High‐performance liquid‐chromatographic determination of fgrivialdehyde in air in the ppb to ppm range using diffusive sampling and hydrazone formation

A diffusive sampler has been developed and validated for determination of formaldehyde with a sensitivity of 5 ppb in an 8‐h sample. The sampler consists of a 20×45 mm filter impregnated with 2,4‐dinitrophenyl‐hydrazine and phosphoric acid and mounted in a polypropylene housing. The uptake rate was determined to be 25.2 ml‐min‐1, with a relative standard deviation of 6.7%. The uptake rate was independent of formaldehyde concentration (0.07–3.7 mg‐m‐3), sampling time (15–480 min), relative humidity (10–80%). The effect of wind velocity (0.05–1.0 m.s‐1) was also studied. The sampler was also validated in the field.