Our honest reviews on the Qiagen QIAxpert DNA quantification machine.
Our team has vast experience in research and diagnosis in Molecular Cytogenetics. We have used so many instruments during our research work. We have worked on different types of PCR, quantification machines, microarrays, sequencers, and other related instruments.
After discussing from past two days, we decided to review the instruments on which we have worked for years. Today we are reviewing the first instrument on which I had worked during my prenatal lab work, Qiagen QIAxpert.
QIAxpert is a quantification machine that quantifies DNA, RNA and even a protein. Quantification is one of the important steps in genomic research. As we are using so many chemicals while extracting DNA, the chance of having impurities is greater and these impurities will affect the quality of DNA as well.
Before going to review QIAxpert we have to understand what is DNA quantification.
Read the article: DNA gel loading dye
DNA quantification/ nucleic acid quantification is performed to measure the amount of DNA, RNA or protein present in the sample. Genomic research is our primitive aim hence we will understand the mechanism with respect to DNA only.
DNA can be quantified using fluorescent tagging (Qubit) or by spectrophotometrically (Nanodrop light or QIAxpert).
The spectrophotometric analysis is more preferable as it is fast and more accurate. UV/ visible spectrophotometer measures the number of DNA molecules present in the sample.
Here the 260nm UV light passes through the sample and the amount of light passes through the sample is measured by the detector.
DNA absorbs UV light at 260nm. As the UV light passes through the sample (at 260nm) some amount of light is absorbed by the DNA and is detected by the detector.
Higher the amount of UV light absorbed by the DNA, the concentration of DNA is higher. Further, the purity of DNA can be calculated using a spectrophotometer.
The UV- visible spectrophotometer measures the light passes through the DNA at two different wavelengths (260nm and 280 nm) and by calculating the difference, purity of the DNA is calculated.
The purified DNA has ~1.8 260/280 ratio and is considered as a pure DNA.
Read the article: PCR primer design guidelines.
The Qiagen QIAxpert is a single channel, UV- visible spectrophotometer which measures the DNA, RNA, and protein as well.
The instrument comes as a single variety of blue and silver-colored; made up of an acrylic body.
At the front, it contains a touch screen, slide entrance gate, USB port and Qiagen branding. While at back, it contains the power switch, IP interface and power plug.
The machine runs on the Qiagen’s own software. The result on the screen contains a graph of absorption, 260/280 ratio, 260/230 ratio, absorption at 260nm and the concentration of DNA.
Further, at another side of the screen, the software contains the information of sample loading in the QIAxpert slide.
Principle of QIAxpert
The machine is a UV/ vis spectrophotometer that works on the principle like a normal spectrophotometer.
The pump transfers the samples from Qiaxpert slide to the micro cuvette and absorption is measured at 260, 280 and 230 nm.
In a single slide, we can quantify 15 samples within a 2 minutes time. The integrated software measures DNA quantity and purity by automated calculations.
The Qiaxpert slide is developed and designed by Qiagen hence it cannot be available to any other company or brand.
The Qiagen QIAxpert slide works on the unique formula of capillary forces. Once the sample is loaded into the well, it is immediately taken into the small capillary.
This protects sample evaporation and cross-contamination and the sample can be stored for the maximum time of 2 hours as well.
The slide is labeled as A to H vertically while 1 and 2 horizontally. It allows proper labeling and facilitate to quantify 15 samples with a blank at once.
For calibrating sample, we need extra 3 slides for pump calibration, position calibration and wavelength calibration.
Advantages of Qiagen Qiaxpert
- It is easy to use and sample preparation is further easy to perform.
- It does not require fluorescent dye for DNA quantification. Hence it is safe to handle.
- The sample processing is fast and can analyze 15 samples at once.
- The sampling requirement is lower as compared to the traditional spectrophotometer. therefore, the chance of error is less.
- The chance of cross-contamination and sample evaporation is negligible.
- The build quality and design of the machine are awesome having the best plastic quality of the machine as well as Qiagen QIAxpert slide.
- The data can be transferred through the USB flash drive into a readable format (.html, .txt, .bin).
Disadvantages of Qiagen QIAxpert
Though the machine is beautiful, accurate and fast, there are several limitations that make Qiagen QIAxpert the second choice for the personal lab.
- The requirement of utility: Qiagen is a pioneer is designing high-end accurate instruments, but their instruments require additional utilities.
- The external QIAxpert slide is always required after every 16 samples which makes it costly.
- However, the instrument itself is costly as compared to other spectrophotometers available in the market.
- Additionally, the cost of a slide is also higher.
- We have to insert the slide into the slide entrance gate which takes the slide inside for some time. It feels like we are using some traditional ATM machine (remember the ATM machines which took the card into the machine).
- The processing noise is felt so weird again, it feels like we are using an ATM machine.
- The sampling requirement is higher as compared to Nanodrop light. Qiagen QIAxpert required up to 2μl of a sample.
- It is always preferable to load the sample directly into the machine. For example, in Nanodrop light we load samples directly to the optical surface which required less amount of sample.
- Here in Qiagen QIAxpert, losing a sample is always a possibility as the slide can be dropped by chance.
- Further, every time we have to set a blank. Which occupies more wells and increases the cost of sample processing as well.
“ A blank is a solution using which we dissolved our DNA. If we dissolve our DNA into TE buffer, then use TE buffer from the same batch as a blank. If our DNA is dissolved in D/W, use D/W as a blank instead of TE buffer.”
My ultimate guide using Qiagen Qiaxpert
Install the machine as per the manufacturer’s protocol and calibrate using a calibration guide of Qiagen or call the Qiagen expert for installation and calibration.
Now place the QIAxpert slide on a flat surface and the first load the blank into the well. Note down the loading pattern into the notebook.
Now load sample in a sequence of A2- B1-B2-C1 up to H2, note it down in the record book. Remember always follow this route of loading.
First, we have to create a user into the create user section of the machine.
Follow the step for sample processing: measure> select user> insert slide> label slide> select dsDNA into quantification section.
Once the processing will over, the slide will come out of the slide gate and the result will be displayed as shown in the figure.
I honestly feel that the Qiagen Qiaxpert is a little complicated and costly as compared with other high-end spectrophotometers available in the market. Nonetheless, Qiagen QIAxpert is more accurate.
If you process more than 20 samples in a day I prefer to use Qiagen QIAxpert, for one or two samples it becomes more costly.
Read the article: DNA fingerprinting
So if your workload is higher and you want to avoid cross-contamination, go for Qiaxpert. If you want a cost-effective option, purchase Qubit for quantification and for purity, do agarose gel electrophoresis (agarose gel electrophoresis gives you a rough idea of purity, but not accurate).
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The article was written by: Tushar Chauhan
The article reviewed by: Tushar Kachhadiya