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What it is. This pH 9 buffer standard is a clear, colorless pH reference solution for calibrating and checking pH meters in the mildly alkaline range. It is supplied in a 500 mL size.
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Where pH 9 fits. Many samples, such as treated drinking water, boiler and cooling water, pool water, and some biological buffers, sit between pH 8 and 9.5. Calibrating with pH 7 and pH 9 places the slope point close to those samples, so readings are interpolated over a narrower range than a pH 7 and pH 10 calibration.
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How a buffer holds its pH. A buffer contains a weak acid and its conjugate base, or a weak base and its conjugate acid, in balanced amounts. When small amounts of acid or base enter the solution, one partner neutralizes them, so the pH barely moves. That resistance to change is what makes a buffer a reliable reference point for calibration, unlike plain water.
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Why choose a clear buffer. Clear buffers contain no dye. That avoids dye residues on electrodes and labware, makes contamination easy to see, and suits labs that prefer dye-free standards. Because color cannot identify it, keep the label legible and the container clearly marked.
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Sensitive to carbon dioxide. Alkaline buffers absorb carbon dioxide from the air, forming carbonic acid and gradually lowering the pH. Keep the container closed, pour out only what you need, and discard used buffer rather than returning it to stock.
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Temperature matters. Buffer pH shifts slightly with temperature, so the stated value applies at 25 °C. Calibrate at the same temperature as your samples, use automatic temperature compensation if your meter has it, and apply temperature-correction values supplied with the buffer when they are provided.
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Calibration best practice. Rinse the electrode with deionized water and blot it gently between buffers, immerse it in a fresh portion of buffer in a clean beaker, stir gently, and wait for a stable reading before accepting each point. Calibrate before each day's measurements, or more often when the method requires, and record the slope reported by the meter to track electrode health.
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Where it is used. Clear pH 9 buffer is used in drinking water and cooling-water labs, environmental testing, aquaculture and pool water analysis, and biotech labs working in mildly alkaline buffers. It pairs with Lab Pro's Buffer Standard pH 7, Clear for a dye-free two-point calibration.
Technical Specifications
| Product |
pH 9 buffer standard, clear |
| Nominal pH |
9 at 25 °C |
| Color |
Clear (colorless) |
| Tolerance and Composition |
See the certificate or SDS supplied with each lot |
| Use |
Mildly alkaline pH meter calibration and verification |
| Physical State |
Liquid, aqueous solution |
| Reference Temperature |
25 °C |
| Calibration Role |
Mildly alkaline slope point (with pH 7) |
| Recommended Pairing |
pH 7 (clear) |
| Odor |
Odorless (typical for aqueous pH buffers) |
| Specific Gravity |
Approx. 1.0 (typical for aqueous pH buffers) |
| Melting / Boiling Point |
Approx. 0 °C / 100 °C (aqueous) |
| Storage |
Room temperature, tightly closed, protected from light and freezing |
| Open-Container Stability |
Alkaline: absorbs CO2 from air; use opened stock promptly |
| Package Size |
500 mL |
Applications / Common Uses
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Mildly alkaline calibration: Sets the slope point for samples between pH 7 and 9.5.
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Water treatment testing: Brackets treated drinking, boiler, and cooling water.
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Dye-free calibration: Pairs with clear pH 7 for a dye-free two-point calibration.
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Check standard: Verifies accuracy after a pH 7 / pH 10 calibration.
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Biotech buffers: Supports measurements of mildly alkaline biological buffers.
Storage, Handling & Shipping
Store the buffer tightly closed at room temperature, protected from light and freezing. Because alkaline buffers absorb carbon dioxide, limit the time the container stays open, keep the label legible, and use opened stock within the period stated on the label or certificate.
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Storage temperature: Store at room temperature and protect from light and freezing.
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Contamination control: Pour the amount needed into a clean beaker; never return used buffer to stock or dip an electrode into the stock container.
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Shelf life: Use before the expiration date on the label; once opened, use within the period stated on the certificate or label.
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Rinsing: Rinse electrodes with deionized water between buffers to prevent carryover.
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Identification: Keep the original label legible; clear buffers cannot be identified by color.
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