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hydrogen-ion-selective glass of the glass electrode, to the solution inside the glass electrode, to the silver of the glass electrode, and finally the voltmeter of the display device. The voltage varies from test solution to test solution depending on the potential difference created by the difference in hydrogen-ion concentrations on each side of the glass membrane between the test solution and the solution inside the glass electrode. All other potential differences in the circuit do not vary with pH and are corrected for by means of the calibration.
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solution to be tested, hydrogen ions in the test solution exchange for other positively charged ions on the glass bulb, creating an electrochemical potential across the bulb. The electronic amplifier detects the difference in electrical potential between the two electrodes generated in the measurement and converts the potential difference to pH units. The magnitude of the electrochemical potential across the glass bulb is linearly related to the pH according to the
331:. Probes are generally kept moist when not in use with a medium appropriate for the particular probe, which is typically an aqueous solution available from probe manufacturers. Probe manufacturers provide instructions for cleaning and maintaining their probe designs. For illustration, one maker of laboratory-grade pH gives cleaning instructions for specific contaminants: general cleaning (15-minute soak in a solution of bleach and detergent), salt (
410:
344:
36:
312:. The reference electrode usually consists of a platinum wire that has contact with a silver/silver chloride mixture, which is immersed in a potassium chloride solution. There is a ceramic plug, which serves as a contact to the test solution, providing low resistance while preventing mixing of the two solutions.
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on its surface, which provides binding sites for alkali-metal ions and hydrogen ions from the solutions. This provides an ion-exchange capacity in the range of 10 to 10 mol/cm. Selectivity for hydrogen ions (H) arises from a balance of ionic charge, volume requirements versus other ions, and the
374:
that span the range of pH values to be measured. For general purposes, buffers at pH 4.00 and pH 10.00 are suitable. The pH meter has one calibration control to set the meter reading equal to the value of the first standard buffer and a second control to adjust the meter reading to the value of the
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by the manufacturers. However, certain aspects of design are published. Glass is a solid electrolyte, for which alkali-metal ions can carry current. The pH-sensitive glass membrane is generally spherical to simplify the manufacture of a uniform membrane. These membranes are up to 0.4 millimeters in
211:
are required on each side of the membrane. Their purpose is to measure changes in the potential on their respective side. One is built into the glass electrode. The other, which makes contact with the test solution through a porous plug, may be a separate reference electrode or may be built into a
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In general there are three major categories of pH meters. Benchtop pH meters are often used in laboratories and are used to measure samples which are brought to the pH meter for analysis. Portable, or field pH meters, are handheld pH meters that are used to take the pH of a sample in a field or
500:
focused on the manufacture of scientific instruments, with the Arthur H. Thomas
Company as a distributor for its pH meter. In its first full year of sales, 1936, the company sold 444 pH meters for $ 60,000 in sales. In years to come, the company sold millions of the units. In 2004 the Beckman pH
179:
pH meters measure the voltage between two electrodes and display the result converted into the corresponding pH value. They comprise a simple electronic amplifier and a pair of electrodes, or alternatively a combination electrode, and some form of display calibrated in pH units. It usually has a
424:
pH meters range from simple and inexpensive pen-like devices to complex and expensive laboratory instruments with computer interfaces and several inputs for indicator and temperature measurements to be entered to adjust for the variation in pH caused by temperature. The output can be digital or
219:
The design of the electrodes is the key part: These are rod-like structures usually made of glass, with a bulb containing the sensor at the bottom. The glass electrode for measuring the pH has a glass bulb specifically designed to be selective to hydrogen-ion concentration. On immersion in the
231:
is insensitive to the pH of the solution, being composed of a metallic conductor, which connects to the display. This conductor is immersed in an electrolyte solution, typically potassium chloride, which comes into contact with the test solution through a porous ceramic membrane. The display
155:. In addition to measuring the pH of liquids, specially designed electrodes are available to measure the pH of semi-solid substances, such as foods. These have tips suitable for piercing semi-solids, have electrode materials compatible with ingredients in food, and are resistant to clogging.
243:
is completed, in which there is a potential difference created and detected by the voltmeter. The circuit can be thought of as going from the conductive element of the reference electrode to the surrounding potassium-chloride solution, through the ceramic membrane to the test solution, the
512:
Corporation of
Denmark was founded in 1935, and began marketing a pH meter for medical use around 1936, but "the development of automatic pH-meters for industrial purposes was neglected. Instead American instrument makers successfully developed industrial pH-meters with a wide variety of
99:
The rate and outcome of chemical reactions taking place in water often depends on the acidity of the water, and it is therefore useful to know the acidity of the water, typically measured by means of a pH meter. Knowledge of pH is useful or critical in many situations, including
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to remove any traces of the solution being measured, blotted with a scientific wipe to absorb any remaining water, which could dilute the sample and thus alter the reading, and then immersed in a storage solution suitable for the particular probe type.
383:
in the electrode probes. The calibration process correlates the voltage produced by the probe (approximately 0.06 volts per pH unit) with the pH scale. Good laboratory practice dictates that, after each measurement, the probes are rinsed with
520:
began to industrialize the production of single-rod measuring cells, a combination of measurement and reference electrode in one construction unit, which led to broader acceptance in a wide range of industries including pharmaceutical production.
476:
registered the first patent for a complete chemical instrument for the measurement of pH, U.S. Patent No. 2,058,761, for his "acidimeter", later renamed the pH meter. Beckman developed the prototype as an assistant professor of chemistry at the
212:
combination electrode. The resulting voltage will be the potential difference between the two sides of the glass membrane possibly offset by some difference between the two reference electrodes, that can be compensated for. The article on the
78:
between a pH electrode and a reference electrode, and so the pH meter is sometimes referred to as a "potentiometric pH meter". The difference in electrical potential relates to the acidity or pH of the solution. Testing of pH via pH meters
358:
Very precise measurements necessitate that the pH meter is calibrated before each measurement. More typically calibration is performed once per day of operation. Calibration is needed because the glass electrode does not give reproducible
247:
For simplicity, many pH meters use a combination probe, constructed with the glass electrode and the reference electrode contained within a single probe. A detailed description of combination electrodes is given in the article on
421:
production site. In-line or in situ pH meters, also called pH analyzers, are used to measure pH continuously in a process, and can stand-alone, or be connected to a higher level information system for process control.
662:
Oxford
Dictionary of Biochemistry and Molecular Biology (2 ed.), ed. Richard Cammack, Teresa Atwood, Peter Campbell, Howard Parish, Anthony Smith, Frank Vella, and John Stirling, Oxford University Press 2006,
908:
263:
of measurement. To measure the pH of a solution, the electrodes are used as probes, which are dipped into the test solutions and held there sufficiently long for the hydrogen ions in the test solution to
1398:
15.3.1957: English Patent – Measuring assemblies for the determination of ion concentrations and redox potentials, particularly suitable for carrying out measurements at elevated temperatures. Patent No.
436:
Specialty meters and probes are available for use in special applications, such as harsh environments and biological microenvironments. There are also holographic pH sensors, which allow pH measurement
379:
of the buffer control. More precise measurements sometimes require calibration at three different pH values. Some pH meters provide built-in temperature-coefficient correction, with temperature
315:
With these electrode designs, the voltmeter is detecting potential differences of ±1400 millivolts. The electrodes are further designed to rapidly equilibrate with test solutions to facilitate
540:
Specialized manufacturing is required for the electrodes, and details of their design and construction are typically trade secrets. However, with purchase of suitable electrodes, a standard
335:
solution followed by sodium hydroxide and water), grease (detergent or methanol), clogged reference junction (KCl solution), protein deposits (pepsin and HCl, 1% solution), and air bubbles.
544:
can be used to complete the construction of the pH meter. However, commercial suppliers offer voltmeter displays that simplify use, including calibration and temperature compensation.
919:
1538:
1164:
AK Yetisen; H Butt; F da Cruz
Vasconcellos; Y Montelongo; CAB Davidson; J Blyth; JB Carmody; S Vignolini; U Steiner; JJ Baumberg; TD Wilkinson; CR Lowe (2013).
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Dr. A. Fiechter, Dr. W. Ingold und A. Baerfuss, Chemie-Ingenieur-Technik 10 (1964) 1000-1004: "Die pH-Kontrolle in der mikrobiologischen
Verfahrenstechnik"
293:
coordination number of other ions. Electrode manufacturers have developed compositions that suitably balance these factors, most notably lithium glass.
375:
second buffer. A third control allows the temperature to be set. Standard buffer sachets, available from a variety of suppliers, usually document the
1238:
Determinants in the evolution of the
European chemical industry : 1900-1939 : new technologies, political frameworks, markets and companies
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Beckman marketed a portable "Pocket pH Meter" as early as 1956, but it did not have a digital read-out. In the 1970s Jenco
Electronics of
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188:, or a combination electrode. The electrodes, or probes, are inserted into the solution to be tested. pH meters may also be based on the
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319:. The equilibration times are typically less than one second, although equilibration times increase as the electrodes age.
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Details of the fabrication and resulting microstructure of the glass membrane of the pH electrode are maintained as
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1946:
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In the 1940s the electrodes for pH meters were often difficult to make, or unreliable due to brittle glass. Dr.
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designed and manufactured the first portable digital pH meter. This meter was sold under the label of the
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have expanded the number of applications in which pH measurements can be conducted. The devices have been
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Because of the sensitivity of the electrodes to contaminants, cleanliness of the probes is essential for
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on the surface of the bulb on the glass electrode. This equilibration provides a stable pH measurement.
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In order to accurately measure the potential difference between the two sides of the glass membrane
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in recognition of its significance as the first commercially successful electronic pH meter.
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thickness, thicker than original designs, so as to render the probes durable. The glass has
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applications, such as in breweries, paper works, alum works, and water treatment systems."
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1961:
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Riddle, Peter (2013). "pH meters and their electrodes: calibration, maintenance and use".
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433:. Some versions use telemetry to connect the electrodes to the voltmeter display device.
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5.739 pH/Ion at 23 °C temperature shown on photo. pH 7110 pH meter manufactured by inoLab
239:
On immersion of the glass electrode and the reference electrode in the test solution, an
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Instrument that indicates acidity or alkalinity in water-based solutions, expressed as pH
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that are available. Additionally, there are commercially available pH meters based on
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Finding Aid to the
Beckman Historical Collection 1911 - 2011 (Bulk 1935 - 2004 )
1276:. foreword by James D. Watson. Philadelphia, Pa.: Chemical Heritage Foundation.
637:
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481:, when asked to devise a quick and accurate method for measuring the acidity of
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1166:"Light-Directed Writing of Chemically Tunable Narrow-Band Holographic Sensors"
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67:
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Click on 'Beckman
Historical Collection Finding Aid' to go to full document.
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308:. The silver chloride electrode is simple to manufacture and provides high
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1956:
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Loiselle, F.B.; Casey, J.R. (2010). "Measurement of
Intracellular pH".
413:
129:
63:
1507:– National Historic Chemical Landmark of the American Chemical Society
2145:
525:
1501:– Overview of pH and pH measurement at the Omega Engineering website
958:
pH Measurement: Fundamentals, Methods, Applications, Instrumentation
355:
publishes a standard for pH measurement using pH meters, DIN 19263.
35:
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with solutions of known pH, typically before each use, to ensure
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743:. Methods in Molecular Biology. Vol. 637. pp. 311–31.
269:
105:
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1997:
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1520:
872:. No. Summer. The Electrochemical Society. pp. 19–20
469:, and electrodes were used for pH measurement in the 1920s.
1011:
MRC lab: How to Store, Clean, and Recondition pH Electrodes
71:
1139:"How to Select a pH Sensor for Harsh Process Environments"
1274:
Arnold O. Beckman : one hundred years of excellence
981:
Ltd, W G Pye and Co (1962). "Potentiometric pH Meter".
741:
Membrane Transporters in Drug Discovery and Development
370:, calibration is performed with at least two standard
842:. Seafriends Marine Conservation and Education Centre
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1272:Arnold Thackray & Minor Myers, Jr. (2000).
1226:
1224:
1116:"A guide to pH Measurement Theory and Practice"
136:, healthcare and clinical applications such as
461:"Here's the new Beckman Pocket pH Meter", 1956
151:, enabling direct measurement of pH inside of
1532:
1513:- A publication of the Thermo-Scientific Co.
1241:. Dordrecht: Kluwer Acad. Publ. p. 332.
449:, rather than conventional glass electrodes.
192:(typically used for rough conditions) or the
8:
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829:
827:
825:
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304:in pH meters, although some designs use the
83:) is used in many applications ranging from
2492:Nuclear magnetic resonance (NMR) instrument
896:Bitesize Bio: How to Care for Your pH Meter
276:pH electrode and reference electrode design
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1994:
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1094:"What is a pH Meter and How Does it Work?"
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776:
74:. The pH meter measures the difference in
1471:"Building the Simplest Possible pH Meter"
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732:
465:The concept of pH was defined in 1909 by
236:, which displays voltage in units of pH.
2857:Instruments used in medical laboratories
1419:"Here's the new Beckman Pocket pH Meter"
891:
889:
887:
678:
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167:Using an early Beckman pH meter in a lab
2373:Inductively coupled plasma (ICP) device
1069:"How to perform a pH meter calibration"
909:"Theory and Practice of pH Measurement"
601:
503:ACS National Historic Chemical Landmark
143:Advances in the instrumentation and in
2421:Transmission electron microscope (TEM)
1381:
1371:
1145:. International Society for Automation
1043:"pH Measurement - pH Measuring Chains"
1006:
1004:
1301:"Development of the Beckman pH Meter"
7:
1305:National Historic Chemical Landmarks
1231:Travis, Anthony S.; Schröter, H.G.;
610:"Beckman Coulter Product Milestones"
496:On April 8, 1935, Beckman's renamed
353:German Institute for Standardization
39:781 pH/Ion Meter pH meter by Metrohm
1505:Development of the Beckman pH Meter
216:has a good description and figure.
2416:Scanning electron microscope (SEM)
479:California Institute of Technology
14:
983:Journal of Scientific Instruments
960:. Weinheim: VCH Publishers, Inc.
487:California Fruit Growers Exchange
104:analyses. pH meters are used for
2461:Thermogravimetric analyzer (TGA)
2271:Nuclear magnetic resonance (NMR)
1326:Luther, Claudia (May 19, 2004).
918:. December 2010. Archived from
717:. Encyclopaedia Britannica, Inc
498:National Technical Laboratories
441:, making use of the variety of
425:analog, and the devices can be
140:; and many other applications.
31:Beckman model 72 pH meter, 1960
1499:Introduction to pH measurement
642:Encyclopædia Britannica Online
366:Consistent with principles of
23:Beckman Model M pH Meter, 1937
1:
363:over longer periods of time.
1137:Olson, Vickie (2015-04-15).
898:, Steffi Magub, 18 May 2012.
749:10.1007/978-1-60761-700-6_17
1446:"Evolution of the pH Meter"
1307:. American Chemical Society
590:Standard hydrogen electrode
580:Saturated calomel electrode
306:saturated calomel electrode
300:is most commonly used as a
2907:
1170:Advanced Optical Materials
995:10.1088/0950-7671/39/6/442
916:Emerson Process Management
684:"pH Measurement and Value"
85:laboratory experimentation
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2616:Time-domain reflectometer
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2383:Liquid chromatograph (LC)
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2006:
1993:
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1423:Science History Institute
1235:; Morris, P.J.T. (1998).
956:Galster, Helmuth (1991).
784:"pH Measurement Handbook"
585:Silver chloride electrode
339:Calibration and operation
298:silver chloride electrode
205:silver chloride electrode
126:environmental remediation
1328:"Arnold O. Beckman, 104"
863:"The Glass pH Electrode"
814:The Biomedical Scientist
793:. Thermo Scientific, Inc
715:Encyclopaedia Britannica
559:Ion-selective electrodes
501:meter was designated an
368:good laboratory practice
361:electrostatic potentials
2451:Melting-point apparatus
1832:Cryogenic storage dewar
1511:pH Measurement Handbook
530:Cole-Parmer Corporation
2891:Scientific instruments
2388:Mass spectrometer (MS)
2378:Gas chromatograph (GC)
1182:10.1002/adom.201300375
861:Vanýsek, Petr (2004).
474:Arnold Orville Beckman
462:
447:solid state electrodes
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377:temperature dependence
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329:accuracy and precision
290:chemical functionality
172:Principle of operation
168:
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2886:Measuring instruments
2763:Acid-resistant gloves
2444:differential scanning
836:"pH Meter Principles"
575:Quinhydrone electrode
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194:quinhydrone electrode
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60:water-based solutions
49:scientific instrument
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22:
2340:Analytical chemistry
1842:Laminar flow cabinet
1548:Laboratory equipment
1332:Chicago Tribune News
1118:. Mettler-Toledo LLC
1096:. Mettler-Toledo LLC
1047:Beuth publishing DIN
711:"Acid-Base Reaction"
709:Bell, Ronald Percy.
76:electrical potential
2876:Acid–base chemistry
2712:Personal protective
1621:Meker–Fisher burner
1352:Jaehnig, Kenton G.
1049:. Beuth Verlag GmbH
1030:Cleaning electrodes
834:Anthoni, J. Floor.
536:Building a pH meter
302:reference electrode
229:reference electrode
201:reference electrode
186:reference electrode
102:chemical laboratory
2555:Function generator
2538:Bench power supply
2477:Analytical balance
2238:Ostwald viscometer
2233:Graduated cylinder
1972:Inoculation needle
1143:automation.isa.org
1016:2015-09-22 at the
554:Antimony electrode
463:
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397:Types of pH meters
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241:electrical circuit
190:antimony electrode
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51:that measures the
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2611:Spectrum analyzer
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1937:Spectrophotometer
1932:Pipeclay triangle
1684:Mortar and pestle
1283:978-0-941901-23-9
1248:978-0-7923-4890-0
967:978-3-527-28237-1
816:. April: 202–205.
758:978-1-60761-699-3
472:In October 1934,
467:S. P. L. Sørensen
405:A simple pH meter
333:hydrochloric acid
209:calomel electrode
132:of wine or beer;
62:, indicating its
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2881:Electrochemistry
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2601:Network analyzer
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1977:Inoculation loop
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108:measurements in
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2900:
2899:
2897:
2896:
2895:
2866:
2865:
2864:
2859:
2842:
2838:Solvent cabinet
2797:
2768:Eyewash station
2751:
2716:
2714:equipment (PPE)
2713:
2701:
2682:
2661:
2630:
2574:
2565:Pulse generator
2531:Control devices
2522:
2501:
2465:
2431:Thermochemistry
2425:
2402:
2342:
2321:
2290:
2247:
2213:Conical measure
2196:
2165:
2102:
2071:
2048:
2032:
2002:
1981:
1962:Test tube brush
1872:
1857:Picotiter plate
1820:
1806:
1802:Lab drying rack
1761:Extension clamp
1737:
1718:
1657:
1643:
1579:
1561:
1550:
1545:
1495:
1490:
1489:
1479:
1477:
1469:
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1119:
1114:
1113:
1109:
1099:
1097:
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1091:
1087:
1077:
1075:
1067:
1066:
1062:
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1041:
1040:
1036:
1028:
1024:
1018:Wayback Machine
1009:
1002:
980:
979:
975:
968:
955:
954:
937:
928:
926:
922:
911:
907:
906:
902:
894:
885:
875:
873:
865:
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631:
621:
619:
617:Beckman Coulter
612:
608:
607:
603:
598:
550:
538:
455:
427:battery-powered
399:
390:deionized water
386:distilled water
341:
325:
310:reproducibility
278:
222:Nernst equation
214:glass electrode
182:glass electrode
174:
161:
138:blood chemistry
118:municipal water
97:
89:quality control
17:
12:
11:
5:
2904:
2902:
2894:
2893:
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2833:Safety cabinet
2830:
2825:
2820:
2815:
2809:
2807:
2803:
2802:
2799:
2798:
2796:
2795:
2793:Safety goggles
2790:
2788:Safety glasses
2785:
2783:Nitrile gloves
2780:
2778:Medical gloves
2775:
2770:
2765:
2759:
2757:
2753:
2752:
2750:
2749:
2744:
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2681:
2680:
2675:
2673:Alligator clip
2669:
2667:
2663:
2662:
2660:
2659:
2654:
2649:
2647:Soldering iron
2644:
2638:
2636:
2632:
2631:
2629:
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2623:
2618:
2613:
2608:
2603:
2598:
2593:
2591:Logic analyzer
2588:
2582:
2580:
2576:
2575:
2573:
2572:
2567:
2562:
2557:
2552:
2551:
2550:
2548:Voltage source
2545:
2543:Current source
2534:
2532:
2524:
2523:
2518:
2511:
2510:
2507:
2506:
2503:
2502:
2500:
2499:
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2482:Colony counter
2479:
2473:
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2173:
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2167:
2166:
2164:
2163:
2158:
2153:
2148:
2143:
2138:
2133:
2128:
2123:
2121:Vacuum (Dewar)
2118:
2112:
2110:
2104:
2103:
2101:
2100:
2095:
2090:
2085:
2079:
2077:
2073:
2072:
2070:
2069:
2064:
2058:
2056:
2050:
2049:
2047:
2046:
2040:
2038:
2034:
2033:
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2020:
2014:
2012:
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2003:
1998:
1991:
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1794:
1792:Test tube rack
1789:
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1768:
1767:Funnel support
1765:
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1676:
1674:Liquid whistle
1671:
1666:
1660:
1658:
1656:
1655:
1652:
1648:
1645:
1644:
1642:
1641:
1639:Vacuum dry box
1636:
1631:
1626:
1623:
1618:
1613:
1608:
1603:
1601:Heating mantle
1598:
1593:
1588:
1586:Alcohol burner
1582:
1580:
1578:
1577:
1574:
1570:
1563:
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1559:
1552:
1551:
1546:
1544:
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1494:
1493:External links
1491:
1488:
1487:
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1436:
1410:
1401:
1391:
1382:|website=
1344:
1318:
1289:
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1247:
1220:
1204:"pH Electrode"
1195:
1156:
1129:
1107:
1085:
1060:
1034:
1022:
1000:
973:
966:
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840:seafriends.org
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485:juice for the
454:
451:
398:
395:
340:
337:
324:
321:
277:
274:
232:consists of a
203:, typically a
177:Potentiometric
173:
170:
160:
159:Design and use
157:
122:swimming pools
96:
93:
15:
13:
10:
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2747:Safety shower
2745:
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2657:Wire stripper
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2487:Spiral plater
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2351:Compositional
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2199:
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1898:
1895:
1893:Balance brush
1892:
1890:
1887:
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1882:
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1879:
1875:
1869:Weighing dish
1868:
1866:Weighing boat
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1757:Burette clamp
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1591:Bunsen burner
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1208:pH-meter.info
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925:on 2016-10-20
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570:Potentiometry
568:
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547:
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543:
535:
533:
531:
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518:Werner Ingold
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443:pH indicators
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387:
382:
381:thermocouples
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114:water quality
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77:
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70:expressed as
69:
65:
61:
57:
54:
50:
46:
37:
29:
21:
2818:Fire blanket
2756:Eye and hand
2742:Rubber apron
2606:Oscilloscope
2570:Potentiostat
2497:Plate reader
2397:
2393:pH indicator
2363:CHN analyzer
2358:AutoAnalyzer
2151:Round-bottom
2044:Boston round
1907:Filter paper
1862:Refrigerator
1779:Retort stand
1747:Clamp holder
1743:Beaker clamp
1709:Vortex mixer
1704:Stirring rod
1699:Static mixer
1629:Teclu burner
1478:. Retrieved
1474:
1465:
1453:. Retrieved
1449:
1444:Buie, John.
1439:
1427:. Retrieved
1422:
1413:
1404:
1394:
1366:
1359:. Retrieved
1354:
1347:
1335:. Retrieved
1331:
1321:
1309:. Retrieved
1304:
1273:
1252:. Retrieved
1237:
1211:. Retrieved
1207:
1198:
1173:
1169:
1159:
1147:. Retrieved
1142:
1132:
1120:. Retrieved
1110:
1098:. Retrieved
1088:
1076:. Retrieved
1072:
1063:
1051:. Retrieved
1046:
1037:
1025:
986:
982:
976:
957:
927:. Retrieved
920:the original
915:
903:
874:. Retrieved
869:
856:
844:. Retrieved
839:
813:
807:
795:. Retrieved
790:
740:
719:. Retrieved
714:
704:
692:. Retrieved
690:. Xylem, Inc
688:Global Water
687:
658:
646:. Retrieved
641:
632:
620:. Retrieved
616:
604:
566:pH electrode
539:
523:
515:
507:
495:
471:
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365:
357:
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314:
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153:living cells
149:miniaturized
142:
98:
95:Applications
80:
53:hydrogen-ion
44:
42:
2806:Other items
2732:Face shield
2579:Measurement
2560:Galvanostat
2520:Electronics
2470:Other items
2456:Thermometer
2439:Calorimeter
2368:Colorimeter
2312:Gas syringe
2295:Other items
2223:Eye dropper
2098:Watch glass
2083:Evaporating
2062:Cold finger
1877:Other items
1783:Screw clamp
1775:Pinch clamp
1764:Flask clamp
1714:Wash bottle
1669:Homogenizer
1450:Lab Manager
1233:Homburg, E.
1078:14 December
429:or rely on
323:Maintenance
317:ease of use
266:equilibrate
110:agriculture
2870:Categories
2737:Respirator
2678:Test probe
2596:Multimeter
2408:Microscopy
2228:Eudiometer
2192:Separatory
2161:Volumetric
2126:Erlenmeyer
2054:Condensers
2018:Dean–Stark
1967:Wire brush
1927:Microscope
1922:Centrifuge
1897:Cork borer
1852:Petri dish
1827:Agar plate
1814:Containers
1797:Wire gauze
1634:Water bath
1596:Desiccator
1455:October 7,
1361:30 October
1176:(3): 250.
989:(6): 323.
929:2017-04-03
638:"pH meter"
596:References
542:multimeter
510:Radiometer
431:line power
257:calibrated
120:supplies,
68:alkalinity
2828:Fume hood
2773:Glove box
2626:Voltmeter
2011:Apparatus
2000:Glassware
1889:Autoclave
1884:Aspirator
1837:Incubator
1771:Iron ring
1694:Sonicator
1664:Chemostat
1606:Hot plate
1384:ignored (
1374:cite book
1311:March 25,
870:Interface
268:with the
234:voltmeter
145:detection
2727:Lab coat
2652:Tweezers
2642:Heat gun
2398:pH meter
2307:Bell jar
2187:Dropping
2141:Florence
2131:Fernbach
2093:Syracuse
1952:Scoopula
1902:Crucible
1611:Lab oven
1480:29 March
1429:6 August
1213:30 March
1190:96257175
1149:31 March
1053:28 March
1014:Archived
846:28 March
797:22 March
791:PragoLab
767:20419443
721:21 March
694:21 March
648:10 March
548:See also
287:silicate
261:accuracy
81:pH-metry
56:activity
45:pH meter
2666:General
2586:Ammeter
2286:Thistle
2243:Pipette
2218:Cuvette
2208:Burette
2177:BĂĽchner
2170:Funnels
2156:Schlenk
2136:Fleaker
2116:BĂĽchner
2037:Bottles
1957:Spatula
1947:Stopper
1917:Forceps
1817:Storage
1734:Holders
1654:Shakers
1625:Striker
1573:Heaters
1560:General
1337:8 March
1122:21 July
1100:21 July
876:3 April
622:5 April
491:Sunkist
453:History
414:Soil pH
130:brewing
64:acidity
2700:Safety
2302:Beaker
2281:Thiele
2266:Cragie
2261:Drying
2182:Hirsch
2146:Retort
2108:Flasks
2076:Dishes
2067:Liebig
2028:Kipp's
1942:Splint
1752:Tripod
1730:Clamps
1726:Stands
1689:Shaker
1651:Mixers
1576:Dryers
1425:. 1956
1399:850177
1280:
1254:29 May
1245:
1188:
964:
765:
755:
667:
644:. 2016
526:Taiwan
184:and a
2635:Tools
2253:Tubes
2088:Petri
1186:S2CID
923:(PDF)
912:(PDF)
866:(PDF)
787:(PDF)
613:(PDF)
564:ISFET
483:lemon
416:meter
47:is a
2317:Vial
2276:Test
1912:File
1616:Kiln
1482:2017
1457:2010
1431:2019
1386:help
1363:2015
1339:2014
1313:2013
1278:ISBN
1256:2015
1243:ISBN
1215:2017
1151:2017
1124:2021
1102:2021
1080:2016
1055:2017
962:ISBN
878:2017
848:2017
799:2017
763:PMID
753:ISBN
723:2017
696:2017
665:ISBN
650:2016
624:2017
508:The
351:The
296:The
270:ions
227:The
116:for
106:soil
1178:doi
991:doi
745:doi
493:).
388:or
207:or
87:to
66:or
58:in
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72:pH
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