The ultra micro spectrophotometer has achieved high-precision analysis of micro liter level biological samples through optimized optical path design and innovative detection principles. Its core mechanism can be summarized as follows:
1、 Optical path design: Breaking through tradition and achieving trace detection
Liquid column optical path fixation technology
Using liquid surface tension, a fixed thickness liquid column (such as 0.05mm or 0.2mm) is formed between the upper and lower detection plates to replace traditional colorimetric dishes. The height of the liquid column is used as the optical path to ensure stable optical path and avoid errors caused by inconsistent optical paths. Some models adopt variable optical path technology (such as 0.02-1mm dynamic adjustment), which automatically adjusts the optical path through real-time absorbance data to expand the detection concentration range.
Four path detection design
Adopting a four path detection method to improve detection stability, repeatability, and linearity. Compared to traditional single path or dual path systems, the four path design can provide a larger detection range and ensure consistency and accuracy of measurement results.
Fiber optic sample stretching technology
Some models use fiber optic sample stretching design to form a 1mm fixed optical path film using liquid surface tension, without the need for traditional consumables such as colorimetric dishes. The fiber optic cable is made of quartz material, with a finely polished surface that does not adhere to liquids. It can be removed by wiping with filter paper. At the same time, the fiber optic cable cover is made of 316L stainless steel, which has strong corrosion resistance and is suitable for complex biological samples.
2、 Detection principle: high-precision analysis based on Lambert Beer law
Application of Lambert Beer Law
This law states that the absorbance (A) is proportional to the sample concentration (C) and the optical path length (L), and the formula is
A=ε⋅C⋅L， Among them, ε
The molar absorptivity. The ultra micro spectrophotometer calculates the sample concentration by measuring the absorbance at a specific wavelength and combining it with the known molar absorptivity.
Multi wavelength synchronous detection
Support full spectrum scanning (190-850nm), which can simultaneously detect multiple wavelengths (such as 260nm nucleic acid, 280nm protein, 230nm salt ions), and evaluate sample purity and concentration through multi parameter analysis. For example, the A260/A280 ratio is used to determine nucleic acid purity, and the high-purity DNA ratio should be between 1.8-2.0.
High sensitivity detection system
Equipped with high stability light sources (such as pulsed xenon lamps or LEDs), with a lifespan of over 5000 hours, reducing preheating time and light intensity fluctuations. The detector adopts UV enhanced CCD or silicon photovoltaic cell, which has a wide linear response range and can capture weak signals (such as 0.5pg/μ LdsDNA) while avoiding saturation effects.