DS-11 Spectrophotometer Sample Measurement Troubleshooting Technical Note 127 Quick Help Most issues concerning accuracy and reproducibility are sample or measurement technique related and are resolved by following the suggestions below: • Ensure that the sample isolation procedure is optimized and samples are purified prior to making absorbance measurements. • Ensure all solutions are homogenous and well-mixed prior to sampling. • Ensure sample concentrations fall within the linear range of the instrument. • Establish a new blank using the appropriate buffer. • Verify that the buffer does not have significance absorbance at the analysis wavelength. Microvolume Mode • Ensure both top and bottom microvolume measurement surfaces are clean prior to making the Blank measurement. • Remove sample solutions from both the top and bottom measurement surfaces immediately after each measurement. • Use calibrated pipettors and properly fitting tips to ensure the full 1 μL aliquot is delivered to the measurement surface. Protein samples may wick to the outside of the tip and may not be properly dispensed. • Use a clean pipette tip and a new aliquot of sample for each microvolume measurement. Launch the Diagnostics app and perform a Microvolume mode Self Test to confirm instrument is working within specifications. If the Self Test fails- clean both the top and bottom surfaces and repeat the test. Cuvette Mode • Use cuvettes with Z heights of 8.5 mm. • Use quartz or UV transparent cuvettes for UV range measurements. • Ensure cuvettes are clean prior to use. • Fill cuvettes to manufacturer's specifications. • Confirm the Mode selection has been changed to Cuvette mode on the Run screen prior to a measurement. • Ensure cuvettes are properly inserted following the etched arrow light path. Launch the Diagnostics app and perform a Cuvette mode Self Test to confirm instrument is working within specifications. Remove any cuvettes prior to tapping the Self Test button. Additional technical help bulletins are available at www.denovix.com. Contact DeNovix Customer Support if further help is required. Please include the serial number of your instrument when contacting Customer Support by email. Outside of the US, please contact your local distributor for assistance. DeNovix, Inc. 3411 Silverside Road Wilmington, DE 19810 USA Phone: +1.302.442.6911 Email: [email protected] www.denovix.com Copyright 2014 DeNovix, Inc. Version: Sept 2014