PDF《采用微波消解火焰原子吸收》

Nick Spivey PerkinElmer, Inc.

Shelton, CT 前言 整个世界都会享受一天的开 始, 在强化谷物中加入牛奶盒 水果能简单快速地解决一个 营养的早餐. 强化早餐麦片也是儿童摄取营 采用微波消解火焰原子吸收 光谱法及FAST火焰自动 进样器测定强化早餐谷物 中的微量营养元素 养的一个重要来源, 而消费者也期待各种谷物质量的提高, 并且能持续从市场上 选择到强化商品. 对于这些营养强化早餐谷物的高效生产 , 需要生产厂家认真进行配方, 而且保证 批与批之间必须保持一致. 如今正在盛行的对谷物和营养添加剂中微量营养元素 的测定, 可以使食品生产商对谷物产品质量进行量化并确保产品一致性. 具备快 速, 准确, 简便地分析他们样品的能力对于及时出报告起着至关重要的作用, 同时 能保证实时对样品进行批量调整并对生产过程进行连续控制. 食品生产商还必须 满足营养标签准则, 其中规定其能准确评估微量营养元素. 应用文章作者: Atomic Absorption

2 While inductively coupled plasma optical emission spectroscopy (ICP-OES) is generally favored in a multi-element analytical environment, the cost savings, simplicity, and speed of operation of a flame atomic absorption (AA) system provides an attractive alternative. Measuring multiple elements by flame AA requires each sample to be analyzed individually for each element, which impacts the speed advantage of flame AA. To address the speed issue, a fast high-throughput sample automation system can be used. Although samples still need to be analyzed multiple times, the analysis time per sample is significantly reduced, thus increasing sample throughput compared to manual sample introduction. In addition, an automated sample introduction system increases the precision of the analysis and frees the chemist to perform other tasks. In this work, we demonstrate the ability of PerkinElmer'

s PinAAcle?

900 atomic absorption spectrometer (operating in flame mode) coupled to a FAST Flame sample automation accessory to analyze common nutritional elements in a variety of fortified cereals. Experimental All analyses were performed on a PinAAcle 900T atomic absorption spectrometer operating in flame mode using a FAST Flame

2 sample automation accessory. The elements of interest and instrument conditions for the analysis of the cereal samples are outlined in Table 1. A high-sensitivity nebulizer was used with the standard spray chamber and a

10 cm burner head. External calibrations were performed using a single intermediate standard made in 2% HNO3 /deionized water which was then diluted in-line using the capabilities of the FAST Flame

2 accessory. The FAST Flame

2 accessory is a combination of high-speed autosampler, peristaltic pump, and switching valve which provides quick sample turnaround with fast rinse-out, short signal stabilization times, and no sample-to-sample memory effect. The FAST Flame

2 accessory rapidly fills a sample loop via vacuum and then switches to inject while the autosampler moves to the next sample. This removes the time delay associated with self-aspiration or peristaltic pumping and eliminates the long rinse-in and rinse-out times as a result of autosampler movement and flushing, resulting in complete sample-to-sample analytical times as short as

15 seconds. The ability of the FAST Flame

2 accessory to mechanically pump the sample during injection allows for ideal optimization of nebulizer and flame conditions, eliminates variability due to changes in sample viscosity, dissolved solids, and tubing length, and also provides long-term sample flow stability. The in-line dilution capability allows the analyst to create a single intermediate standard and then let the FAST Flame