Judul: Analysis of Microcystin Level in Spirulina Products with the Enzyme-Linked Immunosorbent Assay (ELISA)
Abstrak: Spirulina merupakan mikroalga kelompok sianobakteria yang dapat dimanfaatkan sebagai suplemen penunjang kesehatan. Produk spirulina mungkin terkontaminasi oleh sianotoksin seperti mikrosistin yang berasal dari metabolit sekunder Microcystis aeruginosa. Mikrosistin merupakan hepatotoksin monosiklik heptapeptida yang menyebabkan terhambatnya kerja enzim protein fosfatase 1 (PPI) dan 2a (PPIIa) dan paparannya dapat menimbulkan nekrosis, apoptosis, pendarahan, hingga kematian. Analisis perlu dilakukan untuk mengantisipasi risiko bahaya yang timbul akibat mikrosistin dari produk berbasis spirulina yang ada di Indonesia. Metode ELISA indirect competitive dipilih karena dapat mendeteksi keberadaan mikrosistin secara spesifik, sensitif, cepat, menganalisis banyak sampel sekaligus serta pengoperasian yang mudah. Analisis kadar mikrosistin dari produk spirulina dari hulu hingga hilir menunjukkan kadar mikrosistin yang berbeda pada sampel kultur, sisa media, bubur, serta flake dan bubuk pada setiap panennya disebabkan oleh kondisi lingkungan berupa intensitas cahaya dan salinitas. Proses pemanasan (T=60 oC) selama 6 jam mampu mereduksi konsentrasi mikrosistin pada rentang 18,22 – 96,01%. Reduksi tersebut akan semakin besar saat konsentrasi mikrosistin pada bubur kebih tinggi. Konsentrasi mikrosistin pada produk bubuk komersial dari lima panen, 0,26 – 0,56 µg/kg (bk), berada di bawah kadar maksimal yang diperbolehkan pada produk, yaitu 1 µg MC-LR/g. Konsumsi maksimal produk bubuk spirulina komersial berdasarkan TDI (0,04 µg/kg BB/hari) jauh lebih tinggi dibandingkan konsumsi spirulina yang direkomendasikan, sehingga aman untuk dikonsumsi dan produk dapat diekspor ke daerah yang memiliki regulasi terkait kadar maksimal mikrosistin ini., Spirulina is a cyanobacterial microalgae which can be used as a health support supplement. Spirulina products may be contaminated with cyanotoxins such as microcystin derived from Microcystis aeruginosa. Microcystin is a heptapeptide monocyclic hepatotoxin that causes inhibition of the action of protein phosphatase 1 (PPI) and 2a (PPIIa) enzymes and its exposure can cause necrosis, apoptosis, bleeding, and even death. Analysis needs to be carried out to anticipate the risk of harm arising from microcystin from spirulina-based products in Indonesia. The indirect competitive ELISA method was chosen because it can detect the presence of microcystins specifically, is sensitive, fast, analyzes many samples at once and is easy to operate. Analysis of microcystin content of spirulina products from upstream to downstream showed different microcystin levels in culture samples, remaining media, slurry, and flakes and powder at each harvest due to environmental conditions such as light intensity and salinity The heating process (T=60 oC) for 6 hours was able to reduce microcystin concentrations in the range of 18.22 – 96.01%. The reduction will be greater when the concentration of microcystin in the slurry is higher. The concentration of microcystin in the commercial powder product from five harvests, 0.26 – 0.56 µg/kg (bk), was below the maximum level allowed for the product, namely 1 µg MC-LR/g. The maximum consumption of commercial spirulina powder products based on TDI (0.04 µg/kg BW/day) is much higher than the recommended consumption of spirulina, so it is safe for consumption and the product can be exported to areas that have regulations regarding levels of microcystin.
Keyword: ELISA, Mikrosistin, Spirulina

Judul: Performance Test of UHPLC Instrument for  Analysis of Spirulina Microcystins Levels
Abstrak: Mikrosistin adalah hepatotoksin monosiklik heptapeptida yang mengontaminasi spirulina sebagai salah satu sumber pangan yang dapat berefek baik pada kesehatan. Metode yang digunakan untuk proses analisis senyawa mikrosistin-LR dan mikrosistin-RR yaitu dengan Ultra High Performance Liquid Chromatography (UHPLC). Metode analisis ini dapat digunakan secara rutin di laboratorium jika uji unjuk kinerja UHPLC dilakukan terlebih dahulu agar kinerja alat dapat dipastikan sebelum digunakan untuk analisis. Tujuan dari penelitian ini melakukan uji unjuk kinerja instrumen UHPLC sebagai dasar untuk validasi metode analisis kadar mikrosistin-LR dan mikrosistin-RR pada spirulina. Tahapan penelitian yang dilakukan yaitu penentuan kondisi instrumen, uji unjuk kinerja UHPLC dengan larutan standar mikrosistin-LR dan mikrosistin-RR, serta analisis data. Kondisi instrumen sudah memenuhi kriteria kromatografi yang ideal. Hasil uji unjuk kinerja instrumen menunjukkan linearitas yang baik dengan R2 lebih dari 0,995 untuk setiap senyawa. Selain itu, instrumen UHPLC juga memiliki presisi yang baik dengan nilai RSD kurang dari 2% untuk kedua senyawa, baik luas area maupun waktu retensi. Limit deteksi (iLOD) instrumen untuk mikrosistin-LR dan mikrosistin-RR secara berturut-turut adalah 0,04 µg/ml dan 0,08 µg/ml, sedangkan limit kuantifikasi (iLOQ) dua senyawa berturut-turut adalah 0,13 µg/ml dan 0,26 µg/ml. Hasil uji unjuk kinerja UHPLC dapat digunakan sebagai dasar untuk validasi metode analisis mikrosistin-LR dan mikrosistin-RR pada spirulina., Microcystins are heptapeptide monocyclic hepatotoxins that contaminate spirulina as one of the food sources that can have a good effect on health. The method used for the analysis of microcystin-LR and microcystin-RR compounds is Ultra High Performance Liquid Chromatography (UHPLC). This method can be used in the laboratory if the UHPLC performance test is done first so that the performance of the device can be ascertained before being used for analysis. The purpose of this study was to test the performance of the UHPLC instrument as a basis for validating the method for analyzing microcystin-LR and microcystin-RR levels in spirulina. The research stages are determining the condition of the instrument, UHPLC performance test with microcystin-LR and microcystin-RR standard solutions, and data analysis. The condition of the instrument has met the ideal chromatographic criteria. The results of the instrument performance tests showed good linearity with R2 more than 0.995 for each compound. In addition, the UHPLC instrument has good precision with an RSD value of the compounds are less than 2%, both for area and retention time. The detection limits (iLOD) of the instrument for microcystin-LR and microcystin-RR respectively were 0.04 µg/ml and 0.08 µg/ml, while the quantification limits (iLOQ) of the two compounds were 0.13 µg/ml and 0.26 µg/ml. The results of the UHPLC performance test can be used as a basis for validating the microcystin-LR and microcystin-RR analysis methods on spirulina.
Keyword: microcystin-LR, microcystin-RR, performance test, spirulina, UHPLC

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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