- What it is. This pH 3 buffer solution is an acidic pH standard used to calibrate and check pH meters and electrodes in the strongly acidic to mildly acidic range. It is supplied in a 1-pint size.
- 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.
- Where pH 3 fits. Most labs calibrate with pH 4 and pH 7. When samples sit around pH 2.5 to 3.5, such as soft drinks, fruit juices, vinegar-based products, acid rinses, or diluted acid process streams, a pH 3 buffer places a calibration or check point right where the measurements fall, which reduces interpolation error.
- Verification as well as calibration. Because pH 3 sits between the common pH 2 and pH 4 points, many labs use it as an independent check standard: after calibrating with pH 4 and pH 7, reading a pH 3 buffer confirms that the meter's slope holds accurately into the more acidic range.
- Accuracy at low pH. At strongly acidic pH, some glass electrodes read slightly higher than the true value, an effect called acid error. Calibrating or checking near the sample range helps reveal it and keeps acidic readings dependable.
- 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.
- 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 as the method requires, and record the meter-reported slope to track electrode health.
- Where it is used. Use the pH 3 buffer in food and beverage QC, metal finishing, chemical production, environmental testing of acidic waters, and teaching labs. It pairs with Lab Pro's Buffer Solution pH 2, Buffer Solution pH 4, Red, and Buffer Solution pH 7, Yellow for calibration across the acidic range.
Technical Specifications
| Product | pH 3 buffer solution |
| Nominal pH | 3 at 25 °C |
| Use | Acidic-range pH meter calibration and verification |
| Physical State | Liquid, aqueous solution |
| Reference Temperature | 25 °C |
| Calibration Role | Acidic calibration or check point |
| Recommended Pairing | pH 2, pH 4, and pH 7 |
| 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 | Acidic/neutral: low CO2 sensitivity; protect from contamination |
| Hazard Classification | See the Lab Pro SDS |
| Package Size | 1 pint |
Applications / Common Uses
- Acidic-range calibration: Adds a calibration point between pH 2 and pH 4.
- Slope verification: Checks meter accuracy after a pH 4 / pH 7 calibration.
- Beverage and food QC: Brackets measurements of acidic drinks and ingredients.
- Acid rinse monitoring: Supports readings of acidic cleaning and rinse solutions.
- Teaching labs: Demonstrates buffer behavior in the acidic range.
Storage, Handling & Shipping
Store pH 3 buffer tightly closed at room temperature, protected from light and freezing. Keep it free of contamination by pouring portions into a clean beaker for each use and never dipping an electrode into the stock.
- Storage temperature: Store at room temperature and protect from light and freezing.
- Contamination control: Pour the amount needed into a clean beaker; never return used buffer to stock or dip an electrode into the stock container.
- Shelf life: Use before the expiration date on the label; once opened, use within the period stated on the certificate or label.
- Rinsing: Rinse electrodes with deionized water between buffers to prevent carryover.
Related Categories & Services
- Shop pH Buffers for related products in this category.
- Explore Buffers by Lab Pro and Buffers, Standards & Solutions.
- Vendor Managed Inventory (VMI) Program: Lab Pro can stock, track, and replenish this item on site so it never runs out. Contact info@labproinc.com or 888-452-2776 to set up a VMI assessment.
