Uncertaintiy Assessment of Sample Processing, Extraction, Cleanup and Chromatographic Procedures in Pesticide Residue Analysis

Yıl 2010, Cilt: 24 Sayı: 1, 55 - 69, 01.04.2010

Osman Tiryaki

Öz

The estimation of the uncertainty associated to analytical methods is necessary in order to obtain reliable results. Estimation of each uncertainty sources allows to laboratories to establish the accuracy of results. The main uncertainty sources of the most analytical methods are sample processing, extraction and cleanup. Estimation of sample processing also shows that analytical portion represents the whole laboratory sample. The uncertainty of sample processing (CVsp) and the amount of the analytical portion (m) can be calculated by the sampling constant equation (Ks=m x CVsp 2). The “bottom up” and “top-down” strategies is applied for the assessment of uncertainty components of other analytical steps, such as extraction, cleanup. If the analytical method is new, the estimation of contribution of components is imortant, “bottom up” is applied. But if the most important uncertainty sources of method is known, “top-down” strategies is more practical. Actually there is no significant differences between combined standard uncertainty (uc) values calculated with both strategies. In this article, with the basis of update references and our previous study, estimation of uncertainy prosedures are explained. 

Anahtar Kelimeler

Sampling constant, uncertainty of extraction and cleanup, combined uncertainty

Pestisit Kalıntı Analizlerinde Örnek İşleme, Ekstraksiyon, Cleanup ve Kromatografik İşlemlerin Ölçüm Belirsizliği Değerlendirmeleri

Öz

Analiz metodunun ölçüm belirsizlikleri, güvenilebilir sonuçlar elde etmek için gereklidir. Her bir belirsizlik kaynağının saptanması o laboratuvarın sonuçlarının doğruluğunu gösterir. Çoğu analiz metodunun en önemli belirsizlik kaynakları örnek işleme, ekstraksiyon ve cleanup (temizleme, arıtma) işlemidir. Örnek işleme belirsizliğinin hesaplaması, analize alınan porsiyonun tüm laboratuvar örneğini temsil edilebilirliğini de gösterir. Örnekleme sabitesi eşitliğinden (Ks=m x CVsp2), belirsizlik (CVsp) ve porsiyon miktarı (m) bulunabilir. Belirsizlik bileşeni olan diğer analiz basamakların belirsizliklerinde “bireyselden tüme” ve “tümsel” yaklaşımları uygulanır. Yeni bir metot ise belirsizliğe katkısı olan bileşenler saptandığından, birinci yaklaşım, metodun önemli belirsizlik kaynakları biliniyorsa ikinci yaklaşım uygundur. Her iki yaklaşımda birleştirilmiş standart belirsizlikler (uc) arasında önemli bir fark yoktur. Bu makalede, güncel literatürler ve önceki çalışmalarımızın ışığı doğrultusunda, her iki yaklaşım ile belirsizlik saptama prosedürleri açıklanmıştır.

Anahtar Kelimeler

Örnekleme sabitesi, ekstraksiyon ve cleanup (temizleme-arıtma) belirsizliği, birleştirilmiş belirsizlik

Kaynakça

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