High performance liquid chromatography (HPLC) is an essential analytical tool in modern laboratories, and the detector – as the "eye" of the HPLC system – directly affects the accuracy and sensitivity of the analysis. Different types of detectors are suitable for different samples and analytical needs. This article provides a systematic introduction to the common types of HPLC detectors and their appropriate applications, helping you find the right detection solution among the many options available.
I. Evaporative Light Scattering Detector (ELSD)
Market product recommendation: Elite D3270L, D3270 ELSD
Features
Does not rely on the optical properties of the sample; no chromophore required.
Stable baseline under gradient elution with low noise.
Suitable for samples with no or weak UV absorption.
Applications:
Analysis of traditional Chinese medicine components (e.g., saponins, polysaccharides).
Molecular weight distribution determination of polymers.
Analysis of complex systems such as lipids and carbohydrates.
II. Refractive Index Detector (RID)
Market product recommendation: Elite RI‑201H RID
Features:
Based on the difference in refractive index between the sample and the mobile phase.
Temperature control technology effectively suppresses baseline drift; fast stabilisation after start‑up.
Simple operation, suitable for routine laboratories.
Applications:
Sugar analysis (e.g., fructose, sucrose, polysaccharides).
GPC/SEC molecular weight distribution determination.
Detection of non‑UV‑absorbing components in chemical and food industries.
III. UV‑Vis Detector
Market product recommendations: Elite D3210L, D3210, UV3100, D1100
Features:
Wide wavelength range, supporting multiple detection modes (e.g., dual‑wavelength, four modes).
Precise optics, low noise, high sensitivity.
Some models support automatic lamp switching and intelligent temperature control.
Applications:
Drug content determination.
Analysis of biochemical samples and organic compounds.
Routine quality control and research analysis.
IV. Diode Array Detector (DAD/PDA)
Market product recommendations: Elite D3230L, D3230/40, DAD3100
Features
Simultaneous acquisition of multi‑wavelength signals with spectral scanning capability.
High light energy, low noise, resolution up to 0.6 nm.
Built‑in self‑diagnosis, leak alarm, and other intelligent functions.
Applications:
Simultaneous detection of multiple components in complex samples.
Drug purity identification and impurity analysis.
Research applications requiring full‑spectrum confirmation.
V. Fluorescence Detector (FLD)
Market product recommendation: Elite MFD3100 Multi‑wavelength Fluorescence Detector
Features
Extremely high sensitivity, far exceeding UV detectors.
Confocal optical path design, supporting switching between multiple LED sources.
Particularly suitable for naturally fluorescent or derivatised samples.
Applications
Toxin detection (e.g., aflatoxins).
Trace analysis of amino acids, vitamins, hormones, etc.
Monitoring of pollutants in environmental and food samples.
VI. Autosampler
Market product recommendation: Elite S3210 Autosampler
Features
Special steel needle design to prevent clogging.
Supports remote control and unattended operation.
Leak monitoring ensures safe continuous operation.
Applications:
High‑throughput sequential sample analysis.
Long‑duration continuous testing tasks.
Situations requiring high reproducibility and precision.
VII. How to Choose: Key Points for Selecting an HPLC Detector
(1) Based on sample characteristics
Choose the appropriate detector according to whether the sample has UV absorption, fluorescence properties, or lacks a chromophore.
(2) Refer to application field requirements
Consider the sensitivity, qualitative/quantitative requirements of the specific application field to determine the suitable detector type.
Frequently Asked Questions
Q1: What is the difference between a UV detector and a diode array detector (DAD)? How should I choose?
A: The core difference lies in the way light is detected. A UV detector measures at only one or two fixed wavelengths at a time – like looking through tinted glasses. A diode array detector (DAD) captures the entire UV‑Vis spectrum instantly – like taking a full‑colour photograph of the sample.
Choice advice:
If your method is well‑established, the target compounds are known, and only a few wavelengths are needed, a UV detector (e.g., D3210L, UV3100) is cost‑effective and sufficient for routine quantitative analysis.
If you need method development, purity assessment, peak purity checking, or unknown identification, a DAD (e.g., D3230L, DAD3100) is the better choice, as it provides full spectral information, ensuring accuracy and reliability.
Q2: What detector should I choose for samples without UV absorption (e.g., sugars, polymers)?
A: For non‑UV‑absorbing samples, two common choices are the refractive index detector (RID) and the evaporative light scattering detector (ELSD).
RID (e.g., RI‑201H): Works by measuring the difference in refractive index between the sample and the mobile phase. Advantages: universal response to almost all substances. Disadvantages: sensitive to temperature and pressure, unsuitable for gradient elution, relatively low sensitivity. Ideal for sugar analysis and GPC/SEC molecular weight determination.
ELSD (e.g., D3270L): Evaporates the mobile phase and detects the remaining sample particles. Advantages: gradient compatible, stable baseline, higher sensitivity than RID, independent of optical properties. Widely used for complex samples such as saponins, polymers, and lipids.
In short: If you use isocratic elution and sensitivity is not critical, choose RID. If you need gradient elution or higher sensitivity, ELSD is the more modern choice.
Q3: When should I consider using a fluorescence detector (FLD)?
A: When you need to detect extremely low (trace) levels of components, or when the target compounds are naturally fluorescent or can be derivatised to become fluorescent, a fluorescence detector (FLD) is the ideal choice.
Its greatest advantage is ultra‑high sensitivity and selectivity, typically several orders of magnitude higher than UV detectors, effectively avoiding interference from other components in complex matrices.
Typical applications include:
Food safety: Precise detection of mycotoxins such as aflatoxins (the MFD3100 is optimised for this purpose).
Biomedical: Trace analysis of amino acids, vitamins, hormones, etc., in biological fluids.
Environmental monitoring: Detection of polycyclic aromatic hydrocarbons and other environmental pollutants.
If your analysis demands extremely low detection limits, a fluorescence detector provides both high sensitivity and high selectivity.
