Interference with serum indices measurement, but not chemical analysis, on the Roche Modular by Patent Blue V.

BACKGROUND: Patent Blue V is an inert dye increasingly being used during cancer surgery to identify the sentinel lymph node. We recently discovered three cases with falsely elevated lipaemic indices on the Roche Modular, following intramammary injection of Patent Blue. This, and other potential interferences by Patent Blue, is examined in this study. METHODS: Serum samples which visually appeared normal, haemolysed or icteric were spiked with Patent Blue to a concentration of 7.3 mg/L and the effect on the lipaemic, haemolysis and icteric indices and routine chemical analyses (sodium, potassium, urea, creatinine, bilirubin, alanine aminotransferase, gamma-glutamyltransferase, aspartate aminotransferase, magnesium, creatine kinase, lactate dehydrogenase, amylase, albumin, calcium and phosphate) undertaken. Dose-response curves in the range of 4.9 mg/L to 22.7 mg/L of Patent Blue were established for normal, icteric and haemolysed pooled serum samples. RESULTS: Significant positive interference by 7.3 mg/L of Patent Blue was observed in the lipaemic index, with an increase of 149 +/- 6.3 (mean +/- standard deviation [SD]; P < 0.001). Significant negative interference was observed in both the haemolysis and icteric indices, with decreases of 71 +/- 9.7 (P < 0.001) and 46 +/- 8.9 (P < 0.001), respectively. Patent Blue had a linear dose-response effect on the serum indices. No significant differences were observed in the chemical analyses assessed. CONCLUSIONS: The effects observed on the Roche Modular serum index measurements with Patent Blue raises the novel concept of interference in methods routinely used to detect interference. Despite Patent Blue having no direct effect on chemical analysis, failure to reliably detect potential interference, particularly haemolysis, may lead to misleading results being issued.

Analysis of malachite green and metabolites in fish using liquid chromatography atmospheric pressure chemical ionization mass spectrometry.

Malachite green (MG), a traditional agent used in aquaculture, is structurally related to other carcinogenic triphenylmethane dyes. Although MG is not approved for use in aquaculture, its low cost and high efficacy make illicit use likely. We developed sensitive and specific methods for determination of MG and its principal metabolite, leucoMG (LMG), in edible fish tissues using isotope dilution liquid chromatography atmosphere pressure chemical ionization mass spectrometry. MG and LMG concentrations were measured in filets from catfish treated with MG under putative use conditions (ca. 250 and 1000 ppb, respectively) and from commercial trout samples (0-3 and 0-96 ppb, respectively). Concentrations of LMG in edible fish tissues always exceeded those of MG. A rapid cone voltage switching acquisition procedure was used to simultaneously produce molecular ions for quantification and diagnostic fragment ions for confirmation of MG and metabolites. The accurate and precise agreement between diagnostic ion intensity ratios produced by LMG in authentic standards and incurred fish samples was used to unambiguously confirm the presence of LMG in edible fish tissue. This suggested the validity of using LMG as a marker residue for regulatory determination of MG misuse. Additional metabolites derived from oxidative metabolism of MG or LMG (demethylation and N-oxygenation) were identified in catfish and trout filets, including a primary arylamine which is structurally related to known carcinogens. The ability to simultaneously quantify residues of MG and LMG, and to confirm the chemical structure of a marker residue by using LC/MS, suggests that this procedure may be useful in monitoring the food supply for the unauthorized use of MG in aquaculture.

Metabolism of triphenylmethane colours II. Absorption, excretion and distribution of Benzyl Violet 4B (FD and C Violet No. 1) in rats.

Absorption, excretion and distribution of Benzyl Violet 4B were investigated in rats, deterimining the colour by the 2-wavelength technique. This colour was hardly absorbed when given orally; only 0.89% of the dose was recovered from the bile after 24 h. On the other hand, it was rapidly excreted through the bile when given intravenously; the cumulative recovery of biliary excretion amounted to 88.4% at 4 h and 95.9% at 24 h. The levels of the colour distributed in the liver, kidney abdominal muscle and blood serum were in the range of 1--3 microgram/g of tissue in rats fed a diet containing 5% Benzyl Violet 4B for 8 weeks, whereas they were slightly lower in rats fed the diet for 18 weeks. When rats were given the colour intravenously, there was no sex-related difference in the distribution of the colour in either Wistar or Sprague--Dawley rats, but the disappearance of the colour from the brain, liver, abdominal muscle, abdominal skin and ear of Sprague--Dawley rats was slower than from those of Wistar rats.