Metrolab Blog

Turb® 750 – The „fine art“ of turbidity measurement

The new turbidimeter of the WTW Turb® 750 Series from Xylem Analytics answers the wishes of many lab and industrial users for an AQA supported turbidity measurement up to 1100 FNU/NTU:

  • Highly precise readings thanks to the proven WTW® optics
  • Intelligent Reproducibility and Plausibility Check (IRPC)
  • Determination in drinking water acc. to DIN EN / US EPA
  • Menu guided 3-point standard calibration
  • Free calibration with 2-5 calibration points
  • QuickCAL: 1-point-calibration at 10 NTU
  • Space saving despite a considerable functionality
  • AQA, calibration interval and records with PC documentation
  • Smashing price-/performance ratio
Turb® 750: Conforming to standards in drinking water

Turbidity is an important indicator parameter for quality assurance of drinking water: Since particles offer a potential surface to bacterial growth, turbidity can indicate bacterial contamination.

                   Turb<sup>®</sup> 750 – The „fine art“ of turbidity measurement


The Turb® 750 Series offers an IR and a tungsten white light instrument from 0 – 1100 FNU/NTU. This conforms to the guidelines for drinking water analysis according to DIN EN 27027 respectively US EPA 180.1.

Turbidity: An underrated parameter in quality and purity control!

Turbidity measurement adds to the quality and production monitoring in many fields: In medical production and storage, food and beverage from juice to wine, quality check of fuel, filtration processes, production of goods such as wall paint, industrial washing water, quality check for incoming goods in development and production processes such as fuel purity, growth rates in fermentation and many more.

Particularly in these application fields, the analytical quality assurance (AQA) is an important feature: Adjustable calibration interval, calibration record with the standards used and the GLP compliant documentation via PC and LIMS.

The scope of delivery includes the PC software Turb® Data for a highly comfortable documentation: Data with ID for instrument and user can be pre-filtered or completely transferred to PC as CSV formate. From there, they can be also exported to Excel® or imported into the company’s LIMS. Beside the pure findings, data sets contain the corresponding calibration records and AQA flags.

Vial OK – measurement findings OK!

Best practice requirements  are the alignment and marking (indexing) of vials before use. This one-time procedure secures the optimal light path for the measurement and eliminates the influence of scratches, the need of silicon oil and pre-marked vials. Vial preparation together with the Intelligent Reproducibility and Plausibility Check during measurement make findings of Turb® 750 instruments the  ”truly” precise  measurement values: Any glass fault like scratches or inhomogeneities are eliminated without using silicon oil which just adds another stray light factor. A pre-marked vial never can ensure the same elimination of influences. Indexing of vials additionally guarantees a longtime-use of vials, since a valuable light beam and thus a measurement window for precise findings can be achieved then even in presence of small scratches. A check of the vial by aligning it occasionally is considered to be “Good Laboratory Practice”.

A “stable” finding is not automatically a “correct” finding!

A „stable“ output value in turbidity measurement does not necessarily mean a correct finding: Particles are floating and moving and thus do not yield stable results by nature. A guarantee of “correct”, accurate and reproducible measurement values is freezing the plausible value by means of a precise optical system, using aligned vials and a calibration with highly precise and stable calibration standards. The Intelligent Reproducibility and Plausibility Check (IRPC) computes a multiple measurement by evaluation and elimination of outliners. The result is then displayed as a stable and plausible value.

Calibration with AMCO Clear® Standards

Turb® 750 scores with a calibration using the well-proven and reliable AMCO Clear® standards:

  • Long-term stability without drift behavior
  • Higher precision
  • Only ± 1% production tolerance, optimized to optics
  • Traceable to fromazine
  • Non-hazardous and eco-friendly
  • Simple to dispose

A good calibration with AMCO Clear® standards is significantly adding to highly precise and reproducible measurement results.

Tip: To compare different instrument models with their optical variation it is mandatory to perform a calibration of all instruments ahead with one and the same freshly prepared formazine!