Software Architecture And Features - Thermo Scientific NanoDrop 1000 V3.3 User Manual

Table of Contents

Sample Size Requirements

Although sample size is not critical, it is essential that the liquid column be formed so that the gap between the upper and lower

measurement pedestals is bridged with sample.

Field experience indicates that the following volumes are sufficient to ensure reproducibility:

•

Aqueous solutions of nucleic acids: 1 ul

•

Purified protein: 2 ul

•

Bradford, BCA or Lowry assay: 2 ul

•

Microbial cell suspensions: 1-2 ul

It is best to use a precision pipettor (0-2 ul) with precision tips to assure that sufficient sample (1-2 ul) is used. Lower precision pipettors

(0-10 ul and larger) are not as good at delivering 1 ul volumes to the measurement pedestal. If you are unsure about your sample

characteristics or pipettor accuracy, a 2 ul sample is recommended.

Sample Carryover

Prevention of sample being retained on the ND-1000 Spectrophotometer's measurement pedestals is easily addressed. Simple wiping

of the upper and lower measurement pedestal with a dry laboratory wipe is highly effective in eliminating carryover for samples differing

in concentration by as much as three orders of magnitude (see data at www.nanodrop.com). This is possible since each measurement

pedestal is in actuality a highly polished end of a fiber optic cable. There are no cracks or crevices for residual sample to get trapped

within.

Sample Homogeneity

Sampling from non-homogeneous solutions – particularly when using small volumes – can cause significant deviations in the data

generated using all measurement technologies including spectrophotometry. Genomic DNA, lambda DNA and viscous solutions of

other highly concentrated nucleic acids, such as resuspended nucleic acid preparations, are common examples known to the molecular

biologist. Proteins are subject to denaturation, precipitation, and aggregation and therefore may require special handling to ensure

sample homogeneity.

Effect of Evaporation and Solvents

Evaporation of the sample during the measurement cycle usually has just a minimal effect on absorbance readings and may result in a

1-2% increase in sample concentration. This can be observed in the field by measuring the same sample successively over time.

Highly volatile solvents, such as hexane, will likely evaporate before the measurement can be completed. Less volatile solvents such as

DMSO can be used successfully.

Sample Recovery

One of the advantages of the sample retention system is that samples can be recovered from the upper and lower measurement

pedestals by extraction with a pipette.