Qualitative PH Test Paper Phenolphthalein Paper, PH:8.3–10.0, MN
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Price on request €0.00 * (0% Saved) *taxes and shipping not included
Delivery time approx. 5 working days
Item number: 90712 012021057001 Package unit 1 Piece(s) Quantity: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 Add to shopping cart Remember Do you have any questions? Please contact us. Technical data Safety data sheets Certificates of analysis (CoA / CoC) Downloads Technical data White paper, which changes color to red when the pH exceeds 8.3 towards alkaline conditions (red... more Close menuWhite paper, which changes color to red when the pH exceeds 8.3 towards alkaline conditions (red at pH > 10), e.g. for neutralization analyses.
| Platform | Products for pH determination |
| CE certified | No |
| Parameter | pH |
| Detection limit | pH - 8.3–10.0 |
| Color change | pH - white → red |
| Width | 7 mm |
| Shelf life (from production) | 2 Year(s) |
| Storage temperature | 4–30 °C / 39–86 °F |
| Scope of delivery | 1 reel of 5 m length and 7 mm width |
| Gross weight (incl. packaging) | 20.17 g / 0.04 lbs |
| Packaging dimensions | 62 x 17 x 62 mm / 2.44 x 0.67 x 2.44 Inch |
| Hazardous material | No |
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The pH-value indicates whether a water or solution is acidic, alkaline or neutral.
pH-testing using test strips and test papers
A variety of test strips and test papers is available to easily determine the pH of a sample.
Overview pH-testing products
pH - Quick navigation- Using pH test strips and papers
- QUANTOFIX Relax
- Easy sampling
- General information
- Tips & tricks
- Comparative study
pH-Fix – Unmatched pH test strips
For many years, untrained users as well as analytical professionals appreciate the experience of easy pH-testing with pH Fix. In contrast to common indicator papers, the indicator dyes in pH Fix test strips are chemically bound to the test pads. This technology prevents bleeding of the dyes and therefore a contamination of the sample, even in highly alkaline solutions. The fixation enables the strips to remain in solution over extended periods allowing a safe pH determination even in weakly buffered solutions.
PEHANON – pH determination in colored solutions
PEHANON test strips unify pH indicator and reference color chart on one strip. Any sample color has the same effect on both, the reference colors and the reactive pad, allowing unadulterated pH reading even in colored solutions.
pH indicator papers - standard for many applications
pH indicator papers have been available for decades and are the standard for many applications. For each pH value, these papers show a single color that can be matched with the color scale at intervals of 0.2–1 pH units. The indicator papers come in plastic reels that ensure long-term stability and protection against many external influences. They will be always ready-to-use when needed.
Documented results with QUANTOFIX Relax
The strip reader QUANTOFIX Relax provides objective pH-readings with a selection of pH-Fix test strips. Measurement data including time date and sample ID are printed, stored and can be transmitted to an information system. This allows the rapid and reliable documentation of test results, which proved to be especially useful for QC departments.
pH - Quick navigation- Using pH test strips and papers
- QUANTOFIX Relax
- Easy sampling
- General information
- Tips & tricks
- Comparative study
Best pH-Fix product compared to competitor!
According to a comparative study, our MACHEREY-NAGEL pH-Fix 0-14 test stripsperformed as the best! In various tests our strips delivered the most reliablepH values and the best marks in usability compared to the competitor product.
Perfect color matching and clear design
The brilliant color scale on the test strip box allows an exact comparison with thecolor development on the test fields. Above all, the clear design enhances the intuitive and fast determination of the pH value.
Longest test strips in comparison
The long hydrophobic plastic strip protects the user from hazardous or aggressivesamples and allows pH tests in narrow and deep vessels. Especially in handling, the long test strip proves to be a great advantage compared to other products!
Patented technology prevents contamination
The indicator is covalently bound to the test field and does not bleed into the sample. Therefore the test strips can remain in the sample without contaminating it.
Comparative studyCheck out our comparative study and convince yourself of the best pH test strip on the market!
Sample requestSee for yourself! Try the MACHEREY-NAGEL quality.
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Easy sampling
Sampling is often the biggest source of error in the analytical process. In general, the best practice is to draw an aliquot of the sample and measure the pH in this aliquot. However, when analyzing inhomogeneous samples, drawing an aliquot may alter the composition of the sample. In this case, it is often better to dip the strip directly into the sample. Make sure, to not remove particles from the sample with the test strip. Use pH-Fix test strips only, because indicator papers may release small portions of indicator into the sample.
pH - Quick navigation- Using pH test strips and papers
- QUANTOFIX Relax
- Easy sampling
- General information
- Tips & tricks
- Comparative study
General information on pH
pH values play an important role in chemistry, engineering, and biological processes. Many chemical reactions, particularly chemical equilibrium reactions, are strongly influenced by the pH. In many such processes, exact determination and appropriate regulation and compliance with the specified pH is required. Thus, e.g. the EC Directive on the Quality of Water Intended for Human Consumption specifies a pH range between 6.5 and 9.5. To achieve such a pH, the water can be treated with commercially available chemicals.
Normal waters usually have a pH of about 6.5 to 7.5. Domestic sewage is neutral to slightly alkaline, and commercial wastewaters tend to be more acidic, e.g. the pickling waste of the iron working industry.
The definition of the pH is based on the so-called autoprotolysis of pure water. At room temperature, pure water is to a small extent split (dissociated) into equivalent amounts of hydrated hydrogen ions (hydronium ions) H3O+ and hydroxide ions OH–:
| 2 H2O → H3O+ + OH-"Autoprotolysis of pure water" |
The product of the concentrations of H3O+ and OH– is referred to as “ionic product of water” and can be assumed to be an approximately constant value:
| c(H3O+) · c(OH-) = 10-7 mol/L · 10-7 mol/L = 10-14 mol2/L2 (at 25°C) |
Using this ion product, for any given concentration of H3O+ ions (from now on referred to as H+) or OH– ions the respectively associated unknown concentration can be calculated. According to Brønsted, acids act as H+ donors and bases as H+ acceptors. For example, addition of acids to the water increases the concentration of H+ ions, while that of OH– ions decreases accordingly. The pH was introduced to simplify the notation of low concentrations and for better comparison.
H2O = WaterH3O+ = Hydronium-IonOH- = Hydroxide-Ion
pH - Quick navigation- Using pH test strips and papers
- QUANTOFIX Relax
- Easy sampling
- General information
- Tips & tricks
- Comparative study
The pH is thus a measure of the acid or base strength of an aqueous solution. By definition, an aqueous solution is acidic in the pH range < 7 (high H+ concentration, low OH– concentration) and basic (alkaline) in the pH range > 7 (low H+ concentration, high OH– concentration). A pH of 7 (the so-called neutral point) thus means that the concentration of H+ ions corresponds to that from the dissociation of pure water (in equilibrium with the OH– ions).
Mathematically, the pH (lat.: potentia Hydrogenii) is defined as the negative decadic logarithm of the numerical value of the H+ activity given in mol/L, and is derived from the ion product (autoprotolysis of water) of water (as a first approximation, the H+ ion concentration [H+] can be used in the calculation), so that a numeric scale from 0 to 14 is obtained. The pH is a dimensionless unit.
| pH = - log c(H3O+) |
Strong acids and bases, such as hydrochloric acid, HCl, or sodium hydroxide NaOH (caustic soda), are (almost) completely dissociated in solution, i.e. split into their ions. Thus they have a strong influence on the change in concentration of H+ and OH– ions, which results in a low (0–3) or high (11–14) pH. Weak acids (e.g. acetic acid, CH3COOH) and bases (e.g. ammonia, NH3) are not completely split into their ions in water and therefore affect the pH to a lesser degree.
Salts of weak acids and strong bases (e.g. sodium carbonate, Na2CO3) or of weak bases and strong acids (e.g. calcium chloride, NaHSO4) likewise result in pH shifts upwards or downwards, respectively, by hydrolysis (reaction with water / splitting into individual ions). If, however, a salt, such as sodium chloride, NaCl, is dissolved in water, the pH will not change (or only barely), since no new hydrogen ions H+ are produced or consumed (sodium chloride splits into the ions Na+ and Cl–).
The correct pH is an important factor for many detection reactions. The reactions will be affected, if the pH value is not properly adjusted. In most cases, the detection reaction is less selective or does not proceed at all.
Another important role of pH is in biological wastewater treatment. If the pH of 6.0 to 8.0 is not maintained correctly, the bacteria will die, and the purification cannot be performed.
An excessive pH (above 9) over a longer period in the activation tank leads to increasing ammonia content of the water. Inhibition of nitrification or carbon degradation may result. Too high or too low pH levels can also lead to a decomposition of flakes. Proper separation of filterable precipitates is no longer possible.
The pH is changed, especially in sewage treatment plants, by entry of certain detergents, toilet cleaners (WC stones) or industrial effluents. The pH should be checked at various stages of degradation.
The pH is a dimensionless value.
The pH is a dimensionless value.
Reaction basis
pH indicator dyes are chemical compounds whose color changes depend on the pH. Most of them are complex organic molecules. Indicator dyes are acids or bases themselves and thus able to release or absorb protons.
The color change of the indicators is performed under the influence of the changing concentration of H+ ions by alteration of the chemical structure, where especially occurrence of quinoid structures or conjugated double bonds is of importance. An example of this is the indicator dye methyl orange, which shows a change in color from red to orange-yellow in the pH range 3.0–4.4.
pH indicator dyes are chemical compounds whose color changes dependent on the pH.
Indicator dyes belong to various organic dye classes (e.g. azo dyes, phthaleins, sulfophthaleins, benzeines, triphenylmethyl dyes, nitro indicators, etc.). The transition range of the individual indicators extends over 1.2 to 2.5 pH units. Beyond these limits, hue and color depth do not change further.
A special mixture of different indicator dyes shows a characteristic color at any pH. Mixtures of indicator dyes are often referred to as universal indicators, since a combination of appropriate indicators covers large ranges of the pH scale, or even the entire range of 0–14.
Photometric pH determination (VISOCOLOR and NANOCOLOR) takes place in water with phenol red, a triphenylmethane dye, as an indicator. Easy pH measurement is possible with pH indicator strips (pH-Fix).
In strongly acidic media (pH < 1), phenol red shows a red color, at a pH of 1–7.3 a yellow color, while in slightly basic medium (above pH 7.3) the indicator turns purple, and in strongly basic medium (pH > 14) phenol red is colorless. The individual colors are due to the chemical structure.
Sample preservation
The sample should be measured quickly within one day. Long-term preservation is not possible.
Tips & tricks
Common sources of error
- Incorrect measurement results due to failure to observe the influence of temperature:The ion product of water is temperature-dependent. The degree of dissociation, i.e. the percentage of dissociated molecules, increases strongly with temperature. All test papers and indicator strips are calibrated to standard solutions of 20 °C.
- pH measurements in colored solutions:pH measurements in colored solutions always require a special treatment. Theoretically, according to the liquid to be examined, the reference solution should be adjusted to the same color. The same applies to a turbid solution. MACHEREY-NAGEL offers a special form of pH measurement in colored solutions in the form of the PEHANON indicator papers, where the color comparison scale is subject to the same shifts and influences during the measurement as the comparison field is. Stains and turbidities are thus compensated. Color compensation is also done in the colorimetric VISOCOLOR tests.
- Sources of error that may arise from the contents of the solution to be examined:
- Acid-base errorIn terms of their chemical nature, acid-base indicators are themselves acids or bases of more or less pronounced character. Consequently, their very addition to non-buffered or only very weakly buffered solutions (e.g. distilled water, neutral salt solutions, solutions of poorly hydrolyzed salts, very weak acids or bases, very dilute solutions of strong acids and salts) will result in a certain change in pH. This error is called acid or base error, respectively, depending on whether the indicator is an acid or a base. These errors are by no means negligible; in the worst cases, these errors can exceed more than one pH unit.For this reason, caution is advisable when measuring pH values in non-buffered or weakly buffered solutions.
- Salt errorIons other than hydrogen ions H+ likewise cause, albeit small, effects on the color development of the indicators. This can lead to color differences in pH measurements in different salt solutions. This effect is known as “salt error”. At a salt concentration < 0.2 mol/L, a relevant correction can be neglected.
- Alcohol errorWhen using solvents other than water, the position of the acid-base balance and thus also the indicator constant is changed. This means that in direct color comparison of an indicator in an aqueous buffer solution with a solution containing a small amount of alcohol, identical color does not necessarily imply identical pH values of the two liquids. At room temperature, the alcohol error may be up to 0.5 pH units (indicator-dependent).
- Protein errorProteins are amphoteric in character, having both acidic and alkaline properties. Thus, proteins bind indicators with acidic as well as with basic character, whereby the resulting color is affected. Thus, pH determination in protein-containing solutions is often very difficult or even impossible. The error is dependent on the type and quantity of the protein, as well as on the nature of the indicator.
- Alkaloid errorAlkaloids are also capable of forming conglomerates with certain indicators. If alkaloids are present, it is recommended to perform blank value determinations in order to control the influence of the alkaloids on the measurement.
Amphoteric compounds may react in one manner or the other, e.g. as acids and bases.
pH - Quick navigation- Using pH test strips and papers
- QUANTOFIX Relax
- Easy sampling
- General information
- Tips & tricks
- Comparative study
Background information
- Generally, pure water and neutral salt solutions are very sensitive to atmospheric carbon dioxide. Air contains about 0.03 % v/v of carbon dioxide. In equilibrium with air, distilled water absorbs carbon dioxide. Therefore, under normal conditions distilled water does not exhibit a neutral pH of 7.
- Buffer solutions are required to achieve constant pH adjustment. Buffers are solutions of a weak acid and one of its corresponding salts (e.g. acetic acid / acetate buffer) or a weak base and one of its corresponding salts (phosphate / phosphoric acid buffer). The pH of such solutions will change little or not at all in case of dilutions, or even upon the addition of stronger acids or bases, in the pH range defined for them. It should be noted here that all buffer solutions have a certain maximum buffer capacity. Once this is “used up”, the amount added exceeds the availability of the consumed amount of buffer. For pH measurement using indicator papers, above all adequate buffering is necessary.
Sea water suitability
All VISOCOLOR and NANOCOLOR pH tests are suitable for seawater analysis.
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