Analytical Chemistry Team, Health and Safety Executive, Harpur Hill, Buxton, UK.
Ann Work Expo Health. 2019 Apr 19;63(4):407-414. doi: 10.1093/annweh/wxz014.
Diacetyl is a potentially harmful chemical that is used as an artificial flavouring in the food industry and may also be generated during processing of some natural products including coffee. In Europe, an 8-h time weighted average occupational exposure limit (TWA-OEL) of 20 ppb has been adopted for diacetyl, together with a short-term exposure limit (STEL) of 100 ppb. A sensitive new measurement method for diacetyl, and the related compound 2,3-pentanedione has been developed and evaluated. The new method uses Tenax TA sorbent tubes as the sampling media with analysis by thermal desorption (TD) and gas chromatography-mass spectrometry (GC-MS). The sample tubes are suitable for both active (pumped) and passive (diffusive) sampling. Diacetyl is stable on the sample tubes for at least 3 months but 2,3-pentanedione requires analysis within a month. Sample recovery is unaffected by changes in relative humidity and the presence of acetic acid. For short-term sampling, active sampling is recommended. The safe sampling volume for diacetyl is 3 litres which, at a flow rate of 100 ml min-1, equates to a maximum recommended sampling time of 30 min. For long-term samples, in particular collection of personal samples, passive sampling is recommended. Diffusive uptake rates have been determined for both diacetyl and 2,3-pentanedione on Tenax TA tubes fitted with standard diffusion heads over sampling periods of 1 to 8 h. Analytical limits of detection are approximately 0.2 ng for diacetyl and 0.1 ng for 2,3-pentanedione. These values equate to airborne concentrations of around 0.04 ppb of diacetyl and 0.02 ppb of 2,3-pentanedione for a 1.5-litre active sample and 0.3 ppb of diacetyl and 0.1 ppb of 2,3-pentanedione for an 8-h passive sample. In the case of passive sampling, this limit of detection is less than 1/50th of the new European TWA-OEL for diacetyl of 20 ppb. The method can also be used to identify the presence of other volatile organic compounds at sub-ppm concentrations.
乙酰基是一种潜在的有害化学物质，用作食品工业中的人工香料，也可能在包括咖啡在内的某些天然产品的加工过程中产生。在欧洲，已采用 8 小时时间加权平均职业接触限值（TWA-OEL）为 20 ppb 的乙酰基，以及 100 ppb 的短期暴露限值（STEL）。已经开发并评估了一种用于乙酰基和相关化合物 2,3-戊二酮的灵敏新测量方法。该新方法使用 Tenax TA 吸附管作为采样介质，通过热解吸（TD）和气相色谱-质谱法（GC-MS）进行分析。采样管适用于主动（泵吸）和被动（扩散）采样。乙酰基在采样管中至少稳定 3 个月，但 2,3-戊二酮需要在一个月内分析。相对湿度的变化和醋酸的存在不会影响样品的回收。对于短期采样，建议使用主动采样。安全的乙酰基采样体积为 3 升，以 100 ml min-1 的流速计，最大推荐采样时间为 30 分钟。对于长期样品，特别是个人样品的采集，建议使用被动采样。已经确定了乙酰基和 2,3-戊二酮在装有标准扩散头的 Tenax TA 管上的扩散速率，采样时间为 1 至 8 小时。乙酰基和 2,3-戊二酮的检测限约为 0.2 ng 和 0.1 ng。这些值相当于 1.5 升主动采样空气中乙酰基的浓度约为 0.04 ppb，2,3-戊二酮的浓度约为 0.02 ppb，而 8 小时被动采样空气中乙酰基的浓度约为 0.3 ppb，2,3-戊二酮的浓度约为 0.1 ppb。在被动采样的情况下，检测限低于欧洲新的 20 ppb 乙酰基 TWA-OEL 的 1/50。该方法还可用于鉴定亚 ppm 浓度下其他挥发性有机化合物的存在。
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