Summary of the invention
In view of the above problems, the object of the present invention is to provide a kind of detections of dimethyl sulfoxide concentration in air of workplace
Method, to solve the problems, such as that the detection method of dimethyl sulfoxide content in air of workplace still belongs to blank at home.
The detection method of dimethyl sulfoxide concentration, includes the following steps: in air of workplace provided by the invention
Step S1: two activated carbon tubes are placed on sampled point to be measured, one of activated carbon tube and air sampler
It is sampled after connection, another activated carbon tube does blank sampling;Wherein, the flow of air sampler is 0~500ml/min,
Activated carbon tube is solvent desorption type, and activated carbon tube is divided into leading portion and back segment, 100mg active carbon is provided in leading portion, in back segment
Equipped with 50mg active carbon;
Step S2: the active carbon in the leading portion and back segment of the activated carbon tube after sampling is poured into two solvent desorption bottles respectively
In, the carbon disulfide of 1ml~2ml is respectively added in two solvent desorption bottles, then closes two solvent desorption bottle shakings 1~3
Minute, desorption 20~to be measured after forty minutes;And same processing is done to the activated carbon tube of blank sampling;
Step S3: two groups of acquisition dimethyl sulfoxide stripping liquids to be measured, one group of blank sampling stripping liquid are used respectively micro
Sample injector is added in gas chromatograph and is analyzed, qualitative with retention time, is carried out with the peak area of dimethyl sulfoxide chromatographic peak
It is quantitative, obtain the concentration of two groups of dimethyl sulfoxide stripping liquids to be measured and the concentration of blank sampling stripping liquid;
Step S4: the concentration of dimethyl sulfoxide in air of workplace is obtained according to the following formula:
In formula:
C indicates the concentration of dimethyl sulfoxide in air of workplace;
c1The concentration of the dimethyl sulfoxide of activated carbon adsorption in the leading portion of activated carbon tube after indicating sampling;
c2The concentration of the dimethyl sulfoxide of activated carbon adsorption in the back segment of activated carbon tube after indicating sampling;
c0Indicate the concentration of dimethyl sulfoxide in blank sampling;
V indicates stripping liquid volume;
E indicates desorption efficiency;
VtIndicate standard sample volume.
Using aforementioned present invention provide air of workplace in dimethyl sulfoxide concentration detection method, can obtain with
Lower technical effect:
1, detection method provided by the invention is easy to operate, and cost is relatively low, convenient for a large amount of acquisitions and analysis sample;
2, sample pre-treatments are carried out using the method that the invention provides, component loss to be measured is less, and the accuracy of detection is high;
3, lower detection limit, higher sensitivity and faster analysis can be realized using chromatographic condition provided by the invention
Speed, and solvent peak and determinand good separating effect, the standard curve range of linearity is wider, is suitable for carrying out various concentration sample fast
Speed, effective analysis.
Specific embodiment
In the following description, for purposes of illustration, it in order to provide the comprehensive understanding to one or more embodiments, explains
Many details are stated.It may be evident, however, that these embodiments can also be realized without these specific details.
In other examples, one or more embodiments for ease of description, well known structure and equipment are shown in block form an.
The technical side of the detection method of dimethyl sulfoxide concentration in the air of workplace that the present invention will be described in detail provides
Before case, summary first is made to the Integral Thought of the detection method: grab sampling is carried out using air sampler, with activated carbon tube
As solid absorbent, using carbon disulfide as stripping liquid, the chromatographic condition of optimization is proposed, using Desorption Gas Chromatography Method
Dimethyl sulfoxide content in air of workplace is detected.
Instrument and equipment used in the detection method includes:
Agilent 7890B type gas chromatograph has shunting/Splitless injecting samples mouth, matches hydrogen flame ionization detector
(FID);
Plum Teller electronic balance, model: MS105DU;
Sampling flow can be adjusted in air sampler, 0~500mL/min of flow-control scope, be furnished with bracket;
Range is the microsyringe of 5 μ L or 10 μ L;
Compressed air pump, model: SPB-3;
Hydrogen generator, model: TH-300, produced hydrogen purity > 99.99%;
Capillary gas chromatographic column, model: HP-5 (30m × 0.25mm × 0.25 μm);
Solvent desorption bottle, volume 5mL, equipped with seal gasket and desorption bottle cap;
Activated carbon tube, solvent desorption type, built-in 100mg/50mg active carbon;
10mL volumetric flask is several, error ± 0.02mL.
The reagent that the detection method uses are as follows:
Dimethyl sulfoxide (chromatographically pure), manufacturer: Tianjin Yong great chemical reagent Co., Ltd;
It purifies carbon disulfide (chromatographically pure), manufacturer: Environmental Protection Department standard sample research institute;
High pure nitrogen, purity > 99.99% are selected in gas-chromatography carrier gas.
Fig. 1 shows the stream of the detection method of dimethyl sulfoxide concentration in air of workplace provided in an embodiment of the present invention
Journey.
As shown in Figure 1, in air of workplace provided in an embodiment of the present invention dimethyl sulfoxide concentration detection method, packet
It includes:
Step S1: sampling instrument calibration.
According to the regulation of " air of workplace sampling instrument technical specification " (GB/T 17061-1997), sample at the scene
Before progress, air sampler is calibrated, flowmeter accuracy should be within ± 2.5%, and clear scales are accurate, is easy to read
Number and adjusting.
Step S2: spot sampling.
It is well placed bracket in sampled point, bracket is adjusted to operating personnel's breathing zone height, air sampler is placed in bracket
On, flow is adjusted after fixing sampler, connection activated carbon tube is sampled.
Sampling is divided into short time sampling and samples for a long time, and short time sampling refers to sampling time adopting no more than 15 minutes
Sample;Sampling refers to sampling of the sampling time at 1 hour or more for a long time.
Occupational exposure limit is divided into three kinds: 1. maximum permissible concentration;2. short-term exposure allowable concentration;3. time weight is flat
Equal acceptable concentration.It for which kind of limit value certain substance formulates is determined by its toxicity and physicochemical property.If providing one kind
The occupational exposure limit of substance is 1., to need to carry out short time sampling, if a kind of limit value of substance of regulation is 3., to be grown
Time sampling.2. and 3. exist if defined simultaneously, the short time has not only been needed to sample but also needs to sample for a long time.
Short time sampling is with 100mL/min flow collection 15min air sample, and sampling is flowed with 50mL/min for a long time
Amount acquisition 2~8h air sample, while doing sampling blank.Sampling while record scene sampling volume, sampled point temperature,
The information such as air pressure, the both ends of closing activity charcoal pipe immediately after sampling, are sent to experimental determination as early as possible.
Step S3: sample pre-treatments.
The activated carbon tube that step S2 is acquired is opened, and the active carbon in two sections before and after the activated carbon tube for adopting sample is fallen respectively
Enter in a solvent desorption bottle, the carbon disulfide of 1ml~2ml is respectively added in two solvent desorption bottles, then closes two solvents
Desorption bottle shakes 1~3 minute, desorption 20~to be measured after forty minutes;And same processing is done to the activated carbon tube of blank sampling.
Step S4: chromatographic condition setting.
Gas chromatographic device gas circuit is connected, carrier gas, hydrogen generator and air pump are opened, respectively regulating gas output pressure
Power and the flow range to needed for testing, open gas chromatograph power supply, adjustment instrument parameter to following state: detector temperature:
240℃;Injector temperature: 240 DEG C;Chromatogram column temperature uses temperature programming: initial temperature for 60 DEG C, keep 1min, with 20 DEG C/
Min is warming up to 100 DEG C, keeps 1min;Carrier gas uses constant voltage mode, nebulizer gas pressure 5Psi;Hydrogen flowing quantity is 30ml/min;It is empty
Throughput is 400ml/min;Make-up gas flow is 25ml/min;Input mode uses split sampling, split ratio 20:1.
Peak shape is preferable under the above conditions, can effectively realize the separation of solvent and test substance, can satisfy quantitative detection
Needs.
Step S5: Specification Curve of Increasing.
The purifying carbon disulfide of about 5mL is added in the volumetric flask of 10mL, is added after precise with microsyringe pre-
Quantitative dimethyl sulfoxide adds carbon disulfide to the scale of volumetric flask, as Standard Reserving Solution after precise again.With twice
The difference of weighing is Standard Reserving Solution concentration divided by volumetric flask volume, and Standard Reserving Solution is successively diluted to following concentration, is matched
Dimethyl sulfoxide standard series in carbon disulfide processed.Standard curve prepares situation and is shown in Table 1:
1 standard curve of table is prepared
Serial number |
1 |
2 |
3 |
4 |
5 |
6 |
Concentration (μ g/mL) |
0 |
10 |
20 |
40 |
80 |
100 |
Peak area 1 |
0 |
14.2 |
28.4 |
58.1 |
114.2 |
143.1 |
Peak area 2 |
0 |
13.8 |
24.1 |
60.4 |
118.9 |
144.2 |
Peak area 3 |
0 |
13.7 |
27.9 |
57.4 |
116.7 |
147.2 |
Peak area mean value |
0 |
13.9 |
26.8 |
58.6 |
116.6 |
144.8 |
Each concentration replication 3 times, sampling volume is 1.0 μ L, qualitative with retention time, quantitative with peak area mean value,
With concentration to peak area mean value, standard curve is drawn, standard curve regression equation is obtained:
Y=1.4598x-0.6955
In formula: y indicates the mean value of peak area, and x indicates the concentration of dimethyl sulfoxide, the correlation coefficient r of standard curve=
0.9999, related coefficient is better closer to the linear correlation of two groups of data (peak area and concentration) of explanation.
Step S6: sample measurement.
Dimethyl sulfoxide stripping liquid to be measured and blank are sampled respectively with condition identical with dimethyl sulfoxide standard series
Stripping liquid carries out analysis measurement, and 3 measurement peak area average values is taken to bring standard curve regression equation into, obtains two groups of diformazans to be measured
The concentration of concentration and blank the sampling stripping liquid of base sulfoxide stripping liquid.
Desorption efficiency measurement:
6 blank activated carbon tubes are taken, the dimethyl sulfoxide that 10 μ L concentration are 5000 μ g/mL is added with microsyringe respectively
The amount of standard solution, the then dimethyl sulfoxide that every activated carbon tube is added is 50 μ g, behind the cap closure charcoal pipe both ends of active carbon
It stands overnight, desorbs and measure within second day the content of dimethyl sulfoxide in each tube, calculate desorption efficiency, the calculating of desorption efficiency
As the following formula:
In formula:
E indicates desorption efficiency;
M indicates to measure the content of dimethyl sulfoxide;
M indicates the content that dimethyl sulfoxide is added.
Measurement result is shown in Table 2:
2 desorption efficiency measurement result of table
Serial number |
1 |
2 |
3 |
4 |
5 |
6 |
Desorption efficiency (%) |
99.7 |
100.2 |
98.7 |
100.3 |
99.1 |
100.2 |
Six times measurement result shows: desorption efficiency is between 98.7% to 100.3%, average value 99.7%.
Temperature, air pressure, sampling volume substitution are calculated into obtain standard sample volume, according to " nuisance in workplace air
The sampling specification of quality detection " (GBZ 159-2004) regulation, sampled point temperature lower than 5 DEG C and be higher than 35 DEG C, atmosphere forces down
In 98.8kPa and be higher than 103.4kPa when, sampling volume should be converted into standard sample volume as follows:
In formula:
VtIndicate standard sample volume;
V0It indicates to be t DEG C in temperature, the sampling volume of sampled point when atmospheric pressure is P;
The temperature of T expression sampled point;
The atmospheric pressure of P expression sampled point.
Step S7: concentration is calculated.
The concentration of dimethyl sulfoxide in air of workplace is obtained according to the following formula:
In formula:
C indicates the concentration of dimethyl sulfoxide in air of workplace;
c1The concentration of the dimethyl sulfoxide of activated carbon adsorption in the leading portion of activated carbon tube after indicating sampling;
c2The concentration of the dimethyl sulfoxide of activated carbon adsorption in the back segment of activated carbon tube after indicating sampling;
c0Indicate the concentration of dimethyl sulfoxide in blank sampling;
V indicates stripping liquid volume, the volume phase of two groups of dimethyl sulfoxide stripping liquids to be measured and one group of blank sampling stripping liquid
Together, i.e. the stripping liquid and blank that the back segment of the leading portion of activated carbon tube is formed stripping liquid, activated carbon tube is formed sample stripping liquid
Volume it is all the same;
E indicates desorption efficiency;
VtIndicate standard sample volume.
This method detection is limited to 1.6 μ g/mL (three times noise corresponding concentration), concentration limit 1.1mg/m3(sampling
Volume is in terms of 1.5L), measurement range is 1.6~100 μ g/mL, and break through volume > 20mg, desorption efficiency > 90%, above-mentioned performance refers to
Mark can satisfy the related request that detection method develops specification.