CN101382519A - Method for measuring protein nitrogen content in tobacco - Google Patents
Method for measuring protein nitrogen content in tobacco Download PDFInfo
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- CN101382519A CN101382519A CNA200810212239XA CN200810212239A CN101382519A CN 101382519 A CN101382519 A CN 101382519A CN A200810212239X A CNA200810212239X A CN A200810212239XA CN 200810212239 A CN200810212239 A CN 200810212239A CN 101382519 A CN101382519 A CN 101382519A
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Abstract
The invention discloses a determination method for nitrogen content of protein in tobacco, which comprises the following steps: a) the tobacco is weighed; b) the weighed tobacco is put into sufficient acid or copper sulfate solution, and heated until the protein is completely solidified; c) filtering is carried out and the acid or copper sulfate solution in the step b is used for washing the filtered matter; d) the filtrate is combined and the volume limiting thereof is carried out; e) the filtrate is taken for digestive treatment and the volume limiting thereof is carried out; f) the filtrate after volume limiting is added with NaOH solution to determine a first equilibrium potential value; g) the NH4<+> solution is added to determine a second equilibrium potential value; the nitrogen content of non-protein in the tobacco is calculated by combining the first and second equilibrium potential values; h) the total nitrogen content in the tobacco is determined; and i) the nitrogen content of protein in the tobacco is calculated by combining the determination results of the step g and the step h; wherein, the step h and the steps from a to g have no sequencing. The determination method is simple, convenient and efficient.
Description
Technical field
The present invention relates to the assay method that one-tenth is grouped in the tobacco, relate in particular to the assay method of protein nitrogen content in the tobacco.
Background technology
The content of each composition in the tobacco has determined the quality of tobacco, for example the tar of hybrid cigarette and nicotine ratio is 11:1, and fire-cured tobacco type is 13～14:1 mostly, thus hybrid cigarette compare biggest advantage with fire-cured tobacco type cigarette be exactly that perfume quantity foot and tar content are low.Contain protein in the tobacco, protein can make the flue gas bitter taste increase after burning, produces acid and excitement, therefore protein has harmful effect to cigarette odor-absorbing, if but protein content is low excessively, flue gas will seem flat so, and jealous and fragrance also can variation.In addition, protein hydrolyzable in modulated process is an amino acid, and the fragrance of amino acid content and flue gas and richness have tangible positive correlation.
Though it is less that the total amount of protein changes in the alcoholization process of tobacco, other compositions in the tobacco but can change along with the alcoholization process, thereby also cause the variation of protein content in the tobacco.Correspondingly,, all need grasp Protein content in the tobacco, measure Protein content in the tobacco in each stage for the research and development and the production of tobacco industry, very important to understanding quality of tobacco.
At present, tobacco business can carry out with reference to the tobacco business standard YC/T 166-2003 of the People's Republic of China (PRC) the detection method of protein, the test philosophy of the method also is to adopt usually both at home and abroad, its principle is, with the protein nitrogen in the acid precipitation tobacco samples such as acetate, by with nitrogenous thing of nonprotein nitrogen and Separation of Proteins, wash-out, then protein is disappeared together with other sediments and boil, protein nitrogen is converted into ammonium sulfate under the concentrated sulphuric acid and catalyst action, the highly basic distillation discharges ammonia, receive with the standard acid solution, back titration is at last by calculating Protein content in the tobacco.This method is to measure the content of protein nitrogen in the tobacco in essence, thereby by calculating Protein content.In the method mensuration process, sediment is disappeared boil after, also need to collect again the ammonia that discharges by the highly basic distillation, receive and back titration with the standard acid solution, need and will repeatedly sample be shifted, the error that human factor causes in the process of the test is bigger.
Summary of the invention
Technical matters to be solved by this invention be to provide one grow tobacco in the assay method of protein nitrogen content, measurement result is accurate, error is little.
In order to solve above technical matters, the invention provides following technical scheme:
One grow tobacco in the assay method of protein nitrogen content, comprise the steps:
A) take by weighing tobacco;
B) tobacco that takes by weighing is put into the acid or the copper-bath of capacity, be heated to protein and solidify fully;
C) filter and wash and leach thing with acid described in the step b) or copper-bath;
D) merging filtrate and constant volume;
E) get filtrate and carry out digestion process, constant volume;
F) pipette the filtrate that obtains behind the constant volume, add NaOH solution, measure the first equilibrium potential value;
G) add NH
4 +Solution is measured the second equilibrium potential value; Calculate non-protein nitrogen content in the tobacco in conjunction with the first equilibrium potential value and the second equilibrium potential value;
H) measure total nitrogen content in the tobacco;
I) integrating step g) and step h) measurement result calculate protein nitrogen content in the tobacco;
Wherein, step h) there is not sequencing with step a)～g).
The assay method of protein nitrogen content in the tobacco hereto, what step a) and step b) were finished is the fixed nitrogen process; Step c) and step d) are that isolated by filtration is rejected the precipitation that protein solidifies formation; Step e)～g) is for utilizing ammonia gas-sensing electrode method determination step d) nitrogen content in the constant volume rear filtrate; Step h) for measuring the step of total nitrogen content in the tobacco; Step I) is in conjunction with preceding step measured total nitrogen content and non-protein nitrogen content, does difference and calculate protein nitrogen content in the tobacco.Because step a)～g) with step h) be separate, therefore can not have sequencing.Step a)～g) for measuring the step of non-protein nitrogen content in the tobacco.
For whole assay method, at first handle Protein in Tobacco is rejected with the form of precipitation by fixed nitrogen, utilize the method (ammonia gas-sensing electrode method) of mensuration total nitrogen to measure the adding NaOH solution in the filtrate and add NH then
4 +Two potential values after the solution, calculating can obtain the content of nonprotein nitrogen in the tobacco, in conjunction with the content of total nitrogen that determines in the tobacco, by calculating the content that can draw protein nitrogen in the tobacco.Further, the quality corresponding relation by protein and nitrogen element can also calculate Protein content in the tobacco.
By measuring non-protein nitrogen content in the tobacco, and by measuring content of total nitrogen in the tobacco, can be easy to calculate Protein content in the tobacco, need not carry out filter residue again shifts, collect operations such as gas and titration, and in the method for existing direct mensuration protein nitrogen, need carry out suction filtration handles and filter residue is transferred in the digestion vessel, after protein nitrogen is converted into ammonium sulfate, also need to carry out the highly basic distillation and discharge ammonia, receive with the standard acid solution, back titration, these experimental implementation more complicated and exist than big-difference because of experimenter's difference.As can be seen, assay method provided by the invention has reduced artificial operate miss, is the method for protein nitrogen content in a kind of mensuration tobacco of simple and effective.
Below each step is carried out detailed argumentation and introduction, and some preferred or can substitute technical schemes are provided.
Step a) takes by weighing tobacco
Before address, this step is a step of fixed nitrogen process.In the present invention, the fixed nitrogen process refers to the process of Protein in Tobacco and acid reaction generation precipitation.The fixed nitrogen process is also referred to as the process of nitrogen curing etc.Definite says, this step is a weighing step, for simplicity, so this weighing step is defined as a step of fixed nitrogen process.
The weighing step is one of basic operation in the analytical test process.Because the proportion of tobacco leaf is smaller, so sky equality weighing equipment that weighing is used selects for use the high electronic balance of degree of accuracy or optical electrobalance relatively good, the general need of degree of accuracy are with being accurate to 0.001g (gram) or the higher testing tool of degree of accuracy.
Before carrying out this operation steps, also need to measure the moisture in the tobacco usually, what generally adopt is Oven Method.Also can and place dry environment stand-by with the tobacco sample oven dry.
Step b) is put into the acid or the copper-bath of capacity with the tobacco that takes by weighing, and is heated to protein and solidifies fully
This step is the step that the fixed nitrogen reaction takes place, and in this step, Protein in Tobacco and acid or copper sulphate reaction generate precipitation.Described acid needs certain concentration, and its essence is that certain pH is arranged.For different types of acid, also be different to the requirement of the mass percent concentration of acid, can select according to the acid of needs in the reality test.Acid stronger organic acid is generally selected in the acid that participates in reaction for use, and the most frequently used is acetate.Also can be acetate, propionic acid, malonic acid, trichloroacetic acid etc., perhaps their combination.Wherein acetate is the most frequently used, and when selecting acetate for use, the concentration of acetate preferably uses 0.4%～0.6%; Trichloroacetic acid is also comparatively commonly used, and when selecting trichloroacetic acid for use, the concentration of trichloroacetic acid preferably uses 0.8%～2.0%.The invention is not restricted to only use organic acid, also can use other solvent such as copper sulphate etc., if can with Protein in Tobacco generation sex change, it is heavy poly-to condense, thereby can get final product by filtering separate with nonprotein nitrogen.
When adopting acetate to carry out the fixed nitrogen reaction of protein, the concentration of acetate can select 0.4%～0.6% for use, the temperature of reaction is chosen as the boiling temperature of selected acetic acid solution, for the acetate of selecting 0.4%～0.6% for use, need to keep the acetate boiling more than 15 minutes, so that the generation fully of fixed nitrogen reaction.
Step c) is filtered and is leached thing with acid described in the step b) or copper-bath flushing
Step c) is that isolated by filtration is rejected the key step that protein solidifies the precipitation that forms.This step simple to operate adopts filter operation commonly used to get final product, and both can select common filtration for use, also can select the filtered version of suction filtration for use.This also is one of advantage of the present invention, in the process of directly measuring protein nitrogen, a filter process is arranged also in the prior art, but preferably adopt the form of suction filtration, then no this item requirement among the present invention, because the object of mensuration of the present invention is a filtrate, so, the form of employing suction filtration or common filtration can, moreover exist filtrate to shift the problem of difficulty when adopting suction filtration, so the filtration in this step is preferably used common filtered version, normal pressure filtration just.
Filter and leach thing with acid described in the step b) or copper-bath flushing, can so that filter paper or precipitate in residual nonprotein nitrogen enter filtrate, help improving accuracy of test.It is pointed out that the acid of using in this step or copper-bath are just consistent with the material described in the step b), do not represent must be with step b) in the acid of using or copper-bath concentration too.For example, if what use in the step b) is that concentration is 0.5% acetate, so can working concentration in the step c) be 0.7% acetate.Yet preferred mode is still, and the acid of using in the acid of using in the step c) or the concentration of copper-bath and the step b) or the concentration of copper-bath are more or less the same, more electedly, and the acid of working concentration unanimity or copper-bath.
Step d) merging filtrate and constant volume
As previously mentioned, this step is that isolated by filtration rejecting protein solidifies one of step of the precipitation that forms, also can think a step of preparing for next step operation.The filtrate of coming from step c) does not have a volume numerical value accurately, can't provide definite computing formula in follow-up computation process, so need constant volume yet.
Constant volume is a mode of operation commonly used in the chemical experiment, is about to the liquid of uncertain volume, adds certain amount of fluid, makes it have definite volume.The liquid of constant volume is solution if desired, and what then add usually is solvent.
Because the filtrate of coming from step c) has higher temperature, so preferably treat after the filtrate cooling constant volume again, in order to avoid influence the accuracy of constant volume.
Step e) is got filtrate and is carried out digestion process, constant volume
Step e) is the digestion process to filtrate.Digestion process refers to, and the organic nitrogen-containing material is under the effect of oxygenants such as the concentrated sulphuric acid, and through the heat-flash digest and decompose, nitrogen wherein is converted into the process of ammonia.Oxygenant is generally selected strong oxidizer for use.Described strong oxidizer can be selected from the concentrated sulphuric acid, concentrated hydrochloric acid, the concentrated sulphuric acid/hydrogen peroxide potpourri or concentrated hydrochloric acid/hydrogen peroxide potpourri etc.Because the volatility of hydrochloric acid is very strong, so, so must seal pressurization and reacting, prevent volatilization, otherwise the temperature of digestion is very limited, and then influences the effect that digests if use hydrochloric acid as oxygenant.Strong oxidizer is not selected nitric acid for use, and this is that reacting afterwards can be influential to test result owing to contain the nitrogen element in the nitric acid.
In this process, can also add catalyzer, accelerate the carrying out of digestion reaction.Catalyzer can be selected mercury and compound, selenium and compound thereof, copper and compound thereof, and perhaps their combination is concrete as mercury, mercury oxide, selenium, cupric oxide, copper sulphate etc., preferably uses mercury oxide.
Except oxygenant and catalyzer, in digestion reaction, can also add flux.With the concentrated sulphuric acid is example, and the effect of flux is can be so that the elevation of boiling point of the concentrated sulphuric acid, thus can raise the digestion temperature, thus can improve the effect of digestion, reduce digestion time.Flux has glazier's salt, salicylic acid etc.The better effects if of glazier's salt can be so that the elevation of boiling point to 350 of the concentrated sulphuric acid ℃ even higher, and salicylic effect is then weaker a little, and salicylic acid can be so that more than the elevation of boiling point to 340 of the concentrated sulphuric acid ℃.The boiling point of water-free sulfuric acid is 338 ℃.Because generally contain a spot of water in the employed sulfuric acid, so the heating of digestion process generally is divided into two stages, the phase one is to be heated to 100 ℃～150 ℃, makes that the moisture in the sulfuric acid fully is evaporated, and avoids reducing the boiling point of sulfuric acid.If the boiling point of sulfuric acid reduces, part of sulfuric acid will be evaporated in digestion process so, and then causes the loss of ammonia.Flux can be selected glazier's salt, sodium sulphate, salicylic acid or their combination.Preferred a kind of use wherein, and more preferably glazier's salt.
When sulfuric acid and flux use together, often also need to add catalyzer, at this moment, can be heated to sulfuric acid near boiling, and keep can finishing digestion process more than 0.5 hour; Under such reaction conditions, also can keep more than 1 hour, but the time is unsuitable oversize.The inventor points out that the digestion reaction time under this reaction conditions was advisable with 0.5～2.5 hour.
Because the temperature of digestion reaction is very high, can therefore after digestion is finished, need wait a mement more than 300 ℃ usually, treat to carry out next step operation again after filtrate is cooled off a little, also can add low amounts of water and prevent to cool off back ammonium sulfate and form crystal and be difficult for dissolving.
Step f) pipettes the filtrate that obtains behind the constant volume, adds NaOH solution, measures the first equilibrium potential value
Step f) and step g) are adding NaOH solution and NH for measuring postdigestive filtrate
4 +The step of the equilibrium potential value behind the standard solution, the difference in conjunction with two equilibrium potential values that record can calculate non-protein nitrogen content in the tobacco like this.
This step measurements be the first equilibrium potential value.
Step g) adds NH
4 +Solution is measured the second equilibrium potential value; Calculate non-protein nitrogen content in the tobacco in conjunction with the first equilibrium potential value and the second equilibrium potential value.
This step measurements be the second equilibrium potential value.In conjunction with the first equilibrium potential value and the second equilibrium potential value, can obtain the content of nonprotein nitrogen in the tobacco by specific computing formula.
Step h) measures total nitrogen content in the tobacco
This step is for measuring the step of total nitrogen content in the tobacco.Because step a)～g) with step h) be separate, therefore can not have sequencing.
The method of measuring total nitrogen content in the tobacco is a lot, for example continuous flow method, distillation titrimetry, ammonia gas-sensing electrode method or the chromatography of ions etc.The method of measuring total nitrogen content in the tobacco adopts method of the prior art to get final product, and these methods are also comparatively ripe, have and much all formulated industry standard.For example People's Republic of China's tobacco business standard YC/T161-2002 is that " the mensuration continuous flow method of tobacco and tobacco product total nitrogen ", YC/T33-1996 are " the mensuration Ke Daerfa of tobacco and tobacco product total nitrogen ".Wherein Ke Daerfa is exactly above-mentioned distillation titrimetry.The determination of total nitrogen content method in above-mentioned formulation standard, also utilize the ammonia gas-sensing electrode method, the principle of ammonia gas-sensing electrode is by the equilibrium potential difference between bioassay standard ammonium salt solution and the testing sample digestive juice, to utilize formula to calculate the content of nitrogen again.The typical concrete operations step of ammonia gas-sensing electrode method is, accurately pipettes a certain amount of digestive juice in beaker, accurately adds a certain amount of NaOH solution, puts into stirrer, inserts electrode, reads the equilibrium potential value under electromagnetic agitation, can remember and make E
1, accurately add NH again
4 +Standard solution reads the equilibrium potential value under electromagnetic agitation, can remember and make E
2By the relation between equilibrium potential difference and the nitrogen content, calculate nitrogen content then.Also can utilize the chromatography of ions to measure.More than the method for measuring total nitrogen in the tobacco has been done explanation, select any method to measure, can determine to adopt any method according to tester's actual conditions, for example the restriction of some experiment condition can not be used the chromatography of ions, can select other method so, some needs fast measuring, then may need the chromatography of ions or ammonia gas-sensing electrode method etc.The method of measuring nitrogen is not limited thereto, if the method that can determine to measure nitrogen according to the principles of science is feasible, then can be as the step h among the present invention).Do not recommend to use the distillation titrimetry in this step, because such assay method will bother more with respect to existing technology.But, measuring total nitrogen content in tobacco unit is daily test event, if this unit utilization is that the distillation titrimetry is measured total nitrogen so, in conjunction with step a) of the present invention～g) just can be easy to calculate Protein in Tobacco content and do not need to utilize again the Continuous Titration method to remove directly to measure the nitrogen content of protein in the tobacco, omitted the step that tobacco solution is digested so again.
Step I) integrating step g) and step h) measurement result calculate protein nitrogen content in the tobacco
Integrating step g) and step h) measurement result, just can obtain protein nitrogen content in the tobacco according to the corresponding relation of nitrogen element, and Protein content in the tobacco.Perhaps the corresponding relation according to the nitrogen element directly just can calculate Protein content in the tobacco by a formula.
More than the details in each step of the present invention is illustrated, wherein also narrated some and improved and preferred scheme.
Determine after the content of protein nitrogen in the tobacco, just can calculate Protein content.The inventor can alleviate the workload in the work greatly by the realization route of this assay method of design.Because the daily monitoring project that is determined as each tobacco enterprise of total nitrogen content in the tobacco, so in the method, the content that only needs to measure nonprotein nitrogen in the tobacco gets final product, and can't increase workload.Confirm by test, the assay method of protein nitrogen content in the tobacco provided by the invention also can be referred to as the assay method of protein content in the tobacco, and measurement result is stable, the measured value that obtains with original classical approach also has the consistance of height, satisfies the requirement of experiment accuracy.
Above technical scheme of the present invention has been done detailed explanation, assay method for protein nitrogen content in the tobacco provided by the present invention, at first handle Protein in Tobacco is rejected with the form of precipitation by fixed nitrogen, utilize the nitrogen content in the ammonia gas-sensing electrode method mensuration filtrate then, utilize the nitrogen content in the method mensuration tobacco of measuring total nitrogen again, can draw Protein in Tobacco nitrogen content and Protein content by calculating.Because the daily monitoring project that is determined as each tobacco enterprise of total nitrogen content in the tobacco, be equivalent to finish step h of the present invention), so only need experimental procedure a)～g) and calculation procedure i) get final product, and step a)～g) is not directly to measure protein nitrogen content, but measure the content of rejecting nitrogen in the later filtrate of protein, after having avoided protein nitrogen is converted into ammonium sulfate, also need to utilize highly basic distillation discharge ammonia, with the standard acid solution receive, back titration, reduced exist because of the experimenter is different than big-difference.As can be seen, assay method provided by the invention has reduced artificial operate miss, is the method for protein nitrogen content in a kind of mensuration tobacco of simple and effective.
Embodiment
For further understanding the present invention, above-mentioned technical scheme is further elaborated and illustrates below in conjunction with concrete embodiment.
The concrete condition of the reagent of using in following examples sees Table 1, to reagent have specified otherwise except.
Table 1
In the table 1, the AR representative is analyzed pure.
Concrete assay method is:
1) extracts tobacco sample according to the standard GB/T19616-2004 of the People's Republic of China (PRC), tobacco sample is prepared the offal sample, measure moisture in the offal according to the tobacco business standard YC/T31-1996 of the People's Republic of China (PRC);
2) take by weighing about 2g offal, take by weighing precision and be accurate to 0.0001g, placing 100mL (milliliter) concentration is 0.5% acetic acid solution, and heating keeps boiling 15 minutes, filters with no nitrogen qualitative filter paper rapidly, and is that 0.5% acetic acid solution washes sediment with concentration.Merging filtrate, to be cooled after the room temperature constant volume to 200mL.The concentration of described acetic acid solution refers to mass concentration, i.e. mass percent.
3) accurately pipette 10mL filtrate in the 75mL digest tube with transfer pipet, and add 0.1g mercury oxide, 1.0g glazier's salt, 5mL sulfuric acid.Digest tube placed on the digester digest, the digester running parameter is: 100 ℃ keep 1h (hour), 370 ℃ keep 1h.Cold slightly after the digestion, add low amounts of water, cool to room temperature, water are settled to the 75mL scale mark, shake up.Need to prove that the digestion running parameter is 370 ℃ and does not represent the temperature of filtrate also to be 370 ℃.Set instrument parameter being 370 ℃ mainly is in order to keep the filtrate boiling in the digest tube.The mensuration of this temperature also can be other temperature, as long as can guarantee that the carrying out of digestion reaction is just passable.
4) with transfer pipet removing step 3) the digestive juice 10mL that obtains places the 100mL beaker, and beaker is put on the magnetic stirrer, puts into magnetic stirrer in the beaker and mixes son.Accurately add concentration value in 0.1～1.0moL/L scope, precision reaches NaOH solution 10～50mL of 0.01moL/L.Insert ammonia gas-sensing electrode under the situation of electromagnetic agitation, the potential value that reads is the first equilibrium potential value, is designated as E
1Accurately add concentration value again in 0.01～0.5moL/L scope, precision reaches the NH of 0.001moL/L
4 +Standard solution 10～100mL, the potential value that reads under electromagnetic agitation are the second equilibrium potential value, are designated as E
2
In this step, the amount and the NH of the NaOH solution of adding
4 +The amount of standard solution is to do suitable adjustment according to actual test case, and total principle is to make the measurement result error reduce.NH for example
4 +Standard solution can also select practical 1.00 * 10
-2The NH of mol/L
4 +Standard solution.In the process of measuring, E
1And E
2If difference range at 20～50mV (millivolt), the error of measurement result is less, more preferably, E
1And E
2Difference range be 20～50mV.
5) calculate the content of nonprotein nitrogen in the tobacco according to following formula:
In the formula, each alphabetical implication is:
C
S---standard ammonium chloride solution concentration (mol/L)
V
s---standard ammonium chloride solution volume (mL)
V
X---original solution volume (mL)
ΔE＝E
2-E
1(mV)
W---sample quality (g)
6) measure the total nitrogen content of tobacco according to the described method of the tobacco business standard YC/T161-2002 of the People's Republic of China (PRC).
7) calculate Protein content in the tobacco.Computing formula is:
6.25×(t-c)，
Wherein, t represents the measured total nitrogen content of step 6),
C represents the content of the nonprotein nitrogen of measuring in the step 5).
To 16 tobacco samples, each tobacco sample carry out 3 times the test, the non-protein nitrogen content of the tobacco sample of gained the results are shown in Table 2, protein content the results are shown in Table 3.
Table 2 non-protein nitrogen content (mass percent) testing result
Table 2 (continuing) non-protein nitrogen content (mass percent) testing result
Table 3 protein content (mass percent) testing result
In each test, as making a report on data, and the inventor finds that the typical curve related coefficient of testing is all greater than 0.999 at every turn with the mean value of two parallel sample testing results.
Can see that from table 2 data the coefficient of variation of other data is all less than 5% except that a sample.And show more that from the data of table 3 this method repeatability is better, and the coefficient of variation is less than 3%, and the overwhelming majority is all less than 2.4, usually all less than 2.Therefore, meet the requirement of analyzing and testing.
The contrast embodiment
According to the assay method of People's Republic of China (PRC) tobacco business standard YC/T166-2003 tobacco and tobacco product total protein content, above-mentioned 16 tobacco samples are carried out the mensuration of total protein content.What obtain the results are shown in Table 4.Table 4 is the comparison sheet of measured protein content of the present invention and the protein content that utilizes the industry standard assay method to draw.
Table 4
| Sample number into spectrum | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| The inventive method measured value | 7.49 | 11.78 | 9.96 | 8.25 | 10.36 | 9.14 | 10.37 | 9.71 |
| The industry standard measured value | 6.95 | 11.15 | 9.78 | 9.12 | 9.57 | 10.17 | 10.26 | 9.18 |
| Relative deviation, % | 3.72 | 2.73 | 1.10 | 5.01 | 3.96 | 5.35 | 0.55 | 2.82 |
Table 4 (continuing)
| Sample number into spectrum | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
| The inventive method measured value | 10.56 | 9.34 | 10.86 | 10.02 | 4.72 | 6.18 | 6.83 | 8.83 |
| The industry standard measured value | 10.61 | 8.91 | 10.63 | 9.14 | 5.19 | 5.97 | 7.24 | 7.97 |
| Relative deviation, % | 0.25 | 2.36 | 1.36 | 4.58 | 4.71 | 1.73 | 2.94 | 5.12 |
As can be seen from Table 4, the inventive method data measured with utilizing industry standard of utilizing of each sample contrast, and the relative deviation of every pair of data is all less than 6%.Utilizing 16 measured data of the inventive method as one group, utilizing 16 measured data of industry standard as one group, adopt the t check in the mathematical statistics method that these two groups of data are analyzed, obtaining the t value is 1.082, less than the value of tabling look-up t (0.1,15), t (0.1,15)=1.753.In 90% fiducial interval, two groups of data do not have evident difference as can be seen, therefore reach a conclusion: can adopt assay method provided by the present invention to replace original classical detection method.
More than technical scheme provided by the present invention is described in detail.Used specific embodiment in this instructions principle of the present invention and embodiment have been set forth, for one of ordinary skill in the art, according to the thought of the present invention part that may in implementation process, can change in specific embodiments and applications.Therefore, the content of this instructions record should not be construed as limitation of the present invention.
Claims (10)
1, one grow tobacco in the assay method of protein nitrogen content, comprise the steps:
A) take by weighing tobacco;
B) tobacco that takes by weighing is put into the acid or the copper-bath of capacity, be heated to protein and solidify fully;
C) filter and wash and leach thing with acid described in the step b) or copper-bath;
D) merging filtrate and constant volume;
E) get filtrate and carry out digestion process, constant volume;
F) pipette the filtrate that obtains behind the constant volume, add NaOH solution, measure the first equilibrium potential value;
G) add NH
4 +Solution is measured the second equilibrium potential value; Calculate non-protein nitrogen content in the tobacco in conjunction with the first equilibrium potential value and the second equilibrium potential value;
H) measure total nitrogen content in the tobacco;
I) integrating step g) and step h) measurement result calculate protein nitrogen content in the tobacco;
Wherein, step h) there is not sequencing with step a)～g).
2, assay method according to claim 1 is characterized in that, acid is organic acid described in the step b).
3, assay method according to claim 2 is characterized in that, organic acid described in the step b) is an acetate, and concentration is 0.4%～0.6%.
4, assay method according to claim 3 is characterized in that, is heated to protein described in the step b) and solidifies and to be entirely, and is heated to the acetate boiling and keeps more than 15 minutes.
5, assay method according to claim 1 is characterized in that, digestive pharmaceutical comprises catalyzer and oxidizing substance in the step e) digestion process.
6, assay method according to claim 5 is characterized in that, described catalyzer is selected from mercury and compound, selenium and compound thereof, copper and compound thereof, perhaps their combination.
7, assay method according to claim 5 is characterized in that, described oxidizing substance is a sulfuric acid, and described digestive pharmaceutical also comprises flux, and described digestion process is: be heated to boiling, and keep more than 0.5 hour.
8, assay method according to claim 7 is characterized in that, described flux is selected from salicylic acid, glazier's salt or their combination.
9, assay method according to claim 1 is characterized in that, the difference of the described first equilibrium potential value and the second equilibrium potential value is 20～50mV.
10, assay method according to claim 9 is characterized in that, the difference of the described first equilibrium potential value and the second equilibrium potential value is 30～40mV.
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| CN102565425A (en) * | 2011-12-30 | 2012-07-11 | 广东中烟工业有限责任公司 | Method for measuring protein nitrogen content in tobaccos |
| CN102590206A (en) * | 2012-02-17 | 2012-07-18 | 贵州兴化化工股份有限公司 | Measuring method and measuring device for total ammonia content in acetate cuprammonia |
| CN104459021A (en) * | 2014-12-24 | 2015-03-25 | 江苏中烟工业有限责任公司 | Method for determining total nitrogen in tobaccos and tobacco products by automatic water steam distillation titrator |
| CN105548458A (en) * | 2015-12-16 | 2016-05-04 | 贵州省化工研究院 | Composite fertilizer nitrogen content detection method |
| CN111505097A (en) * | 2020-06-12 | 2020-08-07 | 上海烟草集团有限责任公司 | Electrochemical method for measuring nicotine content in tobacco and tobacco related products |
-
2008
- 2008-09-04 CN CNA200810212239XA patent/CN101382519A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102565425A (en) * | 2011-12-30 | 2012-07-11 | 广东中烟工业有限责任公司 | Method for measuring protein nitrogen content in tobaccos |
| CN102590206A (en) * | 2012-02-17 | 2012-07-18 | 贵州兴化化工股份有限公司 | Measuring method and measuring device for total ammonia content in acetate cuprammonia |
| CN104459021A (en) * | 2014-12-24 | 2015-03-25 | 江苏中烟工业有限责任公司 | Method for determining total nitrogen in tobaccos and tobacco products by automatic water steam distillation titrator |
| CN105548458A (en) * | 2015-12-16 | 2016-05-04 | 贵州省化工研究院 | Composite fertilizer nitrogen content detection method |
| CN105548458B (en) * | 2015-12-16 | 2018-04-27 | 贵州省化工研究院 | A kind of detection method of composite fertilizer's nitrogen content |
| CN111505097A (en) * | 2020-06-12 | 2020-08-07 | 上海烟草集团有限责任公司 | Electrochemical method for measuring nicotine content in tobacco and tobacco related products |
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