Hanna Instruments HI781

To Next Page

Tips for an Accurate Measurement

• Ensure the sample does not contain any debris.

• Whenever the cuvette is placed into the checker, it must be

dry outside and free of fingerprints, oil and dirt.

• Wipe the cuvette thoroughly with HI731318 microfiber

cleaning cloth or a lint-free cloth prior to insertion.

• Shaking the cuvette can generate bubbles, causing higher

readings. To obtain accurate measurements, remove such

bubbles by swirling or by gently tapping the cuvette.

• Do not let the reacted sample stand too long after reagent

has been added, as accuracy will be affected.

• Discard the sample immediately after the reading has been

taken or the glass might become permanently stained.

Battery Replacement

To save the battery, the checker shuts down after 20 minutes of non-use and

4 minutes after reading.

A fresh battery lasts for a minimum of 5000 measurements. When the battery is

drained, the instrument displays “bAd” then ”bAt”, and turns off.

To replace the battery, follow the next steps:

1. Press and hold the ON/OFF button to turn the checker off.

2. Turn the instrument upside down and use a screwdriver to unfasten the screw and

remove the battery cover.

3. Remove the old battery, replace it with a new 1.5V AAA battery, inserting the

negative end first.

4. Replace the battery cover, fasten and tighten the screw.

Accessories

Reagent Sets

HI781-25 Reagents for 25 Marine Nitrate Low Range tests

Other Accessories

HI781-11 Marine Nitrate Low Range certified standard kit

HI731225 Cuvette black cap for Checker

HC colorimeters (4 pcs.)

HI731318 Cloth for wiping cuvettes (4 pcs.)

HI731321 Glass cuvette and seal cap for Checker

HC colorimeters (4 pcs.)

HI731353 Cuvette seal cap for Checker

HC colorimeters (4 pcs.)

HI740028P 1.5V AAA battery set (12 pcs.)

HI740226 5 mL graduated syringe (1 pc.)

HI740228 Filter disc (25 pcs.)

HI740270 10 mL syringe with Luer Lock (1 pc.)

HI740271 Filter holder with Luer Lock (1 pc.)

HI740144P Plastic tip for 5 mL syringe (10 pcs.)

HI93703-50 Cuvette cleaning solution, 230 mL

Certification

All Hanna Instruments conform to the CE European Directives.

Disposal of Electrical & Electronic Equipment. The product

should not be treated as household waste. Instead hand it over

to the appropriate collection point for the recycling of electrical

and electronic equipment which will conserve natural resources.

Disposal of waste batteries. This product contains batteries, do

not dispose of them with other household waste. Hand them over

to the appropriate collection point for recycling.

Ensuring proper product and battery disposal prevents potential negative

consequences for the environment and human health. For more information,

contact your city, your local household waste disposal service, the place of

purchase or go to www.hannainst.com.

Recommendations for Users

Before using this product, make sure it is entirely suitable for your specific

application and for the environment in which it is used. Please note that this

test is not recommended for freshwater applications. Any variation introduced by

the user to the supplied equipment may degrade the checker’s performance. For

yours and the checker’s safety do not use or store it in hazardous environments.

Warranty

HI781 Checker

HC is warranted for a period of one year against defects in

workmanship and materials when used for its intended purpose and maintained

according to instructions. This warranty is limited to repair or replacement free

of charge. Damage due to accidents, misuse, tampering or lack of prescribed

maintenance is not covered. If service is required, contact your local Hanna

Instruments Office. If under warranty, report the model number, date of purchase,

serial number and the nature of the problem. If the repair is not covered by the

warranty, you will be notified of the charges incurred. If the checker is to be

returned to Hanna Instruments, first obtain a Returned Goods Authorization (RGA)

number from the Technical Service department and then send it with shipping

costs prepaid. When shipping any product, make sure it is properly packaged for

complete protection.

Hanna Instruments reserves the right to modify the design, construction, or

appearance of its products without advance notice.

All rights are reserved. Reproduction in whole or in part is prohibited without the

written consent of the copyright owner, Hanna Instruments Inc., Woonsocket,

Rhode Island, 02895, USA.

IST781 05/20-1

HI781

Marine Nitrate Low Range

INSTRUCTION MANUAL

Need help?

Do you have a question about the Hanna Instruments HI781 and is the answer not in the manual?

Summary

General Description & Intended Use

Functional Description & LCD Display

Prepare the Filter Holder Assembly

Errors & Warnings

Light High

Excess ambient light reaching the detector. Check zero cuvette.

Light Low

Insufficient light for measurement. Check zero cuvette.

Inverted Cuvettes

Sample and zero cuvettes are swapped. Repeat measurement.

Under Range

Sample absorbs less light than reference. Check procedure and cuvette.

Over Range

Measured value exceeds method limits. Dilute sample.

Battery Low

Battery level too low for proper function. Replace battery.

Drained Battery

Battery is drained and must be replaced.

Tips for an Accurate Measurement

Summary

General Description & Intended Use

Functional Description & LCD Display

Prepare the Filter Holder Assembly

Errors & Warnings

Light High

Excess ambient light reaching the detector. Check zero cuvette.

Light Low

Insufficient light for measurement. Check zero cuvette.

Inverted Cuvettes

Sample and zero cuvettes are swapped. Repeat measurement.

Under Range

Sample absorbs less light than reference. Check procedure and cuvette.

Over Range

Measured value exceeds method limits. Dilute sample.

Battery Low

Battery level too low for proper function. Replace battery.

Drained Battery

Battery is drained and must be replaced.

Tips for an Accurate Measurement

The HI781 Marine Nitrate Low Range handheld checker is a compact and user-friendly colorimeter designed for accurately determining nitrate levels in aquariums and marine biology applications. This device is part of the Hanna Instruments Checker® HC series, known for its single-button operation and ease of use. Its primary function is to provide precise measurements of nitrate concentration in seawater samples, utilizing a colorimetric method where the reaction between nitrate and a specific reagent produces a pink/violet tint. The intensity of this tint is then measured by the device to display the nitrate level in parts per million (ppm).

Function Description

The HI781 operates on a colorimetric principle. When a seawater sample is mixed with the provided reagents, a chemical reaction occurs, resulting in a color change proportional to the nitrate concentration. The device then measures the intensity of this color using a Light Emitting Diode (LED) as the light source and a Silicon photocell as the light detector. The measurement is displayed on a large Liquid Crystal Display (LCD), making it easy to read. The checker is specifically calibrated and developed to work with seawater samples, ensuring accurate results for marine environments. It has a measurement range of 0.00 to 5.00 ppm (as NO3) with a resolution of 0.01 ppm, allowing for fine-grained monitoring of nitrate levels.

Usage Features

The HI781 is designed for straightforward operation, making it accessible even for users without extensive laboratory experience.

Single-Button Operation: The device features a single ON/OFF button that controls all functions, simplifying the measurement process.
Step-by-Step Measurement Procedure:
1. Power On and Zeroing: Press the ON/OFF button to turn on the checker. The display will show all segments briefly, followed by "Add", "C.1" with "Press" blinking, indicating it's ready for the first step of zeroing.
2. Sample Preparation (Step 1):
  - Using a 10 mL syringe, measure exactly 7 mL of the sample into a large mixing vial.
  - Using a 5 mL syringe, add exactly 4 mL of HI781A-0 reagent into the same mixing vial.
  - Add the content of one packet of HI781B-0 reagent to the mixing vial.
  - Replace the cap and shake vigorously for 1 minute to ensure thorough mixing.
3. Filtering the Sample:
  - Remove the plunger from the 10 mL syringe.
  - Attach the syringe to the prepared filter holder assembly using the threaded connection.
  - Remove the cap from the mixing vial.
  - Hold the syringe and filter holder assembly over a cuvette. Carefully pour the contents of the mixing vial into the back of the syringe.
  - Very slowly push the plunger into the 10 mL syringe until the 10 mL cuvette is filled up to the 10 mL mark.
  - Replace the cap on the cuvette.
4. First Cuvette Insertion (Zeroing): Insert the filled cuvette into the checker and close the cap.
5. Zeroing the Checker: Press the ON/OFF button again. The display will show "Add", "C.2" with "Press" blinking, indicating that the checker has been zeroed.
6. Sample Preparation (Step 2):
  - Remove the cuvette from the checker.
  - Unscrew the cap and add the content of one packet of HI781C-0 reagent to the cuvette.
  - Replace the cap and shake vigorously for 2 minutes to ensure the reagent is fully dissolved and reacted.
7. Second Cuvette Insertion (Measurement): Insert the reacted cuvette into the checker.
8. Measurement Initiation: Press and hold the ON/OFF button. The display will show a countdown timer (7:59) prior to the measurement. Alternatively, you can wait 8 minutes for the reaction to complete and then press the button.
9. Reading Display: Once the timer ends, the checker will perform the reading and display the concentration of nitrate in ppm of NO3.
Error and Warning Messages: The device provides clear warning messages to alert the user to potential issues or conditions outside the expected range, ensuring reliable measurements.
- Light High (L.HI): Indicates excessive ambient light reaching the detector. The user should check the preparation of the zero cuvette.
- Light Low (L.Lo): Indicates insufficient light for measurement. The user should check the preparation of the zero cuvette.
- Inverted Cuvettes (InU): Appears if the sample and zero cuvettes are swapped. The user needs to swap them back and repeat the measurement.
- Under Range (0.00 blinking): Occurs when the sample absorbs less light than the zero reference. The user should verify the measurement procedure and ensure the same cuvette is used for both reference and measurement.
- Over Range (5.00 blinking): Indicates that the measured value exceeds the method's limits. The user should check for debris in the sample, dilute it, and repeat the measurement.
- Battery Low (bAt): Signals that the battery level is too low for proper function, requiring replacement.
- Drained Battery (bAd then bAt): Indicates a completely drained battery that needs immediate replacement before restarting the checker.
Auto Shut-off: To conserve battery life, the checker automatically shuts off after 20 minutes of non-use and 4 minutes after a reading has been taken.
Compact Design: With dimensions of 86.0 x 61.0 x 37.5 mm (3.4 x 2.4 x 1.5″) and a weight of 64 g (2.3 oz), the device is highly portable and easy to handle.

Maintenance Features

Proper maintenance ensures the longevity and accuracy of the HI781 checker.

Cuvette Care:
- Always ensure the sample does not contain any debris, as this can interfere with accurate readings.
- Before inserting a cuvette into the checker, it must be dry on the outside and free of fingerprints, oil, and dirt. Using a HI731318 microfiber cleaning cloth or a lint-free cloth is recommended for thorough wiping.
- Avoid shaking the cuvette vigorously, as this can generate bubbles that lead to higher readings. If bubbles form, gently swirl or tap the cuvette to remove them.
- Do not allow the reacted sample to stand for too long after reagent addition, as this can affect accuracy.
- Discard the sample immediately after reading to prevent permanent staining of the glass cuvette.
Filter Holder Assembly: The reusable filter holder requires careful assembly. Ensure the paper filter is placed correctly on the lower piece, on top of the clear colorless gasket, and that it does not overlap the threads when the upper piece is tightened.
Battery Replacement:
- The device uses a 1.5V AAA Alkaline battery, which provides a minimum of 5000 measurements.
- When the battery is drained, the display will show "bAd" followed by "bAt" before turning off.
- To replace the battery:
  1. Turn off the checker by pressing and holding the ON/OFF button.
  2. Turn the instrument upside down.
  3. Use a screwdriver to unfasten the screw and remove the battery cover.
  4. Remove the old battery and insert a new 1.5V AAA battery, ensuring the negative end is inserted first.
  5. Replace the battery cover, fasten, and tighten the screw.
Cleaning: For thorough cleaning of cuvettes, HI93703-50 Cuvette cleaning solution (230 mL) is available as an accessory.
Storage: Store the device in a non-hazardous environment to ensure its safety and performance.
Accessories and Reagents: Regularly check and replace reagents (HI781-25 Reagents for 25 Marine Nitrate Low Range tests) and other consumables like filter discs (HI740228) and plastic tips (HI740144P) to maintain measurement accuracy. Certified standard kits (HI781-11) are also available for calibration and verification.

Hanna Instruments HI781 Specifications

General

Weight	64 g (2.3 oz.)
Light Detector	Silicon Photocell
Environment	0 to 50°C (32 to 122°F); RH max 95% non-condensing
Display	LCD
Power Supply	single AAA 1.5V battery
Dimensions	86 x 61 x 37 mm (3.4 x 2.4 x 1.5")
Light Source	LED
Temperature Compensation	automatic