Have you run the standard material? If you have what was the outcome?

No. I have only sample for development purpose. But i have run previously analysed sample and count rate low found. @Alan F Rawle

I'm not sure how you can state 'count rate too low' without providing a single piece of evidence or even the material you're measuring. The count rate (i.e. intensity of scattered light) is dependent on 3 factors, at least one of which should be working in your favor:

• Sample concentration. Double the concentration and you can expect a doubling of intensity, typically
• Optical contrast i.e. relative refractive index (particle/medium). Metal colloids will always scatter much better than say a protein
• Size of particle - the larger the particle then the greater the scattering intensity. In the Rayleigh region (typically lambda/10 where lambda is wavelength of the impinging radiation) then there's a (volume)3 or (diameter)6 dependence. Thus a 60 nm particle will scatter around 1 million times more light than a 6 nm particle

Thus, we need more information to help you. Can you actually provide any output results and the reason for you stating that the count rate is low?

If the detector is dead, then the count rate will be effectively zero. Is this your situation?

Thank you Sir for your response. I have got a message ' unable to find a suitable attenuator. Count rate is too low for acceptable measurement' in every time with multiple samples.@Alan F Rawle

Either:

• Your sample concentration is too low. Increase it by a factor of 100 to 1000 and re-examine the result
• There is no sample in the measurement zone. Has it settled out?
• The particle size is too low. Are you trying to measure a solution or sub-nm material?
• The relative refractive index is close to unity. Are you measuring a solution or an index-matched situation.

I can help you no further without the appropriate data file and knowledge of the material you’re trying to measure. Contact your local support/help desk and run the standard material to remove the instrument from the equation.

A low zeta potential count rate is usually due to low particle concentration, small particle size, low refractive index contrast, sample impurities, incorrect settings, or instrument issues. Adjusting concentration, ensuring proper dispersion, and optimizing instrument settings can improve the count rate.

A low count rate during zeta potential measurement typically indicates insufficient particle concentration or poor particle stability in the suspension, which can affect the accuracy of the measurement. The count rate refers to the number of photons detected by the instrument’s sensor, and it directly depends on the concentration, size, and scattering intensity of the particles in the sample.

One common reason for a low count rate is that the particle concentration is too low, leading to inadequate scattering events. Additionally, if the particles aggregate or sediment, the effective concentration of dispersed particles in the measurement zone decreases, resulting in a reduced signal. The sample's refractive index mismatch or improper dilution with incompatible solvents can also diminish scattering intensity. Instrument issues, such as improper alignment of the laser or a dirty cuvette, may contribute to the problem.

To resolve this, ensure that the particle concentration falls within the recommended range for zeta potential analysis, typically between 0.1 and 1 mg/mL for most systems. Disperse the particles thoroughly using sonication or appropriate surfactants to prevent aggregation. Check the compatibility of the suspension medium and verify that the cuvette is clean and aligned properly. Optimizing these factors can improve the count rate and lead to reliable zeta potential measurements.

It can be one of the crucial approach.

Hi Rashedul Siddiquei

Can you share a photo of the sample in the zeta cuvette? Is the sample transparent or opaque or totally absorbing/black?

When you insert the cuvette, make sure it's inserted all the way to the bottom. Can you do a size measurement in that cuvette (it is probably a DTS1070 capillary cell), without moving the cuvette, in backscattering? What is the count rate in backscattering?

Also you can check the zeta quality report and any potential hints on what to improve.