Dynamic Sampling Accessories Provide Measurement Consistency

The use of spectroscopy is increasing in agriculture and environmental science, introducing a reliable means of analysing crop readiness, studying soil quality and measuring freshness and quality from field to processing line. To aid this analysis, Ocean Optics (the Netherlands) has introduced a line of spectroscopy accessories that makes dynamic sampling measurements simple and reliable for both solid and liquid samples. Dynamic sampling is a technique where rotational or linear motion is used to measure an “average” signal across the sample, removing localised variance from results and improving measurements of inhomogeneous and irregular samples such as grains, feed and soil.

Dynamic sampling is especially well suited to amassing the data for building NIR calibration models for quantitative analysis of moisture, fat or protein content. The use of Ocean Optics dynamic sampling accessories quickly yields more consistent and repeatable lot measurements to generate average representative spectra.

Ocean Optics offers four dynamic sampling accessories – a diffuse reflectance probe, rotating sampling cup, multiplexer and flow cell – that fit seamlessly with existing UV-Vis and NIR spectrometers and accessories, resulting in a system optimised for the user’s application. Dynamic sampling accessories are ideal for users who take routine measurements of the same sample types or need to measure a large number of different samples frequently.

The Diffuse Reflectance Probe (DR Probe) integrates a light source and collection optics into one unit to measure 45° diffuse reflectance. It is ideal for applications such as color analysis, material identification and quality monitoring of foods. The DR Probe has rugged, all-metal construction with 40 mm focal length and an integrated, 10,000-hour bulb for extended time between servicing.

Also available for diffuse reflectance measurements is the DynaCup, a rotating device that presents samples to the DR Probe. The rotation allows the probe to scan the sample multiple times to collect a more consistent, representative spectrum of the sample. This method is important with inhomogeneous samples like grains, where variables such as shape, moisture and starch distribution within kernels can vary greatly.

To save sample measurement time and streamline sample processing, the multiplexer accessory is a mechanical actuator that distributes light through 10 customisable channels from a single light source. The multiplexer is useful for any kind of light transmission and optical fibre size. Two models offer a choice between fast positioning, or high repeatability and accuracy of performance. The multiplexer features SMA 905 connections and a USB port for communication and remote control.

For flow applications users can select the DynaFlux, an integrated transmission and absorbance flow cell. DynaFlux accepts standard transmission cells with pathlengths up to 10 mm (sold separately) and a temperature controlled sampling chamber. A programmable timer allows the flow cell pump to run for fixed times with options for continuous flow to analyse large volumes, or stop-flow mode to analyse static samples. DynaFlux is an all-in-one accessory for dynamic sampling of liquids, for both NIR and UV-Vis transmissive measurements.