Блок для работы с высококонцентрированными образцами SALD-HC

Для правильного измерения размеров частиц обычно используют образцы, в которых концентрация измеряемых частиц лежит в диапазоне от десятков ppm до 0,1%, чтобы избежать вторичного светорассеяния в образцах с высокой концентрацией измеряемых частиц. Процедура разбавления не всегда решает эту проблему, т.к. при разбавлении исходного образца частицы могут агломерировать или, наоборот, диссоциировать. В практической деятельности мы часто сталкиваемся с объектами, которые легко меняют свое исходное состояние при попытке воздействия на них. Многие суспензии и эмульсии просто расслаиваются при разбавлении или в них происходит агломерация исходных частиц .

К таким объектам относятся, например, мази, кремы, латексы, некоторые виды красок. При этом производителю необходимо знать размеры частиц в этих объектах, т.к. от размера частиц зависят как физические, так и потребительские свойства товара. С помощью стандартных приспособлений (проточная или емкостная ячейка) провести измерения таких образцов невозможно.

Компания Шимадзу предлагает свое решение для работы с высококонцентрированными образцами, которое стало возможным благодаря конструкционным особенностям приборов серии SALD.

Блок для работы с высококонцентрированными образцами представляет собой держатель стеклянных пластин, между которыми помещается образец с толщиной слоя в несколько микрон. Таким образом, можно проводить измерения образцов с концентрацией частиц до 20%, а также работать с ультрамалыми количествами образца – примерно 15 мкл.

Характеристики

Measurement of High Concentrations Achieved Using Laser Diffraction/Scattering

  • This system can measure the particle size distribution of high-concentration samples that up till now could not be measured using previous laser diffraction/scattering methods.
  • You can expect more accurate measurement of even samples, whose particle distribution changes by dilution, since the sample can be measured in its original state or with only the minimum required level of dilution.
  • Commercially-available hand creams, face creams and hair conditioners can be measured with hardly any pretreatment.

No Complex Parameter Settings Required

  • Unlike methods that use ultrasonic waves, this method does not require calibration.
  • Complex parameters related to the properties of the measurement target need not be set.
  • The refractive index is the only item that needs setting.

Количество образца

  • Обычно для работы требуется минимум несколько миллилитров образца, а то и десятки миллилитров. С блоком для работы с высококонцентрированными образцами SALD-HC23  можно работать с ультрамалыми количествами образца – примерно 15 мкл.
  • Важно при работе с ценными образцами.
  • Примеры измерений

Particle Size Distribution of W/O Emulsion

Particle Size Distribution of W/O Emulsion

Particle Size Distribution of 2 Types of Can Coffees with Different Storage Conditions

Particle Size Distribution of 2 Types of Can Coffees with Different Storage Conditions

Notes

  • There are greater restrictions on the measurement range for a high-concentration sample measurement system than there are for standard wet measurement (when using a flow cell or batch cell). Basically, the range is narrower.
  • As a rough guide, measurement is possible for concentrations of up to approx. 20 wt%. Depending on the sample substance, particle size and particle size distribution, however, there are cases where measurement is difficult at concentrations of approx. 10 wt%.
  • Samples with wide distribution widths are more likely to be affected by multiple scattering than samples with narrow distribution widths, and it may not be possible to obtain accurate measurements in some cases.

* Appearance and specifications are subject to change without notice.

Principle of High-Concentration Sample Measurement by the Laser Diffraction/Scattering Method

  • The laser diffraction/scattering method is the mainstream means used for measuring particle size distribution.
  • The basic approach to this method is exactly the same as measurement using a regular flow cell and batch cell.
  • The sample is held between two thin sheets of glass (glass slides), and laser light is irradiated on the sample to measure its particle size distribution.

Principle of Measurement

Particle Size Distribution of 2 Types of Can Coffees with Different Storage Conditions

If a standard flow cell or batch cell is used to measure a sample at a high concentration, the long light path results in multiple scattering and this makes it impossible to obtain accurate measurements.

Measurement is possible by simply holding the high-concentration sample particles to be measured between two glass slides. This significantly shortens the length of the light path, avoids the negative effects of multiple scattering and makes accurate measurement possible.

Shortening the light path to avoid multiple scattering

Particle Size Distribution of 2 Types of Can Coffees with Different Storage Conditions
Measurement with a Standard Flow Cell or Batch Cell

Particle Size Distribution of 2 Types of Can Coffees with Different Storage Conditions
Sample Held between Two Glass Slides

Detection of side scattered light  

Particle Size Distribution of 2 Types of Can Coffees with Different Storage Conditions

Also, placing the sample so that it is diagonal to the optical axis makes it possible to detect side scattered light. Applying particle size calculations to this and also to forward and back scattered light enables measurement of high-concentration samples in sub-micron region. (Side and back sensors are not available for the SALD-300V and SALD-200V ER.

* Appearance and specifications are subject to change without notice.

System Configuration/Accessories

System Configuration

  • Measurement holder for high-concentration sample ...... 2
  • CD-ROM (dedicated software*) ...... 1
  • Polarizing filter ...... 1
  • Glass slides ...... 1 box

* The dedicated software runs under the Windows95/98/Me/NT4.0/2000/XP OS.

Special Accessories  

Particle Size Distribution of 2 Types of Can Coffees with Different Storage Conditions

Glass sample plates created by forming shallow circular indentations in glass slides are available as special accessories.

This glass sample plate combined with a standard glass slide is effective in situations where the concentration is relatively low and merely enclosing the sample between two standard glass slides would make it impossible to attain sufficient diffracted/scattered light intensity.

The plates are available in six types, with indentation depths varying from 0.05 to 0.5 mm. They come in sets of 10 plates. A set consisting of two of each of the differing types (total 12 plates) also is available.

Name Indentation depth
Glass sample plate (0.1 mm) 0.1 mm (100 µm)
Glass sample plate (0.2 mm) 0.2 mm (200 µm)
Glass sample plate (0.3 mm) 0.3 mm (300 µm)
Glass sample plate (0.4 mm) 0.4 mm (400 µm)
Glass sample plate (0.5 mm) 0.5 mm (500 µm)
Glass sample plate (0.05 mm) 0.05 mm (50 µm)
Glass sample plate set 0.05 to 0.5 mm

* Appearance and specifications are subject to change without notice.
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