Below in conjunction with embodiment, foregoing invention content of the present invention is described in further detail.But this should be interpreted as that the scope of the above-mentioned theme of the present invention is only limitted to following embodiment.Without departing from the idea case in the present invention described above, according to ordinary skill knowledge and customary means, make various replacement and change, all should comprise within the scope of the invention.

Embodiment 1

(I) instrument and equipment is selected: the 1260-7700x type High performance liquid chromatography-inductively coupled plasma mass spectrometry combined instrument that Agilent company of the U.S. produces, wherein said High performance liquid chromatography-inductively coupled plasma mass spectrometry combined instrument is furnished with chromatographic column guard column (HM79448, Agilent Science and Technology Ltd. of the U.S.) and anion-exchange column (Hamilton PRP X-100,250mm × 4.1mm × 10 μm); Electronic balance (XS204, degree of accuracy 0.0001g, Mettler company of Switzerland); PH meter (s220k, Mettler company of Switzerland); Ultrapure water instrument (Elix3, Millipore company of the U.S.); Ultrasonic cleaner (KQ-A1500DE, Kunshan Ultrasonic Instruments Co., Ltd.); Heavy metal special grinder (ZM200, German Retsch company); Climatic chamber (Climacell707L, German MMM company); Supercentrifuge (Z300, German HermLe company); 0.45 μm of aqueous phase pin type filter (polyethersulfone, Shanghai ANPEL Scientific Instrument Co., Ltd.); PET bottle (southern packing Co., Ltd.); The argon gas of purity >=99.99%.

(II) reagent preparation and standard solution:

Agents useful for same in embodiment: ethylenediamine tetraacetic acid two is received (EDTA-2Na, top grade is pure, CNW company); Red fuming nitric acid (RFNA) (65%, analyze pure, Tianjin Ke Miou); Ammoniacal liquor (analyzing pure, Tianjin Ke Miou); Cr (III) and Cr (VI) standard items (State center for standard matter); Cr (III) and Cr (VI) standard solution (1000mg/L, Town in Shanghai is composed).

(1) hybrid standard storing solution preparation: using 0.3mmol/L disodium ethylene diamine tetra-acetic acid solution as solvent, preparation Cr (III) and Cr (VI) mixed standard solution, and constant temperature 3h under being placed in 50 DEG C of conditions, obtain Cr (III) that content is 1000.0 μ g/L and Cr (VI) hybrid standard storing solution, store under being placed in 0 DEG C ~ 4 DEG C conditions;

(2) preparation of series standard solution: by hybrid standard storing solution stepwise dilution, be formulated as Cr (III) and Cr (VI) standard solution of variable concentrations, described series standard solution concentration is respectively 0 μ g/L, 0.5 μ g/L, 1.0 μ g/L, 2.0 μ g/L, 5.0 μ g/L, 10.0 μ g/L and 20.0 μ g/L, and matching while using.Wherein, in described series standard solution, concentration is 0 μ g/L is solvent blank (n.s. dissolves neat solvent wherein), i.e. 0.3mmol/L disodium ethylene diamine tetra-acetic acid solution, the series standard solution preparation of described Cr (III) and Cr (VI) is as shown in table 1.

Table 1 series standard solution preparation table (unit: μ g/L)

Sequence number	Cr(Ⅲ)	Cr(Ⅵ)
			Lv1	0 (solvent blank)	0 (solvent blank)
Lv2	0.5	0.5
			Lv3	1.0	1.0
Lv4	2.0	2.0
			Lv5	5.0	5.0
Lv6	10.0	10.0
			Lv7	20.0	20.0

(3) sample treatment liquid: 20mmol/L disodium ethylene diamine tetra-acetic acid solution;

(4) ultrasonic leaching liquor: distilled water;

(5) mobile phase: 0.10mol/L ammonium nitrate solution, regulates pH to be 7.0 with ammoniacal liquor before using.

(III) sample pre-treatments:

By through heavy metal special grinder levigate to 100 object tobacco samples temperature be (22 ± 1) DEG C, after relative humidity is balance 24h in the climatic chamber of (60 ± 2) %, accurately take 1.0000g sample in 50mL PET bottle, add 30mL 20mmol/L disodium ethylene diamine tetra-acetic acid solution, ultrasonic extraction 60min at 50 DEG C, 10mL is pipetted in centrifuge tube after leaving standstill, centrifugal 20min under 3500r/min condition, get supernatant liquor 0.45 μm of aqueous phase pin type frit, obtain treating sample measuring liquid.For eliminating reagent interference, warranty test result is more accurate, should do blank test in sample pretreatment process simultaneously.

(IV) sample determination: treat that sample measuring liquid uses HPLC-ICP-MS combined instrument to carry out upper machine analysis described in the described series standard solution of preparation and process being obtained:

(1) instrument service condition:

Described liquid chromatograph HPLC condition: mobile phase is the 0.10mol/L aqueous ammonium nitrate solution regulating pH=7.0 with ammoniacal liquor, and flow velocity is 1.0mL/min; Sampling volume 50 μ L, auto injection;

Described icp ms ICP-MS condition: RF incident power 1550W, RF matching voltage 1.8V; Concentric circles atomizer, carrier gas is the argon gas of purity >=99.99%, plasma gas flow speed 15.0L/min, flow rate of carrier gas 1.02L/min, assist gas flow velocity 0.90L/min; Peristaltic pump rotating speed 0.3rps; Sampling depth 8mm; Detection job number m/z=52 (Cr), the residence time is 0.5s (m/z=52);

(2) sample separation measures:

(V) sample measurement result calculates:

(1) arrange by described instrument service condition after start, after stable, first use the series standard solution production standard curve prepared, regretional analysis is carried out respectively with the concentration of Cr (III) and Cr (VI) and respective peaks area, obtain respective typical curve, typical curve linearly dependent coefficient (R ²) be all greater than 0.999; (2) described in handling well, treat that sample measuring liquid measures to HPLC-ICP-MS combined instrument sample introduction 50 μ L, treat Cr (III) in sample measuring liquid and Cr (VI) chromatographic peak carries out integration, obtain respective peak area respectively, substitute into typical curve, calculate corresponding concentration value, and then try to achieve the content of Cr in sample (III) and Cr (VI).

Described Cr (III) and Cr (VI) standard solution and treat sample measuring liquid chromatogram as shown in figures 2-3.As can be seen from Figure 2, Cr (VI) retention time is 4.64min, Cr (III) retention time is 5.50min, Cr (III) and Cr (VI) achieves baseline separation, peak shape is symmetrical, and Cr (III) and Cr (VI) can go out peak completely within 6min.As can be seen from Figure 3, the response of Cr (III) and Cr (VI) is all higher, and the peak shape of Cr (III) and Cr (VI) is not subject to the interference of assorted peak, and peak shape close to symmetrical, and can realize baseline separation.Illustrate that the method effectively can realize the separation determination of Cr (III) and Cr (VI) in tobacco and tobacco product thus.

(3) result calculates and expresses:

Through converting to Instrument measuring value counter sample content and actual sample content, in testing sample, the testing result of Cr (III) and Cr (VI) content is as shown in table 4.

The testing result (unit: μ g/kg) of Cr (III) and Cr (VI) content in table 4 sample

Sequence number	Cr(Ⅲ)	Cr(Ⅵ)
			1	32.07	133.14
2	31.65	132.20
			Mean value	31.86	132.67

Test findings shows, mainly exist with the form of Cr (VI) in the tobacco sample of this embodiment, its content is higher than Cr (III).The method good separating effect, quick and precisely, has the advantages such as detection limit is low, highly sensitive, reproducible, can compare the distribution situation of different valence state Cr element in objective appraisal tobacco and tobacco product.

Claims (4)

1. one grow tobacco and the method for separating and assaying of different valence state chromium element in tobacco product, comprise the following steps: (I) selects instrument and equipment, wherein separation determination equipment adopts High performance liquid chromatography-inductively coupled plasma mass spectrometry combined instrument (HPLC-ICP-MS), (II) reagent preparation and standard solution, (III) sample pre-treatments, (IV) sample determination and result calculate and express, and it is characterized in that, concrete technology step is as follows:

(I) select instrument and equipment, wherein separation determination adopts HPLC-ICP-MS combined system, and described instrument and equipment are selected by following condition:

(1) High performance liquid chromatography-inductively coupled plasma mass spectrometry combined instrument: described combined instrument is furnished with the chromatographic column guard column that filler is styrene-divinylbenzene polymkeric substance, and surface bond has the styrene-divinylbenzene polymkeric substance of quaternary ammonium salt functional group to be the anion-exchange column of 250mm × 4.1mm × 10 μm as filler, specification;

(2) ultrapure water instrument;

(3) ultrasonic cleaner;

(4) heavy metal special grinder;

(5) climatic chamber;

(6) supercentrifuge, rotating speed is not less than 3500r/min;

(7) electronic balance, degree of accuracy 0.0001g;

(8) pH meter;

(9) 0.45 μm of aqueous phase pin type filters;

(II) reagent preparation and standard solution:

(1) hybrid standard storing solution preparation: using edetate solution as solvent, preparation Cr (III) and Cr (VI) hybrid standard storing solution;

(2) preparation of series standard solution: by through preparing the hybrid standard storing solution stepwise dilution obtained, prepare the Cr (III) and Cr (VI) the series standard solution that obtain variable concentrations;

(III) sample pre-treatments: the tobacco sample levigate through heavy metal special grinder is balanced in climatic chamber, moisture in tobacco sample to be measured is made to reach balanced, taking a certain amount of sample is dissolved in sample treatment liquid, and ultrasonic, standing, centrifugal, filtration, obtains treating sample measuring liquid;

(IV) sample separation measure and result calculate: by preparation described Cr (III) and Cr (VI) series standard solution with process obtain described in use HPLC-ICP-MS combined instrument to carry out upper machine analysis until sample measuring liquid: arrange by described instrument service condition after start, after stable, first use the series standard solution production standard curve prepared, carry out regretional analysis with the concentration of Cr (III) and Cr (VI) and respective peaks area and obtain typical curve, described in handling well, treat that sample measuring liquid measures to HPLC-ICP-MS combined instrument sample introduction again, treat Cr (III) in sample measuring liquid and Cr (VI) chromatographic peak carries out integration, obtain respective peak area respectively, substitute into typical curve, calculate corresponding concentration value, and then try to achieve the content of Cr in sample (III) and Cr (VI).

2. the method for separating and assaying of different valence state chromium element in tobacco according to claim 1 and tobacco product, is characterized in that, in step (II):

(1) hybrid standard storing solution preparation: using 0.3mmol/L disodium ethylene diamine tetra-acetic acid solution as solvent, preparation Cr (III) and Cr (VI) mixed standard solution, and constant temperature 3h under being placed in 50 DEG C of conditions, obtain Cr (III) that content is 1000.0 μ g/L and Cr (VI) hybrid standard storing solution;

(2) preparation of series standard solution: use 0.3mmol/L disodium ethylene diamine tetra-acetic acid solution stepwise dilution by through preparing the hybrid standard storing solution obtained, the Cr (III) of preparation variable concentrations and Cr (VI) series standard solution, described series standard solution concentration is respectively 0 μ g/L, 0.5 μ g/L, 1.0 μ g/L, 2.0 μ g/L, 5.0 μ g/L, 10.0 μ g/L and 20.0 μ g/L, and matching while using;

(3) sample treatment liquid: 20mmol/L disodium ethylene diamine tetra-acetic acid solution;

(4) ultrasonic leaching liquor: distilled water;

(5) mobile phase: 0.10mol/L ammonium nitrate solution, and regulate pH to be 7.0 with ammoniacal liquor.

3. the method for separating and assaying of different valence state chromium element in tobacco according to claim 2 and tobacco product, it is characterized in that, in step (III): sample pre-treatments: will levigate through heavy metal special grinder be (22 ± 1) DEG C to 100 object tobacco samples in temperature, after balancing 24h in the climatic chamber that relative humidity is (60 ± 2) %, accurately take 1.0000g sample in 50mL PET bottle, add 30mL 20mmol/L disodium ethylene diamine tetra-acetic acid solution, ultrasonic extraction 60min at 50 DEG C, 10mL is pipetted in centrifuge tube after leaving standstill, centrifugal 20min under 3500r/min condition, get supernatant liquor 0.45 μm of aqueous phase pin type frit, obtain treating sample measuring liquid.

4. the method for separating and assaying of different valence state chromium element in tobacco according to claim 3 and tobacco product, is characterized in that, in step (IV):

Sample separation measure and result calculate: by preparation described Cr (III) and Cr (VI) series standard solution with process obtain described in treat that sample measuring liquid uses HPLC-ICP-MS combined instrument to carry out upper machine analysis:

(1) instrument service condition:

Described liquid chromatograph HPLC condition: mobile phase is the 0.10mol/L aqueous ammonium nitrate solution regulating pH=7.0 with ammoniacal liquor, and flow velocity is 1.0mL/min; Sampling volume 50 μ L, auto injection;

Described icp ms ICP-MS condition: RF incident power 1550W, RF matching voltage 1.8V; Concentric circles atomizer, carrier gas is argon gas or the helium of purity >=99.99%, plasma gas flow speed 15.0L/min, flow rate of carrier gas 1.02L/min, assist gas flow velocity 0.90L/min; Peristaltic pump rotating speed 0.3rps; Sampling depth 8mm; Detection job number m/z=52 (Cr), the residence time is 0.5s (m/z=52);

(2) sample separation measures:

Arrange by described instrument service condition after (i) start, after stable, first use the series standard solution production standard curve prepared, linear regression analysis is carried out respectively with the concentration of Cr (III) and Cr (VI) and respective peaks area, obtain typical curve, typical curve linearly dependent coefficient (R ²) be all greater than 0.999;

(ii) described in handling well, treat that sample measuring liquid measures to HPLC-ICP-MS combined instrument sample introduction 50 μ L, treat Cr (III) in sample measuring liquid and Cr (VI) chromatographic peak carries out integration, obtain respective peak area respectively, substitute into respective typical curve, calculate corresponding concentration value, and then try to achieve the content of Cr in sample (III) and Cr (VI);

(iii) result calculates and expresses:

Cr (III) in sample and Cr (VI) content, calculate by formula (1):

$X=\frac{(C-C_0)\×V}{m}$ …………………………(1)

In formula:

The content of Cr (III), Cr (VI) in X-sample, μ g/kg;

The concentration measurement of C-treat Cr in sample measuring liquid (III), Cr (VI), μ g/L;

C ₀the concentration measurement of Cr (III), Cr (VI) in-solvent blank, μ g/L;

The cumulative volume of V-treat sample measuring liquid, mL;

M-sample quality, g.