Although perovskite solar cells have produced remarkable energy conversion efficiencies, they cannot become commercially viable without improvements in durability. We used gas chromatography–mass spectrometry (GC-MS) to reveal signature volatile products of the decomposition of organic hybrid perovskites under thermal stress. In addition, we were able to use GC-MS to confirm that a low-cost polymer/glass stack encapsulation is effective in suppressing such outgassing. Using such an encapsulation scheme, we produced multi-cation, multi-halide perovskite solar cells containing methylammonium that exceed the requirements of the International Electrotechnical Commission 61215:2016 standard by surviving more than 1800 hours of the Damp Heat test and 75 cycles of the Humidity Freeze test.

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Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) is used to obtain fast and accurate determinations of molecular mass, but quantitative determinations are generally made by other techniques. In this study we illustrate the practical utility of automated MALDI-TOFMS as a tool for quantifying a diverse array of biomolecules covering an extensive molecular weight range, and present in biological extracts and fluids. Growth hormone was measured in rat pituitary tissue; insulin in human pancreatic tissue; homovanillic acid in human urine; and LVV-hemorphin-7, epinephrine and norepinephrine in human adrenal and pheochromocytoma tissues. Internal standards including compounds of similar molecular weight, structural analogs or isotopomers were incorporated into each analysis. We report on the current practical limitations of quantitative MALDI-TOFMS and highlight some of the potential benefits of this technique as a quantitative tool. (J Am Soc Mass Spectrom 2002, 13, 1015-1027) © 2002 American Society for Mass Spectrometry S ince its inception and commercial availability, the versatility of MALDI-TOFMS has been demonstrated convincingly by its extensive use for qualitative analysis. For example, MALDI-TOFMS has been employed for the characterization of synthetic polymers [1,2], peptide and protein analysis [3][4][5], DNA and oligonucleotide sequencing [6 -8], and the characterization of recombinant proteins [9,10]. Recently, applications of MALDI-TOFMS have been extended to include the direct analysis of biological tissues and single cell organisms with the aim of characterizing endogenous peptide and protein constituents [11][12][13][14][15][16][17][18].The properties that make MALDI-TOFMS a popular qualitative tool-its ability to analyze molecules across an extensive mass range, high sensitivity, minimal sample preparation and rapid analysis times-also make it a potentially useful quantitative tool. MALDI-TOFMS also enables non-volatile and thermally labile molecules to be analyzed with relative ease. It is therefore prudent to explore the potential of MALDI-TOFMS for quantitative analysis in clinical settings, for toxicological screenings, as well as for environmental analysis. In addition, the application of MALDI-TOFMS to the quantification of peptides and proteins is particularly relevant. The ability to quantify intact proteins in biological tissue and fluids presents a particular challenge in the expanding area of proteomics and investigators urgently require methods to accurately measure the absolute quantity of proteins.While there have been reports of quantitative MALDI-TOFMS applications, there are many problems inherent to the MALDI ionization process that have restricted its widespread use [19 -39]. These limitations primarily stem from factors such as the sample/matrix heterogeneity that is believed to contribute to the large variability in observed signal intensities for analytes, the limited dynamic range due to detector saturation, and difficulties associated ...

Metabolic profiling of amino acids and acylcarnitines from blood spots by automated electrospray tandem mass spectrometry (ESI-MS/MS) is a powerful diagnostic tool for inborn errors of metabolism. New approaches to sample preparation and data interpretation have helped establish the methodology as a robust, high-throughput neonatal screening method. We introduce an efficient 96-well-microplate batch process for blood-spot sample preparation, with which we can obtain high-quality profiles from 500-1000 samples per day per instrument. A computer-assisted metabolic profiling algorithm automatically flags abnormal profiles. We selected diagnostic parameters for the algorithm by comparing profiles from patients with known metabolic disorders and those from normal newborns. Reference range and cutoff values for the diagnostic parameters were established by measuring either metabolite concentrations or peak ratios of certain metabolite pairs. Rigorous testing of the algorithm demonstrates its outstanding clinical sensitivity in flagging abnormal profiles and its high cumulative specificity.

Larvae of the Australian sea urchin Holopneustes purpurascens are induced to settle and metamorphose (termed settlement herein) by a water-soluble compound produced by the red alga Delisea pulchra, the main host plant of new recruits. The settlement cue for H. purpurascens had previously been identified as a floridoside-isethionic acid complex, and this paper presents new evidence correcting that finding. The actual settlement cue produced by D. pulchra was isolated from the polar extract by cation-exchange chromatography and identified as histamine, using one- and two-dimensional nuclear magnetic resonance spectrometry. The chemical identity of the cue was confirmed by gas chromatography-mass spectrometry (GC-MS) and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Synthetic histamine and histamine at 4.5 microM isolated from D. pulchra both induced rapid settlement in 80%-100% of the larvae of H. purpurascens. Lower concentrations of histamine (0.9-2.3 micro M) induced larval settlement, but this response varied from 0%-90%. The histamine content of two host plants of H. purpurascens--D. pulchra and Ecklonia radiata--and of four other common species was quantified using GC-MS. D. pulchra had the highest histamine content, which is consistent with H. purpurascens recruiting to this species. Histamine was also detected in the seawater surrounding these host algae. This is the first time that a settlement cue has been quantified in the habitat of a marine organism.