01 Solution Summary
The DNPH derivatives of aldehydes and ketones such as formaldehyde, acetaldehyde, acetone, and acrolein in ambient air or indoor air aldehyde and ketone samples collected with DNPH sampling tubes are formed as stable derivatives or sample solutions through DNPH sampling and derivatization, and then HPLC performs liquid-phase separation and detection with UV and DAD. Quantification and quality control adopt the following arrangement: external standard calibration with DNPH derivative standard solutions. Analysis batches are also set up with blanks, calibration checks, and applicable quality control samples.
02 Standards and Method Basis
Chinese standard: English standard titles on this page are descriptive translations. The cited Chinese text is authoritative.
| Standard number | Standard name | Status | Source |
|---|---|---|---|
| HJ 683-2014 | Air — Determination of aldehydes and ketones — High-performance liquid chromatography | Formal standard | Official source |
| HJ 1154-2020 | Ambient air — Determination of aldehydes and ketones — Solution absorption-high-performance liquid chromatography | Formal standard | Official source |
03 Samples and Analytes
The specific samples areAmbient air or indoor air aldehyde and ketone samples collected with DNPH sampling tubes, and the analytes areDNPH derivatives of aldehydes and ketones such as formaldehyde, acetaldehyde, acetone, and acrolein. Pretreatment, injection, and detection configurations are determined according to the sample state, target concentration, and the formal method adopted.
04 Method Principle
Aldehydes and ketones in air are trapped by a DNPH sampling medium and form corresponding hydrazone derivatives, converting volatile carbonyl compounds into stable components suitable for liquid chromatography analysis.
After the derivative eluate enters the HPLC, separation is achieved under the action of the mobile phase and liquid chromatography column. UV or DAD records the derivative absorption signals, and external standard calibration is performed with DNPH derivative standard solutions.
05 Sample Collection and Pretreatment
The HJ 683-2014 route uses DNPH-coated sampling tubes for trapping and simultaneous derivatization; after sampling, the tubes are sealed and stored protected from light; after elution with acetonitrile, the eluate is made up to volume and filtered. The HJ 1154-2020 route uses DNPH absorption solution for collection and derivatization; after extraction, concentration, and solvent exchange to acetonitrile, a test sample is formed.
The two routes respectively perform sampling blanks, transport blanks, or absorption solution blanks, and the sampling tube route and solution absorption route are not conflated into a single processing step.
06 Separation and Detection
An HPLC system consists of mobile phase delivery, automatic sampling, a liquid chromatography column, and UV and DAD. UV is suitable for routine detection at fixed wavelengths; DAD can simultaneously record spectral information for peak identification and method confirmation.
Mobile phase composition, column, and detection wavelength are determined by the separation requirements of aldehyde/ketone-DNPH derivatives, and standard derivatives are used to check the separation of key target peaks from coexisting components.
07 Instrument System Configuration
| Module | Configuration | Role in This Solution |
|---|---|---|
| Sampling module | DNPH sampling tube, or DNPH absorption solution and air sampling device | Capture aldehydes and ketones according to the selected standard and complete derivatization |
| Sample preparation | Elution of the sampling tube, or extraction, concentration, and acetonitrile exchange of the absorption solution | Form a derivative solution suitable for HPLC injection |
| Liquid chromatography system | Pump, autosampler, and C18 (ODS) reversed-phase liquid chromatography column or an equivalent column confirmed by the method | Separate aldehyde/ketone-DNPH derivatives |
| Detector | UV, DAD | Record derivative absorption signals at the wavelength specified by the method |
| Data system | External standard calibration with DNPH derivative standard solution | Complete retention time-based identification, external standard quantification, and result review |
08 Huishi Instruments system configuration
This application requiresHigh-performance liquid chromatography systemComplete the analysis of DNPH derivatives of aldehydes and ketones such as formaldehyde, acetaldehyde, acetone, and acrolein. When selecting a configuration, the injection interface, detector, and data system should be determined by taking into account the sample state of ambient air or indoor air aldehyde/ketone samples collected with DNPH sampling tubes, the liquid autosampler, and detection requirements.
09 Analysis workflow
10 Qualitative, Quantitative, and Quality Control
Use aldehyde/ketone-DNPH derivative standard solutions to establish external standard calibration. Sampling blanks, shipping blanks, method blanks, calibration checks, and parallel sampling are used to evaluate the entire sampling and analysis process.
A DAD configuration can assist in comparing the consistency of target peak spectra with standard derivatives; routine quantification is still based on confirmed retention times and calibration relationships.
11 Method and Configuration Selection
- The monitoring targets are airborne aldehydes and ketones, and the sampling end centers on DNPH capture and derivatization.
- Routine quantification can use UV; configure DAD when spectral-assisted identification is needed.
- The liquid chromatography flow path consists of a pump, an autosampler, a chromatographic column, and a matching detector.
12 Frequently Asked Questions
Why is DNPH used for sampling aldehydes and ketones in air?
DNPH reacts with aldehyde and ketone carbonyl compounds to form relatively stable hydrazone derivatives with UV absorption, facilitating collection, transport, and HPLC detection.
Why is HPLC used to analyze aldehyde and ketone DNPH derivatives?
The derivatives are suitable for separation under liquid chromatography conditions, and their absorption signals can be recorded by UV or DAD.
How should one choose between UV and DAD?
UV can be used for routine quantification at a fixed wavelength; DAD can be selected when spectra need to be recorded and to assist peak identification.
How should samples be processed after collection?
Store the sampling tube sealed and protected from light; elute, make up to volume, and filter according to the application method, then perform automated liquid chromatography injection.
Why are sampling blanks set up?
Sampling blanks are used to identify background aldehyde and ketone contamination introduced by the DNPH medium, transport, and processing.
What information affects system configuration?
The target aldehyde and ketone list, air type, sampling batch size, expected concentrations, sampling device, and the laboratory's existing liquid chromatography configuration all affect the selection.
How is quantification performed?
External standard calibration is performed with DNPH derivative standard solutions, and batch quality is monitored through calibration checks and duplicate samples.
13 Related Solutions and Knowledge
14 References
Get Configuration and Technical Consultation
Please provide sample information for ambient air or indoor air aldehyde and ketone samples collected with DNPH sampling tubes, as well as the concentration ranges of DNPH derivatives of aldehyde and ketone compounds such as formaldehyde, acetaldehyde, acetone, and acrolein, the testing batch size, the method basis, and existing equipment. Based on this, Huishi Instruments will prepare a configuration list.
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