Abstract: Solvent oil is one of the five major petroleum products. Solvent oils are used in a wide variety of applications. The largest amount of priming coating solvent oil, about 400-500 solvents are currently on the market, of which solvent oil accounts for about half.
The method uses capillary column and gas chromatograph to detect, nitrogen is carrier gas, FID detector is modified and adjusted according to GB/T5009.37-1996 method, the accuracy is improved, the detected value can be up to 1ppm, and the repetition is repeated. Good sex, can provide effective and accurate results for the quasi-determination of edible oil products.
Key words: gas chromatograph, edible oil, solvent residue detection
In order to improve the detection and control capabilities of the products, and in line with the formulation and implementation of the new five new edible oil standards, the results of solvent residues in edible oil products are more accurately determined and correctly classified.
1, experiment
Reagent: NN-dimethylacetamide (DMA)
No. 6 solvent oil
Instrumentation: Beijing Puri (GC-7800)
Detector: FID
Column: VB-5 (30m × 0.32 × 0.5um)
Chromatographic conditions:
Injector temperature: 250 ° C
Flow rate: 2.5ml/min Detector temperature: 280 °C
Column oven temperature: 85 ° C (1 min) 20 ° C / min 130 ° C (2 min)
2. Reagents:
NN-Dimethylacetamide (DMA): Pipette 1 ml into 100 ml of a well-dried glass bottle with a stopper, place it at 50 °C for 30 minutes, and take 1 ul of the gas into the gas chromatograph for 10 minutes. It can be used without interference. If there is interference, use ultrasonic treatment for 30 minutes.
3, No. 6 solvent standard solution: Weigh the cleaned and dried 10 ml gasification bottle with the mass A, put the DMA in the bottle with 0.5 ml less volume than the gasification bottle, and weigh it to B (M5). A 50 ul syringe is filled with about 0.2 ml of the No. 6 solvent standard through a stopper into the bottle, and mixed, and accurately weighed as C. Calculate the concentration of solvent No. 6 by the following formula: X7=(M5-M6)/(M6-M7)/0.935×1000
4. Drawing of standard curve
The solvent-free product oil (new machine oil) was pre-tested in a gas chromatograph, and 25 g of each of the six gasification bottles which were tested for leaking were weighed and sealed. The No. 6 solvent standard solution was injected into the No. 6 solvent standard solution by 0, 20 ul, 40 ul, 60 ul, 80 ul, and 100 ul. Put in a 50 ° C oven, equilibrate for 30 minutes, respectively, take the gas injection chromatography, and then subtract the blank after each response, draw a standard curve.
5, determination
Weigh 25 grams of edible oil sample, and then heat it for 30 minutes in a constant temperature oven at 50 °C. Immediately after taking out, take 15 ul of liquid gas injection chromatography with a micro-syringe, record the peak height of the component, and compare with the standard curve to find the liquid. The content of solvent No. 6.
6, calculation
Solvent No. 6 = Determination of the quality of the gasifier No. 6 solvent / sample quality
GC-7800 gas chromatograph uses single-chip microcomputer and integrated circuit control, Chinese interface, operating parameter keyboard setting. The instrument has power-down protection and file storage. Large screen LCD display. At the same time, the instrument has a stopwatch timing function. ·The instrument adopts double column and double gas path structure, suitable for various detection and injection combinations. A variety of detectors (TCD, FID, ECD, FPD and NPD) can be configured according to user analysis requirements, and up to three detectors can be installed at the same time. The detector and its control components are in a plug-and-play control mode. · Constant temperature and temperature programmed operation. With over temperature protection. The column chamber is equipped with a flexible rear door automatic temperature control system. It can realize the near-room temperature operation in the true sense, and the fifth-order program temperature rises. ·Injection system can be equipped with multiple injection devices such as packed column head injection, glass liner rapid injection, capillary column split/splitless injection with diaphragm cleaning function; capillary injection system with microcomputer automatic control The electromagnetic on-off valve enables split/splitless injection operation. The gas injector can be configured. · The carrier gas circuit has low pressure and gas shutoff protection. · Preset standby temperature control port for easy expansion.
Main Specifications
Temperature control column chamber: temperature control range: room temperature 3-400 ° C
Temperature control accuracy: better than ±0.1 °C five-step rising six-way temperature-controlled flame ionization detector FID
Detection limit Mt≤1.0×10-11g/s (benzene)
Thermal conductivity detector (TCD) sensitivity: s ≥ 4000mv.ml / mg
Benzene electron capture detector ECD detection limit: Mt ≤ 1 × 10-13g / ml (γ-666)
Flame photometric detector FPD detection limit: Mt ≤ 1 × 10-12g (s, p) / s (thiophene, ethyl -1605)
Instrument size and weight.
Dimensions: 635 × 490 × 470mm
Weight: about 55kg
Beijing Puri Analytical Instrument Co., Ltd.
contact number
Contact: Li Jingsheng (13701307156)
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