Nitrate consumption and the incidence of gastric cancer in Singapore.

The nitrate content of a wide variety of vegetables, fruits and meat purchased in Singapore were determined by high-pressure liquid chromatography. From the 1982 statistical figures of retained imports and local production of these items the average per capita daily consumption of nitrates was calculated and found to be 215 mg, one of the highest reported figures in the world. Two vegetables are not so popular with the Malays and Indians who comprise 21% of the population. If their consumption of these vegetables is ignored then the per capita daily nitrate consumption of the Chinese population amounts to 250 mg and those of the Malays and Indians to 113 mg. Although these may be overestimates they do appear to show an association with the male gastric cancer incidence rates (age-adjusted) of 44.8 for the Chinese, 10.3 for Malays and 19.4 for the Indians. This could, however, be a chance association.

Laboratory diagnosis of opiate drugs.

Where laboratory evidence on the consumption of drugs of abuse is central to rehabilitation of offenders or to prison terms, the techniques employed in drug detection in urine and the interpretation of laboratory results is extremely important. Where the misuse of drugs is wide-spread and rehabilitation includes "Aftercare" programmes involving regular urine tests for considerable periods of time, mass-screening, of up to 1,500 specimens a day, calls for fast, cheap, efficient and reliable tests. This paper deals with Singapore's experience in alternative methods of testing for morphine in urine arising from abuse of opiate drugs including heroin in large-scale screening programmes. Immunological/Thin-layer chromatographic/Gas Chromatographic systems and the cost and performance of combination of these techniques are highlighted. This paper also provides criteria for interpreting test results for codeine consumption.

Spectrophotometric determination of hydralazine hydrochloride tablets using ninhydrin.

A method is described for the assay of hydralazine HCl in tablets, based on the colored product formed by the reaction between hydralazine and ninhydrin. The reaction is conducted at room temperature in a pH 3 buffer solution and the colored product is measured spectrophotometrically at the absorption maximum at 442 nm. Under the stipulated conditions, this reaction is highly specific for hydralazine and is not affected by other drugs which may be used in combination with hydralazine. Results of infrared and mass spectrometric studies suggested that the colored product is a hydrazone. Ultraviolet spectrophotometry also showed that dilute solutions of hydralazine degrade rapidly in the presence of alcohols.

Gas chromatographic study of the urinary codeine-to-morphine ratios in controlled codeine consumption and in mass screening for opiate drugs.

The urinary codeine-to-morphine ratios in fifteen volunteers administered codeine tablets at intervals were studied by gas chromatography (GC) and compared with one month's GC results for enzyme multiplied immunoassay technique (EMIT)-screened urine specimens in a mass-screening programme for abuse of opiate drugs, particularly heroin. It appears that when M less than 2 and C/M greater than 0 or when M greater than 2 and C/M greater than 0.5, where C and M are codeine and morphine concentrations in micrograms per 10 ml of urine, codeine consumption has to be presumed.

Identification of basic drugs by the thin-layer chromatographic profiles of their ninhydrin complexes.

Fifty-two common basic drugs produce various colours when spotted with ninhydrin on plastic thin-layer plates and heated. When the plate is then developed in a suitable solvent each of the coloured spots separates into a variety of additional coloured spots and patches, the number of which depends on the temperature of heating. The relative intensity and spatial arrangement form a profile that is highly characteristic of the compounds. The formation of such profiles was investigated at 100 and 160 degrees C.