Development, evaluation and comparison of two independent sampling and analytical methods for ortho-phthalaldehyde vapors and condensation aerosols in air

Abstract

Two independent sampling and analytical methods for ortho-phthalaldehyde (OPA) in air have been developed, evaluated and compared (1) a reagent-coated solid sorbent HPLC-UV method and (2) an impinger-fluorescence method. In the first method, air sampling is conducted at 1.0 L min−1 with a sampler containing 350 mg of silica gel coated with 1 mg of acidified 2,4-dinitrophenylhydrazine (DNPH). After sampling, excess DNPH in ethyl acetate is added to the sampler prior to storage for 68 hours. The OPA-DNPH derivative is eluted with 4.0 mL of dimethyl sulfoxide (DMSO) for measurement by HPLC with a UV detector set at 3S5 nm. The estimated detection limit is 0.016 µg per sample or 0.067 µg m−3 (0.012 ppb) for a 240 L air sample. Recoveries of vapor spikes at levels of 1.2 to 6.2 µg were 96 to 101%. Recoveries of spikes as mixtures of vapor and condensation aerosols were 97 to 100%. In the second method, air sampling is conducted at 1.0 L mm−1 with a midget impinger containing 10 mL of DMSO solution containing N-acetyl-l-cysteine and ethylenediamine. The fluorescence reading is taken 80 min after the completion of air sampling. Since the time of taking the fluorescence reading is critical, the reading is taken with a portable fluorometer. The estimated detection limit is 0.024 µg per sample or 0.1 µg m−3 (0.018 ppb) for a 240 L air sample. Recoveries of OPA vapor spikes at levels of 1.4 to 5.0 µg per sample were 97 to 105%. Recoveries of spikes as mixtures of vapors and condensation aerosols were 95 to 99%. The collection efficiency for a mixture of vapor and condensation aerosol was 99.4%. The two methods were compared side-by-side in a generation system constructed for producing controlled atmospheres of OPA vapor in air. Average air concentrations of OPA vapor found by both methods agreed within ±10%.

Development of a measurement method to determine the ceiling exposure concentration of ortho-phthalaldehyde handling workers

“…The LOD and LOQ were 0.010 and 0.033 ng/mL (corresponding to 0.050 and 0.165 ng/sample), respectively. These values are much smaller than those of the previous methods, for which LODs of 0.02 and 0.016 µg/sample, have been reported.…”

“…Using our procedure, the reaction yield from OPA to OPA bis‐DNPH in the extraction solution was 91%‐104% at OPA concentrations of 2.55‐509 ng/mL. Tucker reported that with the addition of excess DNPH to the DNPH‐silica cartridge, 100% recovery of OPA was realized after a storage period of 68 hours. This result suggests that the acid (DNPH) in the DNPH‐silica cartridge affects the recovery of OPA, but that the amount of excess DNPH was not sufficient to form OPA bis‐DNPH.…”

A New Working Fluid for Condensation Particle Counters for Use in Sensitive Working Environments

“…Bacteria can convert DMSO into dimethyl sulphide. Therefore, it should be avoided to be disposed into the sewer (Tucker, 2014). Another precaution that should be mentioned here is that DMSO should not be heated to temperatures of over 150°C, since at that threshold it will lose its thermal stability.…”

Extracting the Critical Points of Formaldehyde (HCHO) Emission Model in Hot Desert Climate

“…HCHO was collected using an LpDNPH S10L cartridge (Supelco Inc., U.S) to contain carbonyl compounds (Williams et al, 2019). To remove the interference caused by Ozone (O 3 ), the O 3 scrubber was connected in front of the LpDNPH S10L cartridge, and the sample was collected by clicking it on a flow sampling pump (Tucker, 2014). At this time, 7.0 l of collected air in the chamber was collected at 167 ml/min, and the collected samples were stored in a cool and dark place until extraction (Even et al, 2021).…”