PubMed Health⌕ Search

Biomedical subjects

S J Dickson

Publications and source records attributed to S J Dickson.

14 recordsLinked to original sources
PubMed2001

Analysis of paracetamol using solid-phase extraction, deuterated internal standards, and gas chromatography-mass spectrometry.

A rapid method for determining paracetamol (acetaminophen) in whole blood and liver tissue samples is described. Blank plus single-point calibration gives reliable quantitation at therapeutic and higher concentrations. Whole blood and liver tissue samples containing a deuterated internal standard were extracted using Bond Elut Certify columns. Butyl derivatives were formed using n-iodobutane and tetramethyl ammonium hydroxide under mild conditions and were extracted into ethyl acetate as a cleanup step. Recovery was better than 90%, and sample preparation time was less than 2 h. Gas chromatograph run time was less than 20 min. SIM of two ion pairs formed by electron impact ionization resulted in intraday coefficients of variation (CV) less than 3.03% (7.48% in liver) and interday CVs less than 8.93% (for midtherapeutic concentrations in whole blood). Linearity was observed from subtherapeutic to high, fatal levels. This method has been applied to forensic cases and has significantly reduced analytical time while improving casework quality. Results of a case study involving paracetamol are given.

Acetaminophen↗
PubMed1989

Volatile N-nitrosamines in urinary catheters.

Levels of volatile N-nitrosamines were measured in 10 brands of latex and 2 brands of silicone catheters using high performance liquid chromatography. The cytotoxicity of catheters from identical batches was determined by measuring the inhibitory effect of catheter extracts on the uptake of 3H-labelled thymidine into L-929 fibroblasts in culture (IC50). The most frequently encountered nitrosamines were N-nitrosodi-n-butylamine and N-nitrosodiethylamine. Total N-nitrosamine levels in excess of 100 ng/g were found in 6 of the 16 catheters tested. When compared with the cytotoxicity of the catheters a significant correlation was found, with increasing nitrosamine content being associated with greater cytotoxicity. In view of the reported toxic and carcinogenic effects of these compounds it is suggested that the nitrosamine content of catheters be routinely monitored and safe regulatory limits be imposed.

Cells, Cultured↗
PubMedDate not supplied

Post-mortem digoxin levels--two unusual case reports.

Digoxin levels in post-mortem specimens are reported for two unusual cases. The blood level of digoxin in one of these cases was five times greater than any previously reported. The other case involved specimens from an embalmed body.

Autopsy↗
PubMedDate not supplied

Rapid determination of glyphosate in postmortem specimens using 31P NMR.

Glyphosate was quantified, using 31P NMR, in postmortem blood, liver, and urine specimens taken from two suicide victims. Apart from addition of D2O to give an NMR lock signal, the only pretreatment required of any of the specimens was an enzymic digestion of the liver. Glyphosate was confirmed by its characteristic 31P chemical shift and proton spin coupling and by a downfield shift on addition of NH4OH. Quantitation can be achieved either by comparison with an external standard or by spiking the specimen with glyphosate. Levels of 1 mg/mL could be detected in less than a minute.

Adult↗
PubMedDate not supplied

Analysis of six anticonvulsant drugs using solid-phase extraction, deuterated internal standards, and gas chromatography-mass spectrometry.

A rapid method for simultaneously determining the anticonvulsant drugs carbamazepine, ethosuximide, phenobarbitone, phenytoin, primidone, and valproic acid is described. Blank plus single-point calibration gives reliable quantitation from therapeutic to high fatal concentrations, except for ethosuximide, for which it gives semiquantitative results. Whole blood and liver tissue samples containing deuterated internal standards were extracted using Bond Elut Certify columns. Butyl derivatives were formed using n-iodobutane and TMAH under mild conditions and were extracted into ethyl acetate as a cleanup step. Recoveries were greater than 50%, except for valproic acid (42%). Sample preparation time was less than 2 h, and the GC run time was less than 20 min per injection. At least two ion pairs formed by electron impact ionization were monitored for each drug. Intraday CVs were less than 6.28% (4.20%) and interday CVs less than 14.1% (for midtherapeutic concentrations in blood [liver], except for ethosuximide). Linearity was observed from subtherapeutic to high fatal levels for all drugs. This method has been applied to forensic cases and has significantly reduced analytical time while improving case-work quality. Results of a case study involving anticonvulsant drugs are given.

Anticonvulsants↗
PubMedDate not supplied

Extraction and quantification of paraquat in liver and hemolyzed blood.

A procedure for the extraction and quantification of paraquat from enzyme digested liver and hemolyzed blood is reported. Paraquat is extracted as an ion-pair with sodium dodecyl sulphate and quantified by reverse phase ion-pair high performance liquid chromatography (HPLC) with ultraviolet (UV) detection.

Adult↗