A comparative analysis of derivatization strategies for the determination of biogenic amines in sausage and cheese by HPLC.

The six biogenic amines in sausage and cheese were analyzed by HPLC with UV detection after off-line derivatization with dansyl chloride, 9-fluorenylmethoxycarbonyl chloride, benzoyl chloride and dabsyl chloride, respectively. The results showed that both the off-line 9-fluorenylmethoxycarbonyl and dabsyl derivatization were not suitable for HPLC analysis of biogenic amines when batch injection was used because the derivatives were instable, whereas both the off-line dansyl and benzoyl derivatization were suitable for HPLC analysis of biogenic amines when batch injection was used, but the latter needed to maintain the derivatives at 4 °C to ensure that benzoylated tyramine was not degraded when waiting for the analysis. The off-line dansyl derivatization had an obvious advantage in the analysis of biogenic amines in sausage and cheese samples by HPLC combined with batch injection because the method has a wider linear range and higher sensitivity, accuracy, precision and stability of the derivatives.

[Quantity and distribution of CD44+/CD24- cells in breast cancer tissue and the cell lines].

Objective: To study the distribution and quantity of CD44+/CD24- cells in breast cancer tissue and the cell lines, and as well as its correlation with the expression of various breast cancer markers and molecular subtyping of breast carcinoma.

Methods: The expression of CD44/CD24, estrogen receptor, progesterone receptor, HER2, human estrogen-induced protein PS2, bcl-2 and nm23 in 60 cases of invasive ductal carcinoma of breast were studied by either single or double immunohistochemical staining. The co-expression of CD44 and CD24 in 3 breast cancer cell lines (MCF-7, MDA-MB-468, and MDA-MB-231) was also examined.