How to choose a spectrophotometer
( A ) , the user can select the instrument to meet the requirements of long-term analysis :
Despite the wide range of spectrophotometers , but nothing more than : Simple, mid -and high-end three categories ;
( 1 ) Simple instrument and its features:
Structure: This type of instrument was single -beam , a beam of light that is irradiated only to the sample chamber ; sources generally only tungsten lamp ; sample holder is generally push-pull quadruple cell holder ; mostly manually find the wavelength selection , poor reproducibility ; slit into a fixed-width mode ; lower optical performance indicators ; mostly photodiode detector ; monitors mostly mechanical meter or digital display , data processors generally do not . Such instruments of production in the majority of domestic manufacturers .
Measurement mode : mostly fixed ( fixed wavelength ) absorbance or transmittance measurement , the basic measurement wavelength scanning can not be performed .
Adaptation: a small laboratory and demonstration teaching, analysis of samples is relatively simple, the test results less precision .
Price: relatively inexpensive , generally 20,000 yuan or less , so there is a certain market.
( 2 ) mid -type instrument and its features:
Structure : These instruments are mostly semi- double or double -beam -beam , but there are also single-beam instrument type ; light tungsten lamp and deuterium lamp ; sample cell holder of two fixed, namely sample channel and reference channel ; wavelength automatic setting mode or the search according to the scanning ; fixed slit width 2nm most still mode, there 1.5nm slit width ; majority detector is a silicon photodiode , but a few photomultiplier tubes ; relatively high optical performance , wherein the grating is particularly important technical indicators , the best concave grating , for both in terms of resolution or the stray light better than the simple type indicator instrument ; formula or a liquid crystal display connected to the computer , the data processing apparatus may have its own or external computer processing. And a certain measurement accessories .
Measuring modes: transmittance , absorbance, concentration direct reading , single-beam ; single point and scanning can be.
Adaptation: Such instruments can meet the basic needs of most laboratory analysis .
Price: between 3 to 100,000 yuan , accounting for this type of instrument the largest proportion of the spectrophotometer .
( 3 ) high-grade type of equipment and features:
In addition to the characteristics of the mid-range of the instrument , mainly a higher level of the design and manufacturing process of the optical system , such as using a large-sized concave grating and the grating grooves is larger than 1,800 / mm; detection wavelength in the near infrared range of the instrument and some region has more than 1100nm, up to 2600nm; slits are continuously adjustable to suit the needs , shift the wavelength of a high-resolution scanning speed is increased, the use of high-sensitivity detectors are photomultiplier tubes and infrared detector ; the data processing is now basically a computer to perform ; measure an instrument 's another indicator is to look at whether this instrument has a rich subsidiary measurement device, such as polarization accessories, integrating sphere attachment, reflective accessories, autosampler accessories, color analysis software , film accessories and more.
Measuring modes: transmittance , absorbance, concentration direct reading , reflection mode , power mode , a single point , scanning can be ;
Adaptation: research, optical detection , detection of biological samples , such as detection of complex samples . Not only can measure liquid samples , solid samples can be measured .
Price: 100,000 yuan or more.
(B ) the most appropriate price / performance ratio :
No matter what kind of choice these products, as long as the instrument type selected down , it is necessary to buy based on the price of products in the same type of instrument range , of course , the same instrument, who will buy cheap Whose ; here also Note: Sometimes the price difference does not necessarily want to buy some of the cheapest, but also a comprehensive assessment ; this requires more understanding, more reading, more comparative , and more to those with experience to ask ; do not listen to only one side of the sales personnel of the word .
( C) the excellent service:
"There is no excellent after-sales service , equipment manufacturers would have no life," This is a maxim , the truth is not much talked about in this .
Practice has proved that there is no good after-sales service guarantee instrument manufacturers produce equipment which will not be better to go . macy ( China ) instrument opened 400 phone service 24 hours a day to ensure ,400 -616-4686