Do you have a source for EP Opalescence Standards?

The reference document that defines the visual EP Opalescence scale is:

EP 2.2 Physical and Physico-Chemical Methods for color and opalescence

EP – European Pharmacopoeia, Section 2.2 Physical and Physico-Chemical Methods, Unit European Pharmacopeia, Strasbourg, France (1997: 15-16) http://www.pheur.org

This method describes the visual evaluation of scattering or opalescence in near clear liquids, typically pharmaceutical, relative to distilled water being a perfect clear.

There are two types of physical liquid standards for visual turbidity or opalescence – Formazin solution (with or without stabilizer) and polymer beads (polystyrene micro spheres). The Formazin solution is the historical liquid scattering standard but the polymer beads is considered more stable and homogenous.

Section 2.2.1 Clarity and Degree of Opalescence of Liquids in the EP 4th edition defines a Formazin Primary Opalescent Liquid Suspension (rated at 4000 NTU per EP 5th edition) as a solution of hydrazine sulphate solution and hesamethylenetetramine solution which is stable for 2 months stored in glass.

The EP 4th edition further defines a Formazin Standard of Opalescence (rated at 60 NTU per EP 5th edition) as a dilution of 15.0-ml of the Formazin Primary Opalescent Liquid Suspension (4000 NTU) to 1000.0–ml of water. This suspension must be freshly prepared and stored for no more than 24 hours.

To make the EP Reference suspensions or OP – Opalescence standards, the Formazin Standard of Opalescence (60 NTU) is mixed with distilled water in the following proportions to define 4 levels of liquid EPOP Opalescence Standards. Distilled water is nominally a fifth EPOP standard defining no opalescence or scattering.

Table 2.2.1-1 EPOP Standards 0 I II III IV
 Formazin Standard of Opalescence (60 NTU) 0.0 ml 5.0 ml 10.0 ml 30.0 ml 50.0 ml
Distilled Water (fill to 100.0 ml mark) 100.0 ml 95.0 ml 90.0 ml 70.0 ml 50.0 ml
NTU Rating 0 3 6 18 30

Sources for EPOP Liquid Opalescence standards are:

Hach Company

Loveland, CO 80538 USA

+970-669-3050

www.hach.com

Hach offers the STABLCAL Reference Suspension Set that consists of a range for EP Opalescence Standards per EP is 0 (distilled water >0.1), 3, 6, 18, 30 NTUs. Given the 2-year stability, stabilizers will have been added to these liquid EP standards.

Hach STABLCALC set of EP Opalescence Standards

Hach STABLCALC set of EP Opalescence Standards

Another source for the Formazin Primary Opalescent Liquid Suspension (rated at 4000 NTU) and EPOP Liquid Opalescence standards (rated at 0 – ­30 NTU) is:

RICCA Chemical Company

Arlington, TX 76094 USA

+817-461-5601

www.riccachemical.com

Reporting of EP Opalescence using a HunterLab Sphere Instrument and EasyMatch QC Software

As of EasyMatch QC version 4.82 and higher HunterLab has implemented a correlation method to the EP Opalescence scale based on these standards and is able to report EPOP-10mm (D65/10) for liquid samples measured in a 10 mm path length transmission cell. EPOP values are reported to tenths of a unit, along with NTU values as well.

Is it possible to create ASTM traceable haze standards above 30%?

The current, available ASTM D1003 Haze Standards have nominal Haze% values of 1, 5, 10, 20 and 30 with air (transparent solids) or the transmission cell filled with DI water being 0 (transparent liquids). Here are some thoughts on further options. Continue reading

Can the color of Fresh Spaghetti Sauce be measured with Tomato Scores?

FAQ: “We have another question. Our current Standard for Fresh Spaghetti Sauce is to Run on the TK setting.

It appears as if the Product is Rather orange compared to our Crushed tomato product which is run on the TS setting resulting in a lower color.

What do you believe is the proper setting for Spaghetti Sauce?

The other thing I noticed is That the Calibration record does not have a TK result documented.” Continue reading

SPC Results for Diagnostic Didymium Filter Test

FAQ: “We take the results from the Didymium Filter Test on our HunterLab ColorQuest XT and plot them in an SPC chart over time to look at trends. We are seeing the 430 and 570 nm filters slowly decrease. Can you help us understand what may be occurring?” Continue reading

FAQs on White Tile Replacement for HunterLab sensors

FAQ: “One of our manufacturing departments has a ColorQuest XE that they use to monitor a process at-line. After we saw that their white tile appeared a bit dingy and scuffed, we recommended they get a new one. The new white tile came in, but it comes with a software CD.  My questions? Continue reading

Do you know what Molten Color is?

FAQ:”A client is asking me to measure something they call “Molten Color’. Do you have any information on this? Do Hunterlab instrument have a function for this color?” Continue reading

Do you have a source for color standards related to fruits and vegetables?

USDA/AMS is the most general source for visual color standards for fruits and vegetables and offers a catalogue of color comparators and equipment they have available.

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Do you have references for the equivalency of CIE inverse instrument geometries?

FAQ: “…. the schema of the principle of measuring shows other way of light (source of light -> sample -> sphere -> detector) than our ColorQuest (source of light -> sphere -> sample ->  detector). Please can you explain me difference between both construction? difference between both results of measuring?”

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Can you explain the LabScan XE 0:45 inverted geometry?

FAQ: “Straight from the LSXE Pro-forma, the LabScan XE sample ports are described as:

Port Insert, 3-mm illuminated area; 5-mm measured area
Port Insert, 6-mm illuminated area; 10-mm measured area
Port Insert, 13-mm illuminated area; 17-mm measured area
Port Insert, 25-mm illuminated area; 30-mm measured area
Port Insert, 44-mm illuminated area; 50-mm measured area

I always thought that the measured area was smaller than the illuminated area. Have the illuminated/measured area in the Pro-forma been transposed? Seems like it!”

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Do you have a source for Magnesium Carbonate powder as top-of-scale?

For measuring the brightness of some materials, some dated industrial methods cite a Magnesium Carbonate block standard to be set to Y = 100% in reflectance. This is a very old top-of-scale standard and HunterLab does not recommend using it.

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