LpDNPH Air Monitoring Cartridges

Reporter EU Volume 20

Introduction

The LpDNPH cartridge is an air sampling device designed for sampling carbonyls (e.g. formaldehyde) in ambient, indoor and industrial atmospheres. Carbonyls are trapped on a high purity silica adsorbent coated with 2,4-dinitrophenylhydrazine (2,4-DNPH), where they are converted to the hydrazone derivatives. The derivatives are eluted from the cartridge in acetonitrile and analyzed by HPLC.

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S10 Cartridge (Figure 1)

The unique solid phase extraction configuration makes the cartridge easy to use in the field as well as in the laboratory. Reusable adapters are available to connect the cartridge to the sampling pump. The built-in reservoir eliminates the need for attachment of a syringe for sample extraction/elution. It is recommended that sampling flow be in the opposite direction of elution flow.

Figure 1. LpDNPH S10 Cartridge


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S10x Cartridge (Figure 2)

The LpDNPH S10x cartridge has a shorter tube length than the S10 cartridge, to fit automated samplers such as those manufactured by XonTech Inc. and ATEC Atmospheric Technology. Using a S10x cartridge, the air sampling flow will be in the direction opposite that for the S10 cartridge to accommodate the instrument’s flow pattern.

Figure 2. LpDNPH S10x Cartridge


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S10L Cartridge (Figure 3)

The LpDNPH S10L cartridge is configured for users who prefer the shorter dimensions without the need for an adapter for sampling. The cartridge is reversible and requires a syringe barrel for elution.

Figure 3. LpDNPH S10L Cartridge


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RezorianTM Cartridge (Figure 4)

Rezorian cartridges are polypropylene cartridges with luer lock syringe connections. These cartridges have polypropylene components and polyethylene frits making them solventcompatible. Rezorian cartridges can be used inline with peristaltic pumps and low pressure HPLC systems, or with a syringe and a single sample processor. Rezorian cartridges can be used individually or connected in series.

Figure 4. Rezorian Cartridge


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LpDNPH cartridges feature:

  • Low pressure drop, to enable use at high sampling rates (1.5-2 L/min.), even with personal sampling pumps
  • High purity adsorbent, for better accuracy in trace analysis
  • Bar code labels, for fast and accurate sample identification
  • Individual packaging, to maximize sample integrity

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Method Applications:

US EPA TO11A — Method for the Determination of Formaldehyde in Ambient Air Using Adsorbent Cartridge Followed by High Performance Liquid Chromatography (HPLC)

US EPA IP-6A — Determination of Formaldehyde and Other Aldehydes in Indoor Air Using a Solid Adsorbent Cartridge

US EPA 600-R-98/161 (1998) –– Technical Assistance Document for Sampling and Analysis of Ozone Precursors

US EPA 0100 — Sampling for Formaldehyde and Other Carbonyl Compounds in Indoor Air

NIOSH 2016 — Formaldehyde

ASTM D5197 — Standard Test Method for Determination of Formaldehyde and Other Carbonyl Compounds in Air

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Sample Collection (refer to specific methodology for greater detail)

As with any high purity-sampling device, care in handling the LpDNPH cartridges has to be exercised to minimize unintentional exposure. Ozone is a known negative interference when sampling for carbonyls. If you suspect the presence of ozone, use an ozone denuder or scrubber as described in the methodology. The cartridges can be connected to the sampling pump using appropriate adapters, if necessary. The air sample is collected in the direction recommended for each cartridge configuration (see Figures 1-4), at flow rates up to 2 L/min. To avoid a sample breakthrough, the total amount of carbonyls collected should not exceed 75 μg. After sampling, both ends immediately need to be capped and the cartridges should be placed individually in the white foil bags provided. The bar code labels can be used to uniquely track each sample by placing one label on the bag and its duplicate. These then can be recorded in a sample log with sample identification. The sample loaded tubes should be stored at 4 °C and protected from light. One field blank and one lab blank should be included from the same lot with each batch of 10 samples.

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Sample Desorption

Analyse the sample within 30 days of sampling. Using gravity feed, elute the cartridge with 2 mL aliquots of acetonitrile and collect the eluate to the 3.0 mL mark on a volumetric flask. An elution rack (Fig. 5) or a vacuum manifold can be used to expedite multiple sample desorption. Ideally, desorption is in the direction opposite that of the air flow during sample collection, although this is not critical. Use only high purity acetonitrile that has been tested for carbonyl contaminants. Store the extract at 4 °C until analysis.

Figure 5. Universal Elution Rack


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HPLC Analysis

Analyse the extract by reversed phase HPLC, using a Discovery® HS C18 column with UV detection, as stated in methodology.

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