Assessment of a new lateral flow immunochromatographic (LFIC) assay for the okadaic acid group of toxins using naturally contaminated bivalve shellfish from the Portuguese coast.

A new rapid assay for the okadaic acid group of toxins, based on lateral flow immunochromatographic (LFIC) test strips developed by Jellett Rapid Testing Ltd., was assessed on naturally contaminated bivalves from the Portuguese coast. One prototype was evaluated using samples harvested during 2005, extracted with 80% methanol, followed by dilution with the running buffer of a methanolic extract after alkaline hydrolysis for esters. The second prototype was assessed using samples harvested during 2006, extracted with 100% methanol and, after alkaline hydrolysis, the methanol was evaporated by a nitrogen stream followed by re-suspension with the running buffer. The first prototype failed to detect 20% of samples that were positive by LC-MS in the range 160-480 microg kg(-1), and were classified as negative or trace level by LFIC. The presence of methanol in the extracts made correct detection of toxins more difficult. The second prototype classified as positive all samples above 160 microg kg(-1), as confirmed by LC-MS. However, in the second prototype, matrix effects were a major drawback and led to 45% false positives, particularly for mussels, due to compounds in shellfish extracts interfering with the antibodies and reducing the test line intensity. Extraction with a higher percentage of methanol was thought responsible for these matrix effects. Regarding sample migration, both prototypes needed one hour before reading. In an attempt to speed-up sample preparation, a direct digestion of bivalve tissues with sodium hydroxide was evaluated. Low recoveries for esters were found by LC-MS with this hydrolysis technique compared to conventional hydrolysis of methanolic extracts. While prototype A was not sensitive enough, prototype B had too many false positives to be of use to the shellfish industry or in a monitoring program.

Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS.

Procedures for the quantification of total chromium and hexavalent chromium in UHT milk samples are presented. Total chromium was determined directly in milk with the addition of a surfactant and a mixture of Pd and Mg as a chemical modifier. For the selective separation of hexavalent chromium, the sample pre-treatment consisted in precipitation of proteins and elution of the supernatant through a Chromabond NH2 column. The metal was eluted with nitric acid. Both total chromium and hexavalent chromium were evaluated by atomic absorption spectrometry with electrothermal atomization using the same instrumental conditions. The detection limits were 0.2 and 0.15 microgram l-1 for total chromium and hexavalent chromium, respectively. The linearity ranges under the optimized conditions were 0.2-20 and 0.15-50 micrograms l-1. For total chromium the precision was 4.9 and 5.7% for the analytical and the over-all procedure, respectively, and for hexavalent chromium 4.3 and 4.9%, respectively. The validation of both procedures was performed by the standard additions method and the recoveries were higher than 93% in all cases. For total chromium, a certified reference material was also used to validate the methodology. The methods were applied to the determination of total chromium and hexavalent chromium in 60 UHT milk samples.

Lorazepam in the treatment of neurosis.

An open study was carried out in 40 ambulatory neurotic patients with classical symptoms of anxiety to assess which of their symptoms responded most readily and favourably to treatment with lorazepam. Doses ranged from 2 mg to 15 mg daily and were adjusted to individual patient needs. The study period lasted 4 weeks and patients' individual symptoms were assessed weekly on a 4-point severity rating scale. The results showed a statistically significant and marked improvement during the first week for the majority of the 16 symptoms assessed, particularly emotional tension, irritability and apprehension. Symptoms with a cognitive element of anxiety were controlled to a lesser extent and were slower to respond. The few side-effects which were reported, mainly somnolence, appeared to be dose related and usually occurred during the first few days of treatment.