Gas chromatographic analysis of trace gas impurities in tungsten hexafluoride.

Highly reactive fluorinated gaseous matrices require special equipment and techniques for the gas chromatographic analysis of trace impurities in these gases. The impurities that were analysed at the low-microg/l levels included oxygen, nitrogen, carbon dioxide, carbon monoxide, sulfur hexafluoride and hydrogen. This paper describes the use of a system utilising backflush column switching to protect the columns and detectors in the analysis of trace gas impurities in tungsten hexafluoride. Two separate channels were used for the analysis of H2, O2, N2, CO, CO2 and SF6 impurities with pulsed discharge helium ionisation detection.

Gas chromatographic analysis of trace impurities in chlorine trifluoride.

The gas chromatographic determination of trace gaseous impurities in highly reactive fluorinated gaseous matrices presents unique requirements to both equipment and techniques. Especially problematic are the gases normally present in ambient air namely oxygen and nitrogen. Analysing these gases at the low microl/l (ppm) level requires special equipment and this publication describes a custom-designed system utilising backflush column switching to protect the columns and detectors. A thermal conductivity detector with nickel filaments was used to determine ppm levels of impurities in ClF3.

The rapid and sensitive diagnosis of tuberculous meningitis by the detection of tuberculostearic acid in cerebrospinal fluid using gas chromatography-mass spectrometry with selective ion monitoring.

Tuberculostearic acid (10-Methyloctadecanoic acid) is a lipid component of the mycobacterial cell wall and its presence in cerebrospinal fluid can serve as a diagnostic marker for tuberculous meningitis. Using gas chromatography-mass spectrometry with selective ion monitoring, tuberculostearic acid (TBSA) was detected in nine different mycobacterial reference strains. Analysis of derivatised cerebrospinal fluid specimens from 35 patients showed the presence of TBSA in 5/6 culture-positive samples and 0/19 negative control patients (diagnosed as bacterial or viral meningitis). In addition 4/10 clinically suspected cases of tuberculous meningitis showed the presence of TBSA in the absence of other confirmatory laboratory results. A routine method has been developed for the detection of TBSA, which allows the fast and sensitive diagnosis of tuberculous meningitis within 5 h of receiving the cerebrospinal fluid specimen, compared to the 3 to 8 weeks required to culture the bacteria.

Multiple myeloma presenting with extensive oral and perioral amyloidosis.

The case of a young adult patient, with a kappa-light-chain-secreting multiple myeloma and extensive oral and salivary gland amyloid deposits, is presented. This case illustrates the necessity of a multidisciplinary approach using biochemical, radiographic, and relevant histologic investigations in the diagnosis of multiple myeloma. Factors influencing the prognosis of this neoplastic condition are discussed. Microscopic examination of the oral amyloid deposits supports the suggested central role played by the macrophage in amyloidogenesis.

IgD multiple myeloma. A case report.

A patient with a fracture of the left femur was investigated for suspected multiple myeloma. Serum total proteins, protein electrophoresis, and immunoglobulin G, A and M levels were within normal limits. Bence Jones proteinuria of the lambda type was present. Subsequent investigations revealed the presence of IgD myeloma.

Unusual presentation of multiple myeloma. A report of 2 cases.

The diagnosis of multiple myeloma (overt plasma cell dyscrasia) is usually not considered in patients under 30 years of age. Furthermore, multiple myeloma with coexistent megaloblastic and iron deficiency anaemia is very uncommon. Within 6 months we encountered 2 patients under 30 years of age who had multiple myeloma, one with advanced secondary amyloidosis and the other with severe megaloblastic and iron deficiency anaemia.

Ionized calcium versus total calcium in dairy cows.

Ionized and total calcium levels were determined in 29 Friesian and 5 Drakensberger cows. One Friesian cow had parturient paresis and specimens were taken before and after treatment. It is suggested that due to the easy reliable way in which ionized calcium levels can now be determined this investigation should replace total calcium estimations in dairy cows presenting with parturient paresis. Ionized calcium levels serve as a valuable diagnostic aid but are also important to assess the effectivity of treatment for this condition.

Biclonal gammopathy. A case report.

The presence of two or more monoclonal proteins in serum due to the malignant proliferation of more than one clone of B lymphocytes is uncommon. A patient with raised levels of both immunoglobulin G and M is presented and some clinical and laboratory features are shown.