Fluorometric Nucleic Acid Quantification System

What is the Fluorometric Nucleic Acid Quantification System?

A fluorometric quantification system uses fluorescent dyes selective for double-stranded DNA, RNA or protein to measure concentration in 1–2 µL of sample, complementing fragment sizing with the accurate input values library preparation requires.

Overview

Fluorometric quantification relies on dyes that fluoresce strongly only when bound to their target, so the signal is largely independent of free nucleotides, salts and degraded single-stranded material that bias absorbance readings. A small volume of sample is mixed with a dye working solution in a tube or plate, incubated briefly, and read in a fluorometer with excitation and emission filters matched to the dye. Standard curves are built from a supplied DNA or RNA standard. Reported values are typically linear over two to three orders of magnitude, from about 0.01 ng/µL with high-sensitivity dyes to 1,000 ng/µL in the standard range. Some instruments combine the fluorometer with a microvolume spectrophotometer or a capillary analyzer so that purity and sizing are reported in one workflow.

How does it work?

Fragment analysis separates charged nucleic acid fragments in a sieving matrix and detects them by fluorescence. In capillary systems, samples are injected electrokinetically into a polymer-filled capillary, where smaller fragments migrate faster and reach the detector earlier. A laser excites intercalating dye bound to the DNA or RNA, and the software converts migration times into fragment sizes using an internal ladder and into concentrations using a quantitative marker. Microfluidic chips work on the same principle with shorter separation channels and smaller volumes. Automated agarose gel instruments draw samples through a gel by voltage and image the bands after staining. Because the sizing algorithm depends on the ladder and the polymer lot, run quality flags such as marker height and baseline noise should be reviewed before results are accepted.

What are the key features?

• Dye-selective measurement distinguishes dsDNA, RNA and protein
• Sample volume of only 1–2 µL per reading
• Linear range spanning about 4 to 5 orders of magnitude with kits
• 96-well plate or single-tube formats for flexible throughput
• Built-in standard curves from supplied reference standards
• Optional combination with absorbance purity measurement

What are the technical specifications?

A typical fluorometric nucleic acid quantification system configuration offers dynamic range (dsDNA) of approx. 0.01–1,000 ng/µL (kit dependent), sample volume of 1–2 µL, linear correlation of over 0.99 (typical), excitation of approx. 470–485 nm (blue) or 630 nm (red), emission of approx. 525 nm (green) or 680 nm (red) and assay time of approx. 5 min including incubation. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Fluorometric Nucleic Acid Quantification System is used in library input quantification before sequencing, RNA yield measurement for expression studies, PCR template normalisation and protein concentration assay in a plate format. Across the wider Fragment Analyzers class, laboratories also deploy it for next-generation sequencing library quality control, RNA integrity assessment before expression studies and PCR amplicon and restriction digest checks.

Which standards and certifications apply?

Relevant standards and methods include ISO 20395, ISO 22174, CLSI MM09, IEC 61010-1 and ISO 15189. Certification candidates for this model are CE, ISO 9001 manufacturing and IEC 61010-1 safety; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Install the analyzer on a level bench away from vibration and direct sunlight, because optical alignment and polymer flow are sensitive to movement. Store polymer, ladders and dye kits within their stated temperature range and note lot numbers, since a ladder or polymer change can shift sizing by several percent. Run a ladder and a known control with each batch, and review quality flags before releasing data. Replace polymer and clean electrodes as instructed to prevent carry-over between samples. Keep the instrument in a room with stable temperature to limit baseline drift, and include the analyzer in the laboratory's pipette and instrument calibration schedule. Verify performance after any service or software upgrade.

How do I select the right Fluorometric Nucleic Acid Quantification System?

Select a fluorometric system when downstream steps depend on accurate mass input, such as library preparation, and when samples are scarce. Specify dynamic range, dye kit compatibility, sample format, standard type, plate-reading capability and the option to add absorbance purity measurement.

How does it compare with other Fragment Analyzers variants?

Choose by the sample type, resolution and throughput you need. Capillary systems give the best sizing accuracy and reproducibility, which matters for sequencing libraries and RNA integrity scoring. Microfluidic chip systems run more samples in less time with microlitre volumes but give approximate sizing. Automated gel systems handle many samples at low consumable cost with lower resolution. Check the sizing range against your fragments: amplicons of 100–1,000 bp behave differently from long-read libraries above 20 kb, and high-sensitivity kits are needed below 1 ng/µL. Confirm sample volume, consumable cost, run time, and whether the software exports results to a laboratory information system. Where quantification must be exact, pair the analyzer with a fluorometric or digital PCR method.