GENOVA NANO Accuracy and precision of the Genova Nano Introduction The Jenway Genova Nano spectrophotometer combines a micro volume accessory with the dedicated life science measurement modes of the Genova Plus as well as those of a standard spectrophotometer. The Genova Nano is able to measure sample volumes as low as 0.5µl with a high degree of accuracy, reproducibility and speed. This ability conserves precious samples, reduces the need for dilution and eliminates the requirement for cuvettes. Cleaning is quick and simple: wiping the read heads with a lintfree cloth removes all trace of the sample, allowing faster change over between samples and therefore increasing sample throughput. Fig. 1: Applying samples to the read head of the micro volume accessory. and precision is a measurement of repeatability or reproducibility. The Genova Nano is specified to an absorbance accuracy of +/-2% at 260nm and a precision of < 0.005A between 0 and 1A (at 0.5mm path length). This application note demonstrates this specification on eight individual units and also shows concentration reproducibility when measuring in dsDNA mode. Materials and Methods Each of the Genova Nano units was calibrated using the certified calibration standard solution provided following the instructions detailed in the user manual. To determine absorbance accuracy, the unit was set up in multiwavelength mode to measure at 260nm and 330nm. The unit was zeroed using 2µl of the calibration blank solution then 2µl aliquots of the calibration standard solution were measured. Following each measurement, the sample was wiped off the read head using a lint-free wipe. This test was performed at both at 0.5mm and 0.2mm path lengths and on each individual unit. 10 successive readings were used for data analysis. Fig. 2: A droplet of sample is shown on the Genova Nano read head. In order to measure absorbance precision or repeatability, a sample of green food colouring (Supercook, Leeds, UK) was used. This contains a mix of tartrazine (E102) and Green S (E142). The absorbance spectrum [email protected] www.jenway.com Tel: +44 (0)1785 810433 An important requirement for measurement of micro volumes is accuracy and precision. Accuracy is defined as how close the measured parameter is to a defined value

of the food colouring shows a peak at 430nm and a trough at 520nm (Fig. 3), therefore these wavelengths were chosen for measurement. The food colouring was diluted with water to give an absorbance between 0 and 1 in a path length of 0.5mm. measurement, the sampls was wiped off the read head using a lint-free wipe. This test was performed at 0.5mm path length on each individual unit. 10 successive readings were used for data analysis. Fig. 3: Visible spectrum of green food colouring measured using the microvolume accessory at 0.5mm path length showing a peak at 430nm and trough at 520nm. In a...

The expected absorbance values for the calibration standard solution were 0.490 at 0.5mm path length and 0.196 at 0.2mm path length, according to the certificate supplied with the reagents. All units were well within the specification set at +/-2% of the expected values at both 0.5 and 0.2mm path lengths. In addition there was less than 2% variation between instruments at 0.5mm path length. further the reproducibility of the Jenway Genova Nano. To determine repeatability of measurement, a series of food colouring samples were measured and the maximum and minimum reading of the range determined....

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