Terrestrial contamination in Apollo lunar samples

The Apollo lunar samples were seen to offer a unique opportunity in the search for extraterrestrial organic matter without the ambiguity surrounding meteorite analysis due to their unknown contamination histories. The recognition that only a small amount of indigenous organic material was likely to be present in lunar samples combined with the extreme sensitivity of organic analysis methods made it clear that this opportunity could be realized only by carefully controlling the collection, processing, and analysis of the samples in order that they might remain free of significant levels of contamination. The contamination control procedures adopted are described and the analytical evidence obtained throughout the program on potential contamination sources is presented. The organic contaminants actually found in the lunar samples by the various investigators are summarized. It is shown that the program succeeded in providing investigators with samples containing less than 0.1 ppm total contamination.     

Compounds of the organogenic elements in Apollo 11 and 12 lunar samples: A review

Investigations of low molecular weight compounds of the organogenic elements on lunar samples are reviewed. The three general techniques of vacuum pyrolysis, acid hydrolysis, and crushing have been employed by most investigators. Vacuum pyrolysis of lunar fines produce a variety of gaseous species which are either: (1) indigenous, (2) solar wind products and/or (3) chemical reaction products of mineral phases found in the lunar samples. Acid hydrolysis of lunar fines using deuteriumlabeled acids yields evidence for indigenous methane and ethane. Methane and ethane found in the lunar fines are largely derived from the solar wind with only trace amounts indigenous to the samples. Crushing experiments with lunar fines and breccias produce methane, ethane, hydrogen, nitrogen, hydrogen sulfide and the rare gases.     

Search for amino acids in Apollo returned lunar soil.

The lunar samples from Apollo flights 11 through 17 provided the students of chemical evolution with an opportunity of examining extraterrestrial materials for evidence of early prebiological chemistry in the solar system. Our search was directed to water-extractable compounds with emphasis on amino acids. Gas chromatography, ion-exchange chromatography and gas chromatography combined with mass spectrometry were used for the analysis. It is our conclusion that amino acids are not present in the lunar regolith above the background levels of our investigations.     

Research for amino acids in lunar samples

Water extracts of lunar fines were analyzed for amino acids by a gas-liquid chromatographic technique whereby amino acids were converted to the N-trifluoroacetyln-butyl, esters prior to analysis. The lunar material studied included both Apollo 14 (14240 SESC and 14298) and Apollo 12 (12023) samples. The water extract of the special Apollo 14 sample (14240 SESC) was analyzed both for free and bound amino acids (hydrolysis with 6 N hydrochloric acid). In both the hydrolyzed and unhydrolyzed extracts, the amino acids were not observed above background levels.The analysis of Apollo 12 and 14 samples (12023 14298) yielded similar results. Detection limits were established at 300 pg to 1 ng for different amino acids. A large chromatographic peak with a retention temperature of 126°C was observed on analysis of sample, (12023); it was identified as oxalic acid by GC-MS. The concentration of amino acids in the Apollo 14 SESC samples processed and analyzed in the joint experiments at Ames by GLC and IEC were found to be extremely low (glycine at 3 to 4 ng g^–1). As the quantities were so minute, these identifications could not be confirmed by GLC-MS and therefore should still be considered as tentative. Other studies included the analysis of performance standards at the 2 to 6 ng level of each of 17 amino acids, and the analysis of 5 ml of H₂O containing 2 ppb of each amino acid. Recovery of amino acids added to lunar fines were conducted at the 10, 50, and 70 ng level of each amino acid with 50 to 70 mg of lunar material. The recoveries varied from as high as 80% for some of the aliphatics to complete loss of the amino acids ornithine and lysine.Contributed from Missouri Agricultural Experiment Station Journal Series No. 6255. Approved by the Director. Supported in part by grants from the National Aeronautics and Space Administration (NGR 26-004-011) and the Experiment Station Chemical Laboratories.     

An automatic carbon-14 gas analyzer for organic compounds and biological samples

The present paper concerns automatic measurement of the radioactivity of substances labeled with carbon-14 isotope. The organic compounds or biological samples are combusted in an oxygen chamber. The oxygen excess is converted by hydrogen into water vapor in a reactor filled with copper and copper oxide. The water is retained by condensation and the carbon dioxide is swept by means of a counting gas, preferably propane or butane or a mixture of such gases, into an anticoincidence counter. The carbon-14 gas analyzer allows the measurement of carbon-14 isotope with high accuracy and sensitivity in a fully automated way, entirely free of manual intervention.     

Distribution and isotopic abundance of biogenic elements in lunar samples

A review of the abundance of six biologically important elements (H, C, N, O. P and S) demonstrates that they are present in trace amounts only in lunar matter analysed to date. To the endogenous lunar content, elements are contributed by solar wind irradiation and meteorite impacts. However, it is not yet possible to determine the relative importance of the three sources. Enrichment of the heavy isotopes, C¹³, O¹⁸, S³⁴ suggest that these elements may be lost from the lunar surface by hydrogen stripping (from solar wind protons) as volatile gases. The general lack of water, suggests that organic synthesis could not easily be accomplished in lunar rocks. High energy irradiation of the lunar surface may result in rapid destruction of organic matter not protected by a silicate matrix. It is apparent from present data available, that the ambient lunar surface could not support metabolism of known microorganisms.Publication No. 997 Institute of Geophysics and Planetary Physics, University of California at Los Angeles, Los Angeles, California 90024.     

In situ synthesis during organic analysis of lunar samples

In the development and application of extremely sensitive analytical techniques the need for extreme cleanliness and avoidance of contamination has been generally recognized and complied with in the organic analysis of lunar samples. Much less attention has been paid to the possibility of inadvertent synthesis of certain organic molecules from indigenous smaller organic or even inorganic constituents of the lunar material. At the part-per-billion level of detectability reactions proceeding even at very low yield can lead to detectable products. A particular area of concern should be the amino acid analysis since those substances are known to be formed by condensation of ammonia, cyanide and carbonyl compounds, all potential products of lunar material upon treatment with aqueous media.     

Search for biogenic structures and viable organisms in lunar samples: A review

A review of the work on searches for biogenic structures and viable life forms in Apollo 11 and 12 samples shows no evidence for biology in these samples. The total amount of samples examined and the negative results from the variety of systems conducive to growth and metabolic activity make it highly improbable that life will be found in surface samples yet to be tested.     

Methylation of mercury compounds in soil,sediment and sewage-sludge samples

Summary Sediments of the rivers Rhine and Yssel and sewage sludge samples showed high mercury contents (5–30 ppm). Usually less than 1% — in one sludge sample 5% — of the mercury was in the form of methylmercury. Incubation of these samples, under varied aerobic and anaerobic conditions, with or without HgCl₂ or phenylmercuryacetate added, gave no or only very slight formation of methylmercury.Most agricultural soils have a mercury content below 0.1 ppm and methylation will be no problem.     

On the abiotic formation of amino acids I. HCN as a precursor of amino acids detected in extracts of lunar samples II. Formation of HCN and amino acids from simulated mixtures of gases released from lunar samples

Two studies on the abiotic formation of amino acids are presented. The first study demonstrates the role of hydrogen cyanide as a precursor of amino acids detected in extracts of lunar samples. The formation of several amino acids, including glycine, alanine, aspartic acid, and glutamic acid, under conditions similar to those used for the analysis of lunar samples is demonstrated. The second study investigates the formation of hydrogen cyanide as well as amino acids from lunar-sample gas mixtures under electrical discharge conditions. These results extend the possibility of synthesis of amino acids to planetary bodies with primordial atmospheres less reducing than a mixture of methane, ammonia, hydrogen and water.     

Measurement of the 125I and 14C radioactivity in double-labeled blood samples

A method for detection of 14C and 125I radioactivity in labeled samples with variable quenching using only liquid scintillation counter is described. Precision, sensitivity and reproduction of this method are comparable with those of the previously used ones, but this method is more suitable and adequate for computerisation.     

Scintillation counting of 14C-labeled soluble and insoluble compounds in plant tissue

A method is described for the liquid scintillation counting of 14C in plant tissues. Samples are fixed, in the scintillation vial, in a solution of ethanol and acetic acid (3:1) and decolorized with commercial bleach before the addition of scintillation liquid. The method was compared to other techniques of tissue oxidation or digestion and found to be equally effective at least with thin tissue samples. The technique is simple, rapid, and inexpensive and does not result in loss of 14C.     

LC-MS/MS-analysis of sphingosine-1-phosphate and related compounds in plasma samples

Sphingosine-1-phosphate (S1P) and related compounds are important signaling molecules and are normal constituents of human plasma. So far, only a few methods exist for their determination specifically in plasma demanding radioactive agents, more or less time consuming extraction or derivatization procedures. Here, we describe a very simple, reliable, sensitive standard-addition method for the simultaneous determination of S1P, sphingosine (SPH), sphinganine (SAPH) and sphinganine-1-phosphate (SA1P) in human and rat plasma samples. After methanol precipitation of plasma samples the supernatants were directly assessed by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS). HPLC analysis was done under gradient conditions using a C18 reversed phase column. The lower limit of quantification (LLOQ) was <10.2, <4.6, <1.9 and 0.57ng/ml for S1P, SPH, SAPH and SA1P, respectively. Variations in accuracy and intraday and interday precision were <15% over the range of calibration. All analytes were normal constituents both in human and rat plasma although the SA1P concentrations in a few rat plasma samples were below the lower limit of quantification. This validated method is suitable to generate new pharmacological findings by monitoring plasma concentrations of S1P and related compounds especially when low amounts of plasma samples are present (e.g. plasma samples from rodents).