Csako G
Clin Chem. 1987 Feb;33(2 Pt 1):289-92.
All free-sulfhydryl compounds tested produced false-positive reactions in the Legal test for ketones. The color developed in the ketone pad of urine dipsticks [N-Multistix SG, Multistix 10 SG (Ames), and Chemstrip 9 (Boehringer-Mannheim)] was misinterpreted for ketone bodies, both by visual and automated reading. In contrast to the reaction with true ketones, a drop of glacial acetic acid added onto the ketone pad of dipsticks discharged the false-positive red color. A red-violet also developed instantly with free -SH compounds in the Acetest tablet assay (Ames), but quickly faded. In general, the presence of acidic groups such as -COOH and -SO3H in the structure appeared to increase the nitroprusside reactivity of free -SH compounds, whereas the presence of a -NH2 group appeared to decrease it. Currently, false-positive ketone reactions ascribable to a free -SH group are most likely to be seen for urine containing mesna. The false-positive test for ketones caused by free -SH compounds can be recognized and ruled out by proper procedures. On the other hand, this chromogenic reaction with free thiols might be used for monitoring urinary excretion of mesna.
所有经测试的游离巯基化合物在检测酮体的利伯试验（Legal test）中均产生假阳性反应。尿液试纸[如N - Multistix SG、Multistix 10 SG（Ames公司）和Chemstrip 9（勃林格殷格翰公司）]酮体检测区所呈现的颜色，无论是通过目视还是自动读数，都被误判为酮体。与真正的酮体反应不同，在试纸的酮体检测区滴加一滴冰醋酸可使假阳性的红色褪去。在Acetest片剂检测法（Ames公司）中，游离巯基化合物也会立即产生红紫色，但很快会褪色。一般来说，结构中存在-COOH和-SO₃H等酸性基团似乎会增强游离巯基化合物与硝普盐的反应活性，而-NH₂基团的存在则似乎会降低这种反应活性。目前，在含有美司钠的尿液中最有可能出现归因于游离巯基的假阳性酮体反应。游离巯基化合物导致的酮体假阳性检测结果可通过适当的程序识别并排除。另一方面，这种与游离硫醇的显色反应可用于监测美司钠的尿排泄情况。
