Digital Refractometer for Seawater Analysis – HI96822 – Hanna Instruments

The HI96822 is a rugged, portable digital refractometer designed for the measurement of salinity of natural or artificial seawater. The HI96822 displays results in three popular measurement units: Practical Salinity Units (PSU), salinity in parts per thousands (ppt) and specific gravity (S.G. (20/20)). The instrument’s high accuracy and simple operation gives reliable results each and every time. All readings are automatically compensated for temperature variations and displayed within a 1.5 second response time. The sealed flint glass prism and stainless steel well are easy to clean. Just wipe with a soft cloth in preparation for the next sample.

Sample size as small as 2 metric drops (100 μl)
Sealed stainless steel well with high-grade optical prism made of flint glass
Fast 1.5 second response time for temperature compensated readings

The HI96822 Digital Refractometer eliminates the uncertainty associated with mechanical refractometers by measuring the refractive index to determine the salinity of natural and artificial seawater including brackish, ocean water or saltwater aquarium. The instrument converts the refractive index of a sample to PSU, ppt and specific gravity. These conversions are based on respected scientific publications using the physical properties of seawater (not sodium chloride). The HI96822 is an easy to use tool for measuring salinity in natural and artificial seawater whether in the field, lab or at home.

Designed for seawater salinity analysis (not NaCl)
Automatic Temperature Compensation
High accuracy measurements displayed as PSU, ppt and specific gravity

Making a Standard Solution

Sodium Chloride solutions can be used to check the accuracy of the meter. The table below lists two Sodium Chloride solutions and their expected ppt Seawater value.
To make a Standard NaCl Solution (g/100 g), follow the procedure below

Place container (such as a glass vial or dropper bottle that has a cover) on an analytical balance.
Tare the balance.
To make an X NaCl solution weigh out X grams of high purity dried Sodium Chloride (CAS #: 7647-14-5: MW 58.44) directly into the container.
Add distilled or deionized water to the beaker so the total weight of the solution is 100g.

Example Standard NaCl Solution

NaCl (g)
Water (g)
Total
Expected Seawater value (ppt)

3.5% NaCl
3.50
96.50
100.000
34

10% NaCl
10.00
90.00
100.000
96