GB/T 15690-1995 Determination of oil content in oilseeds by nuclear magnetic resonance
Some standard content:
National Standard of the People's Republic of China
Determination of oil content in oilseeds by nuclear magnetic resonance method
Determination of oil content in oilseeds by nuclear magnetic resonance methodGB/T 15690--1995
This standard adopts the international standard ISO5511:1992 "Oilseeds-Determination of oil content-Continuous wave low-resolution nuclear magnetic resonance determination method (rapid method)".
1 Subject content and scope of application
This standard specifies the definition, instrument, sample preparation, determination steps and result calculation of the rapid determination of oil content in oilseeds by continuous wave low-resolution nuclear magnetic resonance determination method.
This standard is applicable to oilseeds containing completely liquid oil at 20℃. Such as rapeseed, sesame, soybean, sunflower seed, cotton seed, peanut, etc. 2 Reference standards
GB5491 Grain and oilseed inspection sampling and subsampling method GB10358 Determination of moisture and volatile matter in oilseed cakes and dregs GB/T14488.1 Determination of oil content in oilseeds GB/T14489.1 Determination of moisture and volatile matter in oilseeds 3 Definitions
Oil content of oilseeds: Under the conditions specified in this standard, the total amount of all liquid organic matter in oilseeds is measured, expressed as a percentage of the mass of the seeds.
4 Principle of the method
This method uses the nuclear magnetic resonance signal generated by the hydrogen atoms (hydrogen protons) of the liquid organic matter in the oilseeds in the continuous wave low-resolution nuclear magnetic resonance spectrometer as the basis for determination. The oilseeds to be measured are dried at 103±2°C in advance, and the influence of solid oilseeds is considered. The size of the nuclear magnetic resonance signal is proportional to the oil content in the oilseeds. Use a calibration oil of known mass as a standard sample, measure its nuclear magnetic resonance signal, and then measure the nuclear magnetic resonance signal of a sample of known mass under the same conditions. Compare the two to obtain the oil content of the sample. 5 Materials
5.1 Calibration oil: Extracted from the same oilseed of similar production area and chemical composition to the oilseed to be measured according to the method specified in GB/T14488.1. Store under conditions that prevent oil oxidation and use within one month. 5.2 Oil viscosity: The residue after extracting calibration oil from the same oilseed according to the method specified in GB/T14488.1. Store under conditions that prevent oil meal from deterioration and use within one month. Before measuring the oil meal, it should be pre-dried according to the method specified in GB10358. 6 Instruments and equipment
6.1 Equipment used for drying in GB10358.
Approved by the State Administration of Technical Supervision on August 17, 1995, and implemented on January 1, 1996
GB/T15690—1995
6.2 Nuclear magnetic resonance oil content tester (continuous wave low-resolution nuclear magnetic resonance spectrometer). 6.3 Analytical balance: sensitivity 0.01g.
6.4 Culture III: Φ100120mm (for drying samples). 6.5 Dryer: equipped with effective desiccant.
6.6 Test tube: made of glass or polytetrafluoroethylene material, and can be sealed, can hold 20g of oilseeds, suitable for the test tube of the nuclear magnetic resonance oil content tester.
6.7 Test tube rack: can be suitable for placing a group of test tubes. 6.8 Magnet.
6.9 Crusher.
7 Sampling and sub-sampling
Follow the provisions of GB5491. After sub-sampling, use a magnet to remove the iron-containing metal particles in the sample. 8 Sample preparation
8.1 Take 100g of samples of large and medium-sized oil seeds such as peanuts, soybeans, cotton seeds, etc., remove impurities and use a small crusher to crush them into uniform fine particles (particle size less than 2mm), and put the crushed materials into a wide-mouth bottle with a lid for later use. At the same time, determine the moisture content of the sample after crushing, which is used for calculating the oil content and needs to be prepared on the same day.
8.2 100g of the net sample of small oil seeds such as rapeseed and sesame, after removing impurities, is placed in a wide-mouth bottle with a lid for later use, and its moisture content is determined at the same time.
9 Determination steps
9.1 Sample preparation
9.1.1 Sample weighing: Weigh 20g of the sample prepared in Chapter 8 [after drying, it can be filled into the scale of the measuring tube (6.6), accurate to 0.01g, and place it in the culture blood (6.4) with a diameter of 100~～120 mm to spread it flat. 9.1.2 Drying: The sample shall be carried out in accordance with the provisions of GB/T14489.1. Put the dried and cooled sample into the prepared measuring tube (6.6) and seal it for testing.
Put the dryer (6.5) where the sample measuring tube is placed in the same room as the nuclear magnetic resonance oil content analyzer (6.2). The room temperature cannot change suddenly. The sample and the instrument are at the same measuring temperature. 9.2 Preparation of standard samples: Weigh 5 and 1020 g of the calibration oil extracted in 5.1 respectively, accurate to 0.01 g, and place them in three prepared measuring tubes (6.6) with the same zero point, seal them and set aside. Be careful not to let the oil droplets adhere to the tube wall of the measuring tube. 9.3 Instrument calibration
9.3.1 Adjust the instrument according to the instrument manual, and then place an empty measuring tube (6.6) in the instrument measuring probe to adjust the zero point. 9.3.2 Place three calibration oil standard sample measuring tubes prepared according to 9.2 in the instrument measuring probe. Use an appropriate RF energy level to obtain a signal that meets the requirements related to the background noise, but do not produce a saturation greater than about 1%. If the relationship between the instrument's RF energy and saturation is known, the correct saturation level can be selected by the user. If the above relationship is unknown, the correct saturation level should be obtained from the instrument manufacturer. When the instrument integration time is in the best repetitive measurement state, measure the nuclear magnetic resonance signal and obtain the average value of five measurements for each measuring tube, expressed as Rs, R10, and R2. 9.3.3 Use the nuclear magnetic resonance signal R measured in 9.3.2 as the ordinate and the corresponding calibration oil mass (g) in the measuring tube as the abscissa to draw a graph. This graph should be a straight line and the straight line will pass through the origin. If not, make necessary adjustments to the instrument according to the instrument manual. 9.3.4 Check and calibrate the instrument regularly. During the measurement, measure the response value of the 20g calibration oil standard sample every 30 minutes to verify and correct the change in the slope of the straight line.
9.4 Measurement
No change Select the operating parameters when calibrating the instrument. 498
GB/T 15690-1995
9.4.1 Place an empty measuring tube (6.6) in the instrument measuring probe to adjust the zero point. 9.4.2 Place the selected calibration oil standard sample tube (9.2) in the instrument measurement probe, and measure the average value of the five readings of the nuclear magnetic resonance signal as Rx.
9.4.3 Place the prepared sample measurement tube (9.1) in the instrument measurement probe, and measure the average value of the five readings of the nuclear magnetic resonance signal as R. 9.5 Calibration of oil meal
9.5.1 Weigh the dried and cooled oil meal (5.2) mr accurately to 0.01g, and place it in the same measurement tube (6.6) as the calibration oil, fill it to the scale as much as possible), seal it and keep it at the measurement temperature. 9.5.2 Do not change the operating parameters selected during the instrument calibration. Place the oil measurement tube (9.5.1) in the instrument measurement probe, and measure the average response value of the five readings of the nuclear magnetic resonance signal as R. 9.5.3 Use 5 to 10 oil viscosity measurement tubes (9.5.1) of the same mass m, and measure continuously according to the method in 9.5.2, and take the average value of these average response values as T. This value is measured only about once a month. 9.6 Number of measurements
At least two samples of the same test sample shall be measured. 10 Calculation and expression of results
10.1 Apparent oil content of oilseeds W. shall be calculated according to formula (1): W.(%) = RXm.× 100
R, × mg
Where: W——apparent oil content of oilseeds, %mo
The mass of the sample before drying, gi
——The mass of the selected calibration oil standard, g, R——The average value of the instrument's response to the sample measurement tube, R——The average value of the instrument's response to the selected calibration oil standard sample tube. Note: The calibration oil standard generally uses a 20 g calibration oil standard sample tube. 10.2 The response value W of oil cake is calculated according to formula (2): W(%) =
Response value of oil cake, %;
W-
Mass of oil cake after drying,
Mass of selected calibration oil standard sample, g,
T×m×100
TThe average value of the instrument's response value to mass m, oil cake; RThe average value of the instrument's response value to the selected calibration oil standard sample tube. 10.3 The oil content W of oilseed is calculated according to formula (3): (W-W)(1 -- 0.01H)
W(%) =
1 -- 0.01Wr
Wherein: W--Oil content of oilseed, %;
H---Moisture content (% of oilseed mass), %; (1)
(3)
--Apparent oil content of oilseed, %;
w. Response value of oil cake, %.
GB/T15690-1995
Note: For a certain variety of oilseed, the response value of oil viscosity is usually certain. For example, when determining the oil content of rapeseed, there is an approximate formula W=W. -0.30.10.4 Allowable difference of double test results
The allowable difference of double test results shall not exceed 0.4%, and the average value of the two times shall be the test result. Test report
The test report shall state the method used, the results obtained, the selected standard sample, the model and name of the nuclear magnetic resonance instrument used, and the special conditions required by the relevant instrument.
GB/T 15690--1995
Appendix A
Method for determination of small measuring tube
(reference)
When using 1, 2, 4g calibration oil, which can meet A1.3.3, a 3.5g oil seed can be used, which is suitable for determination by nuclear magnetic resonance instrument. A1 Determination steps
A1.1 Prepare the sample
A1.1.1 Weigh the sample: weigh 3.5g of the sample prepared in Chapter 8 (after drying, it can be filled to the scale of the small measuring tube), accurate to 0.001g, and place it in an aluminum box with a diameter of 45mm and spread it flat.
A1.1.2 Drying: The sample is carried out in accordance with GB/T14489.1. Put the dried and cooled sample into the prepared small measuring tube and seal it for testing.
A1.2 Preparation of standard samples
Weigh 1, 2, and 4 g of the calibration oil extracted in 5.1, accurately to 0.001 g, and place them in three prepared small measuring tubes with the same zero point, and seal them for later use. Be careful not to attach oil droplets to the wall of the measuring tube. A1.3 Instrument calibration
A1.3.1 Adjust the instrument according to the instrument manual, and then place an empty small measuring tube in the instrument's small measuring probe to adjust the zero point. A1.3.2 Place three calibration oil standard sample measuring tubes prepared in A1.2 in the instrument's small measuring probe. When the instrument integration time is in the best repetitive measurement state, measure the nuclear magnetic resonance signal and obtain the average value of five measurements for each measuring tube, expressed as R,, R, and R. A1.3.3 Use the nuclear magnetic resonance signal Rx measured in A1.3.2 as the ordinate and the corresponding calibration oil mass (g) in the measuring tube as the abscissa to draw a graph. This graph should be a straight line, and the straight line will pass through the origin. A1.3.4 Check and calibrate the instrument regularly. During the measurement, measure the response value of 4g calibration oil standard sample every 30 minutes to verify and correct the change of the slope of the straight line.
A1.4 Measurement
Select good operating parameters when calibrating the instrument without changing it. A1.4.1 Place an empty small measuring tube in the instrument measurement probe to adjust the zero point. A1.4.2 Place the selected calibration oil standard sample tube (A1.2) in the instrument measurement probe, and measure the average value of the five readings of the nuclear magnetic resonance signal as Rx.
A1.4.3 Place the prepared sample measuring tube (A1.1) in the instrument measurement probe, and measure the average value of the five readings of the nuclear magnetic resonance signal as R.
A1.5 Calibration of oil cake
A1.5.1 Weigh the dried and cooled oil cake (5.2) m, accurate to 0.001g, and place it in the same small measuring tube as the calibration oil (fill it to the scale as much as possible), seal it and keep it at the measurement temperature. A1.5.2 Select the good operating parameters when calibrating the instrument without changing it, put the oil cake measuring tube (A1.5.1) in the measuring probe of the instrument, and measure the average response value of the five readings of the nuclear magnetic resonance signal as the average value. A1.5.3 Use 5 to 10 oil cake tubes (A1.5.1) of the same mass m, and measure continuously according to A1.5.2, and take the average value of these average response values as the average value. This value only needs to be measured about once a month. A1.6 Number of measurements
At least two samples of the same test sample are obtained for measurement. A2 Calculation and expression of results
A2.1 Apparent oil content of oilseeds W. (expressed as mass percentage) 501
Mass of the sample before drying, nom;
Where: mo
GB/T15690--1995
m-——Mass of the selected calibration oil standard sample, g; R——The average value of the instrument's response value to the sample tube; R× mx× 100
R× m.
Rx——The average value of the instrument's response value to the selected calibration oil standard sample tube. Note: For the selection of calibration oil standard samples for small measuring tubes, 4g calibration oil standard sample tubes are generally selected. A2.2 Response value of oil W. (expressed as mass percentage) T×mx× 100
Wherein: m.——mass of oil cake after drying, g; mx
mass of selected calibration oil standard, g;
T—average value of instrument response value for mass m2, R—average value of instrument response value for selected calibration oil standard tube. A2.3 Oil content of oilseed W (expressed as mass percentage) W(%) = (W. = W.)(1 0. 01H)
1 - 0.01W
Wherein H
moisture content (percentage of seed mass), %; W.
apparent oil content of oilseed, %;
W,-response value of oil cake, %.
A2.4 Allowable difference between two test results
The allowable difference between two test results shall not exceed 0.4%, and the average of the two results shall be taken as the test result. Additional remarks:
This standard is proposed by the Ministry of Domestic Trade of the People's Republic of China. This standard is under the jurisdiction of the State Grain Reserves Administration. This standard was drafted by the Xi'an Oils and Fats Scientific Research and Design Institute of the Ministry of Domestic Trade. The main drafters of this standard are Wang Yiqun, Bao Yuanqi and Zhang Ying. 502
. (A1)
(A2)
(A3)1), the average value of five readings of the nuclear magnetic resonance signal is determined as R.
A1.5 Calibration of oil cakes
A1.5.1 Weigh the dried and cooled oil cakes (5.2) m, accurate to 0.001g, and put them into the same small measuring tube as the calibration oil (fill as close to the scale as possible), seal and keep at the measuring temperature. A1.5.2 Do not change the operating parameters selected during the instrument calibration, put the oil cake measuring tube (A1.5.1) into the instrument measuring probe, and measure the average response value of five readings of the nuclear magnetic resonance signal. A1.5.3 Use 5 to 10 oil cake tubes (A1.5.1) of the same mass m, and measure continuously according to A1.5.2, and take the average value of these measured average response values as below. This value only needs to be measured about once a month. A1.6 Number of measurements
At least two samples of the same test sample are taken for measurement. A2 Calculation and expression of results
A2.1 Apparent oil content of oilseeds W. (expressed as mass percentage) 501
Mass of the sample before drying, nom;
Where: mo
GB/T15690--1995
m-——Mass of the selected calibration oil standard sample, g; R——The average value of the instrument's response value to the sample tube; R× mx× 100
R× m.
Rx——The average value of the instrument's response value to the selected calibration oil standard sample tube. Note: For the selection of calibration oil standard samples for small measuring tubes, 4g calibration oil standard sample tubes are generally selected. A2.2 Response value of oil W. (expressed as mass percentage) T×mx× 100
Wherein: m.——mass of oil cake after drying, g; mx
mass of selected calibration oil standard, g;
T—average value of instrument response value for mass m2, R—average value of instrument response value for selected calibration oil standard tube. A2.3 Oil content of oilseed W (expressed as mass percentage) W(%) = (W. = W.)(1 0. 01H)
1 - 0.01WbZxz.net
Wherein H
moisture content (percentage of seed mass), %; W.
apparent oil content of oilseed, %;
W,-response value of oil cake, %.
A2.4 Allowable difference between two test results
The allowable difference between two test results shall not exceed 0.4%, and the average of the two results shall be taken as the test result. Additional remarks:
This standard is proposed by the Ministry of Domestic Trade of the People's Republic of China. This standard is under the jurisdiction of the State Grain Reserves Administration. This standard was drafted by the Xi'an Oils and Fats Scientific Research and Design Institute of the Ministry of Domestic Trade. The main drafters of this standard are Wang Yiqun, Bao Yuanqi and Zhang Ying. 502
. (A1)
(A2)
(A3)1), the average value of five readings of the nuclear magnetic resonance signal is determined as R.
A1.5 Calibration of oil cakes
A1.5.1 Weigh the dried and cooled oil cakes (5.2) m, accurate to 0.001g, and put them into the same small measuring tube as the calibration oil (fill as close to the scale as possible), seal and keep at the measuring temperature. A1.5.2 Do not change the operating parameters selected during the instrument calibration, put the oil cake measuring tube (A1.5.1) into the instrument measuring probe, and measure the average response value of five readings of the nuclear magnetic resonance signal. A1.5.3 Use 5 to 10 oil cake tubes (A1.5.1) of the same mass m, and measure continuously according to A1.5.2, and take the average value of these measured average response values as below. This value only needs to be measured about once a month. A1.6 Number of measurements
At least two samples of the same test sample are taken for measurement. A2 Calculation and expression of results
A2.1 Apparent oil content of oilseeds W. (expressed as mass percentage) 501
Mass of the sample before drying, nom;
Where: mo
GB/T15690--1995
m-——Mass of the selected calibration oil standard sample, g; R——The average value of the instrument's response value to the sample tube; R× mx× 100
R× m.
Rx——The average value of the instrument's response value to the selected calibration oil standard sample tube. Note: For the selection of calibration oil standard samples for small measuring tubes, 4g calibration oil standard sample tubes are generally selected. A2.2 Response value of oil W. (expressed as mass percentage) T×mx× 100
Wherein: m.——mass of oil cake after drying, g; mx
mass of selected calibration oil standard, g;
T—average value of instrument response value for mass m2, R—average value of instrument response value for selected calibration oil standard tube. A2.3 Oil content of oilseed W (expressed as mass percentage) W(%) = (W. = W.)(1 0. 01H)
1 - 0.01W
Wherein H
moisture content (percentage of seed mass), %; W.
apparent oil content of oilseed, %;
W,-response value of oil cake, %.
A2.4 Allowable difference between two test results
The allowable difference between two test results shall not exceed 0.4%, and the average of the two results shall be taken as the test result. Additional remarks:
This standard is proposed by the Ministry of Domestic Trade of the People's Republic of China. This standard is under the jurisdiction of the State Grain Reserves Administration. This standard was drafted by the Xi'an Oils and Fats Scientific Research and Design Institute of the Ministry of Domestic Trade. The main drafters of this standard are Wang Yiqun, Bao Yuanqi and Zhang Ying. 502
. (A1)
(A2)
(A3)
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