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Care and use manual, B. preventing contamination – Waters Sep-Pak XPoSure Aldehyde Sampler User Manual

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[ CARE AND USE MANUAL ]

a. Sep-Pak XPoSure Aldehyde Sampler Description

and Features

Sep-Pak XPoSure Aldehyde Samplers contain acidified
2,4-Dinitrophenylhydrazine(DNPH)-coated silica, packed
in Waters Sep-Pak Plus cartridges.

The samplers are constructed from high-purity and high-
density polyethylene components, triaxially-compressed
packed beds and Luer fittings equipped with end caps and
plugs.

The samplers are designed for flow rates of up to 1.5 L/min
with typical personal pumps.

The gold-colored aluminum compression ring on the
Sep-Pak XPoSure Aldehyde Sampler allows for easy
identification.

Figure 1. Cutaway View.

Table 1: Physical and Chemical Properties

Hold-up Volume

0.7 mL

Collection Efficiency

>95% for sampling rates up to 1.5 L/min

Capacity

a

Approximately 70 µg formaldehyde

Quantity of DNPH Silica

0.35 g/sampler (~1 mg DNPH)

Sampling Temperature

b

10 °C to 100 °C

Dimensions

4.3 cm total length

2.0 cm o.d. at widest point

1.0 cm i.d.

0.9 cm bed length

a.

Based on 50% consumption of DNPH.

b

Evaluate sampler performance for individual high-temperature method.

II. USING T HE SEP-PAK X POSURE

ALDEHYDE SAMPLER

a. Theory of Operation

Sep-Pak XPoSure Aldehyde Samplers trap aldehydes in air by
reacting them with acidified 2,4-dinitrophenylhydrazine(DNPH),
forming stable hydrazone derivatives. The derivitization reaction,
as shown in Figure 2, takes place during sample collection. The
derivatives are later eluted and analyzed using HPLC.


Figure 2. Derivitization Reaction.

b. Preventing Contamination

Contamination is most likely to occur during sample collection.
Before eluting the derivatives, clean all glassware by rinsing with
acetonitrile and heating to 60 °C in a vacuum oven for at least
30 minutes. Eluting the samples in a nitrogen-purged glove box
further reduces the risk of contamination.

The acetonitrile you use to elute the DNPH derivatives can also be
a source of contamination. Even HPLC-grade acetonitrile may have
unacceptable levels of carbonyl contaminants and should be stored
in a carbonyl-free environment. A concentration of 10 µg/L of
any aldehyde or ketone contaminant will add 0.1 µg to the blank
values determined for the DNPH-derivatives per cartridge. Follow
the procedure in Appendix A, Measuring Acetonitrile Purity, to
pre-qualify your acetonitrile.

Polyethylene Filter

DNPH-Silica

Polyethylene Filter

Luer Connector

Aluminum

Compression Ring

Luer Connector

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[ CARE AND USE MANUAL ]

Sep-Pak XPoSure Aldehyde Sampler