chemistry analyser

What is an automated chemistry analyser?

The idea of this article was conceived when hearing a quote from a management course, that was misattributed to Peter Drucker. The original phrase belongs to Lord Kelvin, a world-famous scientist who developed the absolute temperature scale. The original quote says:

“What is not defined cannot be measured. What is not measured, cannot be improved. What is not improved, is always degraded.”

The article focuses on the last two phrases. The first sentence means that to improve our product it is necessary to measure some of its properties. In this way, it will be possible to know if there is any failure during the production process. The last sentence means that if we can’t control the process, our product will more likely degrade over time and we won’t be able to detect it because of the lack of proper quality parameters.

When measuring is a must do

The quote from Lord Kelvin highlights the importance of getting the most reliable data on the qualitative and quantitative composition of our wine. For those who don’t have their own analytical tools, there is always the option to send samples to public or private laboratories dedicated to wine analysis. However, the best alternative, considering time and cost of external analysis, is to have an in-house laboratory. Some time ago, it was usual to see UV-Vis spectrophotometer in most of the winery labs. With these instruments, the winemaking process is manually monitored using different chemical and enzymatic reactions in order to obtain the key parameters. However, the scientific and technical advancement in the last decades make more affordable to the wineries the acquisition of the new automated chemistry analysers.
An automated chemistry analyser is the result of the technological development in various science fields: electronics, robotics, optics, materials, all of them combined to bring a fast, accurate, reliable and secure solution to the analytical needs of a winery. Despite its high-tech components, an analyser is really very user-friendly.
Basically, it consists of three parts: the robotics for the dispensing of samples and reagents, the optics conceived to monitor the reaction and the software that controls all the processes running in the machine and has the user interface.

The “mechanical” hand that rocks the cradle

Every automated analyser has one or more robotic arms whit its corresponding needle that are in charge of systematically repeating the following actions: aspirate the proper volumes of sample and reagents, dispense the liquids inside the optical cuvette and properly homogenise the sample and reagents mixture.
The aspirated volume is defined by the diluter, which in the case of the Miura range of instruments, consists of a ceramic pump that allows the dispensing of volumes in the range of 2-450 uL, with a high degree of accuracy and repeatability. The high quality of the materials used to make the diluter allows the analyser to work in a continuous manner during long times, without lack of precision nor mechanical failures.
The needle of the robotic arm is subjected to automatic cleaning between sample and sample and between sample and reagents, in order to avoid the cross-contamination by carry-over.
Once the sample and reagents are in the cuvette, the same arm homogenise the mixture through several operations of aspiration and discharge, specifically designed to avoid the formation of bubbles which may interfere with the absorbance reading.

The all-seeing “eyes”

Once the mixture is homogenised, the reaction has to take place at an optimum temperature, in order to accelerate the enzyme activity and reduce the waiting time. Usually, the reaction cuvettes are kept at a constant temperature of 37 °C. This control is achieved thanks to an air heating system, that replaces the old and unsafe water heating systems. In this way, the Miura range of analysers can effectively set the reaction temperature at 37.0 ± 0.1 °C.
A belt drive motor operated by the microprocessor rotates the cuvettes allowing them to move in a pre-established order from the dispensing point to the reading point, once the reaction time is over. At the reading point, the optical system basically consists of a lamp, a filter wheel, the reaction cuvette and the photodetector.
The halogen lamp emits light in a wide region of the UV-Vis spectra, whit an estimated life of 2000 hours. A series of filters conveniently selected in the range of 340-700 nm are responsible of producing an almost monochromatic beam of light. This range of the spectra covers almost all of the most important analytical parameters in oenology. The bandwidth of each filter must be low enough (usually, less than 5 nm) to correctly apply the governing laws of the interaction of light with matter.
Once the monochromatic beam of light passes through the cuvette, some photons are absorbed by the reacting mixture of sample and reagents. Then, when the beam of light reaches the detector, the output intensity is measured and compared whit the intensity of light when there is transparency in the cuvette (i.e., cuvette blank). To determine the unknown analyte concentration, a theoretical factor is employed or a calibration curve is previously performed using standards with a known concentration of the analyte. Whatever the method used, the software itself calculates the concentration of the analyte of interest
directly from the readings at the detector. To determine the unknown analyte concentration, a theoretical factor is employed or a calibration curve is previously performed using standards with a known concentration of the analyte. Whatever the method used, the software itself calculates the concentration of the analyte of interest directly from the readings at the detector.
When the reaction is finished and the absorbance is measured, the cuvettes are discarded for the next analysis (if disposables) or go through a cleaning cycle (if reusables). The cleaning cycle is developed at the washing station point. The washing station consists of a series of needles and pumps that absorb the mixture of sample and reagents from the cuvette, wash the cuvettes and then dry them, leaving them ready to use for the following analysis. The cuvette washing is executed in a simultaneous way with the reagent dispensing and the reading, in such a way there is always an available cuvette to continue with the schedule worklist.
One detail to keep in mind: while the heating system ensures the optimum temperature for the cuvettes, the reagents have to be refrigerated in order to extend his lifetime and on-board stability. This difference in temperature is resolved technically by a pre-heating system installed in the robotic arm to increase the temperature of the sample and reagents before they are dispensed inside the reaction cuvette.

The analyser’s “brain”

The operation of the analyser is completed with an integrated software that commands all the movements of the machine. Furthermore, through an easy-to-use interface the analyst can perform many routine tasks such as: sample and reagents positioning, calibrations of the different parameters, quality controls, statistics analysis, running of one or more tests for one or more samples, defining a worklist, visualize current results, search archived results, generate and print reports.
This interface and the automatization of the whole process of dispensing sample and reagents allows the operator to be free to perform other tasks and activities inside the lab and the winery. Therefore, the time of the staff is optimised and the management of the daily activities is improved.
Besides all the positive points we resumed till here, there is one more advantage of an automated analyser. The reagent consumption per test is lower than in a manual spectrophotometer, therefore there is an enormous amount of money saved. Not less important is the fact that an automated analyser increases the staff safety reducing the manipulation of some potentially harmful reagents.

The importance of choosing the right analyser

When the analyser operation is known, the winemaker has to choose the proper type of analyser depending on the number of samples to be tested and the number of parameters to be determined.
Recently, the arrival of new analysers promising to have more features and efficiency, has drawn attention. However, careful must be taken. Although the working principle of an analyser is quite simple as previously shown, not all the analysers have the same performance. First of all, reliability and accuracy of each analyser will depend heavily on the quality of the materials used for the construction of the key pieces (ceramic pump, arm needle, cuvettes, lamp, filters, detector). In second place, not all the analysers perform well when it is working with such complex matrices as wine is. For instance, homogenisation systems and reaction times are very different when comparing oenology analysers with biomedical analysers. A direct application of any automated chemistry analyser to oenology is not straightforward. So, the final user must rely only on those analysers already tested and validated in oenology, because they are the only ones that could give accurate and precise results. At TDI, we were pioneers in the research and development of analysers and reagents for the analytical oenology. More than 30 years of experience give us the technical know-how, that certifies us as the most convenient supplier of analytical solutions in oenology.
Our range of Miura analysers gives accurate, precise and reliable results for the most important parameters for a great diversity of wine and must samples. Furthermore, all the Miura analysers can work correctly for many years with the proper maintenance. This maintenance could be performed periodically by the own operator, and occasionally by a qualified technician.

TDI is the only company that could offer the most complete range of automated analysers, thanks to its exclusive Miura family:
– Miura Micro: the smallest one, conceived and designed for wineries with low analytical needs;
– Miura One: a small bench-top analyser, as reliable as the biggest;
– Miura 200: high throughput, great analytical performance;
– Miura 200 2 Arms: the new member, designed for laboratories and wineries with the highest analytical needs.

Our philosophy will always be to provide the best advice to our costumer in an honest, professional and personalized way according to his real needs. Because we are TDI, we are ENOLUTION.