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The ligase chain reaction (LCR) is a method of DNA amplification. The ligase chain reaction (LCR) is an amplification process that differs from polymerase chain reaction (PCR) in that it involves a thermostable ligase to join two probes or other molecules together which can then be amplified by standard PCR cycling. [ 1 ]
C ratio: with a sample of known date, and a measurement of the value of N (the number of atoms of 14 C remaining in the sample), the carbon-dating equation allows the calculation of N 0 – the number of atoms of 14 C in the sample at the time the tree ring was formed – and hence the 14 C / 12 C ratio in the atmosphere at that time.
In this technique, the response of the sample is measured and recorded, for example, using an electrode selective for the analyte. Then, a small volume of standard solution is added and the response is measured again. Ideally, the standard addition should increase the analyte concentration by a factor of 1.5 to 3, and several additions should ...
The ion source converts and fragments the neutral sample molecules into gas-phase ions that are sent to the mass analyzer. While the mass analyzer applies the electric and magnetic fields to sort the ions by their masses, the detector measures and amplifies the ion current to calculate the abundances of each mass-resolved ion.
Paper chromatography is a technique that involves placing a small dot or line of sample solution onto a strip of chromatography paper. The paper is placed in a container with a shallow layer of solvent and sealed. As the solvent rises through the paper, it meets the sample mixture, which starts to travel up the paper with the solvent.
The analysis of results is performed by determining the ratio of elements from within the sample and working out a chemical formula that fits with those results. This process is useful as it helps determine if a sample sent is the desired compound and confirms the purity of a compound.
If a and b are the signals from two amplicons in the patient sample, and A and B are the corresponding amplicons in the experimental control, then the dosage quotient DQ = (a/b) / (A/B). Although dosage quotients may be calculated for any pair of amplicons, it is usually the case that one of the pair is an internal reference probe.
Quality control begins with sample collection and ends with the reporting of data. [4] AQC is achieved through laboratory control of analytical performance. Initial control of the complete system can be achieved through specification of laboratory services, instrumentation, glassware, reagents, solvents, and gases.