HPLC Analysis of Aldehydes and Ketones in Air Samples

1. Introduction

Aldehydes and ketones from industrial and automotive emission can pollute the environment.  Also, as a lot of these compounds are carcinogens, several US EPA and state methods have been developed for their analysis in air and drinking water.  This application note describes a HPLC method to analyze 15 commonly analyzed aldehydes and ketones in environmental air and auto exhaust.  Prior to analysis, aldehydes and ketones are converted to hydrazone derivatives when the air sample passes through a solid phase extraction (SPE) cartridge composed of silica gel coated with 2,4-dinitrophenylhydrazine (DNPH).  Then, the aldehyde/ketone DNPH derivatives are eluted from the SPE cartridge and analyzed by HPLC separation using a Uitisil® XB-C18 column and UV detection at 360 nm.  

2. Sample Preparation

2.1. Equipment and standards

2.1.1. Reference standard：15 aldehydes and ketones DNPH Derivatives mixture 

2.1.2. Air sampling equipment：adjustable flow rate 200-1000mL/min

2.1.3. Welchrom® DNPH SPE cartridge：350mg/3mL

2.1.4. Welchrom 12-port Vacuum SPE manifold

2.2. Sample collection

Attach the DNPH SPE cartridge to the air sampling equipment and collect air sample at 500ml/min for 30mins. 

2.3. Sample extraction:  wash the sample loaded DNPH SPE column with acetonitrile and collect the elution as working sample.  One can also use the Welchrom 12-port Vacuum SPE manifold to increase the sample throughput.  Working samples are refrigerated at 4 °C for at least 6 hours before HPLC analysis.  

Figure 1 Air sample collection equipment 

Figure 2 Welchrom DNPH SPE cartridge 

3. HPLC method 

• Column: Welch Uitisil® XB-C18 4.6×250mm,5μm
• Gradient: Isocratic ACN: H2O 65:35
• Flow rate：1.0mL/min
• Temperature：30℃
• Injection volume：20μL
• Detector wavelength：360 nm

4. Results and Discussion 

Chromatogram and peak information of the calibration standard mixture of 15 commonly analyzed aldehydes and ketones as DNPH derivatives are shown in Figure 3 and Table 1. The Uitisil® XB-C18 column has a good selectivity for these compounds.  The 15 compounds are well separated in this isocratic condition. There is some overlap between Butanal and Benzaldehyde, p-Methylbenzaldehyde and Hexanal.  This can be resolved by changing the isocratic condition to a gradient. 

Figure 3 HPLC Chromatogram of 15 aldehydes and ketones as 5ppm DNPH derivates

Table 1 Components and peaks information 

This method was applied for the analysis of an indoor air sample and an auto exhaust sample. The chromatogram and test results are shown in Figure 4 and Table 2. 

Figure 4 Chromatograms of (A) an indoor air sample and (B) an auto exhaust sample

Table 2 Test Results for indoor air and auto exhaust samples 

5. Conclusions：

Aldehydes and ketones can be analyzed as DNPH derivatives rapidly and efficiency using welch Uitisil® XB-C18 HPLC column.  Welcome to contact us at sales@auroraprosci.com. 

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