CN103728406A - Method for measuring residual phosphine in tobacco and tobacco products based on pulse flame photometric detector - Google Patents

Abstract

The invention relates to a method for measuring residual phosphine in tobacco and tobacco products based on a pulse flame photometric detector. A target substance detected by the method is trace binding state phosphine in tobacco and tobacco products. The method comprises the following steps: (1) sample pretreatment; (2) preparation of standard phosphine gas; (3) measurement of the content of the phosphine standard gas; (4) forming of a standard work curve, namely putting about 0.5g of un-fumed tobacco and tobacco products into a 20mL of headspace bottle, transferring the standard gas from phosphine standard reserve gas to be injected into the headspace bottle, and performing GC/PFPD (gas chromatography-pulsed flame photometric detector) analysis, wherein blank and five concentration levels are included. The method has the advantages of good stability, sensitivity, limit of detection and selectivity compared with an NPD (Nitrogen Phosphorus Detector), an FPD (Flame Photometric Detector), an MS (Mass Spectrum) detector.

Description

Based on pulse flame photometric detector (FPD), measure the residual method of hydrogen phosphide in tobacco and tobacco product

Technical field

The present invention relates to tobacco and tobacco product method for measuring components, be specifically related to one grow tobacco and tobacco product in the residual GC/PFPD assay method of hydrogen phosphide.

Background technology

1975, hydrogen phosphide started the fumigant as tobacco industry, due to its good disinsection effect, residual low, low cost and other advantages, and the current method of not yet finding to replace it, expection will be the most frequently used measure of storage insecticidal from now on.In 2009, CORESTA tobacco stores insect and health divides group to issue the phosphine fumigation parameter > > guide of < < for lasioderma serricorne and cacac moth control, instructs fumigation technology standard.Because hydrogen phosphide is extremely toxic substance, grain hygienic standard has provided the highest residual limitation, and the FAO of FAO (Food and Agriculture Organization of the United Nation) regulation cereal maximum residue limit (MRL) is 0.1 mg/kg, and China's regulation is not more than 0.05 mg/kg.

China's tobacco business there is no " tobacco and tobacco product hydrogen phosphide detection method standard " and " residue limits " regulation.Along with tobacco business is to Product Safety growing interest, it is necessary carrying out hydrogen phosphide residual method of testing and research of limitation in tobacco.Bibliographical information tobacco is residual at stifling rear hydrogen phosphide is trace level, is not more than 8.3 μ g/kg.1997, Hungary's regulation tobacco hydrogen phosphide maximum is residual was 0.1 mg/kg.

Summary of the invention

For trace combined hydrogen phosphide, analyze highly sensitive requirement, the object of this invention is to provide a kind of based on the residual method of hydrogen phosphide in pulse flame photometric detector (FPD) mensuration tobacco and tobacco product.The method is applicable to tobacco and the residual detection method of tobacco product hydrogen phosphide, without carbon matrix, disturbs, easy to operate, compares NPD, FPD, MS detecting device is having more advantage aspect stability, sensitivity, detectability and selectivity.

In order to realize above-mentioned object, the present invention has adopted following technical scheme:

Based on pulse flame photometric detector (FPD), measure the residual method of hydrogen phosphide in tobacco and tobacco product, the object that the method detects is trace combined hydrogen phosphide in tobacco and tobacco product, comprises the following steps:

1) sample pre-treatments: take approximately 0.5 g tobacco or tobacco product, put into 20 mL head space bottles, sealing after 60 ℃ of heating 3 min, is cooled to room temperature in baking oven, is placed in Static Headspace injector sample introduction, carries out GC/PFPD analysis;

2) standard phosphine gas preparation: aluminum phosphide tablet crushes, take 0.250 g powder, put into 250 mL head space bottles, head space bottle is used nitrogen blowing in advance, add 2.5 mL ultrapure waters, rotational oscillation 5 h make to react completely, and pipette gas inject 20 mL head space bottles in 1 mL head space bottle with syringe, as hydrogen phosphide standard inventory gas;

3) mensuration of hydrogen phosphide calibrating gas content: add 10 mL95% ethanol, 25 mL1.5% mercuric chloride solutions and two methyl red indicators in 150 mL head space bottles, from 250 mL head space bottles, pipette 5.0 mL gas injects wherein, high speed vortex 2 min that vibrate, be titrated to yellow with 0.05 mol/L standard solution of sodium hydroxide, record sodium hydroxide solution consumption;

4) standard working curve: get without stifling tobacco and tobacco product approximately 0.5 g and put into 20 mL head space bottles, pipette Standard Gases and inject wherein from hydrogen phosphide standard inventory gas, comprise blank and five concentration levels, carry out GC/PFPD analysis;

Static Headspace injector condition is as follows:

Quantitatively long-pending 1 mL of ring body;

40 ℃ of heating 1 min of furnace temperature;

80 ℃ of transmission line temperature;

110 ℃ of valve temperature;

Bottle is pressed 500 mbar;

GC conditions is as follows:

Chromatographic column: PoraPLOT Q+Particle Traps, 25 m × 0.32 mm × 0.45incl. 2 × 2.5 m Particle trap, thickness 10 μ m;

Carrier gas: nitrogen, purity >=99.999%, constant current flow velocity: 2 mL/min;

Injector temperature: 200 ℃;

Detector temperature: 200 ℃;

Temperature programme: 50 ℃ of initial temperature, keep 1 min, with 30 ℃/min, rise to 125 ℃, keep 3 min;

Split sampling, split ratio 10:1;

Working times 8.5 min;

PFPD detecting device condition:

Phosphorus optical filter center sees through wavelength 530 nm; Air 1 is 17.0 mL/min, and hydrogen is 13.0 mL/min, and air 2 is 10.0 mL/min, and sensitivity Range is 9, photomultiplier transit tube voltage PMT 500 V, gate delay 4.0 ms, gate-width 10 ms;

Gas circuit polishing filter: moisture is caught long-pending trap, acticarbon is caught long-pending trap and CO ₂catch long-pending trap.

The present invention has set up a kind of new mensuration tobacco and tobacco product hydrogen phosphide analytical approach, compared with existing other technologies, has following advantage:

1. will be loaded in the inventive method pretreatment process tobacco or tobacco product short time heating in baking oven of sealing top empty bottle, contribute to that combined hydrogen phosphide is residual reaches gas phase/matrix balance, and easy to operate;

2. the inventive method is used nitrogen blowing in advance by the head space bottle of configuration standard hydrogen phosphide, can reduce reacting of oxygen and hydrogen phosphide;

3. the inventive method employing PoraPLOT Q+catch long-pending trap chromatographic column, is suitable for gas analysis, and has reduced the pollution of chromatographic column filler to detecting device;

4. the inventive method adopts PFPD detecting device to measure hydrogen phosphide, and highly sensitive, detectability is low, and chromatographic peak does not trail, and does not need to stablize for a long time preheating, has very strong actual application value;

5. the inventive method adopts moisture to catch long-pending trap, and acticarbon is caught long-pending trap, CO ₂catch long-pending trap and purify gas circuit, improve sensitivity, extend the detecting device life-span;

6. the detection limit of the inventive method and quantitative limit.

Residual trace combined hydrogen phosphide in tobacco after the present invention is stifling by headspace gas chromatography external standard method Fast Measurement, adopt PoraPLOT Q+Particle Traps capillary chromatographic column, this post two ends band is caught long-pending trap, prevent that pollutant from entering detecting device, use pulse flame photometric detector (FPD) (PFPD) P pattern to analyze mensuration, PFPD detecting device is high to aeroscope and proportion requirement, moisture is installed in gas circuit and is caught long-pending trap, acticarbon is caught long-pending trap, CO ₂catch long-pending trap and purify air, without carbon matrix, disturb, easy to operate, compare NPD, FPD, MS detecting device is having more advantage aspect stability, sensitivity, detectability and selectivity.

Accompanying drawing explanation

Fig. 1 is hydrogen phosphide Standard Gases chromatogram.

Fig. 2 is tobacco and tobacco product hydrogen phosphide chromatogram after stifling.

Embodiment

The present invention is further described by following instantiation, but does not limit the present invention.

1. instrument and reagent

Adopt Brooker GC456 gas chromatograph, pulse flame photometric detector (FPD) PFPD, phosphorus optical filter center sees through wavelength 530 nm; Brooker SHS-40 head-space sampler; 250 mL and 150 mL head space bottles (domestic), 20 mL head space bottles (Brooker); Lock sample introduction needle 5 mL, 1 mL(Agilent) each one, each one of 10 μ L, 100 μ L syringe; AE163 electronic balance (sensibility reciprocal: 0.0001 g, Switzerland Mettler company); HY-8 velocity-modulated oscillator (Changzhou Guohua Electric Appliance Co., Ltd.); Troemner vortex mixer; Nitrogen is blown.

Gas circuit polishing filter (Agilent): moisture is caught long-pending trap, acticarbon is caught long-pending trap, CO ₂catch long-pending trap.

Analytical reagent: mercuric chloride, NaOH, aluminum phosphate (56% tablet, 3.2 ± 0.1 g/ sheets), methyl red, phenolphthalein, 95% ethanol, ultrapure water.

2. chromatographic condition

Adopt Agilent PoraPLOT Q+Particle Traps(25 m × 0.32 mm × 0.45incl. 2 × 2.5 m Particle trap, m) capillary chromatographic column of thickness 10 μ; Nitrogen does carrier gas, flow velocity 2 mL/min; Injection port, detector temperature are 200 ℃, temperature programme: 50 ℃ of initial temperature, keep 1 min, and with 30 ℃/min, rise to 125 ℃, keep 3 min; Split ratio 10:1; PFPD detecting device: air 1 is 17.0 mL/min, hydrogen is 13.0 mL/min, and air 2 is 10.0 mL/min, and sensitivity Range is 9, PMT voltage, 500 V, gate delay 4.0 ms, gate-width 10 ms.

Head-space sampler parameter: quantitatively long-pending 1 mL of ring body, 40 ℃ of heating 1 min of furnace temperature, 80 ℃ of transmission lines, 110 ℃, valve, bottle is pressed 500 mbar.

3. the preparation method of hydrogen phosphide standard inventory gas

Aluminum phosphide tablet crushes, take 0.250 g powder, put into 250 mL head space bottles (using in advance nitrogen blowing), add 2.5 mL ultrapure waters, rotational oscillation 5 h make to react completely, pipette gas inject 20 mL head space bottles (using in advance nitrogen blowing) in 1 mL head space bottle with syringe, as hydrogen phosphide standard inventory gas.

4. the mensuration of hydrogen phosphide calibrating gas content

In 150 mL head space bottles (using in advance nitrogen blowing), add 10 mL95% ethanol, 25 mL1.5% mercuric chloride solutions and two methyl red indicators, from 250 mL head space bottles, pipette 5.0 mL gas injects wherein, high speed vortex 2 min, be titrated to yellow with 0.05 mol/L standard solution of sodium hydroxide, record sodium hydroxide solution consumption.Aluminum phosphate is met water reaction and is emitted phosphine gas, and hydrogen phosphide reacts with mercuric chloride solution and generates hydrogen chloride, with 0.05 mol/L NaOH, demarcates and obtains hydrogen phosphide calibrating gas concentration.

5. standard working curve and sample pre-treatments

Get without stifling pipe tobacco or sheet cigarette approximately 0.5 g and put into 20 mL head space bottles, pipette Standard Gases and inject wherein from hydrogen phosphide standard inventory gas, (for example, 2 μ l, 4 μ l, 8 μ l, 20 μ l, 30 μ are l) to comprise blank and five concentration levels.Sample bottle heats 3 min in 60 ℃ of baking ovens, takes out and is cooled to room temperature.

6. hydrogen phosphide standard working curve

With external standard method, calculated by peak area standard working curve, under PFPD detecting device P pattern, respond as linear relationship coefficient R ²be not less than this experimental technique of 99.5%(and record R ²be 99.98%, meet the requirements).Often carry out after 20 sample determinations, should add the Standard Gases control sample of an intermediate concentration, if measured value differs, exceed 5%, should re-start the making of typical curve.

7. sample determination

This experimental sample is after phosphine fumigation operation completes, and loose gas 72 h that ventilate test from sampling in the 4th day continuous three days, result show stifling after tobacco and tobacco product have micro-hydrogen phosphide residual (in Table 1).

table 1tobacco and tobacco product hydrogen phosphide residues detection result after stifling

This method is joined to 5 parts of phosphine gas working curve least concentration replicate determinations, get 3 times of analysis result standard deviation and 10 times as this method detection limit and quantitative limit, be respectively 0.0050 μ g/g, 0.015 μ g/g.As shown in table 2.Show that the inventive method is highly sensitive, there is lower detectability and quantitative limit.

table 2tobacco and tobacco product hydrogen phosphide residue detection limit and quantitative limit

The repeatability of the inventive method and recovery of standard addition

In head space bottle, take tobacco and tobacco product that ten parts of approximately 0.5 g do not fumigate, add respectively the hydrogen phosphide standard inventory gas of certain volume, measure respectively in a few days repeatability and in the daytime repeatability (in Table 3).

In head space bottle, take approximately six parts of tobaccos that 0.5 g does not fumigate and tobacco products, add the hydrogen phosphide standard inventory gas of high and low two kinds of volumes, measure respectively the recovery (in Table 4).

Blank sample does not all detect object hydrogen phosphide.

The inventive method is measured tobacco and in a few days repeated RSD(% of tobacco product hydrogen phosphide residual quantity) be 6.5, repeated RSD(% in the daytime) be 2.4.The recovery is between 92.46%-113.81%, and average recovery rate is 98.90%.Show that this method accuracy is high, reproducible.

table 3tobacco and tobacco product hydrogen phosphide residue be repeatability and repeated in the daytime in a few days

table 4tobacco and the tobacco product hydrogen phosphide residue recovery

Claims (1)

1. based on pulse flame photometric detector (FPD), measure the residual method of hydrogen phosphide in tobacco and tobacco product, the object that the method detects is trace combined hydrogen phosphide in tobacco and tobacco product, it is characterized in that the method comprises the following steps:

1) sample pre-treatments: take approximately 0.5 g tobacco or tobacco product, put into 20 mL head space bottles, sealing after 60 ℃ of heating 3 min, is cooled to room temperature in baking oven, is placed in Static Headspace injector sample introduction, carries out GC/PFPD analysis;

2) standard phosphine gas preparation: aluminum phosphide tablet crushes, take 0.250 g powder, put into 250 mL head space bottles, head space bottle is used nitrogen blowing in advance, add 2.5 mL ultrapure waters, rotational oscillation 5 h make to react completely, and pipette gas inject 20 mL head space bottles in 1 mL head space bottle with syringe, as hydrogen phosphide standard inventory gas;

3) mensuration of hydrogen phosphide calibrating gas content: add 10 mL95% ethanol, 25 mL1.5% mercuric chloride solutions and two methyl red indicators in 150 mL head space bottles, from 250 mL head space bottles, pipette 5.0 mL gas injects wherein, high speed vortex 2 min that vibrate, be titrated to yellow with 0.05 mol/L standard solution of sodium hydroxide, record sodium hydroxide solution consumption;

4) standard working curve: get without stifling tobacco and tobacco product approximately 0.5 g and put into 20 mL head space bottles, pipette Standard Gases and inject wherein from hydrogen phosphide standard inventory gas, comprise blank and five concentration levels, carry out GC/PFPD analysis;

Static Headspace injector condition is as follows:

Quantitatively long-pending 1 mL of ring body;

40 ℃ of heating 1 min of furnace temperature;

80 ℃ of transmission line temperature;

110 ℃ of valve temperature;

Bottle is pressed 500 mbar;

GC conditions is as follows:

Chromatographic column: PoraPLOT Q+Particle Traps, 25 m × 0.32 mm × 0.45incl. 2 × 2.5 m Particle trap, thickness 10 μ m;

Carrier gas: nitrogen, purity >=99.999%, constant current flow velocity: 2mL/min;

Injector temperature: 200 ℃;

Detector temperature: 200 ℃;

Temperature programme: 50 ℃ of initial temperature, keep 1 min, with 30 ℃/min, rise to 125 ℃, keep 3 min;

Split sampling, split ratio 10:1;

Working times 8.5 min;

PFPD detecting device condition:

Phosphorus optical filter center sees through wavelength 530 nm; Air 1 is 17.0 mL/min, and hydrogen is 13.0 mL/min, and air 2 is 10.0 mL/min, and sensitivity Range is 9, photomultiplier transit tube voltage PMT 500 V, gate delay 4.0 ms, gate-width 10 ms;

Gas circuit polishing filter: moisture is caught long-pending trap, acticarbon is caught long-pending trap and CO ₂catch long-pending trap.

Images