GB2250590A - Determination of urea - Google Patents
Determination of urea Download PDFInfo
- Publication number
- GB2250590A GB2250590A GB9125040A GB9125040A GB2250590A GB 2250590 A GB2250590 A GB 2250590A GB 9125040 A GB9125040 A GB 9125040A GB 9125040 A GB9125040 A GB 9125040A GB 2250590 A GB2250590 A GB 2250590A
- Authority
- GB
- United Kingdom
- Prior art keywords
- indicator
- urea
- alkali
- buffer
- milk
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 239000004202 carbamide Substances 0.000 title claims abstract description 42
- 239000008267 milk Substances 0.000 claims abstract description 29
- 210000004080 milk Anatomy 0.000 claims abstract description 29
- 235000013336 milk Nutrition 0.000 claims abstract description 29
- 239000003513 alkali Substances 0.000 claims abstract description 18
- 108010046334 Urease Proteins 0.000 claims abstract description 17
- 239000003153 chemical reaction reagent Substances 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 claims description 31
- 239000000203 mixture Substances 0.000 claims description 21
- 239000000872 buffer Substances 0.000 claims description 18
- 238000006243 chemical reaction Methods 0.000 claims description 12
- 239000008363 phosphate buffer Substances 0.000 claims description 5
- 159000000000 sodium salts Chemical class 0.000 claims description 5
- BELBBZDIHDAJOR-UHFFFAOYSA-N Phenolsulfonephthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2S(=O)(=O)O1 BELBBZDIHDAJOR-UHFFFAOYSA-N 0.000 claims description 3
- 229960003531 phenolsulfonphthalein Drugs 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- NUHCTOLBWMJMLX-UHFFFAOYSA-N bromothymol blue Chemical compound BrC1=C(O)C(C(C)C)=CC(C2(C3=CC=CC=C3S(=O)(=O)O2)C=2C(=C(Br)C(O)=C(C(C)C)C=2)C)=C1C NUHCTOLBWMJMLX-UHFFFAOYSA-N 0.000 claims 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000012528 membrane Substances 0.000 description 5
- 239000008280 blood Substances 0.000 description 4
- 210000004369 blood Anatomy 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- FHVDTGUDJYJELY-UHFFFAOYSA-N 6-{[2-carboxy-4,5-dihydroxy-6-(phosphanyloxy)oxan-3-yl]oxy}-4,5-dihydroxy-3-phosphanyloxane-2-carboxylic acid Chemical compound O1C(C(O)=O)C(P)C(O)C(O)C1OC1C(C(O)=O)OC(OP)C(O)C1O FHVDTGUDJYJELY-UHFFFAOYSA-N 0.000 description 3
- 239000004809 Teflon Substances 0.000 description 3
- 229920006362 Teflon® Polymers 0.000 description 3
- 229940072056 alginate Drugs 0.000 description 3
- 235000010443 alginic acid Nutrition 0.000 description 3
- 229920000615 alginic acid Polymers 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 229910000403 monosodium phosphate Inorganic materials 0.000 description 3
- 235000019799 monosodium phosphate Nutrition 0.000 description 3
- 108090000623 proteins and genes Proteins 0.000 description 3
- 102000004169 proteins and genes Human genes 0.000 description 3
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 3
- 239000003086 colorant Substances 0.000 description 2
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 2
- 239000007793 ph indicator Substances 0.000 description 2
- 229940096055 prax Drugs 0.000 description 2
- 210000004767 rumen Anatomy 0.000 description 2
- 210000002700 urine Anatomy 0.000 description 2
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 241000282849 Ruminantia Species 0.000 description 1
- 239000001099 ammonium carbonate Substances 0.000 description 1
- 235000012501 ammonium carbonate Nutrition 0.000 description 1
- -1 ammonium ions Chemical class 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 244000144972 livestock Species 0.000 description 1
- 230000004060 metabolic process Effects 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 210000002381 plasma Anatomy 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000007430 reference method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- NESLWCLHZZISNB-UHFFFAOYSA-M sodium phenolate Chemical compound [Na+].[O-]C1=CC=CC=C1 NESLWCLHZZISNB-UHFFFAOYSA-M 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/02—Food
- G01N33/04—Dairy products
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/58—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving urea or urease
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Proteomics, Peptides & Aminoacids (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Zoology (AREA)
- Immunology (AREA)
- Wood Science & Technology (AREA)
- Food Science & Technology (AREA)
- Microbiology (AREA)
- Biotechnology (AREA)
- Medicinal Chemistry (AREA)
- Molecular Biology (AREA)
- Biophysics (AREA)
- Pathology (AREA)
- General Physics & Mathematics (AREA)
- Bioinformatics & Cheminformatics (AREA)
- General Engineering & Computer Science (AREA)
- Genetics & Genomics (AREA)
- Investigating Or Analysing Biological Materials (AREA)
- Measuring Or Testing Involving Enzymes Or Micro-Organisms (AREA)
- Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
Abstract
Determination of the concentration of urea in a sample, especially milk, is by means of urease, alkali and an indicator. The sample is reacted with urease and alkali in a closed space in which the indicator system is placed such that it is not in contact with the other reagents.
Description
A process and a test means for the determination of urea
The invention relates to a process and a test means for the determination of urea in a sample by means of urease, alkali and an indicator. The process is especially suitable for rapid determination of the concentration of urea in milk.
The metabolism of a ruminant, such as a cow, is essentially affected by the functions of the rumen and the forestomachs. The energy and protein supply of rumen microorganisms affects the feed utilization.
If the supplies of energy and proteins are not balanced, the utilization of feed proteins is deteriorated. This is manifested e.g. in increased urea levels in blood after feeding.
Several researches have shown that the amount of urea in milk varies with the level of urea in blood (e.g. Oltner & Wiktorsson 1983, Livestock Prod.
Sci. 10:457, Refsdal 1983, Acta Vet. Scand. 24:518).
Variation in the level of urea in blood as well as in milk is largely due to changes in feeding (e.g.
Ref sal and Oltner & Wiktorsson, as above). For this reason, the concentration of urea in milk has been used as an indicator in the assessment of successful feeding. In feeding according to standard requirements, a urea concentration range of 20 to 30 mg of urea in 100 ml of milk has been observed (Setälä et al. 1987, Karjatalous 10:52 and 11:54).
Urea can be determined by a process in which it is degraded by urease into ammonium carbonate, and the ammonium ions are reacted with phenol and hypochlorite to achieve a blue compound which can be determined spectrophotometrically (Fawcett & Scott 1960, J. Clin. Path. 13:156). The process has also been applied to milk (e.g. Rajamki & Rauramaa 1984,
Finnish Chemical Letters 2:47-48).
To get the maximum benefit from a urea determination, the determination should be performed as a rapid "cow-side" determination in the cowhouse.
The above-mentioned process is unsuitable for this purpose, because it has to be performed in a laboratory.
Urea can also be determined by reacting a sample containing urea with urease and observing the change in pH caused by the hydrolysis product by means of a suitable indicator. This process is utilized in the determination of the concentration of urea e.g. in blood, plasma and urine (GB Patent
Specification 922 665). A strip test of this type for milk is disclosed in Tierärtzl. Prax. 1985, 13:559.
A common drawback of strip tests is that they are able to analyze only an extremely small amount of sample, and so the obtained result often remains unreliable. The result varies on account of the small amount of sample, but it is also affected by the way the performer of the test pipettes the sample on the strip or dips the strip into the solution to be analyzed. The problem is further aggravated by the fact that when the test strip is dipped into milk, milk as such disturbs accurate reading of the color change in the strip. To eliminate the disturbing influence of milk, strips have been developed in which a reaction zone to be brought into contact with milk is positioned beside an indicator zone (FI Patent Application 891920). The reaction zone contains urease, alkali, glucose and tenside.The strip is kept in a tube closed at one end only until ammonia liberated from the reaction zone has diffused into the indicator zone, which takes place slowly.
The strips are preferably read only after two hours.
A determination process has now been discovered which is more reliable-than strips to be immersed in milk and more rapid than a strip in which the indicator zone is positioned beside the reaction zone to be immersed in milk and which is kept in a tube closed at one end during the reaction time.
The process and the test means according to the invention are characterized by what is disclosed in the claims. In the process, the sample is reacted with urease and alkali and at least the reaction with the alkali is carried out in a closed space in which the indicator system is placed in such a way that it is not in contact with the other reagents. The sample can first be reacted with urease and then with alkali, and at least the last-mentioned reaction is carried out in the above-mentioned closed space. If the sample, instead, is reacted with urease and alkali simultaneously, the reaction is entirely carried out in a closed space. The test means comprises a closed space in which at least the reaction with alkali is carried out and in which the indicator system is placed in such a way that it is not in contact with the other reagents.
The reaction reagents comprise urease and alkali. Urease degrades urea contained in the sample to be analyzed into ammonium salts, and the alkali liberates ammonia from the salts. Ammonia is absorbed into the indicator system and it causes a color change in the pH indicator within a predetermined period of time.
The indicator system comprises one or more pH indicators. The indicator is generally dissolved in a suitable buffer. It is also possible to use several buffer/indicator mixtures which change color at dif ferent pH values. The determination of the concentration of urea in milk is preferably carried out as a so-called double test. The buffer/indicator mixtures of the double test are preferably such that a urea concentration below 20 mg/100 ml does not yet cause a color change in either one of the buffer/indicator mixtures, whereas one of the mixtures reacts at a concentration between 20 and 30 mg/100 ml and both mixtures react when the urea concentration is greater than 30 mg/100 ml. Preferably, the buffer/indicator mixtures both contain a phosphate buffer, though in different concentrations.The phosphate buffers preferably contain sodium salt of phenol red and sodium salt of bromtymol blue at a weight ratio of 1:1, for instance One phosphate buffer is preferably 0.00025M and the other 0.00230M sodium dihydrogenphosphate buffer.
The indicator system may be in liquid or solid form. An indicator system in liquid form can be separated from the other reagents by means of a gaspermeable membrane. The membrane may be e.g. of
Teflon tube tape or Teflon filter membrane with a porosity of 0.5 pm. The indicator system is preferably solidified by using alginate and/or by absorbing in filter paper and drying.
The indicator system is preferably placed in the cover of a closable container. The cover may comprise two parts, in which case two different buffer/indicator mixtures are placed in it. Urease, sample and alkali are introduced to the bottom of the container, and the cover is closed tightly. After a predetermined period of time, the colours of the indicator system are read. The process according to the invention is especially suitable for the determination of the concentration of urea in milk but it can also be applied to other samples, such as urine.
The invention will be illustrated by means of the following non-restrictive examples.
Example 1
Buffer/indicator mixture I containing 25 mg of sodium salt of phenol red, 25 mg of sodium salt of bromtymol blue and 3 g of alginate in 100 ml of 0.00025M sodium dihydrogenphosphate is absorbed in filter paper. Buffer/indicator mixture II otherwise similar to the mixture I except that the concentration of sodium dihydrogenphosphate is 0.00230M is absorbed in another filter paper. The papers are dried at 90"C for 60 min and then placed in a twopart cover of a tightly closable 10 ml container in such a way that a partition wall of the cover separates the papers from each other. Urease (about 60 to 250 U) is introduced to the bottom of the container in liquid or solid form. 1 ml of milk is added to the container, and 0.5 to 1 ml of 0.1M NaOH is added after 2.5 minutes, and the cover is closed.
After 2.5 minutes, the colours of the buffer/ indicator mixtures I and II formed in the cover of the test container are read. The results are compared with a color chart and interpreted as follows:
Color combination of Urea concentration of the cover of the test sample, mg/100 ml container yellow/yellow < 20 orange-red/yellow 20 to 30 orange-red/orange-red > 30
Example 2
Urea concentrations were determined from 118 milk samples as described in Example 1 and by a spectrophotometric reference method (Fawcett & Scott 1960, J. Clin. Path. 13:156). The results are shown in Table 1.
Table 1. Distribution of milk samples (number
of samples) into different urea con
centration classes
Urea mg/100 ml < 20 20-30 > 30 < 20 17 3 20 to 30 2 34 3 > 30 - 8 51
Reference process
Total/samples 19 45 54 118
As compared with the reference process, 8604% of the samples fell into the right class when determined by the process according to the invention.
Table 2 shows the corresponding sample distribution when the internal deviation of the reference process (+ 5t) is taken into account. The proportion of samples fallen into the right class is then 94.1t.
Table 2. Distribution of milk samples (number
of samples) into different urea con
centration classes
Urea mg/100 ml < 20 20-30 > 30 < 20 18 1 20 to 30 1 40 1 > 30 - 4 53
Reference process
Total/samples 19 45 54 118
Example 3
The concentration of urea in 64 milk samples was determined by using AzostixR test strips intended for farm use ( Tierärtzl. Prax. 1985, 13:559), by the above-mentioned reference process and by the process according to the invention. The results are shown in
Tables 3 and 4.
Table 3. Distribution of milk samples (number
of samples) into different urea con
centration classes by the test strip
Urea mg/100 ml < 20 20-30 > 30 < 20 7 20 to 30 6 21 5 > 30 - 1 24
Reference process
Total/samples 13 22 29 64
When using the test strip, 82.8% of the samples (53/64) fell into the right class.
Table 4. Distribution of milk samples (number
of samples) into different urea con
centration classes by the process of
the invention
Urea mg/l00 ml < 20 20-30 > 30 < 20 13 2 20 to 30 - 17 2 > 30 - 3 27
Reference process
Total/samples 13 22 29 64
When using the process of the invention, 89.1t of the samples (57/64) fell into the right class.
Example 4
0.5 ml of the buffer/indicator mixture I mentioned in Example 1 was introduced into a 4 ml container in liquid form, that is, the mixture did not contain alginate. The mouth opening of the container was covered with a Teflon membrane having a porosity of 0.5 pm. To another similar container, 0.2 ml of milk and about 15 U of urease were added. After 2.5 minutes, 200 pl of 0.lM NaOH was added to it. The container with the buffer/indicator mixture and the container with the sample and the other reagents were combined with their mouth openings against each other with tape into a fully closed space in which the gas permeable membrane separated the buffer/indicator mixture from the other reagents. The containers so combined were shaken for one minute, whereafter the color of the indicator mixture was read. A duplicate determination was made by using the liquid-form buffer/indicator mixture II mentioned in Example 1.
The results were interpreted as in Example 1. The concentration of urea in 24 milk samples was determined. 87.5% of the samples fell into the right class. The results are shown in Table 5.
Table 5. Distribution of milk samples (number
of samples) into different urea con
centration classes
Urea mg/100 ml < 20 20-30 > 30 < 20 6 20 to 30 1 8 1 > 30 - 1 7
Reference process
Total/samples 7 9 8 24
Claims (13)
1. A process for determining the concentration of urea in a sample by means of urease, alkali and an indicator, characterised in that at least the reaction with the alkali is carried out in a closed space in which the indicator system is placed in such a way that it is not in contact with the other reagents.
2. A process according to claim 1, characterised in that at least the reaction with the alkali is carried out in a closed container, the indicator system being placed in the cover of the container.
3. A process according to claim 1 or 2, characterised in that the determination is carried out as a double test by using an indicator system comprising two buffer/indicator mixtures changing color at different pH values.
40 A process according to claim 3, characterised in that one buffer/indicator mixture changes color at a urea concentration of at least 20 mg/100 ml and the other buffer/indicator mixture changes color at a urea concentration greater than 30 mg/100 ml.
5. A process according to claim 4, characterised in that the buffer/indicator mixtures contain a phosphate buffer of two different concentrations.
6. A process according to claim 5, characterised in that the phosphate buffers contain the sodium salt of phenol red and the sodium salt of bromthymol blue at a weight ratio of about 1:1.
7. A process according to any of claims 1 to 6, characterised in that the sample is milk.
8. A process for determining the concentration of urea in milk carried out substantially as hereinbefore described or exemplified.
9. A test means for the determination of urea by means of urease, alkali and an indicator, characterised in that it comprises a closed space in which at least the reaction with the alkali is carried out and in which the indicator system is placed in such a way that it is not in contact with the other reagents.
10. A test means according to claim 9, characterised in that the indicator system is in solid form.
11. A test means according to claim 9 or 10, characterised in that it comprises a closable container, the indicator system being placed in the cover of the container and the other reagents on its bottom.
12. A test means according to any of claims 9 to 11, characterised in that it comprises the reagents mentioned in claim 3, 4, 5 or 6 required for a double test.
13. A test means for the determination of urea in milk by means of urease, alkali and an indicator, substantially as hereinbefore described or exemplified.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI905949A FI88310C (en) | 1990-12-03 | 1990-12-03 | FOERFARANDE OCH MEDEL FOER BESTAEMNING AV UREA |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9125040D0 GB9125040D0 (en) | 1992-01-22 |
| GB2250590A true GB2250590A (en) | 1992-06-10 |
Family
ID=8531506
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9125040A Withdrawn GB2250590A (en) | 1990-12-03 | 1991-11-26 | Determination of urea |
Country Status (7)
| Country | Link |
|---|---|
| DK (1) | DK195091A (en) |
| EE (1) | EE02945B1 (en) |
| FI (1) | FI88310C (en) |
| GB (1) | GB2250590A (en) |
| IE (1) | IE913920A1 (en) |
| NO (1) | NO302387B1 (en) |
| SE (1) | SE512818C2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2731276A1 (en) * | 1995-03-03 | 1996-09-06 | D Aquitaine Comp Chimique | Test strip for urea determn. in milk |
| EP1754973A2 (en) * | 2005-07-26 | 2007-02-21 | Raudszus Electronic GmbH | Method and device for sampling and directly analysing collected flowable material, in particular milk deliveries |
| CN102539421A (en) * | 2010-12-21 | 2012-07-04 | 内蒙古蒙牛乳业（集团）股份有限公司 | Method for qualitatively detecting urea in milk |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2711634A1 (en) * | 1977-03-17 | 1978-09-21 | Riedel De Haen Ag | Test kit for urea determn. esp. in serum - comprising spaced reaction and indicator zones in a container and used e.g. to diagnose renal insufficiency |
| EP0339331A2 (en) * | 1988-04-29 | 1989-11-02 | ARZNEIMITTELWERK DRESDEN GmbH | Test strip for the determination of urea, and its use |
-
1990
- 1990-12-03 FI FI905949A patent/FI88310C/en not_active IP Right Cessation
-
1991
- 1991-11-11 IE IE392091A patent/IE913920A1/en not_active Application Discontinuation
- 1991-11-14 SE SE9103370A patent/SE512818C2/en not_active IP Right Cessation
- 1991-11-26 GB GB9125040A patent/GB2250590A/en not_active Withdrawn
- 1991-11-29 NO NO914711A patent/NO302387B1/en not_active IP Right Cessation
- 1991-12-02 DK DK195091A patent/DK195091A/en not_active Application Discontinuation
-
1994
- 1994-07-11 EE EE9400033A patent/EE02945B1/en not_active IP Right Cessation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2711634A1 (en) * | 1977-03-17 | 1978-09-21 | Riedel De Haen Ag | Test kit for urea determn. esp. in serum - comprising spaced reaction and indicator zones in a container and used e.g. to diagnose renal insufficiency |
| EP0339331A2 (en) * | 1988-04-29 | 1989-11-02 | ARZNEIMITTELWERK DRESDEN GmbH | Test strip for the determination of urea, and its use |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2731276A1 (en) * | 1995-03-03 | 1996-09-06 | D Aquitaine Comp Chimique | Test strip for urea determn. in milk |
| EP1754973A2 (en) * | 2005-07-26 | 2007-02-21 | Raudszus Electronic GmbH | Method and device for sampling and directly analysing collected flowable material, in particular milk deliveries |
| EP1754973A3 (en) * | 2005-07-26 | 2008-01-23 | Raudszus Electronic GmbH | Method and device for sampling and directly analysing collected flowable material, in particular milk deliveries |
| CN102539421A (en) * | 2010-12-21 | 2012-07-04 | 内蒙古蒙牛乳业（集团）股份有限公司 | Method for qualitatively detecting urea in milk |
Also Published As
| Publication number | Publication date |
|---|---|
| NO914711L (en) | 1992-06-04 |
| FI905949A0 (en) | 1990-12-03 |
| IE913920A1 (en) | 1992-06-03 |
| DK195091A (en) | 1992-06-04 |
| FI905949A (en) | 1992-06-04 |
| DK195091D0 (en) | 1991-12-02 |
| NO302387B1 (en) | 1998-02-23 |
| FI88310C (en) | 1993-04-26 |
| NO914711D0 (en) | 1991-11-29 |
| GB9125040D0 (en) | 1992-01-22 |
| SE9103370D0 (en) | 1991-11-14 |
| FI88310B (en) | 1993-01-15 |
| SE9103370L (en) | 1992-06-04 |
| EE02945B1 (en) | 1996-10-15 |
| SE512818C2 (en) | 2000-05-22 |
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